SECTION 6 BASELINE RISK ASSESSMENT · BASELINE RISK ASSESSMENT 6.1 APPROACH TO THE BASELINE RISK ASSESSMENT 6.1.1 Background This section of the Remedial Investigation Report presents

SECTION 6

BASELINE RISK ASSESSMENT

6.1 APPROACH TO THE BASELINE RISK ASSESSMENT

6.1.1 Background

This section of the Remedial Investigation Report presents a comprehensive, multiple-pathway assessment of the potential human health and environmental risks associated withpast releases of chlorinated benzenes at the SCD facility. This baseline risk assessmentwas prepared on behalf of SCD under the Comprehensive Environmental Response,Compensation, and Liability Act (CERCLA), as amended by the Superfund Amendmentsand Reauthorization Act of 1986 (SARA).

As part of the RI/FS, this risk assessment has been prepared to document the extent towhich actual or threatened releases of hazardous substances may pose an imminent andsubstantial endangerment to public health and the environment Specifically, and inaccordance with the National Oil and Hazardous Substances Pollution Contingency Plan(NCP) (40 CFR SOD, 1990), this risk assessment evaluates the potential risks associatedwith the SCD site under the no-action alternative, i.e., in the absence of remedial(corrective) action.

Stringent study requirements were considered in planning and executing this riskassessment These requirements are summarized as follows:

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• The risk assessment of the SCO site was an objective assessment using

methodology consistent with the U.S EPA's Risk Assessment Guidance forSuperfund (EPA, 1989c), as well as other guidance applicable to CERCLAsites on the National Priority List.

* Interaction with DNREC, EPA (Region HI), and the National Oceanic and

Atmpspheric Administration (NO AA) was required, particularly in definingcurrent and future exposure scenarios, exposure assumptions, and indefining the methodology and use of other types of information such asecological studies performed in the study area.

.• On the basis of this interaction, a detailed Work Plan for the conduct of

the baseline risk assessment was approved by DNREC and EPA (RegionHI) which served as the framework for the performance of this assessment.

Several objectives are accomplished under the baseline risk assessment for the SCD site.

These objectives include:

* Characterization of the potential human health risks (based on average, and

reasonable maximum exposures) associated with the past releases ofchlorinated benzenes in 1981 and 1986".

• Characterization of the ecological risks and impacts associated with the

SCD site.

In accordance with the National Contingency Plan (NCP), the risk assessment outlinedherein evaluates the potential human health and environmental impacts associated withthe site under the no-action alternative; i.e., in the absence of remedial (corrective) action.The no-action alternative is defined for both present and future uses of the affected media

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(c.g., groundwater) to the extent those uses differ. In addition to defining the baselinerisk, this assessment will help focus the selection of site remedies, if necessary, forreducing the concentrations of site-specific chemicals in the environmental mediaassociated with the greatest potential risks to human and ecological health.

6.1.2 Organization of the Baseline Risk Assessment

This baseline risk assessment summarizes and interprets data collected to date duringremedial investigations at the SCO site in order to:

• Identify and characterize site-specific chemicals in various media.

• Describe potential site-specific chemical exposure pathways and potentially

exposed populations.

• Estimate the intake of site-specific chemicals for relevant pathways.

* Define indices of toxicity for appropriate routes of exposure.

• Assess potential adverse impacts to public health and the environment

from site-specific chemicals in the SCD study area.

The baseline risk assessment is comprised of three principal subsections which include:

* Contamination Characterization (Subsection 6.2).

* Human Health Risk Assessment (Subsection 6.3).

• Ecological Risk Assessment (Subsection 6.4).

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Specifically, Subsection 6.2, Contamination Characterization, presents a summary of theevidence of environmental contamination at the site, and selects the contaminants ofpotential concern to be evaluated in the risk assessment. The available environmentaldata are reviewed and summarized for each environmental medium (soil, groundwater,surface water and sediments).

The Human Health Risk Assessment in Subsection 6.3 incorporates the RI sitecharacterization (described in Sections 2, 3 and 4 of this RI Report) in the determinationof the exposure settings and scenarios of human exposure based on local land and wateruses. In addition, four major subsections make up the human health risk assessment andthese include:

• Exposure Assessment.

* Toxicity Assessment

• Risk Characterization.

• Uncertainty Analysis.

The Ecological Risk Assessment, Subsection 6.4, incorporates the ecologicalcharacterization of the site along with the RI Characterization results in the determinationof the exposure settings and scenarios. In addition, like the human health risk assessment,the following four major categories make up the ecological risk assessment and they arepresented in Subsection 6.4:

• Exposure Assessment.

• Toxicity Assessment

* Risk Characterization.

* Uncertainty Analysis.

STAND-CDSTANDJtPT — 6-4

Figure 6-1 provides a schematic of the baseline risk assessment process and therelationship of the previously mentioned components within that process.

6.2 CONTAMINATIQN CHARACTERIZATION

6.2.1 Introduction

The objective of the contamination characterization is to screen and summarize the datathat are available on site-related contaminants. The results of the contaminationcharacterization are used in both the human health and ecological risk assessments toevaluate risk to the potential receptors in the study area. The relationship of thecontamination characterization to other components of the risk assessment process isillustrated in Figure 6-1.

The studies that have been conducted to characterize the site are summarized inSubsection 1.2, Previous Site Investigations. These studies have indicated that chlorinatedbenzenes and possibly polychlorinated biphenyls (PCBs), may be present at elevatedconcentrations in the study area.

Sampling data are available for a variety of media, including on-site and off-site surface

soils, on-site and off-site groundwater, off-site surface water and sediments, and fishfrom Red Lion Creek.

Subsection 6.2.2 provides a summary of the investigations that were conducted followingthe accidental releases of chlorinated benzenes at the SCD facility in 1981 and 1986. Thedata that were used to determine the potential exposure concentrations and risks for eachof the media evaluated in the risk assessment are summarized in Subsections 6.2.5through 6.2.7.

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AR306025

• Gather and analyze relevantsite data

Identify potential chemicalsof concern

4• Analyze contaminant releases

• Identify exposed populations

• Identify potential exposure pathways• Estimate exposure concentrations foridentified pathways

• Estimate contaminant intakes forthese pathways

'Collect qualitative and quantitativetoxicity information

> Determine appropriate toxicity values

»Characterize potential for adversehealth effects to occur,- Estimate cancer risks- Estimate noncancer hazardquotients

1 Evaluate uncertainty

> Summarize risk information

m

.Source: EPA, 1989a STCHRA61-P/DM-12S1

FIGURE 6-1 SCHEMATIC OF THE RISK ASSESSMENT PROCESS

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ECSGNERSCWSULIWTS

6.2.2 A Review of Previous Investigations

This subsection summarizes the site investigations performed by SCO in association withthe accidental releases of chlorinated benzene products in 1981 and 1986.

An accidental release of industrial grade monochlorobenzene (MCB) occurred at the SCOfacility on 16 September 1981 during the filling of a railroad tank car. As a result of thisrelease, MCB was discharged to the soil around the railroad siding.

Following this release, SOD initiated an investigation to determine the presence ofsubsurface contamination in the release area. Based on the results of this investigation,DNREC and SCD concluded that the potential existed for contamination of groundwaterunderlying the site. Following the completion of the subsurface investigation, SCDcontracted with WESTON to conduct site investigations.

WESTON performed a field investigation and assessment of the release and documentedthe findings in a 25 June 1982 report entitled "Hydrological Concept EngineeringEvaluation of Remedial Action for Monochlorobenzene Release" (WESTON, 1982). Thefirst phase of the investigation included installation and sampling of ten groundwatermonitoring wells and the determination of groundwater depth and water quality. Eachwell except one was sampled for soils at four depths to asses the chemical constituentsin soils and to assess soil stratigraphy. In addition, a pump test was conducted on onewell to determine hydraulic characteristics and predict contamination migration. Watersamples were collected throughout the pump test for chemical analysis. Groundwateranalyses performed during the field investigations indicated the presence of chlorinatedbenzene products in groundwater.

An additional field investigation was initiated by SCD (upon request from DNREC) inJuly 1983. This program included 21 exploratory borings on or near the SCD propertyand ten new monitoring wells. All 20 monitor wells were sampled and analyzed for

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4R306027

DESCNEI&CONSUTHffS

various benzene species. The results of these analyses indicated that the railhead loadingfacility was the principal source area for groundwater contamination and that the plumewas generally flowing in a northerly direction toward Red Lion Creek.

Following the release reported in January 1986, water and sediment sampling, as well asbathymetric mapping of Red Lion Creek were conducted by WESTON. The samplingwas repeated on 22 January 1986. On 29 January 1986, an ecological investigation wasinitiated for the SCD facility. On 12 February 1986, soil samples were collected from

the wetlands for chlorobenzene analysis. A complete description of the investigative andcorrective actions conducted in response to the 1986 release is provided in the "Report

on Response and Cleanup Efforts of a 5 January 1986 Chlorobenzene Release"(WESTON, 1988). Table 6-1 summarizes studies conducted at the SCD facility that wereused in the risk assessment

For a more comprehensive review of previous investigations conducted at the SCDfacility, the reader is referred to the following subsections of this report:•

* Soil - Subsection 2.1,5

• Sediment - Subsection 2.2.4

• Surface Water - Subsection 2.3.4

• Groundwater - Subsection 4.2.2

• Ecological - Subsection 5.4

6.23 Chemicals of Concern

A limited number of contaminants were identified in the RI investigation and consideredby the DNREC and EPA to be site-related and relevant to the risk assessment. Based onthe comments of DNREC and EPA, which are documented in the 20 November 1990 and22 March 1991 letters from DNREC, the following compounds were considered to bepotentially site-related chemicals of concern:

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• 1,2-Dichlorobenzene • Aroclor - 1232

* 1,3,5-Trichlorobenzene • Aroclor - 1242

* 1,2,4-Trichlorobenzene • Aroclor - 1248

* 1,2,3-Trichlorobenzene * Aroclor - 1254

* 1,2,4,5-Tetrachlorobenzene • Aroclor - 1260

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6.2.4 Data Evaluation

The objective of the data evaluation is to characterize the extent of site contamination in

all affected media. Because decisions regarding data useability may influence the riskassessment results, careful consideration must be given to the acceptability of previouslyacquired data. A comprehensive review of all RI data collected for the SCO site has beenconducted and is discussed in Sections 2 through 5 of this RI Report.

The following narrative describes the methods by which the RI data were analyzed andsummarized for use in the risk assessment. Guidance for the evaluation of the data wasderived from the DNREC/EPA (Region m) - approved Baseline Risk Assessment Work

Plan (WESTON, 1991) and several other documents, including:

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• Bisk Assessment Guidance for Superfund Volume 1 (EPA, 1989a)

* Guidance for Data Useabilitv in Risk Assessment (EPA, 1990a)

• Statistical Methods for Environmental Pollution Monitoring, (Gilbert,

1987)

The general approach for evaluating data at the SCD facility is described in Subsection6.2.4.1.

6.2.4.1 General Approach to Data Summarization

The analytical results of the site-related contaminants were summarized by medium. Eachdata summary includes the following for each chemical:

* Upper 95 percent confidence limit

• Frequency of detection.

* Range of detected concentrations.

• Arithmetic mean.

• Method detection limits.

The frequency of detection represents the ratio of the number of sampling locations atwhich the chemical was positively identified to the total number of sampling locations.

6.2.4.2 General Assumptions for Data Evaluation

The statistical evaluation of data required that several assumptions be made, including:

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KSCKHSCCNSUlWfTS

• If a chemical was not positively detected in any samples from a given

medium, because it was reported as a non-detect, it was assumed not to bepresent in that medium.

• All J-qualified data were assumed to be valid data. "J" values are

estimated concentrations that are less than the specific level a laboratorymust be able to routinely and reliably detect, but are still present atdetectable concentrations.

• All R-qualified data were discarded from the data summary. "R" values

are those data which were found to be unusable according to the ContractLaboratory Program (CLP) data validation protocols.

Calculation of the Average Concentration

As approved by DNREC and EPA, the arithmetic mean and the upper 95% confidencelimit on the arithmetic mean were used in developing the summary statistics for the data.The following describes additional assumptions used in evaluating and summarizing datafor the risk assessment.

• When a chemical concentration was reported as non-detectable in a

sample, the chemical was assumed to be present at a concentration of onehalf of the method detection limit.

• For sampling locations for which there were duplicate samples, both results

were averaged and the average was considered to be the concentration forthat location.

STAND-CLSSTAND .RPT — - 6-12

AR3Q6Q32

If duplicate samples consisted of one detected and one non-detectedconcentration, one-half of the method detection limit wassubstituted for the non-detected sample when the average of theduplicates was calculated.

In the case of duplicates with different concentrations, for the

purpose of reporting the minimum and maximum detected value,the individual concentration was used as opposed to the averageconcentration of the duplicates.

Calculation of the Upper 95% Confidence Limit

As agreed to in the workplan for the risk assessment the upper 95% confidence limit onthe arithmetic mean was used for the reasonable maximum exposure concentration. Theupper 95% confidence limit was calculated using the following formula (Wonnacott andWonnacott, 1977):

X « the sample meant^ = t value based on (n-1) degree of freedoms » the sample standard deviationn = the sample size

6.2.5 Summary of Data

This section and the accompanying tables summarize descriptive statistics for thechemicals of concern evaluated in the risk assessment, by medium and study area, asfollows:

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* On-site Surface Soil Analytical Summary - Table 6-2

* Off-site Surface Soil Analytical Summary - Table 6-3

• Off-site Sediment Analytical Summary - Table 6-4

• Off-site Surface Water Analytical Summary - Table 6-5

• On-site Groundwater Analytical Summary - Table 6-6

• Fish Sample Analytical Summary - Table 6-7

The distribution of the substances of potential concern across the media that are evaluatedin the risk assessment are summarized in Table 6-8.

6.2,5.1 Soil Data

Tables 6-2 and 6-3 summarize the frequency of detection, range of detectedconcentrations, range of method detection limits, arithmetic mean and upper 95%confidence limit for on-site and off-site surface soils, respectively.•

Samples for on-site and off-site surface soils were analyzed and summarized separatelyto evaluate risk for potential on-site and off-site receptors. It should be noted thatsubsurface soil samples were collected off-site and on-site and were used to evaluatetypical types of activities that may influence exposure to the potential receptors that aredescribed in Subsection 6.3.2.3. The depth interval included in the analysis of the soilpathways was 0-2 feet.

Polychlorinated biphenyls (PCBs) were eliminated as potential chemicals of concern in

on-site and off-site surface soil locations because they were neither detected in samplesanalyzed in on-site surface soil samples (i.e. frequency of detection, 0/4) nor in samples

analyzed in off-site surface soils (Le. frequency of detection 0/6).


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Ethylbenzene was eliminated as a chemical of concern from the soil pathways becauseit was not detected in 56 soil samples collected on-site (Le., frequency of detection, 0/56)or in 50 soil samples collected at off-site locations (i.e., frequency of detection, 0/50).

6.2.5.2 Sediment Data

Table 6-4 summarizes the frequency of detection, range of detected concentrations, rangeof method detection limits, arithmetic mean, and upper 95% confidence limit for each ofthe chemicals of concern in off-site sediments. Sediment samples were collected fromthe unnamed tributary to Red Lion Creek and Red Lion Creek proper. The sedimentsampling locations are presented in Subsection 2.2.3, Figures 2-11, 2-14 and 2-15.Primarily, benzene and chlorinated benzene derivatives were detected at off-site sedimentlocations.

Except for Aroclor-1260 (detection frequency 3/10), no other PCBs were detected in thesediments of Red Lion Creek and the unnamed tributary; therefore, PCBs other than

Aroclor-1260 were eliminated as chemicals of concern.

6.2.5.3 Surface Water Data

Table 6-5 summarizes analytical results of the off-site surface water samples collected inRed Lion Creek and the unnamed tributary. Figure 2-17 shows the locations andanalytical results of the surface water samples. Eighteen off-site surface water sampleswere collected from Red Lion Creek. PCB isomers were not detected in any of the foursamples analyzed for PCBs and thus were eliminated as potential chemicals of concernfor the surface water pathways.

Ethylbenzene, toluene, and 1,3,5-trichlorobenzene were also eliminated as chemicals ofconcern in the surface water pathway because they were not detected in the 27 samplescollected and analyzed for these specific chemicals.

STAND-CDSTAND.RPT 6~22

Metachioronitrobcnzene was not detected in any of the off-site surface water samples(frequency of detection, 0/27) and was thus eliminated as a chemical of concern for thesurface water pathway.

6,25.4 Groundwater Data

Table 6-6 summarizes the frequency of detection, range of method detection limits, rangeof detected concentrations, and arithmetic mean and upper 95% confidence limits for eachof the detected chemicals for on-site groundwater. Data from the following wells weresummarized in Table 6-6 and included in the human health risk assessment: MW-1, RW-5, TW-2, TW-3, TW-4, TW-5, TW-6A, TW-7, TW-8, TW-10, TW-22, TW-24, TW-25,TW-28, TW-30, and TW-31.

PCBs were eliminated as chemicals of concern for the groundwater pathway because they

were not detected in the two samples analyzed for PCBs (frequency of detection, 0/2).

6.2.5.5 Fish Sampling Results

Table 6-7 summarizes the May 1991 results of the fish sampling analysis for the SCO

facility. Subsection 5.2 of the RI summarizes location and analytical results for fishtissue samples collected from Red Lion Creek. The fish collection stations were locatednear the Route 13 bridge (the upstream location) and near Route 9 (the downstreamlocation). It should be noted that the crappie fish was selected as a representative speciesfor the human health risk assessment as crappie is most likely to be consumed by thehuman population in the area.

Only chlorobenzene was selected as the contaminant of concern for the fish ingestionpathway because it was detected downstream at a concentration of 0.006 mg/kg. All theother chemicals were eliminated as chemicals of concern because none of the chemicalswere detected in any of the samples analyzed for the downstream crappie fish.

STAN&CDSTAND.RPT 6-23

SR3060U3

DESGKRSfCONSLILMKIS

It should be noted that fish tissue data collected from Red Lion Creek as part of theRemedial Investigation of the SCD site are available from two separate fish samplingsurveys, viz, March 1990 and May 1991. During the March 1990 survey, a single

species, the carp (Cyprinus carpio), was collected and prepared for tissue analysis.Following this sampling program, concern was raised by both the DNREC and the EPA,as well as SCD about the relevant use of this data in the baseline risk assessment. It wasagreed that the risk assessment should best reflect the most plausible exposure at the SCDsite. When evaluating human and ecological exposures to fish, several of the moreimportant criteria in selecting an appropriate species include: 1) that the species beharvested by the local population; 2) that the species provide a significant contributionto the recreational diet; or 3) that the species be representative of the contaminant levelsin the primary harvested species (U.S. EPA, 1989).

Because of doubts concerning the carp in Red Lion Creek meeting these criteria, both theagencies and Standard Chlorine agreed to conduct a more comprehensive survey of thefish community of Red Lion Creek in May 1991. The human health and ecological risk•assessments for the SCD site are conducted using only fish tissue data collected from theMay 1991 survey. Notwithstanding the limitations of the carp data collected in March1990 and because carp may serve as a sentinel species for defining decreasingchlorobenzene levels in the Red Lion Creek system, results of the March 1990 fish tissuesurvey are presented in Subsection 5.3 of the RI Report

Although Standard Chlorine recognizes that carp represent a prey species, it is unlikelythat fish of the size collected in March 1990 for tissue analysis (approximately 2-8

pounds) play a significant role in the food web. It is more likely that smaller carp (i.e.,<1 pound), represent the more significant prey for wading birds and piscivorous mammalse.g., raccoon. Moreover, extrapolation from one size class to another is very difficultsince metabolic requirements, diet, lipid content and resultant contaminant concentrations.have been shown to vary greatly among different sized organisms of the same species(Phillips, 1980). Consequently, the size class of the species selected for consideration

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should be representative of those in the diet of the potentially exposed ecologicalpopulation. At the time of the May 1991 survey, a great many wading birds,predominantly heron, were observed predating Centrarchids, viz. pumpkinseed sunfish,Lepomis gibbosus.

6,25.6 Air Data

The DNREC 16 December 1987 report on the study of chlorobenzene ambientconcentrations around the SCO facility was examined in order to assess its suitability asthe basis of the Risk Assessment vapor inhalation pathway. These measuredconcentrations are considered to be inappropriate for the assessment of risk due to vaporsfrom contaminated soils and sediments for the following reasons:

• These ambient concentrations include contributions from sources other than

the soils and sediments and, therefore, would overstate risk.

• Only three compounds, monochlorobenzene, dichlorobenzene, and

trichlorobenzene, were measured. Values for the other compounds specifiedin the protocol would have to be estimated by some alternative means. Inaddition, it should be noted that the measured compounds are among the morevolatile compounds of the compounds of concern, so that inferences fromthese data regarding the concentrations of the other compounds may tend tobe inaccurate.

* These ambient concentrations were measured in 1987, much nearer in time to

the releases of 1981 and 1986 than the present situation. Since the emissionsof vapors from the soil and sediment would be expected to decreasedramatically (even exponentially) with time, their contribution to presentambient concentrations would be expected to be much lower than in 1987.

STAND-dNSTANDJiPT 6-25

DESGWRaCQttltTANTS

This decline in emissions would be particularly the case for the more volatilecompounds which were measured.

Therefore, these measured ambient air concentrations were considered to be unsuitablefor use as the basis of estimating risk from vapors from the soils and sediments.

In the absence of suitable measured concentrations, the primary feasible alternative, asstated in the protocol, is the use of analytical models. One model would be used toestimate the emissions from the soils and sediments and another model to estimate theatmospheric dispersion of the emissions and the resulting ambient concentrations atselected receptor locations. The EPA has assessed the available emission models in

Hazardous Waste Treatment, Storage, and Disposal Facilities (TSDF) - Air EmissionModels (EPA-450/3-87-026; November 1989), In this document, EPA also presentsmodels it has developed for various sources. The model that is the closest reflection ofa release is the land treatment model (which is also available in computerized form as aportion of the CHMDAT7 spreadsheet model or as the LAND? compiled model). The•

land treatment model was developed by EPA from the models available in the literatureto estimate emissions from the use of land treatment as a final disposal method ofhazardous waste. At land treatment facilities, hazardous wastes are spread onto orinjected into the soil, normally followed by tilling into the soil. There are a number ofsignificant differences as listed below between the intended use of the this model and thesituation that exists at the SCD facility:

• Land treatment, and the EPA model reflecting it, are designed to be

comprised of regularly and frequently repeated applications of waste ratherthan one release. Therefore, the model is primarily concerned with emissionsduring a planned series of applications rather than the emissions resultingfrom residual soil concentrations years after a release.

STAND-CL TANDJUT 6-26

ftR3Q60U6

The primary objective of land treating wastes is disposal of organic materials

fay biodegradation, while the chlorofaenzene compounds that were the primarycomponents of the 1986 release at Standard Chlorine are not generallyselected for land treatment

The model considers biodegradation as the primary pathway for less volatilecompounds and volatilization as the primary pathway for volatile compounds,as well as the partitioning of the compounds into liquids in the soil and waste;however, the model does not consider the adsorption of organics into thecarbon and other solid materials in the soil. In the case of semi-volatile,largely nonbiodegradable organics such as most of the compounds of interest,adsorption into the soil could keep a significant portion of these organics frombeing available for volatilization.

The model assumes that the diffusing organic material has a uniform

concentration throughout the soil matrix. This assumption reflects thesituation of land treatment onto unvegetated soil followed by tilling, but is farfrom the situation of an accidental release onto an area largely covered by

vegetation and water.

The model assumes that the wastes are in liquid form while a number of thecompounds of interest are solids at ambient temperatures during all or part ofthe year.

The model had no mechanism to consider soils or sediment covered by water

as is the case for many of the release areas and sampled soils and sedimentsduring all or part of the year.

STAND-CTSSTAND.RPT 6-27

• The model does not consider potential vegetative uptake of released organics

in the soil.

Since no emission models are known to be available that reflect the situation at SCD andthe available models are unrepresentative of the situation at the site for reasons listedabove, modeling to estimate the ambient air emissions of vapors from soil and sedimentis considered infeasible and potentially misleading.

Therefore, without additional information, the risk from vapors emitted from soils and

sediments can not be characterized. In order to properly characterize the risk from thispathway, measurements would have to be made of the flux of the individual compounds

from soils and sediments. Samples could be collected in flux chambers of a measuredvolume, evacuated into stainless steel canisters, and analyzed for the quantities ofindividual compounds of interest using gas chromatography/mass spectroscopy (GC/MS).

Using this measurement technique would have the following advantages: contributionsfrom other sources would not be included, all compounds of interest would be measured,•present emissions would be considered, inappropriate approximation techniques and

emission models would not be used.

6.3 HUMAN HEALTH RISK ASSESSMENT

6.3.1 Introduction

The baseline human health risk assessment conducted herein evaluates the potential for

carcinogenic and noncarcinogenic risks associated with exposure to chemicals of concerndetected in soil, sediment, surface water, groundwater, and fish at the site. This riskassessment evaluates the risk associated not only with current land and water uses at the

STAND-CDSTAND.RPT 6-28 _

AR3060U8

facility and its surroundings but also with future uses that may occur at the site. Inaddition, the baseline risk assessment evaluates the potential human health risks under theno-action alternative, i.e., in the absence of any remedial (corrective) action.

The baseline risk assessment for the SCD site is being conducted to address severalobjectives, including:

• Characterization of the potential human health risks associated with exposure

to site-specific chemicals in air, soil, sediment, surface water, and fish undercurrent use scenarios, and air, soil, and groundwater under future usescenarios.

• Evaluation of the need for corrective action at the SCD site.

.• Establishment of the basis for comparing potential health effects of various

remedial alternatives.

The technical direction for the performance of the risk assessment comes primarily fromseveral EPA documents, including Risk Assessment Guidance for Superfund - HumanHealth Evaluation Manual. Part 1 (EPA, 1989c), the Human Health Evaluation Manual,Supplemental Guidance: "Standard Default Exposure Factors" (EPA, 1991b), and theExposure Factors Handbook (EPA, 1989b). In addition to the published documentation,the risk assessment is also being conducted according to the "Work Plan for Baseline RiskAssessment, Standard Chlorine of Delaware, Inc." (WESTON, 1991) which has beenreviewed and approved by several regulatory agencies, including the EPA (Region El),

DNREC, and NOAA. All exposure models, assumptions, and approaches used in this riskassessment are in accordance with the work plan.

STANEWTDSTANDJEIPT 6-29

flR3060l*9

This risk assessment consists of five principal components that are briefly describedbelow. The relationship of the components of the human health risk assessment processis illustrated in Figure 6-1.

Contamination Characterization (Subsection 6.2)

The contamination characterization is common to both the human health and ecologicalevaluations and is discussed in Subsection 6.2. Media-specific summary statistics,selection of chemicals of concern, and other elements of the contaminationcharacterization are presented.

Exposure Assessment (Subsection 6.3.2)

The objective of the exposure assessment is to estimate the chemical doses to potentialhuman receptors. In this subsection, local land and water uses under both current andfuture use scenarios are characterized, and the pathways through which chemicals maymigrate from the site are identified. Based on this information, potentially exposedpopulations and potential exposure routes are discussed, and exposure scenarios aredeveloped. To facilitate an understanding of the information, a conceptual site model isdeveloped as part of the exposure assessment. The algorithms used to calculate chemicaldoses for all potential receptors through all potential exposure pathways and routes ofexposure are presented, and the doses calculated using these algorithms are summarized.

Toxicity Assessment (Subsection 6.3.3)

This subsection of the risk assessment evaluates the toxicity of each of the chemicals of

concern. Applicable human toxicity values are identified for each chemical of concernfor all relevant exposure routes. These include reference doses (RfDs) with which toevaluate potential noncarcinogenic health effects and cancer slope factors (CSFs) withwhich to evaluate potential carcinogenic risk. The primary sources of RfDs and CSFs are

STAND-CLNSTANDJIPT - . - 6'30 .... -- - ---- - - .

EPA's Integrated Risk Infonnation System (IRIS, 1991), which represents the EPA's mostcurrent database for toxicological information and the Health Effects AssessmentSummary Tables (HEAST) (EPA, 1991a). If an EPA-approved toxicity value is notavailable for a chemical, an appropriate value is derived, when possible, from toxicitydata or from a health-based standard.

Risk Characterization(Subsection 63.4)

In the risk characterization, the results of the exposure assessment and toxicity assessmentare integrated to evaluate the potential carcinogenic and noncarcinogenic risks to humans.Based on the exposure doses calculated in the exposure assessment, and the toxicityvalues identified in the toxicity assessment, potential risks are evaluated for each chemicalthrough each exposure route and for all chemicals through all exposure routes combined.

Uncertainty Analysis (Subsection 6.3.5)

Numerous assumptions are made in each step of a risk assessment In the contaminationcharacterization, assumptions are made with regard to the distribution of the data and howthe data should be evaluated. When the exposure assessment is conducted, the exposure

scenarios that are selected must be health protective yet plausible. Assumptions are madein the absence of site-specific data regarding the most appropriate exposure pathways andcontact mechanisms. These assumptions frequently relate to estimates of ingestion andinhalation rates, exposure frequencies, and exposure durations. Furthermore, there is also

a great deal of uncertainty associated with the toxicity assessment, as health criteria aredeveloped from laboratory studies and are extrapolated not only between, but acrossspecies and also from the high doses of the laboratory studies to the low doses typicallyfound in the environment. The combined effect of numerous uncertainties at each stepof the risk assessment results in compounded uncertainty in the risk characterization when

quantitative results are presented. A more appropriate and meaningful discussion of riskinvolves a presentation of the range of potential risk estimates.

STANtX3,\STAND.RPT 6-31

AR30605!

MS6NEF»CONSULT*«IS _

In order to accommodate such a discussion, an uncertainty analysis for the SCD riskassessment is conducted and includes both qualitative and quantitative components. Thequalitative analysis includes a discussion of site- and non-site-related factors that produceuncertainty in a risk assessment, including key modeling assumptions and exposurefactors. In addition, a quantitative sensitivity analysis is conducted in which certain key

assumptions are varied to determine the impact on the risk estimates.

6.3.2 Exposure Assessment

The exposure assessment evaluates the potential magnitude and frequency of contact withthe chemicals of concern through all migration pathways (e.g., air, groundwater, soil, etc.)for all routes of exposure (inhalation, ingestion, and dermal absorption).

The objectives of the exposure assessment are to:

• Describe local land and water uses.

• Identify significant pathways and routes of exposure.

* Identify potentially exposed human receptors.

* Predict human exposure doses for chemicals of concern.

The following narrative provides the technical discussion to meet each of these objectives.It should be noted that the exposure scenarios, models, and assumptions are in accordancewith the "Baseline Risk Assessment Work Plan" (WESTON, 1991) that is provided inAttachment 2 of the RI Report _

STAND-CL\STAND.RPT 6-32

6.3.2.1 Environmental Setting/Local Land and Water Uses

The environmental setting for the SCD site was described in Subsection 1.1, SiteBackground. Included in this subsection was a description of site location and thesurrounding land and water uses. For the purpose of this assessment and to facilitatefurther discussion, on-site refers to all grounds, buildings, and structures contained withinthe facility fenceline as shown in Figure 1-1. Further, off-site refers to all land andsurface water beyond that fenceline. Additional information concerning local land andwater uses is provided in the paragraphs that follow.

Land Use

Any discussion of land use at the SCD site must consider the geography of thesurrounding area. Because the releases in 1981 and 1986 resulted in migration ofchemicals off the facility proper, i.e., beyond the fenceline, a characterization of off-site

as well as on-site uses is appropriate and necessary.

* Qn-Site. The SCD site is zoned as industriaVcommercial and is expected to

remain so in the future. The site consists of storage tanks, reactor vessels,

distillation/crystallization units, a wastewater treatment plant, andadministrative buildings. The site operates 24-hours, and is patrolled aroundthe clock by security personnel.

* Off-Site. Much of the land in the immediate vicinity of the SCD site is used

for industrial purposes. To the north and east, the site is bounded by landsowned by Occidental Chemical Company. The Air Products Company forms

the western border. Star Enterprise's Delaware City refinery facility is located

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flR306053

DESCNERStt»SUT*KTS

on the .southern boundary of the SCD property. Delmarva Power and Lightoperates a petroleum-coke and petroleum electric power generating plant that

is also located on the southern boundary of the SCD property.

Extensive freshwater, non-tidal wetlands, formed by Red Lion Creek (seeSurface Water below), are located approximately 1,000 feet north of thefacility. The land bordering the south shoreline of Red Lion Creek from the

unnamed tributaiy to the Rt 9 bridge is owned by Oxychem, which prohibitshunting on this land. However, due to the presence of deer and other game,there remains the possibility that hunters may nevertheless use the lands forhunting.

Water Uses

* Surface Water - Red Lion Creek is a four mile long tributary of the

Delaware River located north of the site and west of the Delaware River.*Surface runoff from the site and surrounding area forms a dendritic pattern inthe extensive wetlands created by the creek. The creek and surrounding

wetlands became contaminated following the 1986 release when chlorinatedbenzenes from the ruptured tank flowed along the railroad tracks west of thesite, then northerly down a steep drainage ditch to a small, unnamed tributaryto Red Lion Creek (see Figure 2-1). The released material spread across thetributary channel and continued downstream to the unnamed tributaryconfluence with Red Lion Creek.

Prior to the repair of tide gates east of the bridge at U.S. Route 9, flow in RedLion Creek was influenced by tides. Though the tidal action helped to flushsome contamination from the wetlands that surround the creek, the movementof water into the creek from the Delaware River served to expand the

STAND-CDSTANDJIPT 6-34

contaminated area. Despite the presence of contamination and an advisorypublished by DNREC, Red Lion Creek is still used by recreational fisherman.Although surface water and sediments downstream of the Route 9 bridgeshowed elevated levels of contaminants, the presence of a potential RCRA sitein this area obscures the identification of the source of contamination.Because of this, it was agreed among EPA, DNREC and SCD that theboundary of this RI investigation would be limited to the area west of Route9.

• Groundwater - The SCD facility and vicinity are underlain by shallow and

deep aquifer systems. The shallow unconfined Columbia aquifer is part of theColumbia Formation and is underlain by a continuous layer of PotomacFormation clay. No potable use wells are known to draw water from theshallow Columbia Formation in the immediate site vicinity. The ColumbiaFormation however, does provide the base flow for Red Lion Creek and theunnamed tributary adjacent to the site.

The deep confined Potomac Group of aquifers underlie the ColumbiaFormation at the SCD site. The Potomac Group, which is comprised of threeseparate but ill-defined aquifers, designated as the upper, middle, and lower

• Potomac aquifers, functions as water sources for domestic, municipal, andindustrial uses in New Castle County. For a more comprehensive review ofthe groundwater systems associated with the SCD site, the reader is referredto Section 4, Hydrogeology.

6.3.2.2 Exposure Scenarios

Potential Receptors

Based on current and probable future land use, five potential receptors, three current andtwo future, are identified and include:

STAN&CDSTANDJSPT 6-35 flR306055

OESCNEfWCCHSHTMire

• Current worker.

• Current visitor.

• Future worker.

• Future visitor.

* Hunter/fisherman.

This represents those individuals with the maximum potential for exposure to site-relatedchemicals of concern.

A worker and occasional visitor (e.g., truck driver) are considered in both the current and

future use scenarios. In the current use scenarios, only air and soil related exposurepathways are evaluated. In the future use scenarios exposure to contaminatedgroundwater is evaluated in addition to the air and soil related pathways because there isno current use of groundwater at the site and future groundwater use may be plausible.

Two individuals, an adult and a child, are evaluated hi the hunter/fisherman exposurescenario. These individuals are evaluated because of the potential for exposure tochemicals that have migrated off-site to Red Lion Creek and the surrounding wetlands.

Exposure to chemicals of concern in off-site media (soil, surface water, sediments, andfish) is considered to be likely because of the use of the area for hunting and fishing.

The five exposure scenarios and their respective pathways are listed in Table 6-9. Therelationship between the fate and transport of site-related chemicals of concern and thereceptors is described in the conceptual site model (Subsection 6.3.2.4) and is shown inFigure 6-2. The following narrative discusses the rationale for pathways and routes ofexposure for each of the five exposure scenarios.

STAND-CL TAND.RPT 6~36 .11.. . .... . . _ _ _ .

4R306056

Table 6-9

Exposure Scenarios and Potential Exposure Routes

Current Worker Current Visitor

* Incidental soil ingestion • Incidental soil ingestion• Dermal absorption from soil • Dermal absorption from soil• Inhalation of airborne soil • Inhalation of airborne soil

Future Worker Future Visitor

* Incidental soil ingestion • Incidental soil ingestion• Dermal absorption from soil * Dermal absorption from soil* Inhalation of airborne soil • Inhalation of airborne soil• Ingestion of groundwater • Ingestion of groundwater

Current Hunter/Fisherman

• Incidental soil ingestion* Dermal absorption from soil* Inhalation of airborne soil* Ingestion of fish• Dermal absorption from surface water• Dermal contact with sediment

STAND-CLVRI-T6-9.TBL 6-37

^306057

VOLATILIZATION

DUST GENERATIONAND VOLATILIZATION

SOIL/SEDIMENTS

RUNOFF LEACHING

DISCHARGEWATOR GROUNDWATER

STCHRAS2-P/DM-1291

FIGURE 6-2 POTENTIAL MIGRATION PATHWAYS OF THECHEMICALS OF CONCERN

Future residents are not considered potential receptors for the SCO site because areazoning requirements preclude residential development of the area. Further, a futureresidential scenario of the SCO site is considered highly unlikely because of the existing

industrial development Based on prior discussions with both the EPA and the DNREC,evaluation of a future resident was considered inappropriate and therefore was notincluded in the agreed upon scope of work for the Risk Assessment Work Plan.

• Current Worker/Current Visitor - A current worker and current visitor are

evaluated because they may be exposed to chemicals of concern within thefacility boundary. It is assumed that while on-site both the worker and visitorspend most of their time in the outdoor production and maintenance areasresulting in potential exposure to air and soil-related pathways. The visitoris assumed to be an individual who works on-site on an occasional basis asa delivery person or hauler. The routes of exposure for both individuals are

the same; only the contact rates differ. The routes of exposure considered forthe current worker and current visitor are the following air and soil-relatedpathways: inhalation of suspended dust, incidental ingestion of soil, anddermal contact with soil.

Exposure to chemicals of concern in groundwater is not evaluated in thecurrent use scenarios because there is no current use of the surficial Columbia

Formation. Potable water currently being used at the SCO facility is suppliedby the local public water company. In addition, off-site exposure is not

evaluated for the worker or visitor because they are expected to remain withinthe facility fenceline during the work day.

• Future Worker/Future Visitor - The soil-related routes of exposure

described previously for the current worker and visitor are also evaluated forthe future worker and visitor. The future use exposure scenarios differ

STAND-CL>STAND PT 6-39 . . . . . .

4R306059

from the cuirent use scenarios only in the assumed future use of groundwaterfrom beneath the site. Groundwater from beneath the site is evaluatedbecause the wells located within the facility boundary are the most highlycontaminated and will result in the most conservative risk estimates. The onlygroundwater exposure pathway evaluated in the future use scenarios isdrinking water ingestion.

Hunter/Fisherman - As previously stated, the hunter/fisherman scenario is

developed for the purpose of evaluating chemicals that have migrated outsideof the facility boundary. Both an adult and six year old child are evaluated

in this scenario. The hunter/fisherman could potentially be exposed to site-related chemicals in surface water, soil, sediments, and air. The potentialsurface water exposure routes include ingestion of fish and dermal contact

Air and soil exposure routes could potentially include: the inhalation ofsuspended dust particles, incidental soil ingestion, and dermal contact withsoil. It is assumed that one-half of the total dermal exposure is from contactwith soil.

Exposure to chemicals of concern in sediments is also evaluated. Sediment

exposure is possible because the land on either side of Red Lion Creek isavailable for contact and the hunter/fisherman may be exposed to sediments

while they are hunting or fishing. Exposure to sediments is expected to belimited to dermal contact. It is assumed that one-half of the total dermalexposure is from sediments.

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306060

K5GNERSCOKUTM1TS

6-3*2.3 Conceptual Site Model

The conceptual site model for the SCO site incorporates information on the potentialchemical sources, affected media, release mechanisms, routes of migration, and knownor potential human receptors. The purpose of the conceptual site model is to provide aframework in which to identify potential exposure pathways occurring at the site, as wellas to aid in identifying data gaps. Information presented in previous subsections on thesite characterization, contamination characterization, local land and water uses, andpotential receptors, is used to identify potential exposure pathways at the site.

An exposure pathway consists of four elements (EPA, 1986c):

1. A source and mechanism of chemical release into the environment.

2. An environmental transport medium for the released contaminant (e.g., surface

water) and/or a mechanism of contaminant transfer from one medium toanother (e.g., surface water runoff).

3. A point of potential contact of humans or biota (the receptors) with thecontaminated medium (i.e., the exposure point).

4. An exposure route (e.g., ingestion) at the exposure point

When all of these elements are present, the pathway is considered complete.

The assessment of pathways by which human receptors may be exposed to contaminantsfrom the SCO site includes an examination of existing migration pathways (e.g., soil, air,water) and exposure routes (e.g., inhalation, ingestion, dermal absorption), as well asthose that may be reasonably expected in the future. The determination of exposurepathways (i.e., the course that a contaminant takes from a source to a receptor) is made

STANIMH-VSTANDJIPT 6-41

flR30606l

by an evaluation of the current extent of contamination on and around the site in relationto local land and water uses, and the results of a fate-and-transport assessment thatevaluates contaminant migration pathways. Figure 6-2 presents the potential migrationpathways for the SCO site.

The conceptual site model for the SCD site is provided in Figure 6-3. The primarysources of on- and off-site contamination are the railroad tank car loading are.a (1981release) and a storage tank (1986 release). The release of chlorinated benzenes from theprimary sources contaminated surrounding soils and sediments through primary releasemechanisms that include a release and a tank rupture. The contaminated soil andsediment now act as secondary sources for contaminant releases and potential exposures.

Contaminated soil and sediments are believed to be the major source of potential exposurefor human receptors at the SCD site. The following paragraphs describe the pathways bywhich human receptors can be exposed to contaminated media.

Air

Contaminated soil or sediment may be re-suspended into air by the natural action of windor by routine activities at the site, particularly, vehicular traffic. In addition to exposureto dust, volatile organics may be directly inhaled from contaminated soil or sediment.The inhalation of re-suspended dust from soils was considered in all exposure scenarios.An additional contaminant migration pathway to air is volatilization from soils andsediments and from surface water, principally because of groundwater discharge to Red

Lion Creek; however, insufficient data were available with which to quantitate thispathway.

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t t t J

nr nr

CESCCRS'CGHSU.TWS

Groundwater

Groundwater can become contaminated through infiltration and leaching of chemicals ofconcern from soil. Based on a survey of well permits, there is no known current potableuse of the surficial aquifer hi the vicinity of the SCD site; therefore, exposure togroundwater is not evaluated in any of the current use scenarios. However, groundwateruse was evaluated for the future worker and future visitor scenarios. Guidance from theEPA suggests that if the groundwater, unaffected by contamination, could potentiallyserve as a potable water supply that use must be protected. Consequently, the baselinerisk assessment should evaluate the potential threat that site-related contamination posesto potential users of that resource.

Surface Water

In addition to the direct release of chemicals to Red Lion Creek following the release,soil-bound chemicals may continue to migrate to surface water as they are transported byerosion and runoff following precipitation events. Another pathway through whichchemicals may migrate to surface water is through the discharge of groundwatercontaminants. Sediments contaminated as a result of the release and tank rupture act asa continuing source of chlorinated benzenes in surface water. Exposure to surface waterthrough dermal absorption and fish ingestion is evaluated for the hunter/fishermanscenario.

Sediments

Sediments are only found off-site; therefore, exposure via sediment-related pathways isevaluated only for the hunter/fisherman scenario. The exposure route considered for thehunter/fisherman scenario under the sediment pathway is dermal absorption.


Soil

Soil represents a major secondary source of contamination at the SCD site. Becausecontaminated soil is found on- and off-site, soil-related pathways are evaluated for all fivescenarios. The routes of exposure that are evaluated for the soil pathway for each of thescenarios include incidental ingestion and dermal absorption. The inhalation of particulatematter was considered under the air pathway.

6.3.2.4 Derivation of Exposure Concentrations

Exposure doses for this assessment are calculated using the average and the upper 95percent confidence limit concentrations for each of the media associated with all fivescenarios. Based on comments on the protocol from DNREC and EPA (Region IE), itwas agreed that the data be summarized with the arithmetic mean. Average and upper95 percent confidence limit concentrations are used to provide an assessment of theuncertainty in the data. The upper 95 percent confidence limit on the arithmetic meanis used to provide a conservative estimate of exposure that is still considered possible.In the event that the calculated upper 95 percent confidence limit is greater than themaximum reported concentration, which may result from the wide range of reportedconcentrations, the maximum reported concentration will be used as the exposureconcentration.

Monitoring data were not available for the concentrations of airborne dust from soil. Theconcentration of airborne soil available for inhalation was estimated using the PM10 (theconcentration of particles in air that are ten microns or less in diameter and thus smallenough to be inhaled deep into the lungs). A PM10 of 27.7 pg/m3 is used in the riskassessment in the absence of site-specific data. The PM10 represents the average of datafor Delaware City for 1988-1990 and was obtained from DNREC (DNREC, 1991). The

STAND*CL>STAND:RPT 6-45

flR306Q65

exposure concentrations that are used in the risk assessment are provided in Tables 6-2through 6-7 which provide summary statistics, including the arithmetic mean and upper95 percent confidence limit

6.3.2.5 Exposure Dose Models and Assumptions

This subsection presents the mathematical models that are used to calculate the intakes(i.e., doses) of substances of concern by each receptor through the applicable exposureroutes (see Table 6-9). The models are presented in tabular form. Each table defines thevariables for the exposure route and includes the assumptions (i.e., exposure parameters)used in the model for each scenario. Additional information regarding the assumptions

is presented in the text

Doses, expressed as estimated daily intakes in milligrams of contaminant per kilogramof body weight on a daily basis (mg/kg-day), are calculated for each exposure routeapplicable to the hunter/fisherman, the current and future workers, and the current andfuture visitors. Doses are calculated based on two (worker and visitor scenarios) or three(hunter/fisherman scenario) averaging times, using arithmetic mean and upper 95 percentconfidence limit concentrations. For the hunter/fisherman scenario, doses for the adultand child are averaged over the number of days of exposure (years of exposure x 30days/year) to evaluate subchronic noncarcinogenic health effects. For all scenarios, dosesare averaged over the number of years of exposure (years of exposure x 365 days/year)to evaluate chronic non-carcinogenic health effects, and over a lifetime (70 years x 365days/year) to evaluate potential carcinogenic effects.

Body weights of 70 kg and 16 kg for the adult and child, respectively, are used in the

applicable scenarios (EPA, 1989c). The 70 kg body weight represents the average adultwhile the 16 kg body weight is the 50th percentile value for children one through sixyears old.

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Incidental Soil IngestSon

Incidental soil ingestion can result from placing soil-covered hands or objects in themouth. Soil ingestion is a potential route of exposure for the current and future workers,the current and future visitors, and the hunter/fisherman (both adult and child) scenarios.

It has been estimated that children of ages one through six incidentally ingest 200 mg ofsoil on a daily basis and that individuals over the age of six ingest 100 mg of soil per day(EPA, 1991b). The soil ingestion rates for both age groups take into account theingestion of outdoor soil and indoor dust and represent reasonable upper-bound exposureconditions. Because the workers and hunter/fisherman are not expected to spend theirentire working day at the site, the soil ingestion rates are effectively reduced by one-half

by incorporating a "fraction ingested" factor in the exposure algorithm. The equation andassumptions that are used to calculate soil ingestion doses are presented in Table 6-10.

Dermal Absorption from Soil

The dermal absorption of substances, resulting from dermal contact with surface soil, isa potential route of exposure for all five scenarios. The equation and assumptions usedto calculate dermal absorption doses are presented in Table 6-11.

The exposed skin surface areas for all scenarios are based on 50th percentile body part-and age-specific surface areas for males. The skin surface areas for the current and futureworker and visitor are based on data for adults and include only hands and arms becauseall other areas are expected to be covered while they are working on the site. The skinsurface areas presented in Table 6-11 for the child and adult hunter/fisherman are basedon exposed arms, hands, and legs because some exposure to surface soil is expectedduring the wanner months.

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OES&CRSCGKSU.WRS

Table 6-10

Mode! for Calculating Doses Through the Ingestion of Soil

Soil Ingestion Dose = CS x SIR x FI x CF x EF x ED(mg/kg-day) BW x AT

Where:

CS = Chemical concentration in surface soil (mg/kg)SIR = Soil ingestion rate (mg/day)FI = Fraction ingested at site (unitless)CF = Conversion factor (10~6 kg/mg)EF = Exposure frequency (days/year)ED = Exposure duration (years)BW = Body weight (kg)AT =- Averaging time (years x days/year)

Exposure Assumptions

All Scenarios:

CS = Chemical concentration in surface soil (mg/kg) (see Tables 6-2 and 6-3)CF = 10'6 kg/mgFI = 0.5 (unitless) (assumed value)

Current/Future Worker:

SIR = 100 mg/day (EPA, 1989c)EF = 240 days/year (assumed value)ED = 25 years (EPA, 1991b)BW = 70 kg (EPA, 1989c)AT = 25 years x 365 days/year (for chronic noncarcinogenic risk) (EPA,1989c)

= 70 years x 365 days/year (for carcinogenic risk) (EPA, 1989c)

Current/Future Visitor:

SIR - 100 mg/day (EPA, 1989c)EF = 48 days/year (assumed value)ED = 25 years (EPA, 1991b)BW = 70 kg (EPA, 1991b)AT = 25 years x 365 days/year (for chronic noncarcinogenic risk) (EPA,1989c)

70 years x 365 days/year (for carcinogenic risk) (EPA, 1989c)

STAND-CHL/RI-T6- 10.TBL 6-48 —'- fiR3Q6G68

Table 6-10 (continued)

Model for Calculating Doses Through the Ingestion of Soil

Hunter/Fisherman:

SIR = 100 mg/day (adult) (EPA, 1989c)«-. 200 mg/day (child) (EPA, 1989c)

EF = 30 days/year (assumed value)ED = 25 years (adult) (EPA, 1991b)

« 5 years (child) (EPA, 1989c)BW « 70 kg (adult) (EPA, 1989c)

« 16 kg (chfld) (EPA, 1989c)AT *= 25 years x 365 days/year (adult) (for chronic noncarcinogenic risk)

(EPA, 1989c)« 5 years x 365 days/year (child) (for chronic noncarcinogenic risk)

(EPA, 1989c)= 70 years x 365 days/year (adult) (for carcinogenic risk) (EPA, 1989c)= 70 years x 365 days/year (child) (for carcinogenic risk)= 25 years x 30 days/year (adult) (for subchronic noncarcinogenic risk)= 5 years x 30 days/year (child) (for subchronic noncarcinogenic risk)

STAND-CHURI-T&-IO.TBL 6-49 AR3Q6Q69

DESSKRS/CONSU.TAOTS

Table 6-11

Model for Calculating Doses Through Dermal Contact With SoilSoil Dermal Dose = CS x CF x FE x SA x AF x ABS x EF x ED(mg/kg-day) BW x AT

Where:

CS = Chemical concentration in soil (mg/kg)CF = Conversion factor (10"6 kg/mg)FE = Fraction of daily exposure to medium (unitless)SA = Skin surface area available for contact (cm2/day)AF = Soil to skin adherence factor (mg/cm2)ABS = Absorption factor (unitless)EF - Exposure frequency (days/year)ED = Exposure duration (years)BW = Body weight (kg)AT = Averaging time (years x days/year)


All Scenarios:

CS = Chemical concentration in soil (mg/kg) (see Tables 6-2 and 6-3)CF = Conversion factor (10"6 kg/mg)AF = 1.45 mg/cm2 (EPA, 1989c)ABS = 0.5 (unitless) (volatiles) (assumed value)

= 0.05 (unitless) (semi-volatiles) (assumed value)Current/Future Worker:

FE = 1 (assumed value)SA = 3,120 cm2/day (EPA, 1989c)EF = 240 days/year (assumed value)ED = 25 years (EPA, 1991b)BW = 70 kg (EPA, 1989c)AT = 25 years x 365 days/year (for chronic noncarcinogenic risk)

= 70 years x 365 days/year (for carcinogenic risk)


FE = 1 (assumed value)SA = 3,120 cmVday (EPA, 1989c)EF = 48 days/year (assumed value)ED = 25 years (EPA, 1989c)BW = 70kg (EPA, 1989c)AT = 25 years x 365 days/year (for chronic noncarcinogenic risk)

70 years x 365 days/year (for carcinogenic risk)

STAND-CURIT6-I-11.TBL 6~50 - SR306Q7Q


Model for Calculating Doses Through Dermal Contact With Soil

Hunter/Fisherman:FE — 0.5 (assumed value)SA » 8,620 cmVday (adult) (EPA, 1989c)

= 3,910 cmVday (chUd) (EPA, 1989c)EF = 30 days/year (assumed value)ED « 25 years (adult) (EPA, 1991b)• = 5 years (child) (EPA, 1989c)BW = 70 kg (adult) (EPA, 1989c)

« 16 kg (child) (EPA, 1989c)AT = 25 years x 365 days/year (adult) (for chronic noncarcinogenic risk)

(EPA, 1989c)« 5 years x 365 days/year (child) (for chronic noncarcinogenic risk)

(EPA, 1989c)= 70 years x 365 days/year (adult) (for carcinogenic risk) (EPA, 1989c)»* 70 years x 365 days (child) (for carcinogenic risk)= 25 years x 30 days/year (adult) (for subchronic noncarcinogenic risk)

_______= 5 years x 30 days/year (child) (for subchronic noncarcinogenic risk)

STAND-CURI.T6-l-n.TBL 6-51 fl R 3 0 6 0 7 I

KSOCttCCNXXIANTS

Absorption of soil-bound substances through the skin involves a number of complexprocesses. First, the substance must desorb from the soil to an extent that the compound

is available for absorption. Second, the substance must penetrate the first skin layer andpermeate through the remaining layers. Third, the substance must be taken up by themicrocirculation within the skin. Only when all these processes occur can a substancebe absorbed. To account for all these processes, a relative absorption factor isincorporated into the exposure algorithm so an absorbed dose can be calculated. EPARegion 1 has developed relative absorption factors for classes of soil contaminantsthrough the dermal pathway. The relative absorption factor refers to the fraction of achemical which after contact, is likely to be absorbed through the skin relative toabsorption of the compound in a laboratory study from which the cancer potency factor

or reference dose is derived. Contaminants absorbed onto soils and sediments are

presumed to be less available for dermal absorption than pure compounds or solutions.To account for these differences, the EPA Region 1 has listed the following relativeabsorption factors that can be used for assessing dermal absorption of contaminants fromsoils when data on dermal absorption from soils is not available. The relative absorption•

factors mat can be used for dermal contact with soils are as follows (EPA, 1989e):

Volatile Organic Compounds: ~~: 50%

Semi-volatile Organic Compounds:PAHs: 5%PCBs: 5%Pesticides: 5%

-high sorption to soils: 5%-low sorption to soils: 50%

Inorganics: negligible

Volatile organics were considered to be those organics for which the vapor pressure wasgreater than 100 mm Hg and/or have a Henry's Law constant equal to or greater than IE-04 atmospheres - m3/mole (Smith, 1991). All other organics were treated as semi-

STAND-CLNSTAND.RPT - 6-52

ftR3Q6G72

MSCWRSCWSU.TWTS

volatilcs. The vapor pressure criterion was derived from an inspection of the vaporpressures of chemicals that the EPA classifies as volatiles (EPA, 1986c).

Some disagreement exists within EPA regarding the classification of several of thechlorinated benzenes evaluated in the risk assessment A discussion of the designationof the compounds as either volatile or semi-volatile is provided in the UncertaintyAnalysis, Subsection 6.3.5.

For the: purpose of this assessment, the dichlorobenzenes and trichlorobenzenes weretreated as semi-volatiles with a relative absorption factor of 5%. A complete discussionof the reasons for the classification is provided in Subsection 6.3.5, Uncertainty Analysis -Dermal Pathway.

For the hunter/fisherman pathway, it is further assumed that one-half of the dermalexposure will be to soil and one-half will be to sediment (see Dermal Absorption fromSediment). It is unrealistic to assume that an individual can receive a full day ofexposure from both soil and sediment simultaneously; therefore, a "fraction exposed"factor (FE) is incorporated into the exposure equation to partition the daily dermal dose

between exposure to soil and sediment

Inhalation of Soil/Dust

The inhalation of airborne soil is a potential route of exposure that is evaluated for all

five scenarios. The equation and assumptions that are used to calculate doses frominhalation of airborne soil are presented in Table 6-12.

In the absence of site-specific data, it is conservatively assumed that the concentration ofsubstances in airborne soil are the same as those in surface soil. It is further assumed thatthe worker and visitor will only be exposed to airborne soil that is generated on-site and

STAND-CLNSTANDJ PT 6-53

flR306073

Table 6-12

Model for Calculating Doses Through Inhalation of Soi/Dust

Dust Inhalation Dose = CS x DC x IR x FI x CF x EF x ED(mg/kg-day) BW x AT

Where:

CS = Chemical concentration in surface soil (mg/kg)DC = Dust concentration in air (pg/m3)IR — Inhalation rate (mVday)FI ==- Fraction inhaled at site (unitiess)CF = Conversion factor (10"9 kg/jig)EF = Exposure frequency (days/year)ED = Exposure duration (years)BW = Body weight (kg)AT = Averaging time (years x days/year)


SA11 Scenarios:

CS = Chemical concentration in surface soil (mg/kg) (see Tables 6-2 and 6-3)DC = 27.7 jig/m3 (DNR, 1991)CF = 10-9kg/pg

Current/Future Worker:

IR = 30 m3/day (EPA, 1989c)FI =0.5 (unitiess) (assumed value)EF = 240 days/year (assumed value)ED = 25 years (EPA, 19915)BW = 70 kg (EPA, 1989c)AT = 25 years x 365 days/year (for chronic noncarcinogenic

~ 70 years x 365 days/year (for carcinogenic risk) (EPA,


IR =.; 30 mVday (EPA, 1989c)FI = 0.25 (unitiess) (assumed value)EF = 48 days/year (assumed value)

IED = 25 years (EPA, 1989c)BW = 70kg (EPA, 1989c)AT = 25 years x 365 days/year (for chronic noncarcinogenic

= 70 years x 365 days/year (for carcinogenic risk) (EPA,

risk) (EPA,1989c)1989c)

risk) (EPA,1989c)1989c)

-STAND-CL/RI-T6- 12.TBL 6-54 AR30607U


Model for Calculating Doses Through Inhalation of Soi/Dust

Hunter/Fisherman:

IR = 30 mVday (adult) (EPA, 1989c)» 26 mVday (child) (exp fat)

H = 0.5 (unidess) (assumed value)EF = 30 days/year (assumed value)ED = 25 years (adult) (EPA, 1991b)

« 5 years (child) (EPA, 1989c)BW = 70 kg (adult) (EPA, 1989c)

= 16 kg (child) (EPA, 1989c)AT s= 25 years x 365 days/year (adult) (for chronic noncarcinogenic risk)

(EPA, 1989c)= 5 years x 365 days/year (child) (for chronic noncarcinogenic risk)

(EPA, 1989c)= 70 years x 365 days/year (adult) (for carcinogenic risk) (EPA, 1989c)= 70 years x 365 days/year (child) (for carcinogenic risk)= 25 years x 30 days/year (adult) (for subchronic noncarcinogenic risk)» 5 years x 30 days/year (child) (for subchronic noncarcinogenic risk)

STAND-CURI-T&-12.TBL 6-55 flR306075

that the adult and child hunter/fisherman will be exposed to airborne soil that is generatedoff-site. This assumption is made because exposure to airborne soil is believed to be alocalized phenomenon.

An inhalation rate of 30 mVday is assumed for the worker, visitor, and adulthunter/fisherman and represents the reasonable worst-case inhalation rate (EPA, 1989b).The child fisherman inhalation rate of 26 mVday is based on the following inhalation rates

and activity levels for a six year old; eight hours of moderate activity (2 m3/hour), eighthours of light activity (0.8 nvVhour), and eight hours at rest (0.4 mVhour) (EPA, 1989b).To account for the fact that receptors will only be present at the site for a fraction of theday, a factor (FI) is included in the exposure algorithm that adjusts the exposure dose for

the amount of time spent at the site. It is assumed that workers and the hunter/fishermanwill spend 50 percent of the day at the site, and that the visitor will spend 25 percent ofthe day at the site.

Dermal Absorption from Sediment•

Dermal- absorption from sediments is only evaluated for the adult and child in thehunter/fisherman scenario because sediments are found only off-site. The adult and child

hunter/fisherman are expected to have dermal exposure to sediments as they hunt and/orfish in the wetlands located north of the site and along Red Lion Creek.

The exposed skin areas and absorption factors used to evaluate dermal contact withsediment are the same as those described above for the dermal contact with soil pathway.The equation and assumptions used in the dermal contact with sediment pathway arepresented in Table 6-13.

STAND-CL>STAND.RPT 6-56 ._..._ .

AR306076

Table 6-13

Model for Calculating Doses Through Dermal Contact with Sediment

Sediment Dermal Dose = CSxCFxFExSAxAFx ABS x EF x ED(mg/kg-day) BW x AT

Where:

CS « Chemical concentration in sediment (mg/kg)CF = Conversion factor (10"6 kg/mg)FE = Fraction of daily exposure to medium (unitiess)SA « Skin surface area available for contact (cm2/day)AF = Soil to skin adherence factor (mg/cm2)ABS « Absorption factor (unitiess)EF = Exposure frequency (days/year)ED = Exposure duration (years)BW - Body weight (kg)AT = Averaging time (years x days/year)


Hunter/Fisherman:

CS « Chemical concentration in sediment (mg/kg) (see Table 6-4)CF « Conversion factor (10"6 kg/mg)FE = 0.5 (assumed value)SA - 8,620 cm2/day (adult) (EPA, 1989c)

« 3,910 cm2/day (child) (EPA, 1989c)AF = 1.45 mg/cm2 (EPA, 1989c)ABS » 0.5 volatiles (assumed value)

» 0.05 semivolatiles (assumed value)EF « 30 days/year (adult) (assumed value)

« 30 days/year (child) (assumed value)ED = 25 years (adult) (EPA, 1991b)

= 5 years (child) (EPA, 1989c)BW « 70 kg (adult) (EPA, 1989c)

= 16 kg (child) (EPA, 1989c)AT = 25 years x 365 days/year (adult) (for chronic noncarcinogenic risk)

(EPA, 1989c)- 5 years x 365 days/year (child) (for chronic noncarcinogenic risk)

(EPA, 1989c)« 70 years x 365 days/year (adult) (for carcinogenic risk) (EPA, 1989c)= -70 years x 365 days/year (child) (for carcinogenic risk) (EPA, 1989c)= 25 years x 30 days/year (adult) (for subchronic noncarcinogenic risk)« 5 years x 30 days/year (child) (for subchronic noncarcinogenic risk)

STAND-CUR1-T&-I3.TBL __ . g- c~O-57

AR306077

^ w ™

As described above (dermal absorption from soil) a "fraction exposed" factor (FE) isincluded in the exposure equation to account for the partitioning of the daily dermal dosebetween the two media (soil and sediment) to which an individual may potentially beexposed.

Dermal Contact with Surface Water

The dermal absorption of substances of concern from surface water is only evaluated forthe adult and child hunter/fisherman. The equation and assumptions that are used tocalculate dermal absorption from surface water are presented in Table 6-14.

The exposed skin area for the hunter/fisherman is assumed to be the same as that whichis available for dermal contact through the soil dermal contact pathway, i.e., hands, arms,and legs. It is assumed that the hunter/fisherman will be exposed to surface water fourhours per day, 30 days per year, primarily during the warmer months.

In order to evaluate exposure from dermal contact with substances dissolved in water, it

is necessary to quantify the amount of the substance that penetrates the skin. In the

absence of empirical dermal permeability constants, permeability can be estimated usinga semi-empirical equation (Brown and Rossi, 1989). The equation is based on, and highlycorrelated with, the octanol-water partition coefficient (Kow) of the compound. The skinpermeability equation, K s, and permeability constants are presented in Table 6-15.

Ingestion of Fish

Red Lion Creek is a popular fishing area that is located north of the SCD site. The creekreceives runoff from the site via a drainage swale that forms a wetland adjacent to the

creek. Contaminated sediment and groundwater currently act as secondary releasemechanisms of substances of concern to the creek. The fish ingestion pathway is

STAND-CLNSTANDJIPT 6~58

...... SR306078

DE9GHBB.tOWU.TWTS

Table 6-14

Model for Calculating Doses Through Dermal Contact Surface Water

Surface Water Dermal Dose = CW x SA x PC x CF x ET x EF x ED(mg/kg-day) BW x AT

Where:

CW «« Chemical concentration in surface water (mg/1)SA « Skin surface area available for contact (cm2)PC = Chemical-specific dermal permeability constant (cm/hour)CF = Conversion factor (1/1,000 cm3)ET « Exposure time (hours/day)EF = Exposure frequency (days/year)ED « Exposure duration (years)BW = Body weight (kg)AT «! Averaging time (years x days/year)


Hunter/Fisherman:

CW = Chemical concentration in surface water (mg/1) (see Table 6-5)SA = 8,620 cm2 (adult) (EPA, 1989c)

« 3,910 cm2 (child) (EPA, 1989c)PC «= Calculated value, see Subsection 6.2.3.5 (Brown and Rossi, 1989)CF = 1 liter/1,000 cm3ET «= 4 hours/day (assumed value)EF « 30 days/year (assumed value)ED « 25 years (adult) (EPA, 1991b)

« 5 years (child) (EPA, 1989c)BW = 70 kg (adult) (EPA, 1989c)


(EPA, 1989c)» 5 years x 365 days/year (child) (for chronic noncarcinogenic risk)

(EPA, 1989c)« 70 years x 365 days/year (adult) (for carcinogenic risk) (EPA, 1989c)» 70 years x 365 days/year (child) (for carcinogenic risk)= 25 years x 30 days/year (adult) (for subchronic noncarcinogenic risk)= 5 yeafs~x 30 days/year (child) (for subchronic noncarcinogenic risk)

STAND-C2JRI-T6-14.TBL 6-59

——-. /5R306079

DESOJERS'HNSLI.UNTS

Table 6-15

Calculation of Dermal Permeability Constants*

38$%&M<$&$$$&

BenzeneChlorobenzene1 ,2-Dichlorobenzene1 ,3-Dichlorobenzene1 ,4-DichlorobenzeneEthylbenzeneHexachlorobenzeneMetachloronitrobenzeneNitrobenzenePCB'SAroclor-1260Pentachlorobenzene1,2,3,4-Tetrachlorobenzene1 ,2,4,5 -TetrachlorobenzeneToluene1 ,2,3-Trichlorobenzene1 ,2,4-Trichlorobenzene1,3 -Trichlorobenzene

L48E+026.92E+02

3.02E+03

3.24E+03

2.88E+03

1.62B+031.51E+06

2.75E+02

7.24E+016.31E+06

1.17E+05

5.25E+04

5.01E+04

5.13E+021.12E+04

1.66E+041.66E+04

fe|l ; ^ ^ ^

EPA, 1987EPA, 1987EPA, 1987

EPA, 1987

EPA, 1987

EPA, 1987

EPA, 1987

TDS, Syndex, 1991EPA, 1987

EPA, 1987

EPA, 1987

EPA, 1987

EPA, 1987

EPA, 1987EPA, 1987

EPA, 1987TDS, Syndex, 1981

2.61E-025.29E-02

7.72E-02

7.8 IE-02

7.66E-02

6.80E-02

9.97E-02

3.60E-02

1.7 IE-029.99E-02

9.81E-02

9.67E-02

9.65E-02

4.73E-029.01E-02

9.24E-029.24E-02

Calculated from Brown and Rossi (1989) using PC=0.1x(Kow a/7(120+Kw°-75)).

STAND-CL/RI-T6-1S.TBL 6-60

evaluated for the hunter/fisherman scenario using fish tissue concentrations that are basedon field sampling results. The equation and assumptions for the fish ingestion pathwayare shown in Table 6-16.

Ingestion of Groundwater

There is no known current use of groundwater from the Columbia Formation, therefore,ingestion of groundwater is not evaluated in the current use scenarios. Although futureuse of on-site groundwater from the Columbia Formation for drinking is highly unlikely,exposure to substances of concern in groundwater is evaluated in the future worker andfuture visitor scenarios. The equation and assumptions that are used to calculategroundwater ingestion doses for the future worker and future visitor are presented inTable 6-17.

The groundwater ingestion rates for the future worker and future visitor are based on adrinking water ingestion rate of 2 liters/day, which represents the 90th percentile foradults (EPA, 1989c). To account for the amount of time the receptors will spend on-site,

the ingestion rate of 2 liters/day is multiplied by a "fraction ingested" factor of 50 percent(0.5) for the future worker and 25 percent (0.25) for the future visitor.

6.3.2.6 Summary of Calculated Doses

Exposure doses are calculated and presented for the current worker, current visitor, futureworker, future visitor, and hunter/fisherman scenarios. Chronic exposure duration-

averaged and lifetime-averaged exposure doses are calculated for individuals in all

scenarios. For the adult and child hunter/fisherman, subchronic exposure duration-averaged doses are also calculated to account for subchronic exposure. Doses for the fivescenarios are presented in the following tables:

STANIXa^TANIXRFT 6-61

flR30608l

OESBNeAS.nHSU.TWTS

Table 6-16

Model for Calculating Doses Through the Ingestion of Fish

Fish Ingestion Dose = CF x IR x H x EF x ED(mg/kg-day) BW x AT

Where:

CF = Chemical concentration in fish (mg/kg)IR = Fish rngestion rate (kg/day)FI = Fraction ingested from site (unitless)EF = Exposure frequency (days/year)ED = Exposure duration (years)BW = Body weight (kg)AT = Averaging time (years x days/year)


Hunter/Fisherman:

CF = Chemical concentration in fish (mg/kg) (see Table 6-7)IR = 0.284 kg/day (adult) (assumed value)

= 0.142 kg/day (child) (assumed value)FI = 0.5 (unitless) (assumed value)EF = 30 days/year (assumed value)ED =25 years (adult) (EPA, 1991b)

= 5 years (child) (EPA, 1989c)BW = 70 kg (adult) (EPA, 1989c)


(EPA, 1989c)= 5 years x 365 days/year (child) (for chronic noncarcinogenic risk)

(EPA, 1989c)= 70 years x 365 days/year (adult) (for carcinogenic risk) (EPA, 1989c)= 70 years x 365 days/year (child) (for carcinogenic risk)

STAND-CURI-T6-16.TBL 6-62

SR306082

OtSGHEKCOBULTWTS

Table 6-17

Model for Calculating Doses Through the Ingestion of Groundwater

Groundwater Ingestion Dose = CW x IR x FI x EF x ED(mg/kg-day) BW x AT

Where:

CW - Chemical concentration in groundwater (mg/1)IR « Water ingestion rate (I/day)FI - Fraction ingested at site (unitless)EF = Exposure frequency (days/year)ED « Exposure duration (years)BW « Body weight (kg)AT = Averaging time (years x days/year)


All Scenarios:

CW = Chemical concentration in groundwater (mg/1) (see Table 6-6)IR = 2 I/day (EPA, 1989c)ED = 25 years (EPA, 19915)BW = 70 kg (EPA, 1989c)AT » 25 years x 365 days/year (for chronic noncarcinogenic risk)

(EPA, 1989c)- 70 years x 365 days/year (for chronic carcinogenic risk) (EPA, 1989c)

Future Worker:

FI = (unitless) (assumed value)EF - 240 days/year (assumed value)

Future Visitor:

FI « 0.25 (unitless) (assumed value)EF = 48 days/year (assumed value)

STAND-CMU-76-17.TBL 6-63

flR306083

OEaGNQtWXHSUTWTS

• Current Worker - Appendix G; Tables G-l through G-4.

* Current Visitor - Appendix G; Tables G-5 through G-8.

• Future Worker - Appendix G; Tables G-9 through G-l2.

• Future Visitor - Appendix G; Tables G-13 through G-16.

• Hunter/Fisherman - Appendix G; Tables G-17 through G-28.

6.3.3 Toxicity Assessment

6.3.3.1 Introduction

The purpose of the toxicity assessment is to identify the toxicity values (i.e., cancer slopefactors and reference doses) that are used in Subsection 6.3.4 to evaluate potential humanhealth risks. When available, current human health toxicity values that have beendeveloped by the EPA were used. Values that are entered into the Integrated RiskInformation System (IRIS) computer database (IRIS, 1991) were preferentially used,because these are the most current, approved toxicity values. If a value was not presentin IRIS, the Health Effects Assessment Summary Tables (HEAST) (EPA, 199la) wasconsulted for an appropriate value. When EPA toxicity values were not available, interimvalues were developed from toxicity data or other existing toxicity values.

In evaluating potential health risks, both carcinogenic and noncarcinogenic health effectsmust be considered. Excessive exposure to all chemicals can potentially producenoncarcinogenic health effects, while the potential for carcinogenic effects is limited toexposure to certain substances that have evidence of carcinogenicity. Therefore, it wasnecessary to identify and select noncancer toxicity values for each of the substancesselected for evaluation and to identify and select cancer toxicity values only for thosesubstances that have evidence of carcinogenicity.


WS5*RKW3U.TWT5

6.33.2 Cancer Slope Factors

The toxicity values that are used in the evaluation of carcinogenic risk in Subsection 6.3.4are cancer slope factors that have been developed by EPA. In developing these cancerslope factors it was assumed that the risk of cancer is linearly related to dose.' Thismeans that even if all of the cancer data obtained from laboratory animals orepidcmiological studies are for relatively high doses, it is conservatively assumed thatthese high doses can be extrapolated down to extremely small doses, with some risk ofcancer remaining until the exposure to the chemical is zero. Figure 6-4 illustrates thisapproach. This is a nonthreshold theory that assumes that even a small number ofmolecules (possibly even a single molecule) of a carcinogen may cause changes in asingle cell that could result in the cell dividing in an uncontrolled manner, eventuallyleading to cancer. The slope factors are usually derived by EPA utilizing a linearizedmultistage model and usually reflect the upper-bound limit of the potency of the chemical.As a result, the calculated carcinogenic risk is likely to represent a plausible upper limit

to the risk. The actual risk is unknown, but is likely to be lower than the calculated risk,and may be even as low as zero (EPA, 1986b; EPA, 1989c).

There is some debate as to whether the extrapolation from high to low doses is a realisticapproach. It is argued that at low doses, cells may have the ability to detoxifycarcinogens or repair cell-induced damage. Although it is important to recognize thelimitations of using data from high dose studies, quantitative adjustments to publishedslope factors are not available. This baseline risk assessment uses the same slope factorsas those used in other studies, so that the estimated risk numbers are comparable.

Table 6-18 summarizes EPA and IARC categorization of carcinogens based on human andanimal evidence. All substances in this study that have evidence of carcinogenicity inanimals and/or humans and are classified as carcinogens by EPA (Groups A, B, or C)(EPA, 199la) and/or the International Agency for Research on Cancer (IARC) (Groups1, 2A, or 2B) (CIS, 1988) are evaluated in Subsection 63.4 (Risk Characterization) for

STANIX£>STAND.KPT 6-65 —— - - - - _AR306085

DOSE, ARBITRARY UNITS(LOGARITHMIC SCAIJE)

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6-66 ::,_: _SR306086

DESCNER5XONSU.TWTS

Table 6-18EPA and IARC Categorizations of Carcinogens

Based on Human and Animal Evidence

EPA Categorization of Carcinogens (U.S. EPA, 1986b)Animal Evidence

Sufficient Limited Inadequate No Data No EvidenceHuman EvidenceSufficient A A A A ALimited Bl Bl Bl Bl BlInadequate B2 C D D DNo data B2 C D D ENo evidence B2 C D D E

fsxGroup A - Human carcinogen (sufficient evidence from epidemiological studies).

Group Bl - Probable human carcinogen (at least limited evidence of carcinogenicity tohumans).

Group B2 - Probable human carcinogen (a combination of sufficient evidence in animals andinadequate data in humans).

Group C - Possible human carcinogen (limited evidence in animals in the absence of humandata).

Group D - Not classified (inadequate animal and human data).

Group E - No evidence for carcinogenicity (no evidence for carcinogenicity in at least twoadequate animal tests in different species, or in both epidemiological and animalstudies).

STAND.CDRI-T6-lt.TBL 6-67

Table 6-18 (continued)EPA and IARC Categorizations of Carcinogens

Based on Human and Animal Evidence

IARC Categorization of Carcinogens (WHO, 1987)

Group 1 - Human carcinogen (sufficient evidence of carcinogenicity in humans).

Group 2A - Probable human carcinogen (limited evidence of carcinogenicity inhumans and sufficient evidence of carcinogenicity in experimentalanimals).

iroup 2B - Possible human carcinogen (limited evidence of carcinogenicity inhumans and insufficient evidence of carcinogenicity in experimentalanimals, insufficient evidence of carcinogenicity in humans andsufficient evidence of carcinogenicity in experimental animals; orinsufficient evidence of carcinogenicity hi humans and limited evidenceof carcinogenicity in experimental animals, with supporting evidencefrom other relevant data).

Group 3 - Not classifiable (substances in this category do not fall into any othercategory).

Group 4 - Probably not carcinogenic to humans.

STAND-CL(RJ-T6-18.TBL 6-68 = -==,-_. -

flR306088

potential carcinogenic risk. Nine of the substances of concern, including benzene, thepolychlorinafed biphcnyls (i.e., Aroclors), hexachlorobenzene and 1,4-dichlorobenzene arecategorized as carcinogenic. The EPA and IARC carcinogenicity categorizations arepresented in Table 6-19.

The carcinogenic potency of a substance depends, in part, on its route of entry into thebody (e.g., oral, inhalation, or dermal). Therefore, slope factors are developed andclassified according to the route of administration. EPA has developed oral and/orinhalation slope factors for some carcinogens. Dermal slope factors have not beenderived by the EPA for any chemicals, however some EPA guidance is providedconcerning the use of oral slope factors in place of dermal slope factors. The slopefactors that were used in this evaluation are discussed, by exposure route, in the followingsubsections.

6.3.3.2.1 Oral Route

EPA-derived oral slope factors were available for the nine carcinogenic substances ofconcern. The oral slope factor that has been developed for PCBs in general was used forthe Aroclor mixtures.

633.2.2 Inhalation Route

EPA-derived inhalation slope factors were available for only two of the carcinogenicsubstances of concern. An inhalation slope factor was not available for the PCBs,hexachlorobenzene or 1,4-dichlorobenzene. The oral slope factor was used by defaultwhen an inhalation slope factor was not available.

6.33.23 Derma! Route

Although few data are available concerning the carcinogenic activity of chemicals that aresystemically absorbed through dermal exposure, it is assumed that all the chemicals that

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6-70 flR306090

are carcinogens through the oral route are potentially carcinogenic through the dermalroute.

In calculating the dermal dose for a chemical, a relative absorption factor was used, inaccordance with EPA Region I guidance (EPA, 1986e). The relative absorption factortakes into account the absorption of die chemical through the skin relative to absorptionfrom the vehicles used in laboratory studies on which the toxiciry values are based.Using this corrective factor allows the oral slope factor to be used to assess risk throughdermal absorption.

Summary

Table 6-20 summarizes cancer slope factors for carcinogens through the oral, dermal, andinhalation exposure routes. The reference source for each of the slope factors is alsoindicated.

6.3.3.3 Reference Doses.

Unlike the approach used in evaluating cancer risk, for noncarcinogenic health effects itis assumed that a threshold dose exists below which there is no potential for adversehealth effects. A "no-observed-adverse-effect level" (NOAEL) is that dose at which notoxic effects are observed in any of the test subjects. Figure 6-5 illustrates this approach.The toxicity values used to evaluate the potential for noncarcinogenic health effects are

generically referred to in this assessment as reference doses (RfDs), The term RfD wasdeveloped by the EPA to refer to the daily intake of a chemical to which an individualcan be exposed without any expectation of noncarcinogenic adverse health effectsoccurring (e.g., organ damage, biochemical alterations, birth defects). This term is usedin this assessment to apply to any established or derived toxicity value fitting this

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flR306093

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description. In general terms, the RfD is derived from a NOAEL or a LOAEL (lowest-observed-adverse-effect level) by the application of uncertainty factors of 10 each, anda modifying factor of up to 10 which accounts for a qualitative professional assessmentof additional uncertainties in the available data (EPA, 1989c).

RfDs, like cancer slope factors, are developed for specific exposure routes. In addition,separate RfDs are derived to evaluate different exposure periods. Chronic RfDs aredeveloped to evaluate exposures of seven years or longer. Subchronic RfDs aredeveloped to evaluate exposure periods of two weeks to seven years (EPA, 1989c).Because visitors, workers and the hunter/fisherman were assumed to be exposed for 25years, chronic RfDs were used to evaluate noncarcinogenic health effects. Subchronic

RfDs were also used in the hunter/fisherman scenario to evaluate daily-averagedexposures. Chronic and Subchronic RfDs have been derived by the EPA for a number

of chemicals for the oral and/or inhalation routes, but have not been developed for thedermal route for any chemical.

6.3.33.1 Oral Route

Chronic

Current EPA-derived chronic RfDs were available for nine of the 23 substances that were

evaluated through chronic oral exposure routes. For the PCBs, the chronic oral RfD forpolybrominated biphenyls (PBBs) (EPA, 199la) was used as a default The chronic oralRfD for 1,2,4-trichlorobenzene was used for 1,2,3- and 1,3,5-trichlorobenzene. Thechronic oral RfD for 1,2,4,5-tetrachlorobenzene was used for 1,2,3,4-tetrachlorobenzene,and the chronic oral RfD for 1,2-dichlorobenzene was used for 1,3- and 1,4-dichlorobenzene.

STAND-CLNSTANDJOT 6'74

A chronic oral RfD was derived for benzene from subchronic toxicity data according toEPA guidelines (EPA, 1989c). The RfD was based on a NOAEL of 1 mg/kg/day froma 26 week study in which leucopenia and erythrocytopenia were toxic end points (Wolf,et al., 1956). Applying uncertainty factors of 10 each for extrapolating from a subchronicto a chronic exposure, for extrapolating from animals to humans, and for human variation,a chronic oral RfD of LOB-03 mg/kg/day was derived for benzene.

Subchronic

Current EPA - derived subchronic oral RfDs were available for 8 out of the 23 chemicalsthat were evaluated through subchronic oral exposure routes. For the PCBs, thesubchronic oral RfD for PBBs was used.

The subchronic oral RfD for 1,2,4-trichlorobenzene was used for 1,2,3- and 1,3,5-trichlorobenzene. The subchronic oral RfD for 1,2-dichlorobenzene was used for 1,3- and1,4-dichlorobenzene. The subchronic oral RfD for 1,2,4,5-tetrachlorobenzene was usedfor 1,2,3,4-tetrachlorobenzene.

The study that was used to derive the chronic oral RfD for benzene (Wolf, et al.» 1956)was also used to derive a subchronic RfD. Using a NOAEL of 1 mg/kg/day, uncertaintyfactors of 10 each were applied for extrapolating from animals to humans and for humanvariation. A subchronic oral RfD of l.OE-02 mg/kg/day was calculated for benzene.

6.33.3.2 Inhalation Route

Chronic

A chronic inhalation reference dose or reference concentration (RfC) was available for7 out of 23 chemicals. RfCs were converted to RfDs by assuming the inhalation of 20

m3 of air/day and body weight of 70 kg (EPA, 1991b).

STAND-CDSTAND.RPT 6-75

AR306095

In the absence of a chronic inhalation RfD or RfC for a chemical, an inhalation RfD wascalculated, where possible, based on an occupational exposure limit (OEL). Theoccupational exposure limits (OEL) that were considered included:

• American Conference of Governmental Industrial Hygienists (ACGffl) -

threshold limit value-time weighted average (TLV-TWA) (ACGffl, 1991).

* Occupational Safety and Health Administration (OSHA) -

permissible exposure limit (PEL) (DOL, 1989).

* National Institute for Occupational Safety and Health (NIOSH) -

recommended exposure limit (REL) (CDC, 1988).

It is recognized that there are several factors that limit the usefulness of occupationalguidelines in the derivation of chronic RfDs. OELs are intended to protect healthy

workers from adverse health effects when exposed to a chemical in the workplace overa 40-hour work week. Inhalation RfDs are intended to protect the general population,including sensitive subpopulations, based on a continuous exposure. Furthermore, OELsare derived by a consensus as opposed to a procedure that incorporates standard

uncertainty factors according to the nature of the lexicological database from which the

RfD is derived. OELs also may be based on toxic endpoints other than chronicnoncarcinogenic health effects.

In consideration of the limitations of the OELs, an equation was developed to derive

inhalation RfDs from OELs, incorporating uncertainty factors to account for potential

continuity of exposure and variability in human sensitivity. In addition, the support dataand/or toxic endpoints for each of the applicable OELs were reviewed to ensure that theOEL was suitable to serve as the basis for a chronic inhalation RfD (ACGffl, 1986; CDC,1988). For each chemical, the most conservative OEL that has been developed, and


48306096

(L;which is based on or protective against noncarcinogenic effects, was used to derive theinhalation RfD. The equation and assumptions that were used to calculate chronicinhalation RfDs from OELs are presented in Table 6-21. The approach is consistent withEPA guidelines for deriving a chronic RfD from a NOAEL (EPA, 1989c). The equationcalculates a daily dose to an exposed worker normalized over a 7-day exposure period(Le., the NOAEL). This dose is adjusted by an uncertainty factor of 10, which takes intoaccount human variability, and, by a modifying factor of 10 which accounts for thepossibility of continuous daily exposure over a lifetime. It may be noted that themodifying factor of 10 for continuous exposure is conservative for the evaluation of thevisitor hunter/fisher scenario.

For those chemicals for which an OEL was not available, the chronic oral RfD was used

as the chronic inhalation RfD.

Subchronic

A subchronic inhalation RfD or RfC was available for 7 out of 16 chemicals. If asubchronic inhalation RfD or RfC was not available, then the chronic inhalation RfD wasused as the subchronic inhalation RfD, with the following exception. If the chronic oralRfD for a chemical was used by default as the chronic inhalation RfD, the subchronic oral

RfD was used as the subchronic inhalation RfD.

6*33.33 Dermal Route

As in the case of cancer slope factors, no RfDs have been developed for the dermal route.Therefore, the chronic oral RfDs were used as the dermal RfDs for the organic chemicalsof concern. As discussed in the previous section, the used of a relative absorption factorin denying the dermal doses allows the oral RfDs to be used to evaluate the dermalexposure route.

STAND-CLNSTANDJIPT 6-77

flR306097

Table 6-21

Approach to Deriving a Chronic Inhalation ReferenceDose (RfD) from an Occupational Exposure Limit (OEL)

Air breathed WorkChronic OEL per work day adjustmentinhalation = (mg/m3) x (mVday) x factorRfD ______;______________ . _________

g/kg-day) Body weight x Uncertainty factor(kg)

Where:

Chronic = Chronic inhalation reference dose.inhalationRfD

EL = Occupational exposure limit.

Air breathed = 20 mVday, estimated inhalation rate for a worker (EPA, 199 Ib).per work day

Work week = 5 days/7days. Because the OEL is based on a 5-day work week, an adjustment was madeadjustment to average the dose over a 7-day week.factor

Body weight = 70 kg (weight of an average adult) (EPA, 1991b).

Uncertainty = 100.A factor of 10 is recommended by the EPA when deriving RfDs from humanfactor data to account for human variation (i.e., to protect sensitive members of the general

population (e.g., children and the elderly) (EPA, 1989a). An additional modifying factorof 10 was included to take into account a continuous exposure for a resident (versus anintermittent exposure for a worker) and a lifetime exposure for a resident (versus a lessthan lifetime exposure for a worker). Uncertainty factors of 10 to 100 are commonlyused by government agencies when deriving public health criteria from OELs (MDNR,1989; PAMS, 1983).

TAND-CH/RI-T6-21.TBL 6-7 8

flR306098

6.33.4 Summary

Table 6-22 summarizes chronic reference doses for the inhalation and oral exposureroutes.. Table 6-23 summarizes subchronic inhalation and oral reference doses. Thereference or basis of each of the RfDs is also indicated.

6,3.4 Risk Characterization

The objective of the risk characterization is to integrate the information developed in theexposure assessment (Subsection 6.3.2) and the toxicity assessment (Subsection 6.3.3) intoan evaluation of the current and potential health risks associated with exposure tochemicals of concern at the SCD site. This Subsection presents an analysis of the natureand degree of health risks posed to the potential receptor populations described inSubsection 6.3.2.2, Exposure Scenarios.

Human health risks are discussed independently for potential carcinogenic andnoncarcinogenic effects because of the different toxicological endpoints, relevant exposuredurations, and methods employed in characterizing risk. Excessive exposure to all of thechemicals of concern can potentially produce noncarcinogenic effects, while the potentialfor carcinogenic effects is limited to exposure to only certain substances.

Potential carcinogenic and noncarcinogenic risks are evaluated for each exposure scenariobased on the doses summarized in Appendix G. The general approaches to evaluatingcarcinogenic and noncarcinogenic health effects are summarized in Subsection 6.3.4.1.

The results of the risk characterization are summarized in Subsection 6.3.4.2.

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6.3.4.1 Approaches to Evaluating Risk

Noncarcinogenic Risk

Noncarcinogenic health effects are evaluated by comparing estimated daily intakes of thechemical of concern, which are averaged over the period of exposure, to reference doses

(RfDs). This is accomplished by the calculation of hazard quotients and a hazard index.The hazard quotient for a particular chemical of concern is the ratio between theestimated daily intake through a given exposure route and the applicable RfD. Estimateddaily intakes for individual chemicals and routes of exposure are compared to RfDsbecause the RfD represents the daily intake of a chemical to which a receptor can beexposed over a given length of time without any reasonable expectation of adversenoncarcinogenic health effects. The hazard quotient-RfD relationship is illustrated by thefollowing equation:

HQ = EDI/RfD

Where:HQ = Hazard quotient

EDI = Estimated daily intake (averaged over the exposure period)(mg/kg-day)

RfD « Reference dose (mg/kg-day)

The hazard quotients are summed to determine the hazard index (HI) for each chemicalof concern, for each exposure route, and for each exposure scenario (Le., all chemicalsand exposure routes combined). The hazard index is calculated to account the

STAND-CLVSTANDJtPT 6-83

4R306I03

additivity of noncarcinogenic health effects. The principal of adaptivity assumes thatsimilar organ systems and health endpoints will be affected by the chemicals of concern.

The methodology used to evaluate noncarcinogenic risk, unlike the methodology used toevaluate carcinogenic risk (see below, Carcinogenic Risk), is not a measure of and cannotbe used to determine quantitative risk. The hazard quotient or hazard index is not amathematical prediction of the incidence of effects or the severity of those effects (EPA,1985). If a hazard quotient or index exceeds "one" (>1), it simply indicates that theremight be a potential for noncarcinogenic health effects occurring under the definedexposure conditions. Because RfDs incorporate a margin of safety, if the criterion of one(1) is exceeded, it does not necessarily indicate that an adverse effect is likely.

Conversely, however, a hazard quotient or index of less than or equal to one (<1)indicates that it is unlikely for even sensitive populations to experience adversenoncarcinogenic health effects.

Carcinogenic Risk•

Carcinogenic risk for the potentially carcinogenic chemicals of concern is calculated bymultiplying the estimated daily dose that is averaged over a lifetime (lifetime-averageddoses) by a compound and exposure route-specific (oral, inhalation, dermal) carcinogenicslope factor (CSF). The calculation of carcinogenic risk is illustrated by the followingequation:

Risk = LAD*CSFWhere:

LAD = Lifetime-averaged dose (dose averaged over a 70-year lifetime)

(mg/kg-day)

CSF = Compound and route specific carcinogenic slope factor (mg/kg-day)'1

STAND-CDSTAND.RPT 6~84

AR30610U

DESGNBBCCKSUHNTS

Carcinogenic risks for individual compounds and routes of exposure are then summed tocalculate a total carcinogenic risk for the site. Unlike the calculation of noncarcinogenichealth effects, the carcinogenic risk calculation yields a probability of developing cancerunder the defined exposure conditions. That is, the excess lifetime carcinogenic riskpredicted by the above equation represents the number of individuals that may developcancer following a lifetime of exposure. Because the CSFs are based on the upper 95%confidence limit of the dose-response curve, there is only a 5% chance that the incidenceof cancer predicted by the above equation will be exceeded.

The discussion of the carcinogenic risk results (see Subsection 6.3.4.2) should be viewedin the context of "acceptable" versus "unacceptable" levels of risk. In general, whenexposure to a site results in incremental individual lifetime cancer levels that are less thanone in one million (<IE-06) the ERA will not require remediation. The EPA may setremediation goals for sites if exposure to chemicals of concern results in an excessuppcrbound lifetime cancer risk of between one in one million and one in ten-thousand(IE-06 to IE-04) (40 CFR 300, 1990).

6.3.4.2 Results of Risk Evaluation

Typically, the carcinogenic and noncarcinogenic risk results are discussed separatelybecause of different health effects. However, because of the number of scenariosevaluated in this report, the risk results will be discussed by scenario and not by healthendpoint

As described below, carcinogenic and noncarcinogenic risk from the ingestion ofgroundwater is evaluated hi the future worker and future visitor scenarios. Not evaluatedhowever, is the risk from inhalation of volatile organic compounds (VOCs) during waterusage. The cumulative effect of multiple noningestion water uses could result in risksthat are significantly higher than the risk from ingestion alone. The risk to thehypothetical future worker at the SCD site from exposure to groundwater through

STAND-OLVSTANDJtPT 6-85

flR306!05

noningestion uses would result primarily from inhalation of volatiles while showering.The risks from inhalation of VOCs while showering could be one-half to double the

ingestion risk for the VOCs (McKone and Knezovich, 1991). The results of the riskcharacterization are presented below.

Current Worker

Carcinogenic and chronic noncarcinogenic health effects were evaluated for soil ingestion,

dermal contact with soil and inhalation of airborne soil for the current worker for bothaverage and upper 95% exposure concentrations. The hazard quotients and hazard indicesfor the current worker are presented in Tables 6-24 and 6-25 for average and upper 95%exposure concentrations, respectively.

The total hazard indices (all compounds and all routes of exposure) under average andupper 95% exposure concentrations are 3 and 5, respectively. Under average and upper95% exposure concentrations, dermal contact with soil accounts for 84% of thenoncarcinogenic risk. The total hazard indices for the current worker are higher than onewhich indicates that there is a potential for adverse noncarcinogenic health effects.

Carcinogenic risks for the current worker are presented in Tables 6-26 through 6-29. Thetables present the carcinogenic risks for average and upper 95% exposure concentrationsand the distribution of the risk by chemical of concern and route of exposure. The totalcarcinogenic risks for all pathways under average and upper 95% exposure concentrationsare 7.1E-05 (7 in 100,000) and 1.2-04 (1 in 10,000), respectively. Dermal contact with1,4-dichlorobenzene accounts for approximately 78% and 77% of the total carcinogenicrisk under average and upper 95% exposure concentrations, respectively.

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Current Visitor

The exposure pathways evaluated in the current visitor scenario are identical to thoseevaluated for the current worker, only the exposure frequencies differ. The total hazardindices for the current visitor are 0.6 and 1.1, under average and upper 95% exposureconcentrations, respectively. Dermal contact with soil accounts for most of thenoncarcinogenic health effects under both exposure concentrations. The hazard quotientsand indices for this scenario are presented in Tables 6-30 and 6-31. The hazard indicesfor the current visitor indicate that adverse noncarcinogenic health effects under thedefined exposure conditions are not likely.

The total carcinogenic risks for the current visitor are presented in Tables 6-32 through6-35. The risks for average and upper 95% exposure concentrations are 1.4E-05 (1 in100,000) and 2.4E-05 (2 in 100,000), respectively. Dermal exposure to 1,4-dichlorobcnzene accounts for 78% and 77% of the total carcinogenic risk under averageand upper 95% exposure concentrations, respectively.

iFuture Worker

Ingestion of groundwater from on-site wells is evaluated in the future worker scenario inaddition to those pathways described above for the current worker. The hazard quotientsand indices for the future worker are presented in Tables 6-36 and 6-37 for average andupper 95% exposure concentrations. The total hazard index under average exposureconcentrations is 210, with ingestion of groundwater accounting for 98% of the total. Thetotal hazard index for upper 95% exposure concentrations is 329 with 98% of the totalattributable to ingestion of groundwater. Although the hazard indices for the futureworker greatly exceed one, exposure to on-site groundwater, which accounts for most ofthe risk, is considered unlikely for the following reasons: potable water is currentlysupplied to the site by a public vendor and the surficial aquifer may not have sufficientyield to meet the needs of SCD. The carcinogenic risks and risk distributions for average

STAND-CLVSTANDJIPT 6-93 ._..._

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AR30612I

and upper 95% exposure concentrations arc presented in Tables 6-38 through 6-41. Thetotal carcinogenic risk for the future worker is 3.0E-03 (3 in 1,000) while the risk forupper 95% exposure concentrations is 4.5E-03 (5 in 1,000). ingestion of benzene ingroundwater accounts for 52% of the total risk under average concentrations and 56%under upper 95% concentrations. These risks are believed to be overstated because mostof the risk results from ingestion of groundwater which is considered to be unlikely forthe reasons described above.

Future Visitor

The exposure pathways evaluated in the future visitor scenario are identical to thoseevaluated for the future worker; only the exposure frequencies differ. The hazardquotients and indices for the future visitor are presented in Tables 6-42 and 6-43 for

average and upper 95% exposure concentrations, respectively. The noncarcinogenic riskunder average exposure concentrations is 22, with 97% attributable to groundwateringestion. The total hazard index for upper 95% concentrations is 33, with ingestion of«groundwater accounting for 97% of that total. The carcinogenic risks and riskdistributions for the future visitor are presented in Tables 6-44 through 6-47 for the futurevisitor scenario. The total carcinogenic risk under average exposure concentrations is

3.1E-04 (3 in 10,000), with ingestion of groundwater accounting for 95% of the total risk.The total carcinogenic risk under upper 95% exposure concentrations is 4.6E-04 (5 in

10,000) with groundwater accounting for 95% of the total risk. For the reasonspreviously stated, the degrees of the adverse noncarcinogenic health effects predicted forthis scenario are believed to be overstated because most of the risk is attributable togroundwater ingestion and exposure through this pathway is unlikely.

STAND-CL\STANDJtPT 6~102

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^306132

Hunter/Fisherman Scenario

The hunter/fisherman scenario evaluates the potential for adverse health effects followingexposure to off-site contaminants. In addition to the air and soil exposure pathwaysdescribed above for the preceding scenarios, exposure to surface water and sediment arealso evaluated.

Because of the potential for short-term (subchronic) exposure in the hunter/fishermanscenario, hazard quotients and indices were calculated using daily-averaged doses inaddition to the chronic doses evaluated in all other scenarios. The subchronic hazardindices and quotients for the adult and child hunter/fisherman under average and upper95% exposure concentrations are presented in Tables 6-48 through 6-51.

The adult subchronic hazard indices under average and upper 95% exposureconcentrations are 1 and 2, respectively. The child subchronic hazard indices underaverage and upper 95% exposure concentrations are 3 and 4, respectively. The hazardindices for the adult hunter/fisherman indicate that adverse noncarcinogenic health effectsare unlikely under the defined exposure conditions.

Chronic hazard quotients and indices for the adult and child hunter/fisherman underaverage and upper 95% exposure concentrations are presented in Tables 6-52 through6-55. The adult chronic hazard indices under average and upper 95% exposureconcentrations are 0.8 and 1.0, respectively. The child chronic hazard indices underaverage and upper 95% exposure concentrations are 2 and 3, respectively. Although two

of these values exceed one, because of the margin of safety incorporated in RfDs, adversenoncarcinogenic health effects may not be experienced by the hunter/fisherman under thedefined exposure conditions.

STAND-CLVSTANDJIPT 6-113

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Carcinogenic risks and risk distributions for the adult and child hunter/fisherman underaverage and upper 95% exposure concentrations are presented in Tables 6-56 through6-63. The total carcinogenic risk for the adult under average exposure concentrations is3.0E-05 (3 in 100,000), with dermal contact of sediment representing 42% of the totalrisk. For upper 95% exposure concentrations, the total carcinogenic risk for the adult is5.0E-05 (5 in 100,000) with dermal contact of sediment accounting for 44% of the totalrisk.

The carcinogenic risks for the child under average and upper 95% concentrations are1.4E-05 (1 in 100,000) and 2.3E-05 (2 in 100,000), respectively. Dermal contact of

sediment accounts for 36% of the total risk under average concentrations and 37% underupper 95% exposure concentrations. The carcinogenic risks for the adult and childhunter/fisherman are within the range generally considered by EPA to warrant site

remediation.

6.3.5 Uncertainty Analysis

The principal goal of this uncertainty analysis is to provide the appropriate decisionmakers (i.e. the risk managers) and the public with a discussion of the key assumptionsmade in the risk assessment, as well as other site-specific conditions, that may havesignificantly influenced the estimate of risk. This discussion investigates the sources of

uncertainty, and the affect that they have on the results of the risk assessment.

Uncertainty plays a part in all of the principal components of the risk assessment,

including the contamination characterization, exposure assessment, toxicity assessment,and risk characterization. Thus, the resulting risk estimates are based on a number ofassumptions that incorporate varying degrees of uncertainty resulting from many sources,including (EPA, 1986c):

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• Environmental monitoring and data evaluation,

• Selection of, and assumptions about scenarios of exposure,

• Choice of models for exposure, and input parameters to these models,

* Choice of models for evaluation of lexicological data in dose-response

quantification.

In the absence of empirical or site specific data, assumptions are developed based on bestestimates of exposure or dose-response relationships. To assist in the development ofthese estimates, the EPA recommends the use of guidelines and standard factors in riskassessments conducted under CERCLA. The use of standard factors, principally providedby the EPA, is intended to promote consistency among risk assessments, and therefore

does not necessarily take into account certain site-specific conditions that may exist.Although the use of standard factors no doubt promotes comparability, its ability toaccurately estimate risk is directly proportional to an assumption's applicability to the

actual site-specific condition.

Table 6-64 presents the potential effect that certain assumptions may have on theestimates of risk. The following subsections address those areas of the risk assessmentthat may significantly affect the estimated risk.

6.3.5.1 Contamination Characterization

Two general sources of uncertainty potentially exist in the contamination characterization

that may significantly affect the estimate of risk: 1) the identification of the potentialcontaminants of concern, and 2) the representativeness of the available data to the overallconditions at the site.

STAND-CUSTANDJtPT 6-131

flR306i5l

Table 6-64Effect of Assumptions on Risk

Effect on Risk

AssumptionEnvironmental Sampling) and AnalysisSufficient samples may not have been taken tocharacterize the matrices being evaluated.Systemic or random errors in the chemicalanalyses may yield erroneous data.The risk assessment is based on the chemicalsof potential concern only. These chemicals mayrepresent a subset of the chemicals possible atthe site.The available sampling data is representativeof conditions over the entire site.Exposure Parameter EstimationThe standard assumptions regarding bodyweight, period exposed, life expectancy,(Population characteristics, and lifestyle may notbe repre-sentative for any actual exposure situation.The amount of media intake is assumed to beconstant and representative of the exposedpopulation.The inclusion of groundwater ingestion as apotential future exposure route.Exposure to contaminants remains constantover exposure period.Concentration of contaminants remainsconstant over exposure period.

MayOverestimate

Risk

High

Moderate

Moderate

High

Moderate

Low

MayUnderestimate

Risk

Low

May Over- orUnderestimate

Risk

Low

Low

STAND-CURI-T6-64.TBL 6-132 -- —-

SR306152

KSONERMSKSJUAHTB

List 6-64 (Cont'd.)Effect of Assumptions on Risk

Effect on Risk

AssumptionFor most contaminants all intake is assumed tocome from the medium being evaluated. Thisdoes not take into account other contaminantsources such as diet, exposures occurring atlocations other than the exposure point beingevaluated, or other environmental media, whichmay contribute to the intake of the chemical(i.e., relative source contribution is notaccounted for).Fate and Transport ModelingUse of LAND? model to estimate emissionratesUse of screening model to estimate dispersionToxtcologtca! DataThe cancer potencies used are upper 95percent confidence limits derived form thelinearized multistage model.Cancer potencies and non-carcinogenicreference doses are acceptable intake levelsthat are primarily derived using laboratoryanimal studies and, when available, humanepidemtological or clinical studies. Extrapolationof data from high to tow doses, from onespecies to another, and from one exposureroute to another may introduce uncertainty.In general, conservative assumptions tend tobe used.Not all carcinogenic potencies or acceptableintakes used present the same degree ofcertainty. All are subject to change as newevidence becomes available.

MayOverestimate

Risk

Moderate

Moderate

High

Moderate

MayUnderestimate

RiskModerate

May Over- orUnderestimate

Risk

,1

Moderate

Adapted from ERA, 19S9c.

3TAND-CUR1-T6-64.TBL JT 6-133 __. _

flR306!53

Identification of the Contaminants of Concern

Only those compounds that can be attributed to site-related activities, that are present atlevels above background, and that are significantly toxic at the observed concentrationsshould be evaluated in a risk assessment (EPA, 1989c). Based on discussions with

USEPA and DNREC, a list of potential site-related chemicals were selected for theRemedial Investigation. The following were included as potential contaminants of

concern for the purposes of this risk assessment. ^

• Benzene and chlorinated derivatives (12 total).

• Ethylbenzene.

• Nitrobenzene.

PCBs (7 total).

• Toluene. ._ ~ ...

\The accidental release of chlorinated benzenes at the site in 1981 and 1986 accounts forthe majority of the risk at the site. Only one PCB (Aroclor-1260) was detected at the sitein only one medium, i.e., sediments. There is some uncertainty as to the inclusion of thisPCB as a contaminant of concern at the site, because PCBs were not in widespread use

at the site, nor is there any documentation of PCB releases at the site. However, thecontribution of Aroclor-1260 to the total carcinogenic risk or hazard index was less thanone percent for all of the scenarios. Similarly, toluene and ethylbenzene each contributedless than one percent to the hazard index. As a result, the selection of the contaminantsof concern are not believed to significantly contribute to the uncertainty of the risk

estimates at the site.

STAND-CLSSTAND SPT 6~ 134

AR3Q6I5U

DESG«a$COKSJLT.«!S

Representativeness of Data

The intent of the remedial investigation was to characterize the nature and extent of site-specific chemicals in various media due to the known releases that have occurred at thesite. To achieve this goal in a timely, cost-effective manner, the investigation focused onthose areas of the site that were known or suspected to be affected by chemical releases.The sampled area represents approximately 20 percent of the total site area. In theabsence of a representative sample population (i.e. an equally distributed number of datapoints from all portions of the site), the available data were assumed in the RiskAssessment to be representative of the entire site. This assumption probably results in

an overestimate of risk at the site, since potential receptors may be spending less time inthe sampled areas than in the site as a whole. In addition, some of the soil samples weretaken beneath a gravel railroad bed on the site. It is unlikely that individuals will comein contact with these on-site soils, and thus the use of these soil samples in the riskassessment may potentially overestimate risk.


There are numerous assumptions made in an exposure assessment, including the selectionof exposure routes to be evaluated for each scenario, and the exposure factors (i.e.,contact rates, exposure frequency, body weight) used to estimate exposure doses. Thissubsection discusses, by exposure route, the uncertainties associated with assumptions

used in the risk estimates. The future worker scenario is used as an example, since the

highest risk was calculated for this scenario. However, much of the discussion onuncertainty for the future worker also applies to the other scenarios e.g., soil ingestion,dermal absorption, etc for the current worker, current and future visitor, and thehunter/fisherman.

STANIJ-CLSSTANDJUT 6-135

flR306!55

MSMflSWWOMms

Inhalation of Vapors

As previously mentioned in Subsection 6.3.2, the inhalation of vapors from chemicalcontamination of soils and sediments represents a pathway of potential exposure to humanreceptors. As noted in Subsection 6.2.7, insufficient data, as well as, inappropriate airmodels by which to predict air concentrations are available. Because the inhalation ofsite-related chemical vapors would necessarily increase the receptor dose, one would alsoexpect the estimates of risk to increase. The extent to which vapor inhalation contributesto the carcinogenic and non-carcinogenic risk, however, cannot be estimated at this timeand, therefore, represents a source of uncertainty in this assessment.

Groundwater Ingestion

The groundwater ingestion exposure route accounts for about 97 percent of the totalcarcinogenic risk and 98 percent of the total non-carcinogenic risk for the future worker,

based on upper 95 percent exposure concentrations. The ingestion of groundwater alsoaccounts for the majority of risk in the future visitor scenario. The ingestion of

groundwater is assumed to occur from the shallow aquifer, the Columbia Formation.However, it is highly unlikely that the Columbia Formation would actually be used as asource of drinking water at SCO for the following reasons:

• SCD and the surrounding area already obtain water from a public water

supply company utilizing sources other then the Columbia Formation.

• The yield from the Columbia Formation is too low to meet the needs of

an industrial client.

* A reliable source of potable groundwater is available in the deeper

Potomac Formation.

STAND-CDSTAND.RPT 6-136 - .

SR306I56

Thus, including exposure through the ingestion of groundwater from the ColumbiaFormation, in all likelihood, overstates the potential future risks at the site.

Soil Digestion "

Under the future worker scenario, it is assumed that the average adult ingests 100 mg/dayof soil, and that one-half of that ingestion (50 mg/day) occurs at the site. The most recentEPA guidance also suggests that 50 mg/day is a reasonable maximum estimate of theamount of soil a worker would ingest in an industrial or commercial setting (EPA,1991b). However, direct contact with the soil in some of the on-site affected areas isimprobable due to existing structures (i.e., the gravel railroad bed covers a portion of the1981 release pathway). This may reduce the amount of contaminated soil that is ingested,resulting in a lower risk estimate for the soil ingestion route.

Dermal Absorption

The future worker scenario assumes a year-round exposed skin surface area of 3120 cm2,based on exposed arms and hands (USEPA, 1990). It is likely that during the colder six

months of the year, only the hands would be exposed. In addition, it is likely thatexposure occurring to the arms would be limited to the forearms. Recalculation of themean surface area accounting for cold weather conditions results in a mean surface areaof 820 cm2 (i.e., hands only). Using this value in estimating dermal absorption wouldresult in a lower estimate for the dermal absorption dose. The effect of this assumptionin the overall estimate of carcinogenic and non-carcinogenic risk is presented in theSensitivity Analysis at the conclusion of this section.

In addition to the uncertainty associated with the estimate of the surface area of exposedskin, the question of dermal permeability, i.e., the amount of chemical capable of beingabsorbed through the skin, is another source of uncertainty. USEPA Region 1 hasdeveloped relative absorption factors for classes of soil contaminants through the dermal

STAN&CDSTAND.RPT ' 6-137

flR306i57

pathway. The relative absorption factor refers to the fraction of a chemical which aftercontact, is likely to be absorbed through the skin relative to the absorption of thecompound in a laboratory study from which the cancer potency factor or reference dosewas derived. Contaminants adsorbed onto soils and sediments are presumed to be lessavailable for dermal absorption than pure compounds or solutions. To account for thesedifference, the USEPA Region 1 has developed relative absorption factors that can beused for assessing dermal absorption of contaminants from soils when data on dermalabsorption from soils is not available. These relative absorption factors that can be usedfor dermal contact with soils are as follows (USEPA, 1989).

Volatile Organic Compounds: 50%

Semi-volatile Organic Compounds:PAHS: 5%PCBs: 5%Pesticides: 5%

-high sorption to soils: 5%(e.g., chlordane ODD, DDT)

-low sorption to soils: 50%

(e.g., lindane, acrolein)

Inorganics: negligible

As previously discussed (Subsection 633.2), volatile organic compounds are consideredto be those organics for which the vapor pressure is greater than 100 mm Hg and forwhich Henry's Law Constant is greater than 10"4 atm-m3/mole (Smith, 1991). Some

disagreement exists within the EPA as to the status of chemicals that fit one criterion butnot both. For example, although the vapor pressure of 1,4 dichlorobenzene is about 1.2

mm Hg and is clearly below 100 mm Hg, its Henry's Law Constant is 2.89 E-03 atm-nvVmole which is well above 10"4 atm-m3/mole (EPA, 1986). Further, although the EPAsQuality Criteria for Water 1986 clearly defines 1,4 DCB as a volatile organic compound,

the EPA's Analytical Contract Laboratory Program defines; 1,4 DCB as a semi-volatile •

STAND-CL\STAND.RPT ' 6-138 - .... - --"- - _ _ _ . . . . . .

AR306I58

organic compound (EPA, 19%). For the purpose of this assessment, 1,4 dichlorobenzene,as well .as other compounds fitting this description, principally the dichlorobenzenes and

trichlorobenzenes, were treated as semi-volatiles.

In addition, because the organic carbon partitioning coefficient is relatively high for thedichlorobenzenes and the trichlorobenzenes (K = 1,700 to 2,900) in comparison withsuch volatile compounds as benzene (K s= 83) and since much of the site consists oforganically rich soils and sediments, the relative absorption factor selected for use withthe semi-volatiles in this assessment was 5%. It should be noted, however, that althoughEPA guidance defines the absorption factors as either 50% or 5% depending onclassification, the actual relative absorption of some of the compounds may residesomewhere between these factors. The extent of this uncertainty is unknown.

Also, as discussed under the soil ingestion route, the potential for contacting soilscontaining site-specific chemicals at the SCD site may be reduced due to the railroad bedwhich covers a portion of the 1981 release pathway.

Similar uncertainty exists for dermal exposure to the hunter/fisherman. Chemicalconcentrations used in assessing risk through the dermal pathway were derived from soiland sediment samples collected in areas specifically thought to be contaminated. For off-

site exposure, the area from which most samples were collected, as well as that havingthe highest chemical concentrations was the unnamed tributary adjacent to the facility.Consequently, the derived average and upper 95% C.I. concentrations us l to determinedose reflect this bias. Since the unnamed tributary comprises only about 6% of the off-site area, it is likely that a hunter/fisherman would be exposed to much lower levels of

contamination. In addition, the majority of the fishing activity occurs at the Route 13 andRoute 9 bridges where they cross Red Lion Creek. Similarly, hunting activity would beexpected to occur in the upland regions away from the wetlands. Thus, it is likely thatthe risk to the hunter/fisherman is over-estimated.

6-139 - - — -

/IR306I59

6.3.5.3 Toxicitv Assessment

There is a great deal of uncertainty in the development of both non-carcinogenic andcarcinogenic health criteria (i.e., RfDs and CSFs). In many cases, toxicity data isextrapolated across species, as well as from high to low doses, in order to estimate safeexposure levels for humans. = ,

Reference Doses -i

In the development of RfDs it is assumed that a threshold dose exists below which thereis no potential for adverse health effects. In general terms, the RfD is derived from a

NOAEL (no-observed-adverse-effect level) or a LOAEL (lowest-observed-adverse-effectlevel) by the application of uncertainty factors of 10 each, and a modifying factor of upto 10 which accounts for a qualitative professional assessment of additional uncertaintiesin the available data (EPA, 1989c). In most cases, the application of numerousuncertainty factors is likely to result in an RfD that is overly protective.

Cancer Slope Factors

In the development of CSFs the EPA uses a nonthreshold theory in which it is assumedthat even a small number of molecules (possibly even a single molecule) of a carcinogenmay cause changes in a single cell, eventually resulting in cancer. The CSFs are usuallyderived by EPA using a linearized multistage model, and usually reflect the upper-boundlimit of the potency of the chemical. As a result, the calculated carcinogenic risk is likelyto represent an upper limit to the risk. The actual risk is unknown, but is likely to belower than the calculated risk (EPA, 1986a; EPA, 1989c)s and niay even be as low aszero.

STAND-CLVSTAND.RPT " 6-140

-"-;•- An 306 I 60

For the future worker, approximately 41 percent of the total carcinogenic risk can beattributed to 1,4-dichlorobenzene (1,4-DCB), based on upper 95 percent exposureconcentrations. EPA currently classifies 1,4-DCB as a Class C carcinogen, i.e., a possiblehuman 'carcinogen, based on limited evidence in animals in the absence of human data.1,4-DCB has been shown to be carcinogenic in animal studies following oraladministration, but not following long-term inhalation (ATSDR, 1989). Thus, it ispossible that the potential cancer risk from exposure to 1,4-DCB at the site may be lowerthan the calculated risk.

6-3.5.4 Risk Characterization

The primary source of uncertainty in the risk characterization involves the inhalation ofvolatilized contaminants from soils and sediments affected by the spills mat occurred in1981 and 1986. It is difficult to characterize risk associated with inhaling volatilizedcontaminants because accurate predictive models do not exist and SCD is an activefacility that routinely generates a small amount of emissions through their productionprocesses. Measuring existing air concentrations would be difficult because the routinefacility emissions would compound the results of ambient monitoring data therebyresulting in artificially elevated risk levels. Nevertheless, inhalation of volatilized

contaminants from soils and sediments and possibly groundwater affected by previousspills would necessarily increase total exposure of potential receptors and resultant risk.The extent to which this risk contributes to the overall site risk cannot be adequatelydefined at this time.

6.3.5.5 Sensitivity Analysis

This subsection discusses the specific routes of exposure and associated parameter valuesthat were observed to have the most significant influence on the resultant estimates ofrisk. The purpose of this analysis is to complement the uncertainty analysis bydemonstrating quantitatively the range of risk under specified conditions such that the risk

STAND-CDSTANDJtPT 6-141

flR306!6l

(SSIGN0&CON3U.TIWTS

managers, the decision-makers, and the public can interpret.the results as objectively aspossible. Since it is extremely cumbersome to attempt to evaluate all of the numerousparameters and assumptions used throughout the assessment, the approach taken is toevaluate only those parameters likely to have a significant impact on the risk estimates*

Tables 6 -65 and 6-66 summarize the contribution of the individual routes of exposure tothe total carcinogenic and non-carcinogenic risk for each exposure scenario. Theinformation is presented graphically in Figures 6-6 and 6-7.

For the future worker scenarios, groundwater ingestion as a. route of exposure contributedabout 97 percent of the total carcinogenic risk and 98 percent of the total non-

carcinogenic risk, based on the upper 95 percent exposure concentrations. Moreover, forthe future visitor, groundwater ingestion accounted for 95% of the total carcinogenic risk

and 97 percent of the total non-carcinogenic risk. ....,......_

For the current worker and visitor scenarios, dermal contact with soils dominates thecarcinogenic (82% of the total) and non-carcinogenic risk (84% of the total) based on theupper 95% exposure concentration.

In the scenario for the hunter and fisherman both, the carcinogenic and non-carcinogenicrisk is dominated by the dermal absorption of chemicals from sediments and soils. Therisk to the hunter/fisherman due to dermal contact represents about 75% of the totalcarcinogenic risk and 74% of the total non-carcinogenic risk at the upper 95% confidencelimit concentration.

Therefore, based on the key contributors to the overall risk for each of the scenarios, thefollowing assumptions are varied in the sensitivity analysis.

STAND-CLNSTAND.RPT 6-142 - _ - , , , = _

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CONTACTSEDIMENT DERMALCONTACTNnmbers indicate ccmtribnttry

Careanogenic Risk

AVERAGE UPPER 95HUNTER/FISHERMAN

FIGURE 6-6 PRINCIPAL PATHWAYS CONTRIBUTING TO THECARCINOGENIC RISK

STCHRA22-PAJI

6.145 AR306I65

E3 SOIL DERMAL CONTACT-ED SOU, DUST INHALATIONIB GROUND WATER INGESTION

plumbcn indicate con tributary______Hazard fade*Zo

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r PERCENT CONTRIBUTION TO

HAZARD

INDICES

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Hazard Index

AVERAGE UPPER 95

FIGURE 6-7 PRINCIPAL PATHWAYS CONTRIBUTING TO THENON-CARCINOGENIC HAZARD INDICES

6-146 fiR306i66

KSGWRSWSUUJWTS

Groundwater Consumption - Under the scenarios for future use, it wasconservatively assumed in die baseline assessment that both future workersand future visitors may possibly consume water from a well finished in theshallow Columbia Formation underlying the site. The uncertaintyassociated with this assumption has been discussed previously. For thesensitivity analysis, it was assumed that future workers and visitors wouldconsume water from an alternative water supply such as that whichcurrently exists, and therefore, no consumption of contaminatedgroundwater would occur.

Tables 6-67 and 6-68 present the results of the sensitivity analysis forvarious key assumptions used in the Risk Assessment.

Dermal Absorption - The dermal pathway for the current and future

workers assumes a total surface area contact rate of hands and arms (3,120cm2). Although this may be realistic for warm-weather conditions, itprobably overestimates dermal exposure in the cold weather months.Consequently, the sensitivity analysis evaluates dermal exposure throughcontact with hands only, which represents a total surface area of 820 cm2.In addition, since most hunting occurs in the cooler autumn months whenit is unlikely that legs and arms would be exposed, an evaluation ofexposure to hands only for the hunter/fisherman is also conducted. Note

that the exposed surface area for arms, hands, and legs is 8,620 cm2.

Similarly, the reduction in risk to a child associated with changes in totalexposed surface area was also evaluated.

STAND-CLNSTANDJlFr 6-147

AR306I67

OESCHEBSOKSJlTWrS

TABLE 6-61RANGE OF TOTAL CARCINOGENIC ftlSK ESTIMATES

Based on Variations of Key Assumptions

Groundwater

FutureWorker

FutureVisitor

Average

U95%

Average

U95%

Risk AssumingGroundwater Consumption

3.00E-03

4.50E-03

3.G7E-04

4.62E-04

Risk Assuming noGroundwater Consumption

7.00E-05

1.20E-04

1.40E-05

2-40E-05

% Change inTotal Risk

-98%

-98%

-95%

-95%

Dermal Absorption

CurrentWorker

FutureWorker

Average

U95%

Average

U95%

Risk Assuming Exposure toHands and Arms

7.I3E-05

1.22E-G4

3.00E-03

4.50E-03

Risk Assuming Exposure toHands only

1.8SE-05

3-21E-05

7.89E-04

U8E-03


-74%

-74%

-74%

-74%

•

Hunter/Fisherman(Adult)

Hunter/Fisherman(Child)

Average

U95%

Average

U95%

Risk Assuming Exposureto Legs, Hands & Arms

2.03E-05

3.81E-05

1.36E-05

2.34E-Q5

Risk Assuming Exposure toHands Only

1.93E-06

3.62E-06. .

9.71E-07

2.46E-06


-90%

-90%

-90%

-90%

* - Includes soil, dust and sediments.

STAND-CL\R1-T6-67.TBL 6-148 , mr\r\r\r>lfr*.flR306 i 68

TABLE 6-68RANGE OF TOTAL NON CARCINOGENIC RISK ESTIMATES

(Chronic Hazard)Based on Variations of Key Assumptions

Groundwater Consumption

FutureWorker

FutureVisitor

Average

U95%

Average

U95%

Risk AssumingGroundwater Consumption

2.10E+02

3.29E+02

2.13E+01

334E+01

Risk Assuming noGroundwater Consumption

4-OOE-fOO

5.00E+00

7.00E-01

l.OOE-01


-99%

-99%

-97%

-97%

Dermal Absorption

CurrentWorker

FutureWorker

Average

U95%

Average

U95%

Risk Assuming Exposure toHands and Arms

3.20E+00

5.28E400

2.10E+02

3.29E4O2

Risk Assuming Exposure toHands Only

8.42E-01

1.39E-KX)

5.52E+01

8.65E+01


-74%

-74%

-74%

-74%

Hunter/Fisherman(Adult)

Hunter/Fisherman(Child)

Hunter/Fisherman(SubchronicHazard)

Average

U9596CL

Average

U95%

Average

U95%

Risk Assuming Exposureto Legs, Hands & Arms

7.46E-01

132E4OO

L85+00

33400

2.59EOO

4.44E-KK)

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7.10E-02

1.25E-01

1.94E-01

3 0E-01

l.OOE+00

1.73E+00


-90%

-90%

-90%

-90%

-61%

-61%

* - Includes soil, dust and sediment

STAND-CLNRl .76-6*.TBl. 6-149 AR306I69

KSKWERSffiXSULTJWIS

6.4 ECOLOGICAL RISK ASSESSMENT

6.4.1 Introduction

The purpose of this ecological risk assessment is to characterize the environmental risksand impacts associated with the chemicals of concern at the Standard Chlorine site. This

evaluation focuses on identifying potential adverse effects of the chemicals of concern on

the flora and fauna in the area. _

The process used to evaluate ecological risk approximately parallels that for evaluatinghuman health risk. In both cases, Tthe integration of information on chemical exposures

with toxicity data for the chemicals of concern is used to estimate the potential risk fromthat exposure. Consequently, the principal tasks for this ecological assessment includethe following: r : :L

• Selecting chemicals of concern. ^

• Analyzing environmental receptors/pathways.

• Estimating exposure point concentrations and doses.

• Identifying environmental toxicity.

• Characterizing ecological risk.

The primary technical guidance for the performance of this ecological risk assessmentcomes from the following sources:

• Ecological Risk Assessment (EPA, 1986a).

• Ecological Assessment of Hazardous Waste Sites: A Field and Laboratory

Reference (EPA, 1989a).

STAND-CDSTANDJRPT 6-150 - , '

BESJCNEftS'CCtlW.MWS

• Risk Assessment Guidance for Superfund - Volume n, Environmental

Evaluation Manual (EPA, 1989d).

• User's Manual for Ecological Risk Assessment (Oak Ridge National

Laboratory, 1986).

In addition to the published guidance, this ecological risk assessment is also beingconducted in accordance with a previously submitted and reviewed workplan for theperformance of this assessment (WESTON, 1991) (Attachment 2). This workplan wasreviewed by the EPA (Region 3), the Delaware Department of Natural Resources(DNREC), and the National Oceanic and Atmospheric Administration (NOAA). Agency

comments were reviewed and incorporated in this assessment.

The subsections that follow describe the approach used to evaluate potential

environmental impacts associated with chemicals that have migrated from the StandardChlorine site. This assessment focuses on environmental receptors that may be affecteddirectly or indirectly by chemicals associated with the site, and the likelihood and extentof those effects.

6.4.2 Chemicals of Potential Concern

The selection of potential chemicals of concern is a screening process that is used toreduce the number of chemicals requiring detailed evaluation in the ecological riskassessment Subsection 6.2.1 describes the selection process used for both the humanhealth and ecological risk assessment, and provides reasoning for eliminating chemicalsfrom further evaluation.


flR306!7l

In general, chemicals of potential concern were selected based on their frequency ofdetection, environmental toxicity, and physical and chemical parameters affecting

environmental mobility and persistence. Chemicals of potential concern for the ecologicalassessment in surface waters, soil, sediment and fish tissue are presented in Table 6-7.Groundwater at the Standard Chlorine site discharges to Red Lion Creek, therefore surfacewater concentrations in Red Lion Creek reflect the chemical contribution of thegroundwater.


An ecological exposure assessment evaluates the potential magnitude and frequency by

which chemicals from the site migrate through various pathways to affected terrestrial,aquatic, and/or wetland habitats. In addition, the assessment evaluates all routes ofexposure (e.g. water, soil, sediment, plant, and fish ingestion) by which species inhabiting

those areas may be exposed. The specific objectives of the exposure assessment are to:

• Identify habitat types that have received or may receive chemicals from the

Standard Chlorine site.

• Identify the plants, fish, and/or wildlife that may be potentially exposed to

the chemicals of concern.

• Select indicator or target species.

• Identify significant pathways/routes by which target species are potentially

exposed. . . . . . . . . _ . . . . . _ .

• Predict exposure concentrations or body burdens of chemicals whenever

measured tissue concentrations are unavailable.

STAND-CLNSTANDJtPT 6-152 ....... . . .

flR306f72

MSGNSBCCHSU.TANTS

Consequently, the first step of any exposure assessment is to identify both the potentiallyaffected habitats and the target species within each of these habitats.

6.43.1 Ecological Setting

The terrestrial and aquatic communities in the vicinity of Standard Chlorine along RedLion Creek and its tributary were investigated by Roy F. Weston, Inc. (WESTON) inDecember of 1989 and September of 1991. These investigations were performed as partof the Remedial Investigation in support of the ecological risk assessment. Thecommunities investigated are described in detail in Subsection 5.4. A list of the speciesobserved or expected to occur in the vicinity of the site is presented in Table 6-69.

Endangered, Threatened, or Special Concern Species and Communities

Table 6-70 presents a list of the threatened and endangered wildlife species for the stateof Delaware. This list is currently being revised and updated by the Delaware Divisionof Fish and Wildlife. None of the wildlife species listed have been observed or areexpected within the Standard Chlorine site vicinity.

Heron Rookery

A heron rookery, approximately one to two miles east of the Standard Chlorine site, islocated on the northern side of Pea Patch Island (90 acres) in the Delaware River, directlyacross from Red Lion Creek. It is probably the largest heron rookery in the northeasternUnited States (Fleming, 1978). As of 1976, more than 7,000 pairs of wading birds werefound to be nesting on the island. The island serves as a post-breeding roosting area forsome of the birds. During the breeding season, some species may travel distances up to40 miles in search of food in times of short supply. There is considerable post-breeding

STAND DSTAND PT 6-153

flR306!73

Table 6-69WUdUfe Species Observed or Expected to Occur

^ ISif iiiSlliiSiHiBirdsGreat EgretDouble Crested CormorantKiiideerCatbirdRed-winged BlackbirdTree SwallowRuby-throated HummingbirdStarlingTurkey VultureKestralMarsh HawkGreat Blue HeronMallardGreater Yellow LegsSwamp SparrowMourning DoveCommon GrackleRock DoveRoyal TernWhite-eyed VlreoGullRed-tailed HawkBlue JayMocking BirdWhite-throated SparrowYellow WarblerBlack-capped ChickadeeCommon Yellow ThroatField SparrowPewoeNorthern CardinalCommon Flicker

MammalsWhite-tailed DeerGround HogFoxRaccoonGray SquirrelMuskrat

Amohibians/ReotilesPainted TurtleTadpoles

FjshMosquitofishCarpSun fishCatfish

Casmerodius albusPhalacrocorax auritosCharadrius vociferusDumetella carottnensisAgelaius phoenlceusIridoprocne bicolorArchiiochus colubrtsSturnus vuigarisCathartes auraFalco sparveriusCircus cyaneusArdea herodiasAnas platyrhynchosTringa malanoieucaMelospiza georgianaZenaida macrouraQuiscalus quisculaColumba tiviaSterna maximaVireo griseusLarusspp.Buteo jamaicensisCyanocitta cristataMimus pofygtottosZonotrlchia albicoliisDendroica petochiaParus atricapilfusGeothlypis trtchasSpizQila pusillaContopus vitensCardinalis cardinal/sColaptes auratus

Odocoileus virginianusMarmota spp.Vulpesspp.Procyon lotorSciurus carolinensisOndatra zibethicus

Chrysemys spp.

Gambusia affinusCyprinusspp.Lepomis spp.Ictalurus spp. ...._._

Bi

XXXXXXXXXX

X

X

XXXXXXXXXXX

XX

XXX

XX

XXXX

ffiS

XXXXXXXXXX

X

X

XXXXXXXXXXX

XX

XXX

XX

XXXX

X

X

X

XXXXXXXXXXXXX

XXX

XXX

1 C/f

Table 6-70

Endangered and Threatened Species List for the State of Delaware

Common Name .

Delmarva Fox SquirrelSperm WhaleBlue WhaleRnback WhaieSei WhaleHumpback WhaleRight WhaleHawksbill Sea TurtleLeatherback Sea TurtleKemp's Ridley Sea TurtleTiger SalamanderBog TurtleCope's Gray TreefrogBarking TreafrogBald EaglePeregrine FalconBrown PaiicanShortnose SturgeonPiping PloverGreen TurtleLoggerhead Turtle

. . ," •,,. Sdirtfiflc -Naiii| ||gi:•:• *:,;X-:*x-:-:v:-A':::::;.-::

Sciurus niger brant/Physeter catodonBalaenoptera musculusBalaenoptera physalusBalaenoptera borealisMegaptera novaeangliaeEubalaena spp.Eretmochelys imbricataDermochelys coriac&aLepidochelys kernpiiAmbystoma tigrlnumClemmys muhlenbergilHyla chrysoscefisHyla gratiosaMali aeetus feucocephalusFalco peregrinusPelocanus occid&ntalisAcip&nser brevirostrumCharadrius melodusChQlonia mydasCatena caretta

Status

E*E*E*E*E*E*E*E*E*E*EEEEE*E'E*E'TTT

E-lndugind

T-Thi»»ttn»d

6-155AR306I75

wandering, particularly in a northerly direction. Because of the proximity of this rookeryto Red Lion Creek and its tributaries, it was assumed thai: birds from this island couldobtain a portion of their diet from the Standard Chlorine site.

6.4.3.2 Pathways of Potential Exposure _;;:_

This subsection presents the selection of potential exposure pathways for the ecologicalrisk assessment at the Standard Chlorine site. It eliminates those pathways and exposureroutes that are not of concern based on the analysis of site characteristics. The principal

factors included in the pathway selection process include: ?

• Local topography.

• Local land use.

* Surrounding terrestrial habitat

• Surrounding aquatic/wetland habitat

• Evaluation of chemical migration.

* Persistence and mobility of migrating chemicals.

There are five environmental media by which receptors may contact chemicals ofpotential concern present at the Standard Chlorine site, these include: surface water,surface soils, sediments, fish tissue and vegetation. Exposure to chemicals of potentialconcern in these media may occur through several routes including:

* Ingestion of surface water.

* Ingestion of soil/sediment

• Ingestion of fish.

* Ingestion of vegetation.

STAND-CDSTAND.RPT 6-156 1 17! "\=.__ -1

: ftR306!76

Conceptual diagrams of the potential chemical transport pathways, the routes of exposure,and target species selected are presented for the aquatic and terrestrial habitats for the sitein Figures 6-8 and 6-9, respectively. Actual chemical transport pathways, routes ofexposure and target species selected for this aquatic and terrestrial ecological evaluationare presented in Figures 6-10 and 6-11, respectively.

6.433 Selection of Target Species

The following presents the rationale incorporated in the selection of target species for theStandard Chlorine site. The principal criteria used to select appropriate target species(States et al., 1978) include:

* Species that are threatened, endangered or of special concern.

* Species that are valuable for recreational purposes.

• Species that are important to the well-being of either or both of the above

groups.

• Species that are critical to the structure and function of the particular

ecosystem in which they inhabit

* Species that serve as indicators of an important change in the ecosystem.

• Species for which appropriate toxicity values currently exist or can be

readily derived.


AR306I77

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6-161

6.43.3.1 Terrestrial Habitat

Terrestrial Vegetation

The phytotoxic potential of site-related chemicals identified in the soil was initiallyevaluated by comparing observed soil concentrations to soil concentrations or applicationlevels reported in available published scientific reports at which adverse effects to plants(e.g., necrosis, chlorosis, and reduced growth) have been observed. However, due to thelack of available phytotoxicity data for site-related chemicals, a more definitive seedgermination study was conducted. Lettuce seeds (Lactuca sdtiva) were exposed to soiltaken from the site. These soils contained a range of site-related chemical concentrationsand were evaluated to determine the extent to which the site-related chemicals inhibitedgermination of the seeds.

Soil Fauna

Toxicity data pertaining to the effects of site-related chemicals to soil fauna were foundto be limited in the literature. To evaluate the potential toxicity of site-related chemicalsin the soil, toxicity tests were performed on earthworms (Eiseniafoetidd) using soil takenfrom the site. The soils contained a range of site-related chemical concentrations. Thedata were evaluated to determine the extent to which the chemicals resulted in significantmortality of the earthworms.

Amphibians and Reptiles

Although the presence of several amphibian and reptile species is known or expected

(Table 6-69), there is insufficient information available in the toxicological literature toadequately address the risk potential associated with exposure to the chemicals from theStandard Chlorine site. Therefore, no further assessment of the potential risk to theseorganisms was performed. r- -——-

STAND-CLNSTANDJiPT 6-162 flR3Q6!82

Avian

Birds which ingest fish in the site vicinity may potentially be exposed to chemicals whichare present in the surface waters. A piscivorous avian species was chosen for evaluationin this assessment since they occur in the area (Table 6-69), and based on their fish-eatinghabits, are expected to represent a maximum-plausible exposure scenario for thebioaccumulation of chemicals from the site.

The greatest exposure to avian species is expected to occur in the wetlands and Red LionCreek and therefore is discussed in greater detail in the "Aquatic/Wetland Habitat"section.

Mammals

Exposure to mammals may occur when they feed in those areas affected by chemicalsfrom the site. The habitat surrounding the Standard Chlorine site provides substantialcover and undergrowth to support a wide variety of wildlife. A partial list of mammalscommonly observed or expected to occur on-site has been provided in Table 6-69.

Based on several site surveys it was evident that white-tailed deer, Odocoileus

virginianus, is a prevalent mammalian species at this site. For this assessment, the white-tailed deer was chosen as a target mammal species for the following reasons:

• They are year-round residents in the area (Table 6-69).

* They are valuable for recreational purposes (Le. harvesting and

aesthetics).

STAND-CL'StAND.RPT 6-163

AR306I83

• They are often critical to the structure and function of an ecosystem by

regulating the rate of succession in a terrestrial ecosystem.

• They are potentially exposed to site-related chemicals through ingestion of

browse, sediment and surface water.

The methodology and processes by which the total exposure dose to white-tailed deer iscalculated are presented in Subsection 6.4,3,5. A summary of appropriate ecologicalinformation for the white-tailed deer is provided in Appendix H of this report.

The meadow vole (Microtus pennsylvanicus) was also evaluated as a target species. The

meadow vole was chosen due to its herbivorous diet and its presence as a year-roundresident. In addition, the meadow vole may be one of the most important as well as themost preferred prey item by many of the secondary consumers expected at the site(Chapman and Feldhammer, 1982). The meadow vole will be evaluated for exposurethrough the ingestion of soil, vegetation and surface water. For this assessment, suitablemeadow vole habitat characterized by contamination is restricted to the area above thedike. The methodology and processes by which the total exposure dose to the meadowvole is calculated are presented in Subsection 6.4.3.4.

6.4.3.3.2 Wetland/Aquatic Habitat

Water Column Flora/Fauna

The aquatic life of the area surrounding the Standard Chlorine site was described inSubsection 6.4.3.1. Several species of fish have been identified in addition to amphibianand reptile species (Table 6-69). Wetland plant species identified are described inSubsection 6.4.3.1.

STAND-CLSSTANDJIPT 6-164

J: ftR306!8H

KsertHS.coN3U.Twns

The transport and fate of chemicals migrating from the Standard Chlorine site via surfacewater runoff, groundwater discharge, or air transport of dust or vapors, may potentiallyresult in the exposure of flora and fauna that inhabit these surface waters. It was notnecessary to select target species for aquatic systems since the potential for adverseeffects was assessed using available criteria. The State of Delaware and the EPA (RegionHI) have developed ambient water quality criteria (AWQC) for the protection offreshwater aquatic life. Comparison of surface water concentrations with these criteriawas used to assess the likelihood of adverse effects to aquatic life.

Sediment Flora/Fauna

In order to assess the potential adverse effects to aquatic life from exposure to sediments,chemicals of concern identified in the sediments were compared with the results of site-specific sediment toxicity bioassays using the benthic amphipod, Hyallela azteca.

Avian Species

Piscivorous avian species either known to exist or possibly occurring within the area ofthe Standard Chlorine site include various species of herons, egrets, and ducks, as well

as kingfishers and osprey. The great blue heron, Ardea herodias, was chosen as a targetspecies for several reasons. The vicinity of the Standard Chlorine site is much moresuitable' for a wading, fish-eating bird like the heron as opposed to a kingfisher whichprefers wooded areas and the flowing water of smaller streams.

Habitat information is available for the great blue heron for evaluation in an ecologicalassessment A summary of appropriate ecological information for the great blue heronis provided in Appendix I of this report The heron plays an important role in thestructure and function of the aquatic habitat located at this site. In addition, Pea Patch

STANr CDSTANDJRPT 6~ 165

AR306I85

Island heron rookery, a unique breeding area of national significance, is located in theDelaware River, directly across from Red Lion Creek. Heron from the rookery are likelyto obtain a portion of their diet from Red Lion Creek. :

6.4.3.4 Exposure Estimation

This section discusses the methods by which chemical intakes were estimated for theselected target species chosen for evaluation in Subsection 6.4.3.3. The models used toestimate exposure doses in milligrams of chemical intake per kilogram of body weightper day (mg/kg-day) are presented here. The estimation of doses for aquatic life andvegetation was not necessary since media (i.e., water, sediments, and soils) concentrationspresented in Subsection 6.2 were used to assess potential effects on these organisms. Inaccordance with the Risk Assessment Guidance for Superfund (EPA, 1989d), the upper95% confidence limit of the arithmetic mean of the concentrations (or the maximumconcentrations, if lower) in each media were used as the reasonable maximum exposureconcentrations for use as input values into dose models, or for comparison with criteria.•

In addition, the arithmetic mean concentrations were used to evaluate an averageexposure.

White-Tailed Deer (Odocoileus vireinianus)

White-tailed deer were assumed to be exposed to chemicals of concern through ingestingchemicals contained in sediment (incidental) as well as in browse, and drinking thechemicals concentrated in surface waters in the vicinity of the Standard Chlorine site.

The models by which the dietary exposure of white-tailed deer to site-related chemicalswas estimated are presented.

STAND-OLNSTANDJUT 6-166

OBJGNEftS'COtJSUlWITS

Ingestion of Chemicals in Sediment

The equation and assumptions that were used to estimate doses to deer through theingestion of sediment are presented in Table 6-71. The mean and upper 95% estimateddaily intake (EDI) of chemicals by deer due to sediment ingestion is presented in Tables6-72 and 6-73, respectively.

As determined in previous studies, incidental soil ingestion rates of deer vary seasonallyand range from 7.7 g/day in summer to 29.6 g/day in spring. Based on these soilingestion rates, an average ingestion rate of 16 g/day has been suggested (ICF/Clement,1988). Due to the lack of sediment ingestion data in the literature, the value for soilingestion was applied to the sediment ingestion rate used in the white-tailed deer exposureevaluation. Home ranges for white-tailed deer reported in the literature vary considerablyand are dependent on the quality of habitat Values as low as 40 acres for areas of highquality (Banfield, 1974), and values as high as 672 acres for areas of low quality (Nelsonand Mech, 1981) have been reported. Based on this information, it was assumed that thearea available to the white-tailed deer for forage was of moderate quality, thus, the homerange of the deer was expected to lie toward the lower acreage estimates (-200 acres).However, based on known habitat conditions and available contaminant information, only12 acres on-site, (where contamination has been documented), were included in theestimate of exposure to the white-tailed deer. This represents about 6% (i.e., 12/200) ofthe forage range previously described. This area was located in the downstream segmentof Area 1 and consisted of approximately 12 acres of herbaceous-type vegetation suitablefor forage. For the purposes of this ecological assessment, it was assumed that the white-tailed deer would obtain 3% of its daily forage intake from within the 12 acre vicinity.

Approximately 70% of the vegetation within the 12 acres of concern consists of thecommon reed, Phragmites, which is not a preferred food of the white-tailed deer. Thepercentage of daily forage intake from within the 12 acre vicinity was derived based onthe dominant occurrence of Phragmites and the availability of more nutritious forage inthe nearby upland areas and soybean and corn fields. The remaining daily forage intake


/1R3G6I87

Table 6-71

Model for Calculating Doses to White-Tailed Deer Through theIncidental Ingestion of Sediment

Where:CSSIRBWFI

Sediment Ingestion Dose CS * SIR * FT(mg/kg/day) = BW

-

= Chemical concentration in surface sediment (ing/kg)= Sediment ingestion rate (kg/day)= Body weight (kg)= Fraction ingested

•kExposure Assumptions™ *CS - Surface sediment exposure concentrations presented in Subsection 6.2

SIRBWFI

= 0.016 kg/day (ICF/Ciement, 1988)= 50 kg, average weight of an adult white-tailed deer (Doutt et al.,= 0.03 -^ -

1977)

6-168

(97%) was assumed to be from upland areas within the site vicinity and from theneighboring farmlands outside of the vicinity of the Standard Chlorine site.

Ingestion of Chemicals in Browse

The mean and upper 95% estimated daily intake of chemicals by deer due to browseingestion are presented in Tables 6-72 and 6-73, respectively. The equations andassumptions that were used to estimate the doses to deer through the ingestion of browseare presented in Table 6-74.

Dose estimates through the ingestion of browse (i.e., vegetation) were determined byapproximating the uptake of chemicals from sediments into plants, and multiplying thesevalues by the amount of plant material estimated to be consumed daily by deer. Theconcentrations of organic chemicals in plants were calculated using the following equation(Travis and Arms, 1988):

^pi s Qoa -"v

Where:Cp, = Chemical concentration in plant (mg/kg dry weight).Qoji t = Chemical concentration in sediment (mg/kg).Bv «= Plant uptake factor (chemical-specific factor for foot absorption

and translocation to the edible portion of the plant).

The uptake factors (ByS) for 29 organic chemicals into vegetative plant parts have been

compared via regression to the octanol-water partition coefficients (Kow) for those

substances (Travis and Arms, 1988). The comparison established the followingrelationship:

6-169

flR306i89

Table 6-72

Summary of Mean Estimated Daily Intakes for White-Tailed Deer(mg/kg-day)

fiihsitiHil 1 ill Iln 1 11BenzeneChlorobenzene1 ,2-Dichlorobenzene1 ,3-Dichlorobenzene1 ,4-DichlorobenzeneEthylbenzeneHexachlorobenzeneMetachloronltrobenzeneNitrobenzenePCBAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248ArocIor-1254Aroclor-1260Pentachlorobenzene1 ,2,3,4-Tetrachlorobenzene1 ,2,4,5-TetrachlorobenzeneToluene1 ,2,3-Trichlorobenzene1 ,2,4-Trichlorobenzene1 ,3,5-Trichlorobenzene

S Kientll;jr|Djestk>n

6.72E-051.08E-038.64E-043.07E-043.69E-021.06E-041.31E-061.71E-069.17E-06

NANANANANANA

5.38E-071.25E-042.11E-046.72E-051.25E-042.21 E-041.92E-044.19E-06

• :',:,;$iaii'l$ lllIrigeifilli!

1.38E-033.84E-039.00E-044.80E-042.64E-03NA

1.80E-04NA

3.00E-04

NANANANANANANA

3.00E-041.80E-041.80E-04NA

2.40E-043.00E-04NA

illlllili: I:lliiite i1.63E-021.08E-013.67E-021.25E-021.61E+006.42E-031.52E-062.89E-043.36E-03

NANANANANANA

2.75E-076.38E-041.72E-035.62E-041.48E-024.39E-033.04E-036.63E-05

tii® fell1.77E-021.13E-013.84E-021.33E-021.65E-I-006.52E-031.83E-042.91 E-043.67E-03

NANANANANANA

8.13E-071.06E-032.11E-038.09E-041.49E-024.85E-033.53E-037.05E-05

NA - Not applicable: chtmical concentration btlow detection tevcl and tfitrtfort Era not calculaied

6-170

AR306I90

Table 6-73

Summary of Upper 95% Estimated Daily Intakes for White-Tailed Deer(mg/kg-day)

Chemical

BenzeneChlorobenzane1 ,2-Dlchlorobanzene1 ,3-Dichlorobenzene1 ,4-Dfehlorot3enzan9EthytbanzaneHexachlorobenzeneMatachloronitrobenzeneNitrobenzene

Sedimentingestion

1.15E-041.67E-031.62E-037.39E-046.51 E-022.88E-041.75E-062.29E-069.60E-06

-:-';:3&irtac:;::;. ;jv|gj

. 1i jes8oW?l

2.34E-037.20E-031.62E-038.40E-045.10E-03NA

1.80E-04NA

3.00E-04

|;|Bniw||Jf:IB ji M !2.79E-021.66E-016.88E-023.01 E-022.84E+001.75E-022.04E-063.89E-043.52E-03

'!:';SiiiSl1firigestel:

3.04E-021.75E-017.21 E-023.17E-02Z91E+001.78E-021.84E-043.91 E-043.83E-03

PCSArocIor-1016ArocIor-1221Aroclor-1232ArocIor-1242Aroclor-1248Arocior-1254Aroclor-1260Pentachlofobsnzane1 ,2,3,4-Tetrachlofobenzene1 ,2,4,5-TetrachlorobenzeneToluena1 ,2,3-TrfchIorobenzene1 ,2,4-Trichlorob9nzena1 ,3,5-TrIchlorobenzene

NANANANANANA

1.29E-062.30E-043.84E-041.06E-042.98E-043.74E-043.74E-045.85E-06

NANANANANANANA

5.40E-041.80E-041.80E-04NA

3.00E-044.80E-04NA

NANANANANANA

6.58E-071.18E-033.13E-038.84E-043.52E-027.44E-035.93E-039.27E-05

NANANANANANA

1.94E-061.95E-033.69E-031.17E-033.55E-028.11E-036.79E-039.85E-05

NA - Not sppfcablt; chtmkaJ oonotntration b«k>w detection l«vil and lh«r»fw» EDI not calculated

6-171

flR30619!

Table 6-74*»• •*'

Model for Calculating Doses to White-Tailed Deer Through theIngestion of Browse

Where:CBRBRIRBW

^

BExposurCBRBRIRBWFI

BrowseIngestion Dose(mg/kg/day)

= Chemical concentration in= Browse ingestion rate (kg= Body weight (kg)= Fraction ingested

e Assumptions

CBR * BRER * FI- - - - - - - B W

browse (mg/kg dry weight)dry weight/day)

= Browse concentrations presented in Table (5-75= 0.16 kg dry weight/day (Magruder, 1957, as cited in Blair et al.,= 50 kg, average weight of an adult white-tailed deer (Doutt et al.= 0.03 -

1977), 1977)

6-172

HaQtR5.CONSW.TWS

log (Bv) = 1.588 - 0.578 * log K ,

This relationship was used to estimate Bvs for the chemicals of concern in sediment. Thelog KOWS, the calculated Bvs, and the calculated plant concentrations are presented in Table6-75. It should be noted that the uptake factors evaluated in this study are based on analgorithm which uses soil concentrations of chemicals at or below their solubility. Sincethe uptake mechanism into plants is largely a function of the bioavailability (solubility)of the chemical in the interstitial water of the root zone, application of this algorithm tocases where soil/sediment concentrations greatly exceed the solubility of the chemicalprobably results in an overestimate of the predicted plant concentration. Despite the largeuncertainty associated with using this approach, the algorithm was applied in the absenceof site-specific plant tissue data or an alternative method.

Ingesfion of Chemicals in Surface Water

White-tailed deer may be exposed to site-related chemicals through the ingestion ofsurface water. There are several areas where deer may drink surface water in the vicinityof the site, including Red Lion Creek. All surface water locations were assumed to bewithin the range inhabited by the deer. Because of the proximity of Red Lion Creek and

its tributaries, it was assumed that the white-tailed deer would consume 100% of its dailywater intake from within the site vicinity.

The equation and assumptions that were used to calculate doses to white-tailed deerthrough the ingestion of on-site surface water are presented in Table 6-76. The mean and

upper 95% estimated daily intake (EDI) of chemicals by white-tailed deer due to surfacewater ingestion is presented in Table 6-72 and 6-73, respectively.

STAND-CLNSTANDJ5FT 6-173

4R306I93

Table 6-75Browse Concentrations for White-tailed Deer Evaluation

iii :&MS &Mi ,

BenzeneChlorobenzene1 ,2-Dichlorobenzene1 ,3-Dichlorobenzene1 ,4-DichlorobenzeneEthylbenzeneHexachiorobenzeneMetachloronitrobenzeneNitrobenzene

IIIBililiiiJ2.172.843.483.513.463.216.182.441.86

lllii illllIllillJilS2.16E+008.84E-013.77E-013.62E-013.87E-015.40E-011.04E-021.51E+003.26E+00

||1$$^

SlMfeiiJriil1.51E+019.99E+013.39E+011.16E+011.49E+035.94E+001.41E-032.68E-013.11E+00

Illrisp,;:;!2.59E+011.54E+026.37E+012.79E+012.63E+031.62E+011.89E-033.60E-013.26E+00

PCSAroclor-1 01 6Aroclor-1 221Aroclor-1 232Aroclor-1 242Aroclor-1 248Aroclor-1 254Aroclor-1 260Pentachlorobenzene1 ,2,3,4-Tetrachlorobenzene1 ,2,4,5-TetrachlorobenzeneToluene1 ,2,3-Trichlorobenzene1 ,2,4-Trichlorobenzene1 ,3,5-Trichlorobenzene

NANANANANANA6.805.074.724.702.714.054.224.22

NANANANANANA

4.55E-034.55E-027.24E-027.44E-021.05E+001.77E-011.41E-011.41E-01

NANANANANANA

2.55E-045.91 E-011.59E+005.21 E-011.37E+014.06E+002.82E+006.14E-02

NANANANANANA

6.09E-041.09E+002.90E+008.18E-013.26E+016.89E+005.49E+008.58E-02

NA - Not applicable, chamlcaJ not above dtttctlon tevol

6-174

Table 6-76

Model for Calculating Doses to White-Tailed Deer Through theIngestion of Surface Water

Where:cswSWIRBWnExposureCSWSWIRBWFI•

Surface WaterIngestion Dose CSW * SWIR * Fl(mg/kg/day) ' s BW

« Chemical concentration in surface water (mg/1)= Surface water ingestion rate (I/day)- Body weigbt (kg)« Fraction ingested within site vicinity

Assumptions= Surface water concentrations presented in Subsection 6.2« 3.0 I/day, based on body weight (Hungate, 1966; Tasca et al.,» 50 kg, average weight of an adult white-tailed deer (Doutt et— 1

1989)aL, 1977)

6-175

4R306/95

Summary of Calculated Doses to White-Tailed Deer

The doses to white-tailed deer that were calculated for the incidental ingestion ofsediment, the ingestion of browse., and the ingestion of surface water exposure routes are

summarized hi Tables 6-72 and 6-73. The total ingestion dose for each chemical ofconcern is also indicated. The total exposure to deer to chemicals was derived as follows:

EDIT = EDU_ + EDL + EEHL,

Where:EDIT = Total estimated daily intake (mg/kg-day)

= Estimated daily intake via sediment ingestion (mg/kg-day)= Estimated daily intake via browse ingestion (mg/kg-day)= Estimated daily intake via surface water ingestion (mg/kg-day)

Meadow Voie (Microtus pennsvlvanicus)•

The meadow vole is assumed to be exposed to chemicals of concern through theincidental ingestion of sediment, ingestion of vegetation that has assimilated chemicals,

and ingestion of surface water. '~ 7 7

Ingestion of Chemicals in Sediment

The incidental ingestion of sediment by the meadow vole can occur during such behavior

as preening, burrowing, or foraging. A sediment ingestion rate of 1% of the dietary

intake was assumed for the meadow vole, based on a similar assumption made by EPAfor the mole (EPA, 1990b). This value was arbitrarily chosen by EPA as a best estimateof soil ingestion, based on a postulation by Young and Cockerman (1985) that beachmiceliving around a dioxin-contaminated area at Elgin Air Force Base in Florida had elevateddioxin liver concentrations due to their burrowing and preening behavior.

STAND-CL\STANDJtPT - 6-176

fiR306!96

A dietary intake of 1.5 g diy weight/day was assumed for the vole, which resulted in asediment intake rate of 0.015 g dry weight/day. The ingestion of sediment by the voleis assumed to occur solely in contaminated areas above the dike at the site. The modeland assumptions used to calculate a sediment ingestion dose for the meadow vole arepresented in Table 6-77. The mean and upper 95% estimated daily intake of chemicalsby the meadow vole due to sediment ingestion is presented in Tables 6-78 and 6-79,respectively.

Ingestion of Chemicals in Vegetation

The meadow vole is herbivorous, and feeds primarily on grasses, sedges, legumes, tubersand roots. Seeds are also an important food source beginning in midsummer.Occasionally, the meadow vole's diet includes insects and other animal remains; howeverthese alternative food sources normally do not comprise a substantial portion of themeadow vole's diet (Merritt, 1987).

Estimates of chemical exposure through vegetation ingestion for the meadow vole weredetermined by approximating the uptake of chemicals from sediment into vegetation and

the amount of vegetation consumed daily by the vole. Consequently, the first step indetermining exposure to the vole from the ingestion of vegetation was the prediction ofchemical concentrations in vegetation.

Chemical concentrations in vegetation resulting from uptake from the sediment werecalculated using the following equation:

= edimcol


/5R306I97

DESOBBCONSULTWTS

Table 6-77

Model for Calculating Doses to the Meadow Vole Through theIncidental Ingestion of Sediment

Where:

Csed =

SIR =FIBWCF

Exposure

•CSSIR =FIBW =CF

SedimentIngestion Dose = C^ * SIR * FI * CF(mg/kg-day) BW

Chemical concentration in sediment (mg/kg)Sediment ingestion rate (g/day)Fraction ingested from contaminated source (unitless)Body weight (kg)Conversion factor (kg/g)

Assumptions

Sediment exposure concentrations are presented in Subsection 6.2.5.20.015 g/day*lb _ __ ,:.._.:0.0425 kg (Merritt, 1987)0.001 kg/g

'Assumed to be 1 percent of food intake (EPA, 1990)The home range of the meadow vole (1.6 acres) is within the contaminated site acreage

6-178STAND-CURI-T6-77.TBL

RR306I98

Table 6-78

Summary of Mean Estimated Daily Intakes for the Meadow Vole(mg/kg/day)

Chemical

BenzeneChlorobenzene1 ,2-Dtehlorobenzene1 ,3-D*ch!orobenzene1 ,4-Dfch!arobenzeneEthy&enzeneHexachlorobenzeneMetachloronitrobenzeneNitrobenzenePCBAroclor-1016ArocIor-1221ArocIor-1232ArocIor-1242ArocIor-1248Arocior-1254ArocIor-1260Pentachlorobenzene1 ,2,3,4— Tetrachlorobenzene1 ,2,4,5— TetrachlorobenzeneToluene1 ,2,3-TrfchIorobenzene1 ,2,4-Trichlorobenzene1 ,3,5— Trichlorobenzene

SedimentIngestion

1.06E-033.35E-026.21 E-023.85E-029.47E-011.62E-024.45E-055.58E-051.74E-04

NANANANANANA

6.88E-059.53E-031.66E-023.53E-031.48E-021.27E-021.41E-031.34E-04

Surface :Water

Ingestion

7.65E-032.60E-024.94E-032.71 E-031.71 E-02NANANA

5.88E-04

NANANANANANANANA

3.53E-043.53E-04NA

8.24E-041.88E-03NA

VegetationIngestion

5.33E-013.53E+001.20E+004.09E-015.26E+012.10E-014.98E-059.46E-031.10E-01

NANANANANANA

9.00E-062.09E-025.61 E-021.84E-024.84E-011.43E-019.95E-022.17E-03

TotalIngestion

5.42E-013.59E+001.26E+004.51E-015.36E-f012.26E-019.42E-059.51E-031.11E-01

NANANANANANA

7.78E-053.04E-027.31 E-022.23E-024.98E-011.57E-011.03E-012.30E-03

NA — Not applicable for this medium; chemical concentration below detection level

6-179flR306!99

Table 6-79

Summary of Upper 95% Estimated Daily Intakes for the Meadow Vole(mg/kg/day)

Chemical ;. :; :;;";; ";:;":;:;;i;;, "v;;;;;;;: ;";,:;;'";

BenzeneChiorobenzene1 ,2-DichIorobenzene1 ,3-Dichlorobenzene1 ,4-DichlorobenzeneEthylbenzeneHexachlorobenzeneMetachloronftrobenzeneNitrobenzenePCBAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260Pentachlorobenzene1 ,2,3,4-TetrachIorobenzene1 ,2,4,5-TetrachlorobenzeneToluene1 ,2,3-Trichlorobenzene1 ,2,4-Trichlorobenzene1 ,3,5-Trichlorobenzene

SedimentIngestion

2.12E-038.72E-021.67E-011.03E-012.56E+004.41 E-029.04E-059.07E-052.89E-04

NANANANANANA

2.58E-042.40E-024.38E-028.12E-034.06E-023.35E-022.82E-031.99E-04

Surface ;V;:;

i':';vfeir ttIngestion

1.56E-025.72E-021.13E-025.65E-034.02E-02NANANA

5.88E-04

NANANANANANANANA

4.71 E-043.53E-04NA

1.18E-033.53E-03NA

VegetationIngestion

9.14E-015.44E+002.25E+019.85E+009.28E+015.72E-016.67E-051.27E-021.15E-01

NANANANANANA

2.15E-053.85E-021.02E-012.89E-021.15E+002.43E-011.94E-013.03E-03

:Tbtar;Ingestion

9.32E-015.58E+002.27E+019.96E+009.54E+016.16E-011.57E-041.28E-021.16E-01

NANANANANANA

2.79E-046.25E-021.47E-013.73E-021.19E+002.78E-012.00E-013.23E-03

NA- Not applicable for this medium; chemical concentration below detection level

6-180; flR3062QO

«SO€RSCCHS«.T«S

Where:Cveg « Chemical concentration in vegetation (mg/kg)

= Chemical concentration in sediment (mg/kg)

PUF = Plant uptake factor (chemical-specific factor for root absorption andtranslocation to the edible portion of forage).

The equation used to calculate chemical concentrations in vegetative plant parts wasderived based on a model for 29 organic chemicals. The PUFs for these 29 organicchemicals into vegetative plant parts have been compared via regression to the octanol-water partition coefficients (K ) for those substances (Travis and Arms, 1988). Thecomparison established the following relationship:

log (PUF) - L588 - 0.578 * log K,,

This relationship was used to estimate PUFs for the chemicals of concern in the sediment.The log K s and the calculated PUFs are presented in Table 6-75. The plant uptakefactors (PUFs) are reported in dry weight, which resulted in the calculation of dry weightvegetation concentrations.

The estimated daily dose of chemicals received by the meadow vole through vegetation

ingestion was determined based on the model and assumptions presented in Table 6-80.A vegetation ingestion rate of 15 g wet weight/day was assumed, based on a dailyconsumption rate of 35% of the average vole body weight (42.5 g) (Chapman andFeldhammex, 1982). This wet weight ingestion rate was converted to a dry weightingestion rate by assuming that the vegetation ingested is 90% water by weight (Baes etal, 1984), resulting in a dry weight ingestion rate of 1.5 g/day. The fraction ingestedfrom the area above the dike was assumed to be 100% based on the home range of thevole (average 1.6 acres) (Merritt, 1987) and the size of the contaminated area (estimatedgreater than 2 acres).

6-181 _

flR30620

Table 6-80

Model for Calculating Doses to the Meadow Vole Through theIngestion of Vegetation

VegetationIngestion Dose = G^ * VIR * FI * CF(mg/kg-day) BW

Where:

C = Chemical concentration in vegetation (mg/kg)VIR = Vegetation ingestion rate (g/day)FI = Fraction ingested from contaminated source (unitless)BW = Body weight (kg).CF = Conversion factor (kg/g)

Exposure Assumptions•

Q = Vegetation concentrations are presented in Appendix L.VIR = 1.5 g/day (Chapman and Feldhammer, 1982) ;FI .= -I4 .__ ._ _ _ _ _ _ _ _ _ _ ___T" '..':

BW = 0.0425 kg (Merritt, 1987)CF = 0.001 kg/g'The home range of the meadow vole (1.6 acres) is within the contaminated site acreage

6-182STAND-C1ARI-T6-80.TBL

QR306202

The mean and upper 95% estimated daily intake of chemicals by the meadow vole dueto vegetation ingestion are presented in Tables 6-78 and 6-79, respectively

Ingestion of Chemicals in Surface Water

The meadow vole may also be exposed to chemicals through the ingestion of surfacewater. The model and assumptions used to calculate a surface water ingestion dose forthe meadow vole are presented in Table 6-81. A surface water ingestion rate of 0.005L per day was assumed for the vole which is based on water ingestion rates for othersmall mammals (e.g., house mouse) with similar body weights and metabolisms(Chapman and Feldhammer, 1982). It was assumed that the vole will consume 100% ofits daily water intake from the area above the dike at the site.

The mean and upper 95% estimated daily intake of chemicals by meadow vole due tosurface water ingestion is presented in Tables 6-78 and 6-79, respectively.

Total Exposure to the Meadow Vole

Based on the previous discussion, the total exposure of the vole to chemicals from the site

will be derived as follows:

EDITottJ - EDI + EDI + EDI ^

Where:EDITottI = Total estimated daily intake (mg/kg-day)

— Estimated daily intake from vegetation ingestion (mg/kg-day)

= Estimated daily intake from surface water ingestion (L/kg-day)

= Estimated daily intake from sediment ingestion (mg/kg-day)

STAND-CLNSTAMDJUTT 6-183

fiR3G6203

Table 6-81Model for Calculating Doses to the Meadow Vole Through the

Ingestion of Surface Water

Surface WaterIngestion Dose = C,^ * WIR * FI(mg/kg-day) BW

Where:

0 = Chemical concentration in surface water (mg/L)WIR = Surface water ingestion rate (L/day)FI = Fraction ingested from contaminated source (unitless)BW = Body weight (kg)

Assumptions

C te* = Surface water concentrations are presented in Subsection 6.2.5.3.WIR = 0.005 L/dayFI = r . . . . . . . . . __ _ ... -__._BW = 0.0425 kg (Merritt, 1987)

"The home range of the meadow vole (1.6 acres) is within the contaminated site acreage

STAND-CIARI-T6-8I .TBL 6-184 _: _

! flR30620U

CCSlGNEf&CCI&UANTS

Great Blue Heron (Ardea kerodias)

Great blue heron are assumed to be exposed to chemicals of concern through theingestion of fish and surface waters in the vicinity of the Standard Chlorine site. For thepurposes of this assessment, it was assumed that great blue heron would obtainapproximately 30% of their daily intake offish and surface water from within the vicinityof the Standard Chlorine site.

Ingestion of Chemicals in Fish

Great blue heron inhabiting the wetland area surrounding the site can be potentiallyexposed to chemicals of concern through the ingestion of fish. A heronfbokery is locatedapproximately one to two miles from the site. Numerous wetlands and tidal streams inthe vicinity of Red Lion Creek provide additional foraging habitat for the heron.Nevertheless, it was conservatively assumed that one-third of the heron diet would be

obtained from Red Lion Creek in the site vicinity. It was conservatively assumed that30% of a heron's total diet would be obtained from Red Lion Creek in the vicinity of theStandard Chlorine site. The equations and assumptions that were used to calculate dosesto the great blue heron through the ingestion of fish are presented in Table 6-82. Themean and upper 95% estimated daily intakes of chemicals by great blue_heron due to fishingestion are presented in Tables 6-83 and 6-84, respectively.

Ingestion of Chemicals in Surface Water

Great blue heron can be potentially exposed to chemicals of concern through the ingestionof surface water. The equations and assumptions that were used to calculate doses togreat blue heron through the ingestion of surface water are presented in Table 6-85. Thepercentage of daily intake of surface water obtained from this vicinity was assumed to be

5TAND-CLVSTANDJRPT 6~ 185

AR306205

Table 6-82 ....._.....

Model for Calculating Doses to Great Blue Heron Through theIngestion offish

Where:CFFIRBWFI

ExposureCF.FIR.BWFI

Fish Ingestion Dose CF *(mg/kg/day) -

= Chemical concentration in fish (mg/kg)= Fish ingestion rate (kg/day)= Body weight (kg)= Fraction ingested within site vicinity

FIR « PD * FIBW

Assumptions= Fish tissue concentrations presented in Subsection 6.2= 03 kg/day (Patuxent, 1986; Marin, 1951)= Average body weight of adult great blue heron, 3 kg (Terres, 1980)= 030

6-186"AR3062Q6

Table 6-83

Summary of Mean Estimated Daily Intakes for Great Blue Heron(mg/kg-day)

ChemicalB*nz»r»Chlorobenzene1 ,2-DichIor ofoenzene1 .S-Dichlorobenzsne1 ,4-Dfchlorofa«nz»n«EthylbenzeneH«xachlof ob t nzeneM*tftchlofonfaobenzeneNfrob*nz*ne

Fish*Ingestion

IMA1 .05E-03MANANANANANANA

SurfaceWater

Ingestion5.98E-071.66E-063.90E-0708E-071.14E-06NA7.80E-08NA1.30E-07

TotalIngestion

5.98E-071.05E-033.90E-072.08E-071.14E-06NA7.80E-08NA1.30E-07

PCBAroclw— 1016Arodor-1221Aroclor— 1232ArocIor-1242ArocIof-1243ArocIor-1254Arodor-1260Pantachlwobenzene1 ,£3,4-T«trachIorobenzene1 ,2,4,5— TetrachlofobenzeneToluan*1 ,2 — Trichlorobenzene1 ,2.4— Trichlorofaanzen©1 .5-TrichlorobenzKne

. NANANANANANA9.60E-03NANANANANA6.30E-03NA

NANANANANANANA1.30E-077.80E-087.80E-08NA1.04E-071.30E-07NA

NANANANANANA9.60E-031.30E-077.80E-087.80E-08NA1.04E-076.30E-03NA

NA- Notawsteibl«:e*MmtotIoono«nlr«tionb«towdatoctionlavei, theraroraEDlcoutdnotbgcalcxdatod

* — Fish Ingtttiai valu* rapr«Mnts a samplo ste* of 1

6-187AR306207

Table 6-84

Summary of Upper 95% Estimated Daily Intakes for Great Blue Heron(mg/kg-day)

ChemicalBenzeneChlorobenzene1 ,2-Dichlorobenzene1 ,3-Dichlorobenzene1 ,4-DichlorobenzeneEthylbenzeneHexachlorobenzeneM etachl oronitrobenze naNitrobenzene

Fish*Ingestion

NA1 .05E-03

NANANANANANANA

Surface ;Water

Ingestion1.01E-063.12E-067.02E-07

3.64E-072,21!=- 06NA7.80E-08NA1.30E-07

#6tai ;*!Ingestion

1.01E-063.12E-067.02E-073.64E-07

2.21 E-06NA7.80E-08NA1 .30E-07

PCBAroclor-1016Aroclor- 1 221Aroclor- 1 232Aroclor-1242Aroclor- 1248Aroclor- 1254Aroclor- 1260Pentachlorobenzene1 ,2,3,4-TetracNorobenzene1 ,2,4,5-TetrachlorobenzeneToluene1 ,2,3-Trichlorobenzene •*•1 ,2,4— Trichlorobenzene1 ,3,5 -Trichlorobenzene

NANANANANANA9.60E-03NANANANANA6.30E-03NA

NANANANANANANA2.34E-07

7.80E-087.80E-08NA1.30E-072.08E-07NA

NANANANANANA9.60E-032.34E-07

7.80E-087.80E-08NA1.30E-072.08E-07NA

NA- Not applicable: chemical concsntration below detection level, therefore EDI oouldnotbe calculated

* - Fish Ingestion value represents a sample size of 1

6-188

4*306208

KSCWRSOKSUTWT5

Table 6-85

Model for Calculating Doses to Great Blue Heron Through theIngestion of Surface Water

Surface WaterIngestion Dose CSW * SWIR • PD • FT(mg/kg/day) " BW

Where:CSW = Chemical concentration in surface water (mg/1)SWIR « Surface water ingestion rate (I/day)BW » Average body weight of adult great blue heronFI » Fraction ingested within site vicinity

Exposure AssumptionsCSW = Surface water concentrations presented in Subsection 6.2SWIR « Water ingestion rate based on body weight, 026 I/dayBW ' « Average body weight of adult great blue heron, 3 kg (Terres, 1980)FI = 030

6-189

Ulftt&RS ^ DSIGt«RS£aNSUl.TWI5

30%. The daily water ingestion rate for great blue heron was estimated using thefollowing allometric relationship between drinking water ingestion rate and body weight(BW) (EPA, 1988):

1.7872Drinking Water Ingestion Rate (L/day) = 0.11 * BW°

Where:

BW = Body weight of average adult great blue heron, 3 kg (Terres,1980).

Summary of Calculated Doses to Great Blue Heron

The mean and upper 95% estimated daily doses for the ingestion of fish and surface waterfor the great blue heron are summarized in Tables 6-83 and 6-84, respectively. The totalingestion dose for each chemical of concern was derived as follows:

EDIT = EDL* + EDL.fish

Where:

EDIT = Total estimated daily intake (mg/kg-day)EDIfeh = Estimated daily intake via fish ingestion (mg/kg-day)EDIdw = Estimated daily intake via surface water ingestion (mg/kg-day)

6.4.4 Toxicity Assessment

The toxicity evaluation characterizes the toxicity of the chemicals of potential concern to— ecological receptors. A comprehensive literature and database search was performed to

STAND-CLSSTAND.RPT 6-190 . T "' !"' / 1."

4R3062JO

identify relevant toxicological data for aquatic and terrestrial receptors. The data sourcesthat were reviewed included:

* Registry of Toxic Effects of Chemical Substances (RTECS)

• Aquatic Information Retrieval Toxicity Data Base (Aquire)

• Quantitative Structure Activity Relationship (QSAR)

• Hazardous Substances Database (HSDB)

* Agrochemical Handbook (Hartley and Kidd, 1987)

• Integrated Risk Information System (IRIS)

• Phytotox Data Base

• Federal and State Ambient Water Quality Criteria

6.4.4.1 Toxicity to Terrestrial Life

Toxicity information obtained from these databases and other primary literature sourceswas used in the development of critical toxicity values (i.e., estimated allowable dailyintakes) (Stevens, 1988) for target species and ecological communities. When toxicity

data were not available for a specific chemical, toxicity data for related isomers wereused.

Species-specific toxicity data for target wildlife species were often not available for thechemicals of potential concern. Thus, toxicity data from the literature were selected usingthe most closely related species, where possible. Toxicity data selected for this

assessment were the lowest exposure doses reported to be toxic or the highest dosesassociated with no adverse effect. Data for chronic toxicity were preferentially used,when available.

STAND-CLVSTANDJtPT 6-191

AR3Q62H

DESIGNEB$«JNSU.T*HTS

Generally, toxicity data available for.terrestrial wildlife are not nearly as extensive as datafor aquatic species. Consequently, extrapolation of toxicity data from other animal studiesis often necessary to derive critical toxicity values (CTVs). Because of the uncertaintyassociated with these extrapolations, safety factors are applied to toxicological endpointsto derive CTVs. The approach taken hi this ecological assessment to derive CTVs isprovided i n Table 6-86. . . . . . . . _ _ _ _ _ _ _ :

For those chemicals for which only acute lethality values were available, toxicity values

for this assessment were derived by dividing the acute toxicity value by the appropriatesafety factors. Based upon the guidance provided by the EPA (1986a), a median lethaldose (LD50) may be extrapolated to an acute no-observable-effect-level (NOEL) by

dividing the LD50 by a safety factor of 5. This safety factor is based on an analysis ofdose-response data for pesticides. A dose-response 5 times lower than the LDSO wouldbe expected to result in a mortality rate of about 0.1% under typical conditions, and upto 10% when the responses in the test population are very variable. Protection of 90 to99% of a population is expected to provide an adequate margin of safety. In the absence

*of similar information from chronic studies, a safety factor of 5 was applied in the

extrapolation of a chronic lowest-observable-effect-level (LOEL) to a chronic NOEL.There is currently no EPA guidance available for the extrapolation of acute toxicity datato chronic NOELs. However, several studies have evaluated the relationship betweenLDjo values and chronic NOELs for the same chemical in small mammals (Venmen andFlaga, 1985; Layton'et al., 1987) and have found that the ratio of LD50 to a chronicNOEL (LD50/NOEL) typically ranges from 10 to 1000. For the purpose of this ecologicalassessment, a safety factor of 500 (5 for LD50 -» acute NOEL, and 100 for acute NOEL

—» chronic NOEL) was used to extrapolate from an LD50 concentration to a chronic

NOEL. An additional safety factor of 5 was applied in cases when the test speciesdiffered from the target species selected for the site, since animal species can exhibitdifferences hi sensitivity to a chemical.

5TAND-CL\STAND.RPT 6-192- " " . . . . _ . . ..

AR3062I2

Table 6-86

Safety Factors Used to Derive Critical Toxicity Values forTerrestrial Target Organisms

Avai

Acute Lethality (i.e., LD50)

Acute NOEL

Chrome LOELWithin Phylogcnetic ClassSensitivity (i.e., differentspecies but same class)

Acute NOEL

Chronic NOEL

Chronic NOEL

Target Species Toxicity

100

For example, in developing a critical toxicity value for a white- tailed deer when the only dataavailable is an LD for a rat, the following steps would be taken:

Rat LD50 for Compound X - 500 mg/kg.

(1) Acute Lethality -> Acute'NOEL 500 mg/kg = 10Q mg/kg

•

(2) Acute NOEL -» Chronic NOEL 100 mg/kg = l mg/kg

(3) Within Phylogenetic Class -» Target Species CTV =0.2 mg/kg

6-193

flR3062J3

White-Tailed Deer (Odocoileus virginianus)

Toxicity data specifically for white-tailed deer were unavailable for the chemicals ofconcern. CTVs, therefore, were extrapolated from data on other mammalian species.Because of the uncertainty associated with these extrapolations, the safety factorspreviously described were applied to toxicological endpoints to derive the CTVs. Thetoxicity data and the total safety factors applied to derive the CTVs for the white-tailed

deer are presented in Table 6-87. _ ._.'.':....

Meadow Vole (Microtus pennsylvanicus)

Toxicity data specifically for the meadow vole were unavailable for the chemicals of

concern. CTVs, therefore, were extrapolated from data on other mammalian species.Because of the uncertainty associated with these extrapolations, the safely factorspreviously described were applied to toxicological endpoints to derive the CTVs. Thetoxicity data and the total safety factors applied to derive the CTVs for the meadow vole-•

are presented in Table 6-88. - - - • - __J_T:r"="

Great Blue Heron (Ardea herodias)

Toxicity data were not available for the great blue heron for the chemicals of concern.In addition, toxicity data were not available for most of the chemicals of concern forclosely related avian species. The toxicity data and the total safety factors applied toderive the CTVs for the great blue heron are presented in Table 6-89.

£

Earthworm (Eisenia foetida)

The potential toxicity of chemicals of concern was evaluated for the earthworm. Off-sitesoil concentrations were compared to soil concentrations which produced adverse effects

in the earthworm toxicity tests.

STAND-CL\STANDJIPT 6-194

Table 6-87Toxicity Values Used for White-Tailed Deer Exposure Evaluation

(mg/kg-day)

Chemical

Benz*n«Chk>rob«nz»no1 ,2-Dlchtorobenzena1,3-Dichlorob«nz«n0 (a)1,4-Dichtorobanzan*EthylbenzoneHftXachlorobanzoneM«t«chtoronttrob«nzan«Nrtrobenzon*PCSAroclor— 101C

Aroctof-1221Arodof-1232Aroctar-1242Arodor-1248Aroctor-1254AfocJor~12flOP«nt*chlorobanzan*1 ,2,3,4-Tatrachforobanzane1 ,2,4,5-TotracWorobBnzenftToluona1,2,3— TrichJofobenzene (b)1 ,2,4— Trichtorobftnzfln*1,3,5-TricWorobenranft {b}

ToxicltyValue

9.30E+02

1.44E+011.88E+01

1.88E+011.88E+011.36E+02

5.00E-023.80E+02

1.00E+02

2.30E+031.00E+00

4.47E+03

3.00E+00

1.10E+04

1.00E4-00

1.32E+03

l.OOE+02

1.17E+03

1.04E4-03

3.12E+02

5.00E+00

2.50E+01

5.00E+00

ToxicifyEffect

LD50Chronic NOAELOironic NOAEL

Chronic NOAEtChronic NOAELChronic NOAEL

Chronic NOAELLD50

Acute NOAEL

LD50Chronic NOAELLD50LD50

LO50

Chronic NOAELLD50Chronic NOAELLD50LD50

Chronic NOAEL

Chronic NOAELChronic NOAELChronic NOAEL

' • TeSt .- - :;::,,

Species ;

RatRatRatRatRatRatPigMouseRat '

RatRabbitRatMinkRatRabbitRatMouse

RatMouseRatRatRhesus MonkeyRat

_ . ,,„„,.... ........ ..%..;.,.,...;. .. .;.

• :;pefeir0nce" ;;')'.' '';"Spu'roe7:;r';'':'

RTECS, 1981

HSDB.1991

HSDB.1991

HSDB.1991HSDB, 1991IRIS, 1991

Clayton, 1981RTECS, 1991

Gold stein, 1984

RTECS, 1991HSDB, 1991RTECS, 1991HSDB ,1991RTECS, 1991

HSDB, 1991

RTECS, 1991HSDB, 1991

HSDB, 1991

RTECS, 1991

IRIS, 1991

HSDB, 1991HSDB, 1991HSDB, 1991

SafetyFactor

. 2500,

5

5

5

5

5

5

2500

50

2500

5

2500

2500

2500

5

2500

5

2500

2500

5

5

55

(•) Tt»fc)ty data UMd tor 1,3-OCS wm cbt»h«d trcmth* 1,2-DCB tecrrwr

t: cxnvwt«d to mgAg BW

6-195

flR3062i5

Table 6-88

Toxicity Values Used for Meadow Vole Exposure Evaluation(mg/kg/day)

«

Chemical . ..•• • :• '••"•'•;•"•• •"••:'•" '

BenzeneChlorobenzene1 ,2-Dichlorobenzene1 ,3-DichIorobenzene1 ,4-DichlorobenzeneEthylbenzeneHexachlorobenzeneMetachloronitro benzeneNitrobenzenePCBAroclor-1016Aroc lor- 1221Aroctor-1232Aroclor-1242kAroclor-1248fArocIor-1254Arocbr-1260Pentachlorobenzene1 ,2,3,4-Tetrachlorobenzene1 ,2,4,5-TetrachlorobenzeneToluene1 ,2,3-Trichlorobenzene1 ,2,4-Trichlorobenzene1 ,3,5-Trichlorobenzene

,:'T6xifeBy':[J.:;i''Value V''vy

9.30E+021.90E+018.57E+018.57E+018.57E4-019.71 E+018.00E-023.80E+021.00E+02

2.30E+031.00E+004.47E+033.00E+001.10E+041.00E+001.32E+038.30E+001.17E+033.40E-012.23E-HD25.00E+005.00E+005.00E+00

Toxlcity jtJHfedt ::"::;:':': :•:••;

acute LD50Chronic NOELChronic NOELChronic NOELChronic NOELChronic NOELChronic NOELacute LD50acute NOEL

acute LD50Chronic NOELacute LD50acute LD50acute LD50

Chronic NOELacute LD50Chronic LOELacute LD50

Chronic NOELChronic NOELChronic NOELChronic NOELChronic NOEL

•; -"Test." :', :':;!:••;;•,"'•;' .'Species'' '*

RatDogRatRatRatRatMouseRatRat

RatRabbitRatMinkRatRabbitRatRatRat.Rat .RatRatRatRat

Reference ;"•;Source:.?/ v-1-;1

RTECS, 1991IRES, 1992IRES, 1992IRSS, 1992.IRSS, 1992IRIS, 1992IRIS, 1992RTECS, 1991ATSDR, 1990

RTECS, 1991HSDB, 1991RTECS, 1991HSDB, 1991RTECS, 1991HSDB, 1991RTECS, 1991JRIS, 1991HSDB, 1991IRIS, 1992IRIS, 1992HSDB, 1991HSDB, 1991HSDB, 1991

- Safety'.'"•:':>f tOT"' '

2500555555

250050

25005

2500250025005

250025250055555

6-1964R3062I6

Table 6-89Toxicfty Values Used for Great Blue Heron Exposure Evaluation

(mg/kg-day)

ChemicalBenzeneChkxobenzene1 ,2-Dfchlorobenzene1 ,3 - Dfchtef obenzene1 -DtehkxobenzeneEthytbenzeneHexftchlorobenzeneMeUchkxonrtrobenreneNftrobenxenePCBArockx-1016Arockx-1221Aroctor-1232Arockx-1242ArockM-1248AroclOf-1254Afoctef-12SOPentachtorobenzen*1 ,2 ,4-T»tr»chkxt)b»ra«i«1 ,2,4,5 -Trtr*chkxob*nz*n«Totu»n«1 4-*TKchbfob*naMM1 ,2.4-Trichbrobwizvn*1 ,3,5-Trichbfob»nz«>«

ToxlcityValueNDANDA

NDANDANDANDA1.00E-01

NDANDA

NDA4.SOE+033.00E+031 .OOE-011.00E-01

1.00E4-00

7.47E-J-02

NDANDANDANDANDANDANDA

ToxicrtyEffect

******

Chronic NOAEL**

*

Chronic NOAELLD50

Chronic NOAELChronic NOAELChronic NOAEL

LD50*******

TestSpecies

******

Quail**

*

Bobwhrt* QuailNorthern BobwhiteChickenChickenMallardNorthern Bobwhfte

*******

ReferenceSource******

Verschueren, 1863**

*

HSDB.1901HSDB.1991Cecil etal., 1074Cecil etal., 1874Custer and Heinz, 1 980HSDB,1991

*******

SafetyFactor

******5*

*

*

560055

5

500*******

6-197AR3Q62I7

6.4.4.2 Toxicity to Aquatic Life

The toxicity of chemicals of potential concern to aquatic life was assessed by comparingsurface water concentrations of Red Lion Creek to State of Delaware and Federal (EPA)ambient water quality criteria (AWQC). AWQC were derived by the EPA to protect 95%of all aquatic organisms, including fish, invertebrates, and aquatic plants. Table 6-90presents the AWQC used for the surface water evaluation. In addition, the evaluation ofthe chemicals of concern to organisms living in the sediments was evaluated bycomparing off-site sediment concentrations to sediment concentrations which producedadverse effects on the survival and growth of the benthic amphipod Hyallela azteca.

6.4.4.3 Toxicity to Terrestrial Plants

There is currently no EPA guidance for quantitatively evaluating the potential adverseeffects to terrestrial plants growing in soils containing chemicals of potential concern.

For this ecological assessment, the phytotoxic potential of chemicals of concern was.

evaluated by comparing the off-site soil concentrations to the soil concentrations which

produced adverse effects in the lettuce (Lactuca sativa) seed germination toxicity tests.A comparison of off-site soil concentrations to seed germination toxicity test results ispresented.

6.4.5 Ecological Risk Characterization

6.45.1 General Approach

The potential risk posed to environmental receptors (great blue heron, white-tailed deer,soil fauna, vegetation, aquatic life) was assessed by comparing estimated daily intakes(EDIs) or media-specific concentrations with critical toxicity values or site-specifictoxicity data. With the exception of site-specific toxicity data, this comparison, describedas a hazard quotient (HQ), was made for each chemical and is expressed as:


AR3G62I8

Table 6-90

Ambient Water Quality Criteria Used in Surface Water Evaluation

- g«nor»t

(") - Cri*wi« (of dtaWarobmMnw("*) - Offtwta I<x PCSs - general

NOA - No crftifi* data avanabt*

ChemicalB«nzan«Chlofobenzene (*)1,2-Dtehlorobenane (*«}1 ,3-Dtehlarobenz»ne (**)1,4— Dichlorobenzene (**)Ethyl bonzoneHexachlorob&nzene (*)MotnchloronitrobenzeneNftrobenzftne

Ambient Water Quality Criteria(m L)

Federal5.3 acute0.05 chronic0.763 chronic0.763 chronic0.763 chronic32 acute0.05 chronic

NDA27 acute

State of DelawareNDANDANDANDANDANDANDANDANDA

PCB (***)ArocIor-1016Aroclor-1221ArocIor-1232Aroclor-1242Arocior-1248Aroclor-1254AfOclor-1260P«ntachlorob«nzene (*)1,2 ,4-Ttttrachlorobenzane (*)1 ,2,4.5-T*trachlorc 3enzene (*)ToJu«o«1 ,2 -Trichlorofaenzsne (*)1 ,2,4-Trfchlorobenzene (*)1,S,5-Trichloroben «e (*)

1.40E-05 chronic1.40E-05 chronic1.40E-05 chronic1.40E-05 chronic1.40E-05 chronic1 .40E-05 chronic1.40E-05 chronic

0.05 chronic0.05 chronic0.05 chronic17.5 acute0.05 chronic0.05 chronic0.05 chronic

1.40E-05 chronic1.40E-05 chronic1.40E-05 chronic1.40E— 05 chronic1.40E-05 chronic1.40E-05 chronic1.40E-05 chronicNDANDANDANDANDANDANDA

6-199

flR3062!9

DESGWWCOOJITANTS

HQ =Where:

Qned = Concentration of a chemical in a medium.CTVmed = Critical toxicity value for the same chemical in the same medium.

Or:HQ = EDI/CTV^

Where:

EDI = Estimated daily intake of a chemical through a specific exposureroute (i.e., sediment, food, or water ingestion) (mg/kg-day).

= Critical toxicity value for the same chemical through the ingestionroute (mg/kg-day).

It is important to note that this methodology is not a measure of and cannot be used todetermine quantitative risk, i.e., it does not predict the relative likelihood of adverseeffects occurring. If the calculated hazard quotient (HQ) exceeds unity (Le.>l) then itsimply indicates that the species of concern may be at risk to an adverse effect from thatchemical through that exposure route.

Because critical toxicity values incorporate a number of safety factors, if the criticaltoxicity value is exceeded, i.e., the hazard quotient exceeds unity, it does not necessarilyindicate that an adverse effect will occur.

Exposures to the same chemical through multiple exposure routes are assumed to becumulative. Consequently, a hazard index for a specific chemical (ffl ) examines the

STAND-CXNSTAND PT 6-200 " '„. ! .^ ' ~.

- flR3Q6220

potential risk posed by a chemical through more than one exposure route. As anexample, the cumulative hazard index for an individual chemical in all media wasdetermined for the deer as follows:

/ CTV-/ ^x ving

Where:— Hazard index for a chemical.

= Hazard quotient for the same chemical through sedimentingestion.

= Hazard quotient for the same chemical through browseingestion.

» Hazard quotient for the same chemical through drinking wateringestion.

= Total estimated daily intake for a chemical added across allingestion routes (i.e., sediment, browse, and water ingestion)

(mg/kg-day).

= Critical toxicity value for the same chemical through the

ingestion route (mg/kg-day).

In addition, when a cumulative hazard index (HI J is greater than 1, it is suggested thatthe total exposure to all chemicals of concern through all exposure pathways maypotentially pose a risk for adverse effects to the species of concern. However, as with

STANEWlASTANDJftPT 6-201

AR30622I

the hazard quotient, if the cumulative hazard index is greater than 1, this does notnecessarily indicate that an adverse effect will occur but rather that the potential foradverse effects may exist

The following is a discussion of the potential risks posed to aquatic life and terrestrialwildlife by the chemicals of concern. Again, this risk is specific to the previously

presented exposure scenarios.

6.4.5.2 Risk Characterization for Terrestrial Wildlife

Potential risk to terrestrial wildlife inhabiting the area surrounding the Standard Chlorine

site was estimated by comparing the estimated total ingestion doses of chemicals ofconcern for the white-tailed deer and the great blue heron with the critical toxicity values

derived in Subsection 6.4.4.

White-Tailed Deer (Odocoileus virsinianus)•

The white-tailed deer was assumed to be exposed to chemicals of concern through the

ingestion of chemicals in sediment and browse, and drinking surface waters containing

chemicals from Red Lion Creek. Tables 6-72 and 6-73 present the mean and upper 95%estimated daily intakes for the white-tailed deer for sediment, browse, and surface wateringestion. Table 6-91 presents the results of the comparison of critical toxicity valuesderived for the white-tailed deer to the estimated daily intake of chemicals of concern.The total hazard index for the mean values (5.74E-01) and the upper 95% values (9.87E-01) fell below the criterion of 1. The results of this evaluation indicate that potentialadverse effects to the white-tailed deer through the ingestion of browse are unlikely to

occur within the Standard Chlorine site vicinity.

STAND-CL>STAND.RPT 6-202

8R306222

Table 6-91

Hazard Indices Based on White-Tailed Deer Exposure

Chemical

B«nz«n«

Chtofobanzone1,2-Dfchtorob«nzon«1 ,3— DIchforobenzon*1 ,4— DIchtorob*nzBnaEthylbenronaHaxachforobanzenftMotachloronfrabonztneNhrobanzftna

Total .,,,;,;;,,:3Estimated Daily Intake

(mg/kg-day)Mean

1.77E-021.13E-013.84E-021.33E-021.65E+00

6.52E-031.83E-04

2.91 E-043.67E-03

Upper 95%

3.04E-02

1.75E-01

7.21 E-023.17E-02

2.91 E +00

1.78E-02

1.84E-04

3.91 E-043.83E-03

CriticalToxicity

:" Value '?""::---,' '"'(mg/kg-<iay)

3.72E-01

2.88E+00

3.76E+003.76E+00

3.76E+00

2.72E-(-011.00E-021.52E-012.00E+00

Hazard Indices

'--'Mean"::":

4.77E-02

3.92E-02

1.02E-023.54E-03

4.38E-01

2.40E-04

1.83E-02

1.92E-03

1.83E-03

Upper 95%

S.17E-02

6.08E-02

1.92E-02S.44E-03

7.73E-01

6.54E-04

1.84E-02

2.57E-03

1.91 E-03

PC©

Arodor-1016Arodor-1 221Arodor-1 232Arodor-1 242Arodor-1243Arodor-1 254Arodor-12flOP«nt»chtorob*nzen*1 ,2,3,*-T«trachtorob«nz«r»1 ,2,4,5 -Totr«chtorob«nz<neTolu«n«1,2,3-Tridilorobonzerwt1 ,2,4-Trichtofobenzen*1 ,3,5-Trichterob«nror»

MA

NA

NAMANANA8.13E-071.06E-032.11 E-03

8.09E-04

1.49E-02

4.85E-03

3.53E-03

7.05E-05

NANANANANA

NA1.94E-061.95E-033.69E-031.17E-03

3.55E-02

8.11 E-03

6.79E-03

9.85E-05

9.20E-012.00E-011.79E+001.20E-034.40E+00

2.00E-01

5.28E-01

2.00E+01

4.68E-01

4.16E-01

6.24E-HN

1.00E-HJO

5.00E+00

1.00E4-00

Cumulative Hazard Index

NANANANANANA

1.54E-06

5.31E-05

4.51 E-03

1.95E-03

2.38E-04

4.85E-03

7.07E-04

7.05E-05

5.74E-01

NANANANANANA3.68E-06

9.74E-05

7.89E-03

2.81 E-03

5.69E-04

8.11E-031.36E-03

9.85E-05S.87E-O1

NA - Not ippfciMft: c*wnl=if oonointmScn b«tav ejection tau*I Ihcnfore Hazard Index could not ba calculBtad

6-203SR306223

Meadow Vole (Microtus vennsvlvanicus]

The meadow vole was assumed to be exposed to chemicals of concern through theincidental ingestion of sediment, ingestion of vegetation, and the ingestion of surfacewater from the area above the dike. Tables 6-78 and 6-79 present the mean and upper95% estimated daily intakes for the meadow vole for sediment, vegetation, and surfacewater. Table 6-92 presents the results of the comparison of critical toxicity values derivedfor the meadow vole to the estimated daily intake of chemicals of concern. Hazardindices developed for each chemical of concern are also provided in this table. The totalhazard index, mean and upper 95%, were above the criterion of 1 (i.e., 7.11 and 13.7,respectively).

The majority of the calculated mean risk (78%) can be attributed to benzene,chlorobenzene, and 1,4-dichlorobenzene through the ingestion of vegetation. The majorityof the calculated upper 95% risk (79%) can be attributed to benzene, chlorobenzene, 1,2-

dichlorobenzene, and 1,4-dichlorobenzene through the ingestion of vegetation. The results'•

of this evaluation indicate a potential for adverse effects to occur to the meadow volethrough the ingestion of vegetation in the area above the dike within the vicinity of theStandard Chlorine site. ;

Great Blue Heron (Ardea herodias)

The great blue heron was assumed to be exposed to chemicals of concern through theconsumption of fish and ingestion of surface water from Red Lion Creek. Table 6-93

presents the results of the comparison of critical toxicity values for the great blue heronto the estimated total daily intake of chemicals of concern. Critical toxicity values for

the majority of the chemicals of concern could not be calculated because publishedtoxicity information for the great blue heron or related avian species was only availablefor hexachlorobenzene and PCBs. The concentration of PCBs in fish tissue and the

surface water was below the detection level and therefore this class of chemicals was not

STAND-CDSTANDJOT ~ 6-204

'•-AR3.06221*

Table 6-92

Hazard Indices Based on Meadow Vole Exposure

Chemical

BenzeneChtorabenzene1 ,2-Dteh lore-benzene1 ,3-Dfchlorobenzene1 ,4-DtohtorobenzeneEthylbenzeneHexaohlorobenzeneMetachtoronitrobenzeneNitrobenzene

•loou —-- ••"•Estimated Daily Intake

IngestionMean

5.42E-013.59E+001 .26E+004.51 E-015.36E+012.26E-019.42E-059.51 E-031.11 E-01

Upper 95%

9.32E-015.58E+002.27E+019.96E+009.54E+016.16E-011.57E-041.28E-021.16E-01

'..•.. i flTOr-S :-,,,,;' ;'TF03ticl :' f ,

"•• --Value ,'"•;-;•(mg/Kg-daW

3.72E-013.80E+001.71E4-011.71E-HD11.71E+011.94E+011.60E-021.52E-012.00E-01

Hazard Indices

Mean .

1.46E+009.44E-017.39E-022.64E-023.13E+001.16E-025.89E-036.26E-025.53E-01

Upper 9596

2.51 E+001.47E+001.33E4-005.82E-015.58E+003.17E-029.82E-038.42E-025.80E-01

PCBArodor-1016Arodor-1221Arodor-1232Aroctor-1242Aroctor-1248Aroctor-1254Aroctor-1260Pentachtorobenzene1 ,2.3,4— Tetrachforobenzene1 ,2,4,5— TetrachtorobenzeneToluene1 ,2,3-Trichtorobenzene1 ,2,4-Trichtorobenzene1 ,3,5-Trichtorobenzene

MAMANANANANA

7.78E-053.04E-027.31 E-022.23E-024.98E-011.S7E-011.03E-012.30E-03

NANANANANANA

2.79E-046.25E-021.47E-013.73E-021.19E+002.78E-012.00E-013.23E-03

9.20E-012.00E-011 .79E+001 .20E-034.40E+002.00E-015.26E-013.32E-014.70E-016.80E-024.46E+011.00E+001.00E+001.00E+00

Cumulative Hazard Index

NANANANANANA

1.48E-049.15E-021.55E-013.28E-011.12E-021.57E-011.03E-012.30E-037.1tE+00

NANANANANANA

5.31 E-041.88E-013.12E-015.49E-012.67E-022.78E-012.00E-013.23E-031.37E+01

. eh«ttol «oc*r»«fan brtawdrticltan hvri 1h« tef» Hazard lotto could not b» otculatod

6-205RR306225

Table 6-93

Hazard Indices Based on Great Blue Heron Exposure*"1

Chemical

Hexachlorobenzame

:;::::" •:<i:;., T !:,:::ni:Li;:/S: Estimated Daily intake

Ong/kg-day)Mean

7.80E-06

Upper 95%

7.80E-08

.,L;':::;:'.;:C!iticaf •'!••:•';-..-= -liOXiC ity.!:' ,,::,

'•:.',:.':::• Value "•..:.:':••(rhg/kg-da

2.00E-02

; . . ;• • . ' , • .; •: :,, ,,',. ':< ,-•';• iCu imitative Hazard in<tek ••: • .:• -:

Hazard Indices '• ';ri

';:";! ::::MeM:"r,'

3.90E-06

3Jk» - 6c

Upper 95%

3.90E-063.ME-06

(a) - Hazard tndlcM could only to calculated for tiow chemicals wtfri crHcaJ toxiclty v«Juts and atwvt dataction lavate

* - Only on* sampid analyzed for arocIor-1260

6-206

evaluated. The mean and upper 95% hazard index calculated for hexachlorobenzene was3.9E-06. This value is below unity and therefore the presence of this chemical in surfacewater does not pose a potential threat to the great blue heron. However, it should benoted, that as a result of the lack of toxicity data for the remaining chemicals of concern,a determination of the potential for adverse effects to occur to the great blue heronthrough fish and surface water ingestion cannot be made at this time. Nevertheless, asensitivity analysis was conducted in which the toxicity value for hexachlorobenzene wasapplied to all other chlorinated benzenes to evaluate the effect to evaluate the effect ofthese chemicals on the great blue heron. Since increase chlorination of organiccompounds generally translates to increased toxicity, it is assumed that this approach isreasonable, although uncertain.

6.4.5.3 Risk Characterization for Aquatic Life

Surface Water ~

The potential for adverse effects to aquatic life were estimated by comparing surfacewater concentrations of Red Lion Creek with Delaware and Federal ambient water qualitycriteria (AWQC) (Table 6-90). AWQC were derived by the EPA to protect 95% of allaquatic organisms, including fish, invertebrates, and aquatic plants. Chronic or acute

AWQC are available for the majority of the chemicals of concern. Table 6-94 presentsthe calculated hazard indices based on off-site surface water concentrations and AWQC.

The cumulative hazard indices calculated for the mean and upper 95% values barelyexceed one (i.e., 1.83 and 3.19, respectively). Only chlorobenzene exceeded a hazardindex of one. Thus, the potential for possible adverse chronic effects to occur to theaquatic life of Red Lion Creek and its tributaries can be attributed to the concentrationsof chlorobenzene in the surface water.


flR306227

Table 6-94 '

Hazard Indices Based on Surface Water Concentrations and Criteria Values

ChemicalBenzeneChlorobenzene1 ,2— Dichlorobenzene1 ,3-Dichlorobenzene1 ,4-DichlorobenzeneEfriylbenzeneHexachlorobenzeneMetachloronitrobenze neNitrobenzene

::;:,:;::;;?:;:ê;:l;i.s;i;.;..: Surface WaterConcentrations ' ; :

'•''•MMean

0.0230.0640.0150.0080.044ND0.003ND0.005

Upper 95%0.0390.120.0270.0140.085ND0.003ND0.005

Ambient•''.;$&*?&•. ::Qwali ' ^Criteria ;<nrag/P5.30.050.7630.7630.7S3*

0.05*

27

:; :'. :'::iHaiardiri ftces ; " •

Mean4.34E-031 .28E+001.97E-021.05E-025.77E-02

*

6.00E-02*

1.85E-04

Upper 95%7.36E-032.40E+003.54E-021.83E-021.11E-01*

6.00E-02*

1.85E-04PCBAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor- 1 254Aroclor-1260Pentachlorobenzene1 ,2,3,4— Tetrachlorobenzene1 t2,4t5-TetrachlorobenzeneToluene1 .2,3— Trichlorobenzene1 .2,4- Trichlorobenzene1 ,3,5 -Trichlorobenzene

NDNDNDNDNDNDND0.0050.0030.003

ND0.0040.005

ND

NDNDNDNDNDNDND0.0090.0030.003ND0.0050.008ND

*

*

*

*

*

*

*

0.050.050.05*

0.050.05*

Cumulative Hazard Indox :

*******

1. OOE-016.00E-026.00E-02

*

8.00E-021. OOE-01

*

1 83E+00

*

**

**

**

1.80E-016.00E-026.00E-02*

1 .OOE-011.60E-01*

3.19E+00NO- Chemical below detection level

•- not applbable, chemical below detection level

6-208 •-"""•,'-- ^306228

K90NERSCONSUI.TJWIS

Sediment

The potential effects of site-specific sediment on the survival and growths of the benthicinvertebrate Hyallea azteca were evaluated (Appendix J). A summary of the toxicity testresults are presented in Table 6-95. The potential for possible adverse effects to occurto benthic and epibenthic life was estimated by comparing sediment concentrations withinthe Standard Chlorine Site vicinity with the site-specific sediment toxicity results (Table6-96). It should be noted that an initial sediment toxicity test was performed, however,chronic level effects could not be determined as a result of the test concentrations used.The test results from this initial toxicity test are presented in Appendix K but are notincluded in this discussion. The sediment toxicity discussion is limited to the results ofthe toxicity test reported in Appendix J.

In performing the sediment toxicity test, sediment from the Standard Chlorine site was

mixed with clean control sediment to create a series of concentrations of total chlorinatedbenzenes (TCBs) representing a 100%, 50%, 25%, 12.5%, 3.25% mixture, in addition toa control. The test organisms were then exposed to the aforementioned concentrationsfor a ten day period to determine acute and chronic effects. The TCB concentrationsassociated with each treatment level, the mean survival, and the mean length results are

presented in Table 6-95.

Based on the sediment toxicity test results, the TCB concentration that resulted in 50%mortality to Hyallela azteca (LC50) was determined to be 446 mg/kg. The no-observable-adverse-effect-level (NOAEL) was determined to be 68 mg/kg (12.5%treatment level). Mean and upper 95% concentrations of TCBs measured in the sedimentat the Standard Chlorine site (4168 mg/kg and 7354 mg/kg, respectively) were greaterthan the reported LC50 and NOAEL toxicity test concentrations. Figures 6-12 and 6-13present maps which identify those sampling locations where sediment concentrations ofTCBs exceed the LC50 for Hyallela azteca, for the wetlands and Red LionCreek/unnamed tributary, respectively. There are a number of exceedances of the LC50,

STANT>CLSSTAND PT 6-209 __ . _ __ _.

AR306229

Table6-95

Sediment Toxicity Testing Results (*)

Control6.25%12.5%25%50%100%

33.967.8135.7271.4542.7

9083.39078.368.333.3

1.931.71.641.461.431.22

******

(*) — Toxicity test species was a benthic invertebrate, Hyallela azteca** - Denotes statistically significant effect at <0.05

6-210

Table 6-96

Comparison of Off-Stte Sediment Concentrations to Toxlcity Test Results

Total ChlorinatedBenzenes

4168

Illiflilll

7354 446 67.8

6-211

AR30623

'\sNLt. V'vr"*-"? • ,*'iii---' • &f* ''' ~<S&, , "','

•':'! W-V^P"i/';y:;r r ?",'

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eainpa-i j g

oS

3(0 >. O UJ<3*aSi7JC9<<S= |-SOT.,-. ; .- < -J H; tc- •: • ^:, U, ... 3sSo

" . ' • ; O OC Ui"-) • -iPoco< ., i_ Q Z. LU;r S S o zif li^gQZ<lSi"SE 01w=>£j

^ t|'illS... w ^ 'iK''1- - '%'"' •lili''':";p;- .,.rt . »S^P .•:•.- V*!

"".' •'•- i... •• "•.."'•'

''''' ','„.".,-* ....'... ;, •*'=1\ .••>••«..-".- •%••.., ">*ff;*-> • • ••/

£ ^ £ 313 r* * "3 -f-iTR^

^ coecw sw gccwô: col '3's ScS^

iu • y »o auj 9

Table 6-97

Lettuce Seed Germination Toxicity Test Results

Sample

ControlSLTX-1SLTX-2SLTX-4SLTX-5SLTX-6SLTX-7

TCBConc.(mg/kg)

2.2238832.8485

15,1151642

;. ';Aveirage;'::;.;;;;:,:;;;;;,<3erminaii«n:V;.::-::#>1?-:; --:-:;f:|

927722 :

389811

::;;;iSiiliEsip| .'Jj'* :''Bels'"'v;';

*****

Denotes statistically significant effect at <0.05

6-215- -..„-!:.,.._;-.- - -- . , - ', : AR3Q623U

particularly in the wetlands, as noted on the maps. As a result of the sediment toxicitytest data, it is concluded that there are locations where total chlorinated benzenes arepresent' in sediments at concentrations greater than the NOAEL (68 mg/kg), and thus,there may be a potential for adverse effects to occur to the epibenthic and benthic

populations.

6.4.5.4 Risk Characterization for Soil Flora and Fauna

Soil Flora

The effects of site-specific soils on the germination of lettuce seeds (Lactuca sativa) wereevaluated (Appendix K). A summary of the results is presented in Table 6-97. Potentialeffects to terrestrial plants inhabiting the area surrounding the Standard Chlorine site wereassessed by comparing mean and upper 95% off-site soil concentrations for chemicals ofconcern to site-specific seed germination toxicity test results (Table 6-98). The lowestobservable effect level (LOEL) and the no observable effect level (NOEL) were calculated•

from the results of the toxicity test The LOEL and NOEL for lettuce seeds expressedin concentrations of TCBs was 32.8 and 2.2 mg/kg, respectively. The mean and upper95% off-site soil concentrations detected within the site vicinity were 3735 mg/kg and7551 mg/kg, respectively, both of which exceed the LOEL and NOEL. In addition,Figures 6-14 through 6-16 present maps which identify those sampling locations where

sediment or soil concentrations of TCBs exceeded the LOEL for lettuce seeds. Figure 6-14 presents these data for the wetland sediment samples, Figure 6-15 presents these datafor soils based on the 1986 release pathway, and Figure 6-16 presents these data for soilsbased on the 1981 release pathway. There are a number of exceedances as shown on themaps. Based on these results, TCBs are present in the soil and sediments inconcentrations that may potentially produce adverse effects on flora.

6-214

5R30S235

Table 6-98

Comparison of Off-Site Soil Concentrations to Seed Germinatoln Toxlclty Test Results

Total Chlorinated Benzenes 3735 7551

SSS^^ft'fcilMjMt^S-s

32.8 2.2

6-216 _;; : ; - . . _ . .STAND-CL\HI-T6-9B.TBL ..,_.__.__.. __ __ .. - ^ _ -

flR306236

• TSL'.v .. ". • . ;..• -. •, ,. „„.__ -.. - •:?*v* '.C - ^ '- "' :' ' ~~ -~- ^ • i//¥ . '

"*\'"' T ; ^ • ' f~ \'/ Mf/ %•'h;V NX . ' •• - //..... . .. 1V<;,.,..X ...-*i&J*jf /-A •;%

lll -s, --'-'"••-. M ^ r M''' ' *a * E " ' y ':i .< V'iv"-x --"• '*'

Soil Fauna ^

The effects of site-specific soils on the survival of earthworms (Eisenia foetida) wasevaluated (Appendix K). A summary of the results of the toxicity test is presented in

Table 6-99, The potential for adverse effects to occur to the soil fauna was estimated bycomparing off-site soil concentrations with site-specific soil toxicity test results. Thecalculated NOEL and LOEL for the earthworm toxicity test expressed in concentrationsof TCBs was 32.8 and 485.6 mg/kg, respectively. According to Table 6-100, the meanand upper 95% off-site soil concentrations detected within the site vicinity were 3735 and7551 mg/kg, respectively, both of which exceed the NOEL and LOEL. In addition,

Figures 6-17 and 6-18 present maps which identify those sampling locations where soilconcentrations of TCBs exceed the LOEL for earthworms along the 1986 and the 1981release pathways, respectively. There are a number of exceedances as shown on themaps. Based on these results, TCBs are present in the soil in concentrations that maypotentially produce adverse effects to the soil fauna .of the Standard Chlorine site.

6.4.6 Ecological Uncertainties

An ecological risk assessment, like a human health risk assessment, is subject to a widevariety of uncertainties. Virtually every step in the risk assessment process involvesnumerous assumptions which contribute to the total uncertainty in the ultimate evaluationof risk. : ..L_

In the exposure assessment, numerous assumptions were made in order to estimated daily

intakes for the selected target species (Le., white-tailed deer, meadow vole, and great blueheron). Since limited site-specific information was available, assumptions were maderegarding ingestion rates, frequency of exposure, and exposure point locations. An effort

was made to use assumptions that were conservative, yet realistic.


Table 6-99

Earthworm Toxicity Test Results

::Sanipifi::5i::;

ControlSLTX-1SLTX-2SLTX-4SLTX-5SLTX-6SLTX-7

Gj iGonoi'f;g;|mi)]';i::;;

2.2238832.8485

15,1151,642

StiiV ilss!;;KK

1001000937000

SWtistec&l .;:':::vResui6'.'l

..is;

*

* ~ " f

*

*

- Denotes statistically significant effect at <0.05

6"221

Table 6-100

Comparison of Off-She Soil Concentrations to Earthworm Toxlcfty Test Results

Total Chlorinated Benzenes

Mean

3735 7551 485.6 32.8

STANO-OLWITHOQ.TBL 6-222 AR3062U2

o- - - u t6fe->•! r CO

-JOJ<*Od>

xi?i iSffii|fe§g§151o:.

KSIGMEKSOttSULTiWTS

Site-related chemical exposure to the white-tailed deer and meadow vole throughsediment-mediated pathways, such as incidental sediment ingestion and consumption ofbrowse or vegetation, was derived from off-site sediment concentrations only. Soilconcentrations were excluded from this evaluation because suitable browse or vegetationfor ingestion by the white-tailed deer or meadow vole was not present in contaminatedsoil areas.

The interpretation and application of lexicological data in the toxicity assessment isprobably the greatest source of uncertainty in an ecological risk assessment. Frequently,data from literature sources are not species-specific and therefore, extrapolation of the

data to the species of concern is necessary. When extrapolating ecological data, everyeffort was made to use data for the most closely related species to the target organism.Even so, species sensitivity may vary even among closely related species. Variations inspecies sensitivity may be due to differences in some of the following factors: toxicitytolerance thresholds, toxic symptoms exhibited, toxicity onset times, and metabolism ofthe ingested chemical. i :

In calculating critical toxicity values (CTVs), safety factors are applied to toxicity datato account for differences in species and differences in toxicological endpoints (e.g. LC50,NOAEL, LOAEL). One of the safety factors which is applied has been recommended byEPA for use in data extrapolation (i.e., acute LC50 to an acute NQAEL). The remainingsafety factors have been developed based on best professional judgement. Thus, there areuncertainties resulting from the use of these safety factors. ~

An uncertainty which may result in an underestimate of risk in the risk characterization,is the absence of toxicity criteria or guidance values (i.e., CTVs, water quality criteria,sediment criteria, phytotoxicity data) for certain chemicals. In the absence of suchtoxicity criteria, the potential risk from exposure to these chemicals can not bequantitatively evaluated, and thus are not included in the total hazard index. This was

STAND-CLNSTAND.RPT ' 6-225 ^30621^5

evident in the great blue heron evaluation. Only one chemical of concern,hexachlorobenzene, was evaluated due to lack of lexicological data available in thepublished literature.

A comparison of bioassay results with soils and sediment concentrations at the SCD sitesuggests that populations of plants and animals similar to those used in the bioassays mayexhibit some form of stress in those areas of the site where the chemical levels exceedtoxicity thresholds.

This stress may be exhibited as either a direct or an indirect biological effect. Severaltypes of direct biological effects may be possible and include the mortality of adults (asdemonstrated by amphipod and earthworm survival studies), mortality or impairment ofother life stages, the disruption of normal growth function and the disruption ofreproductive or germinal cycles (as demonstrated by lettuce seed bioassay).

Each of these direct effects can result in direct changes in populations of chemically-affected species ultimately resulting in changes in community structures. It should benoted, however, that direct mortality of individuals, may not necessarily lead to populationreduction. The differential sensitivity of target organisms can allow compensation to

occur in which less affected individuals have an enhanced survival rate because oflowered competition. Moreover, other effects may not result in mortality directly, butcould cause sublethal physiological behavioral effects that may produce "indirect"biological effects and consequently population or community level impacts. Of particular

concern, these indirect effects include changes in trophic level relationships, changes in

competitive interactions and changes due to disruptions in habitat. Although the bioassaysand predictive assessment of risk to key species suggest some level of stress is probableat the individual organism level, it is not possible to predict the extent to which these datademonstrate substantial changes in the structure and function at the community andecosystem level.

STAND-CLNSTAND-RPT 6-226

D£SCN£RS«JNSttTANTS

6.4.6.1 Sensitivity Analysis

As a result of the absence of available toxicity data for the chemicals of concern for thegreat blue heron, the toxicity value for hexachlorobenzene was applied to thechlorobenzenes in order to evaluate the effects of these chemicals. Table 6-101 presents

the results of this evaluation. Based on the mean and upper 95% values for thecumulative hazard indices (3.7 IE-01), a potential for adverse; effects to occur to the greatblue heron through the ingestion of fish and surface water does not exist when thehexachlorobenzene toxicity value is applied as a surrogate for other chlorinated benzenes.

STAND-CLNSTAND.RPT 6'227 -—i M3062U7

Table 6-101

Hazard Indices Based on Great Blue Heron Exposure

B*nz»n*Chlofob*nz»ne1 ,2- Dtehlor ob»nzan«1 ,3 - D fch [orob «nz*n«1 ,4-DtehlorobonzwwBhy1b«nz*naHtxacHorob«nzan«M*tachkxonHrob*nzeneNftrofa«nz»r>0

TotalEstimated Dally intake

' {B*fl/taMoan5.98E-071 .05E-033.90E-072.08E-071.14E-06NA

7.80E-OSNA

1 .30E-07

3-day)Uppar 95%

1.01E-061.05E-037.02E-073.64E-072.21 E-06NA

7.80E-08NA

1 .30E-07

CriticalTflxfcftjrVaUtHi

(mg/kfl-day)NDA0.020.020.020.02

NA0.02

NDANDA

Hazard Indices

MfftrtNA

5.26E-021.95E-051.04E-055.72E-05NA

3.90E-06NANA

Upper 95%NA

5.27E-023.51 E- 05

1 .82E-051.11E-04NA

3.90E-06NANA

PCBAroctof-1016Arodof-1221AfOdof-1232ArocIor-1242Aroclor-124©ArocIof-1254Arodor~126aP»ntachlofobeoz»no1 ,2 ,4— T»trachlorobenzene1 ,2,4,5— T»trachlorobenzaneTotucn*1 ,£3-Tr$ehlofofa»nz8n«1 ,2,4— TricNorob*nz*ne1 ,3,5— TrichkKofa«iz»ne

NANANANANANA

9.60E-031.30E-077.80E-087.80E-08NA

1.04E-076.30E-03NA

NANANANANANA

9.60E-032.34E-077.80E-087.80E-08NA

1 .30E-076.30E-03NA

NANANANANANA2.9880.020.020.02

NA0.020.020.02

' " • Cumulative Hazard Index

NANANANANANA

3.21 E-036.50E-063.90E-063.90E-06NA

5.20E-063.15E-01NA

3.71 E-01

NANANANANANA

3.21 E-031.17E-053.90E-063.90E-06NA

6.50E-063.15E-01NA

3.71 E-01NA- PtotapplicableNDA - No toxictty data available

Documents

SECTION 6 BASELINE RISK ASSESSMENT · BASELINE RISK ASSESSMENT 6.1 APPROACH TO THE BASELINE RISK ASSESSMENT 6.1.1 Background This section of the Remedial Investigation Report presents