Health Canada

SantéCanada

FEDERAL CONTAMINATEDSITE RISK ASSESSMENT INCANADA

PART I:GUIDANCE ON HUMAN HEALTHPRELIMINARY QUANTITATIVERISK ASSESSMENT (PQRA)

Contaminated Sites Program

FEDERAL CONTAMINATED SITE RISK ASSESSMENT IN CANADA

PART I: GUIDANCE ON HUMAN HEALTH PRELIMINARY QUANTITATIVE

RISK ASSESSMENT (PQRA)

September 2004

Prepared by:

Environmental Health Assessment Services Safe Environments Programme

Our mission is to help the people of Canada maintain and improve their health. Health Canada Published by authority of the Minister of Health Également disponible en français sous le titre : Partie I : L’évaluation quantitative préliminaire des risques (ÉQPR) pour la santé humaine This publication can be made available in/on computer diskette/large print/audio-cassette/braille upon request. Her Majesty the Queen in Right of Canada, 2004 Cat. H46-2/04-367E ISBN 0-662-38244-7

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PREFACE This guidance document was prepared in support of the Federal Contaminated Sites Accelerated Action Plan (FCSAAP), a program designed to ensure improved and continuing federal environmental stewardship as it relates to contaminated sites located on federally owned or operated properties. As is common with national guidance, this document will not satisfy all of the requirements presented by contaminated sites or risk assessors in every case. Federal Contaminated Site Risk Assessment in Canada: Part I was prepared by the Environmental Health Assessment Services Division, Safe Environments Programme, Health Canada. Both internal (federal government) and external peer reviews were undertaken to ensure, to the degree possible, that the broad requirements of contaminated sites’ custodial departments and of contaminated site risk assessment in general were addressed. Following completion of Health Canada’s and inter-departmental review, the document was submitted to the following external risk assessment practitioners: • Kathryn E. Clark, P.Eng., Ph.D., BEC Technologies, Inc., Aurora, Ontario • Brett Ibbotson, Angus Environmental Ltd., Don Mills, Ontario • Ross Wilson, M.Sc., DABT, Wilson Scientific Consulting Inc., Vancouver, BC Identification of peer reviewers should not be construed as endorsement of, approval of, or agreement with the risk assessment methods delineated herein. Comments were sought in an attempt to make the document as complete and defensible as possible, within the limitations presented by the federal contaminated sites program and Health Canada commitments, policies, and obligations with respect to health risk assessment and protection. As the practice of risk assessment advances, and as the FCSAAP proceeds, new and updated information on soil quality guidelines, drinking water guidelines, toxicological reference values, contaminant bioavailability, human characteristics and exposure factors, and other aspects of risk assessment will be published. As a result, it is anticipated that revisions to this document will be necessary from time to time to reflect this new information. Health Canada should be consulted at the address below to confirm that the version of the document in your possession is the most recent edition and that the most recent assumptions, parameters, etc., are being used.

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Questions, comments, criticisms, suggested additions or revisions to this document should be directed to:

Contaminated Sites Program Environmental Health Assessment Services Safe Environments Programme Health Canada 2720 Riverside Drive Sir Charles Tupper Building, 4th Floor, PL 6604M Ottawa, ON K1A 0K9 Fax: (613) 941-8921 E-mail: cs-sc@hc-sc.gc.ca See also: http://www.hc-sc.gc.ca/hecs-sesc/ehas/contaminated_sites.htm

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TABLE OF CONTENTS Preface...............................................................................................................................................i Abbreviations and Acronyms .........................................................................................................v 1. Introduction .............................................................................................................................1 1.1 Background................................................................................................................................2 1.2 Purpose ....................................................................................................................................2 1.3 Preliminary Quantitative Risk Assessment versus More Complex Site-Specific Risk

Assessment ................................................................................................................................4 1.4 Petroleum Hydrocarbons and Radiological Contaminants........................................................4 2. Scope of Work / PQRA Report Content................................................................................6 2.1 Executive Summary...................................................................................................................6 2.2 Introduction ...............................................................................................................................6 2.3 Description of the Property/Site ................................................................................................6

2.3.1 Concentrations of Contaminants in Environmental Media ............................................6 2.4 Problem Formulation.................................................................................................................7

2.4.1 Screening and Identification of Contaminants of Potential Concern .............................7 2.4.2 Identification of Potential Receptors ..............................................................................9 2.4.3 Identification of Operable Exposure Pathways ..............................................................9 2.4.4 Problem Formulation Checklist ......................................................................................9

2.5 Exposure Assessment ................................................................................................................10 2.5.1 Characterization of Potential Receptors .........................................................................11 2.5.2 Exposure Frequency and Duration .................................................................................11 2.5.3 Exposure Equations ........................................................................................................13 2.5.4 Airborne Respirable Dust Levels....................................................................................14 2.5.5 Models ............................................................................................................................14 2.5.6 Relative Absorption Factors and Exposure via Multiple Pathways ...............................18 2.5.7 Carcinogens ....................................................................................................................20

2.6 Hazard Assessment....................................................................................................................21 2.7 Risk Characterization ................................................................................................................22

2.7.1 Non-carcinogens: Single-Substance Exposures .............................................................22 2.7.2 Carcinogens: Single-Substance Exposures.....................................................................22 2.7.3 Exposure to Mixtures......................................................................................................23

2.8 Non-standard Assumptions and Toxicological Reference Values ............................................23 2.9 Uncertainties..............................................................................................................................23 2.10 Conclusions and Discussion ......................................................................................................24 2.11 Recommendations .....................................................................................................................24 2.12 References .................................................................................................................................24 3. References ................................................................................................................................24

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Appendix A Screening Contaminants of Potential Concern for Local or Regional Background (Natural) Soil, Groundwater and Surface Water Concentrations ..............................27

Appendix B Essentially Negligible Cancer Risk for Contaminated Site Risk Assessment...........30

LIST OF TABLES Table 1 Specific Characteristics of Preliminary Quantitative Risk Assessments (PQRAs)

vs Site-Specific Risk Assessments (SSRAs)……………………………………5

Table 2 Problem Formulation Checklist…………………………………………………10

Table 3 Recommended Human Receptors and Their Characteristics for Preliminary Quantitative Risk Assessments…………………………………………………..12

Table 4 Exposure Duration and Frequency Assumptions for Preliminary Quantitative Risk Assessments…………………………………………………………………...…13

Table 5 Recommended General Equations to Be Used to Estimate Doses…………….…15

Table 6 Relative Dermal Absorption Factors (RAFDermal) Recommended for Preliminary Quantitative Risk Assessments…………………………………………………..19

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ABBREVIATIONS AND ACRONYMS ADI Acceptable daily intake ATSDR Agency for Toxic Substances and Disease Registry CAAL Canadian Association of Analytical Laboratories CCME Canadian Council of Ministers of the Environment CMHC Canada Mortgage and Housing Corporation COPC Contaminant of potential concern CWS Canada-Wide Standard DNAPL Dense non-aqueous phase liquid DWQG Drinking Water Quality Guidelines ESA Environmental site assessment FCSAAP Federal Contaminated Sites Accelerated Action Plan HQ Hazard Quotient ILCR Incremental lifetime Cancer risk IRIS Integrated Risk Information System LNAPL Light non-aqueous phase liquid MRL Minimum risk level OMEE Ontario Ministry of Environment and Energy PHCs Petroleum hydrocarbon compounds PQRA Preliminary quantitative risk assessment PRG Preliminary remediation goal RAF Relative absorption factor RAIS Risk Assessment Information System RfC Reference concentration RfD Reference dose SF Slope factor for carcinogenic potency SSRA Site-specific risk assessment TC Tolerable concentration TC05 Concentration (air, water) found to induce a 5% increase in the incidence

of, or deaths due to, tumours considered to be associated with exposure TD05 Dose found to induce a 5% increase in the incidence of, or deaths due to,

tumours considered to be associated with exposure TDI Tolerable daily intake TRV Toxicological reference value UCL Upper confidence limit U.S. EPA United States Environmental Protection Agency WHO World Health Organization

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1. INTRODUCTION

Risk assessment, whether at the screening level (i.e., preliminary) or more complex, is not an exact science. A wide variety of advice and direction is offered by international, national and provincial/territorial environmental agencies regarding the conduct of risk assessments, and different risk assessors access and rely on the available regulatory advice and direction differently. This results in extensive variability in the estimates of chemical exposure and risk. For example, in 1997, the Canada Mortgage and Housing Corporation (CMHC) commissioned a study whereby nine consulting firms were contracted to estimate the risks posed by a contaminated residential property. The resulting estimates of exposure and risk produced by the different firms varied over nine orders of magnitude for non-cancer endpoints and over 10 orders of magnitude for cancer, despite being given the same site data set. The large variability related primarily to the differing receptors and exposure scenarios assumed by the different firms. Variability was also introduced by the selection of different toxicological reference values (TRVs) for risk characterization. Likewise, a comparison of 10 preliminary quantitative risk assessments conducted on behalf of Fisheries and Oceans Canada (Risklogic, 2003) revealed widely differing approaches, assumptions, and risk-related conclusions, despite the fact that all 10 sites were similar in land use and public access. The toxicological reference value for just one contaminant, evaluated at all 10 sites, varied by a factor of five among different consulting firms. Numerous other variables and assumptions also varied widely, both among consulting firms, and in one case within the same firm, making it virtually impossible to rely on (at face value) and compare the conclusions among sites and reports with respect to the presence or absence of human health risk, without further analysis and recalculation. Provincial regulatory agencies across Canada offer differing guidance on many aspects of risk assessment. For example, definitions of acceptable cancer risk vary (BC, Alberta and the Atlantic provinces accept an incremental lifetime cancer risk of 1 x 10-5, while Ontario targets 1 x 10-6). When characterizing the risks posed by exposure to non-carcinogenic substances, British Columbia accepts a Hazard Quotient of 1, while Alberta and Ontario target 0.2. Provinces also differ in their preferred statistics for exposure calculations, varyingly prescribing the maximum contaminant concentration, the 95% upper confidence limit of the mean concentration, or the 90th percentile or 95th percentile of the concentration data distribution. Based on the above observations, it became apparent that standardized guidance was required at the federal level to assist with the consistent assessment of risks posed by contaminated sites under federal custodianship across the country.

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1.1 Background In 2003 the federal government established the Federal Contaminated Sites Accelerated Action Plan (FCSAAP), a new contaminated sites initiative to assist in identifying, assessing and managing the risks at contaminated properties under the custodial care of Canadian federal government departments. A major emphasis of the FCSAAP is to give priority for remediation or risk management to those sites and properties posing the greatest risks. The purpose of a preliminary quantitative risk assessment (PQRA) is to quantify the degree of potential human health risk posed by the presence of contamination at a subject site. The results of a PQRA for federal sites/properties may be used by Health Canada to rank and prioritize the subject site for remedial funding under the FCSAAP. As a result, with the current disparity in risk assessment methods, there is a need for standardized risk assessment guidance that will ensure that all federal sites are evaluated for that priority on an equal and defensible basis. Preliminary quantitative risk assessments generally prescribe methods and assumptions that ensure that exposures and risks are not underestimated. In this way, if negligible or acceptable risks are indicated using these conservative methods, then actual site use patterns and conditions will almost certainly present negligible or acceptable risks. However, the converse is not necessarily true; where PQRA suggests a potential for unacceptable risks, this does not immediately indicate that actual site conditions are unacceptable. Often, further assessment may be necessary to resolve conservatism and uncertainty in the PQRA process before the actual extent of the health risk can be fully quantified and defined. When risk management strategies are implemented on the basis of the results of a PQRA, the remediated or managed site conditions will almost certainly achieve a reduction in health risk that was greater than might have otherwise been necessary if the on-site risks had been more extensively and accurately ascertained. It becomes a question of cost and feasibility of risk management action when deciding whether to implement remediation on the basis of a PQRA or to further reduce risk assessment uncertainties at a given site before defining the most suitable risk management strategy. 1.2 Purpose The purpose of this guidance document is to prescribe, to the degree possible, standard exposure pathways, receptor characteristics, toxicological reference values, and other parameters required to quantitatively assess the potential chemical exposures and risks at federal contaminated sites.

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The standard PQRA approach presented herein is designed specifically for the assessment of sites that are to remain the properties of federal agencies, properties for which greater consistency in risk assessment methods and interpretation of results is required. For properties being divested to a private party or to provincial governments, or for assessments that address risks from off-site migration of contamination (to an adjacent provincial water body or neighbouring private property, for example), risk assessments may have to be completed in accordance with local provincial/territorial regulatory requirements. Local regulatory requirements may differ from the standardized methods described in this guidance document. When the methods being employed in such cases differ significantly from those presented in this document, risk assessors should identify those assumptions, methods, and interpretations required by provincial agencies that differ from this method, and discuss the implications for the custodial department. At first glance this guidance may seem overly demanding. However, the length of this document stems predominantly from the inclusion of explanatory text to ensure that the guidance is understood. In other words, an attempt has been made to describe why the methods are requested, not just to delineate those methods. Most risk assessors have standard spreadsheets containing the various equations, assumptions, TRVs, etc., that they routinely use for risk assessments. The primary requirement for federal sites is to ensure that those spreadsheets comply with the prescribed equations, assumptions, TRVs, etc., outlined herein. Health Canada is flexible on the format and presentation of data and results, as long as the key components described below are included. Although the guidance offered here is prescriptive in nature, it is not designed or intended as a substitute for the sound professional judgement of a qualified and experienced risk assessment practitioner. It is recognized that many sites will present unique situations not specifically addressed here. Risk assessors are encouraged to ensure that their assessments are complete and that they address all relevant risks. The methods delineated below should not be viewed as a “black box” of equations and assumptions that negate the need for sound professional judgement. However, where possible and appropriate, the guidance provided here should be used. Where alternate or unique approaches have been determined to be necessary, these must be sufficiently documented and described to enable peer review, and must be evaluated for their impact on risk estimates relative to the application of the standard methods prescribed below. The guidance that follows is organized according to subject areas that Health Canada wants included in the final report. However, it is recognized that different writing styles or corporate standard formats may differ somewhat from those of the outline presented below. Alternate formats are acceptable as long as all of the requested information is presented.

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1.3 Preliminary Quantitative Risk Assessment versus More Complex Site-Specific Risk Assessment Preliminary quantitative risk assessments (PQRAs) and the more complex site-specific risk assessment (SSRA) are not independent but represent opposite ends of a continuum of complexity in risk assessment. The general characteristics of SSRA versus PQRA are outlined in Table 1. PQRA is not intended as a substitute for SSRA. A complex SSRA may be particularly appropriate in those situations where there is a large degree of variability across the site in terms of land use, contaminant types and concentrations, soil quality and other site characteristics, and receptors and their interaction with the site. The increased detail and complexity of SSRA will generally reduce the degree of uncertainty associated with PQRA, resulting in the more accurate, precise, realistic, reliable, and defensible quantification of risks, as well as serving as a critical tool in the identification of complex remedial and risk management alternatives. When PQRA determines that, for maximal exposures, potentially unacceptable human health risks may exist, it may be appropriate to undertake a more detailed and complex SSRA prior to defining remedial or risk management options. Guidance on conducting complex site-specific risk assessments is currently being formulated by Health Canada and will be published when work on it is completed. 1.4 Petroleum Hydrocarbons and Radiological Contaminants The guidance presented below focuses exclusively on chemical contaminants other than petroleum hydrocarbon compounds (PHCs) or radiological contaminants. For PHCs, a Canada-Wide Standard (CWS) has been established and published by the Canadian Council of Ministers of the Environment (CCME) (2000, 2001), including spreadsheets to assist in the derivation of modified generic (Tier 2) soil quality guidelines incorporating limited site-specific data. Those methods should be employed where PHCs are encountered. For sites presenting radiological risks, Health Canada should be consulted for advice on the most appropriate methods and approach to risk assessment for the type of contaminant and site in question.

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TABLE 1 Specific Characteristics of Preliminary Quantitative Risk Assessments (PQRAs)

vs Site-Specific Risk Assessments (SSRAs)

Preliminary Quantitative Risk Assessment (PQRA)

Tier 2/3 Site-Specific Risk Assessment (SSRA)

Environmental Media Sampled

Generally, soil only; occasionally groundwater, if a concern

Generally, will include soil, groundwater, vegetation, indoor air, outdoor air (volatiles and/or particulate), indoor dust, other environmental media as required

Quantity of Data Limited; generally restricted to data collected during ESA 2/3 for confirmation of contamination and very limited delineation of hot spots

Extensive; Tier 2/3 SSRA generally includes a sampling plan designed to provide reliable and representative quantification of the contaminant(s) in each environmental medium/pathway

Statistic Used to Represent COPC Level(s)

Generally, the maximum measured concentration

Generally, the arithmetic average or the upper 95% confidence limit on the arithmetic average.

Use of Modelling Extensive, since COPC concentrations in all media but soil (and perhaps groundwater) are usually estimated with the use of models.

Limited; generally direct data will be collected for all environmental media that are expected to be contaminated and/or contribute significantly to exposure.

Characterization of Site

Limited to measurement of COPCs in soil (and perhaps groundwater)

Extensive; physical (soil grain size, depth to groundwater, etc.) and chemical (pH, organic carbon content, buffering capacity, etc.) characterization of on-site soils and groundwater; precise measurement of distance from on-site structures (house, etc.) to contamination sources (hot spots); other characteristics as required

Characterization of Receptors

Limited to standard, conservative assumptions available from published sources

May be site-specific, particularly with respect to the nature and extent of land use as well as time-activity patterns (when and how the land is used by receptors); quantification of receptor characteristics tends toward greater precision and less conservatism

Risk Characterization

For non-carcinogens, based on 20% of the tolerable daily intake since exposure from background sources (unrelated to the site) is not quantified For carcinogens, based on 100% of the acceptable risk value of 1 x 10-5 since the incremental lifetime cancer risk (ILCR) is independent of background sources

Based on 100% of the tolerable daily intake since exposure from background sources is quantified For carcinogens, based on 100% of the acceptable risk value of 1 x 10-5 since the ILCR is independent of background sources

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2. SCOPE OF WORK / PQRA REPORT CONTENT

The human health preliminary quantitative risk assessment (PQRA) report should include the chapters/sections listed below. It is important for risk communication purposes that each PQRA report be able to “stand alone”. Therefore, all relevant equations, assumptions, models, etc., required for the PQRA must be presented in each report. 2.1 Executive Summary A brief synopsis of the site, the definition of the problem, the results and conclusions of the PQRA, and any recommendations stemming from the analysis must be presented. 2.2 Introduction This section should briefly identify the client department, the project manager/departmental contact, and the assessor undertaking the risk assessment. 2.3 Description of the Property/Site A brief but complete description of the site should be provided, including all site characteristics that may be pertinent to the understanding and/or quantification of potential exposures and risks on-site. Subsections may include but not necessarily be limited to:

• site location; • current site use; • topography; • geology; • hydrogeology, including the use of groundwater as a source of drinking water; • identification of current land uses and potential receptors on neighbouring properties; • distance to the nearest community (village, town, city, etc.); if the site is within

municipal boundaries, this should be mentioned; • an estimate of the size of the population of the nearest community; • proximity to local surface water; • summary of on-site contamination, including identification and description of any

plumes, dense non-aqueous phase liquid (DNAPL), light non-aqueous phase liquid (LNAPL), etc.;

• local or regional background concentrations of contaminants (as available and appropriate); and

• reference to appropriate reports that provide a detailed description of the property. 2.3.1 Concentrations of Contaminants in Environmental Media The data on concentrations of contaminants measured on-site should be adequately summarized. At the least, for all sampled media (soil, groundwater, surface water, vegetation, etc.) the

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minimum, maximum, and arithmetic average concentrations should be reported, along with the number of samples analyzed. For soil samples, the depth at which samples were collected should be indicated. A map depicting sampling locations is often helpful in demonstrating or determining if the sampling plan has been adequate to reflect the distribution of contaminants across the property. Direct pathways of exposure to soil contaminants (i.e., ingestion, dermal absorption, inhalation of suspended particulate matter) will relate predominantly to “surface” soil. The precise definition of surface soil will vary from site to site, depending on the depth of sample collection and may be represented by depths ranging from ≤ 5 cm to 1.5 m. The CCME (1996) defines surface soil from “grade” to 1.5 m below grade. Barring sampling from shallower depths, the CCME definition should be used to define surface versus subsurface soils. The laboratory performing chemical analyses should be certified by the Canadian Association of Analytical Laboratories (CAAL) or similar organization. Further information on sample collection, analysis, and data management is offered by the CCME (1993a, 1993b). 2.4 Problem Formulation It is essential that a brief but thorough problem formulation be provided. Specifically, report subsections will likely include but not necessarily be limited to:

• screening and identification of contaminants of potential concern (COPCs); • identification and description of potential receptors; • identification of operable exposure pathways; • a brief summary paragraph describing the COPCs, critical receptor(s), and exposure

pathways; and • presentation of the Problem Formulation Checklist (see section 2.4.4, Table 2).

2.4.1 Screening and Identification of Contaminants of Potential Concern For soil-borne contaminants, COPCs should be identified (screened) employing CCME Environmental Quality Guidelines for protection of human health, where possible. Where CCME human health guidelines are not available, human health-based provincial guidelines may be used, provided those for non-carcinogens are derived on the basis of 20% of the toxicological reference value (TRV). The CCME applies 20% of the tolerable daily intake (TDI; also termed a reference dose (RfD) or acceptable daily intake (ADI)) when setting guidelines for soil and other media. Where no Canadian jurisdiction has established a human health-based environmental quality guideline for a particular contaminant, the U.S. Environmental Protection Agency’s preliminary remediation goals (PRGs) (U.S. Environmental Protection Agency [U.S. EPA],

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2002) may be used, again adjusting those for non-carcinogens to reflect 20% of the U.S. EPA RfD. In the event that a contaminant has no corresponding health-based soil quality guideline, the contaminant should be included as a COPC for further risk assessment, unless the measured concentrations are consistent with natural or background concentrations (see below). For contaminants in groundwater, the Health Canada Guidelines for Canadian Drinking Water Quality (http://www.hc-sc.gc.ca/hecs-sesc/water/index.htm) should be used for screening of COPCs if the groundwater is potable. If it is non-potable, available provincial guidelines should be reviewed and employed as appropriate in the professional judgement of the risk assessor. Before a site is considered contaminated, on-site concentrations of contaminants, particularly natural elements, should also be compared to data from local or regional surveys of background soil quality and groundwater quality (and surface water quality if relevant) in uncontaminated areas, if data are available. If it is found that concentrations of contaminants of potential concern at the site are representative of background levels, then the site may not be contaminated despite the fact that generic guidelines are exceeded. A further discussion of background levels is presented in Appendix A. Various sampling procedures will have been applied to the site to collect samples of contaminated environmental media that could include soil, indoor dust, drinking water, indoor or ambient air, vegetation and/or other biota. A variety of methods could have been used to select sampling locations, including random, systematic (grid), or targeted (at known or suspected “hot spots” or in locations of frequent/continuous receptor occupation), etc. The soil sampling conducted at contaminated sites during typical environmental site assessments (ESAs) is usually targeted at zones of known or suspected contamination. As a result, the sampling is not random, and areas with elevated concentrations will typically be subject to more frequent sampling than are areas without contamination. Therefore, the maximum concentration determined from such targeted sampling will in all probability exceed the true average, on-site soil concentration of contaminants. Depending on the quantity and quality of available data for a given site, and on professional judgment, a variety of possible statistics may be used to represent the on-site contaminant concentration in appropriate media (air, water, soil, etc.) for screening purposes. The statistic could be the maximum concentration, the arithmetic average, the 95% upper confidence limit (UCL) of the mean, or the 90th or 95th percentile value of the available data, etc.

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In most cases, it is anticipated that the maximum measured concentration of a contaminant will be used to characterize its concentration at the site under investigation. However, where in the opinion of the risk assessor the data are sufficiently rigorous, the arithmetic average concentration should be used for screening purposes. In any case, a brief justification for the statistic selected should be provided (for example, only 20 samples were collected and, therefore, the maximum concentration was most appropriate). 2.4.2 Identification of Potential Receptors The receptors likely to visit or inhabit a site will depend on land use and may include members of the general public, departmental personnel, members of specific population subgroups, etc. Exposure calculations may be done for all potential receptors/receptor age groups or only for those critical receptors that are confirmed to have the greatest exposure per unit of body weight per day. Due to the nature of federally owned and operated properties, receptors will often include employees of the custodial department and members of the general public. Members of specific population subgroups (Native Canadians, for example) may also access the site. Critical receptors in all such subgroups should be evaluated if it is anticipated that these groups would be exposed to on-site contaminants. Age groups to be addressed are those specified by Health Canada (1994) and the CCME (1996): infants (0 to 6 months of age); toddlers (7 months to 4 years of age); children (5 to 11 years); teens (12 to 19 years); and adults (20+ years of age). In the case of industrial properties, there may be concern regarding risks posed to construction workers during occasional short-term work on-site, particularly work involving soil excavation. If, in the opinion of the risk assessor, soil excavation may present significant risks to these construction workers, even over short time periods, this receptor should also be included in the risk assessment. 2.4.3 Identification of Operable Exposure Pathways One or more exposure pathways may not be functional at a given site. Operable and inoperable exposure pathways should be identified and a rationale provided for pathways deemed inoperable (i.e., to be excluded from exposure calculations) at the subject site. 2.4.4 Problem Formulation Checklist Table 2 presents an example checklist to aid in, and summarize, the problem formulation for the subject site. It identifies land use, receptors, and operable/inoperable exposure pathways. This or a similar checklist should be included with the risk assessment report.

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TABLE 2 Problem Formulation Checklist

Land Uses

(check [√] as appropriate)

Receptor Group(s)

(check [√] as appropriate)

Critical Receptors

(check [√] as appropriate)

Exposure Pathways

(check [√] as appropriate)

Agricultural General public Infant Soil ingestion

Residential/ urban parkland Employees Toddler Soil dermal

absorption

Commercial with daycare Construction

workers Child Particulate inhalation

Commercial without daycare Canadian Native

communities Teen Vapour inhalation

Industrial Other (specify) Adult Groundwater ingestion

Other (specify) Other (specify) Water dermal absorption

Produce ingestion

Fish ingestion

Wild game ingestion

Other (specify)

Other (specify)

Other (specify)

Other (specify)

2.5 Exposure Assessment This section should include all exposure equations, chemical-specific characteristics, any necessary assumptions, the concentration (maximum, arithmetic average) used to represent the concentrations of COPCs in applicable media (air, water, soil, vegetation, etc.), and identification of and the results from the application of any methods or models required to estimate concentrations in one environmental medium based on those in another medium. Models may include those that employ measured soil-borne concentrations to estimate concentrations in groundwater, in surface water, in indoor air (volatile contaminants only), in ambient air, in agricultural produce, in vegetation used as country foods, in wildlife or fish that serve as food, etc.

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In some cases, assessors may believe that the assumptions and equations presented in this guidance document are inadequate or inappropriate for the site in question. In these cases, the assessor should discuss his/her concerns with the client department and, where deemed appropriate, alternate assumptions and/or equations may be employed. However, it is imperative that the PQRA report contain a clear description of the inadequacies of the guidance presented here as it relates to the issue at hand, and that a convincing rationale (with citations) to support the use of alternate methods or assumptions is provided. For these cases, exposures should be estimated using the prescribed methods and assumptions and employing the assessor’s preferred approach so that the impact on risk estimates is obvious and transparent. 2.5.1 Characterization of Potential Receptors The physical characteristics (required for exposure calculations) for a variety of common receptor groups are presented in Table 3. When considering exposure pathways and circumstances beyond those encompassed by the equations and assumptions outlined in this document, additional receptor characterization assumptions should be drawn from Richardson (1997), if available. Where Canadian data on required receptor characteristics have not been published, alternate sources such as the U.S. EPA Exposure Factors Manual (U.S. EPA, 1997) should be used. Where alternate data sources are consulted, they must be clearly cited and fully referenced. A table of the specific values employed in the PQRA should be included in the report. 2.5.2 Exposure Frequency and Duration Most assumptions concerning exposure frequency and duration are arbitrary in nature, being based on best professional judgment. While it is not the intent to question such professional judgment, a less arbitrary basis for these assumptions is desirable. For purposes of preliminary quantitative risk assessments, the frequency of site visits (days per year) and duration of such visits (hours per day) should be based on the guidance presented in Table 4 unless, in the opinion of the risk assessor, alternate assumptions are more defensible. Justification for alternate assumptions must be provided and fully referenced.

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TABLE 3: Recommended Human Receptors and Their Characteristics for Preliminary Quantitative Risk Assessments

Canadian General Population

Receptor Characteristic Infant Toddler Child Teen Adult Construction Worker Source

Age 0 – 6 mo. 7 mo.- 4 yr 5 – 11 yr 12 – 19 yr $ 20 yr >20 yr Health Canada, 1994

Body weight (kg) 8.2 16.5 32.9 59.7 70.7 70.7 Richardson, 1997

Soil ingestion rate (g/d) 0.02 0.08 0.02 0.02 0.02 0.1

CCME, 1996 MADEP, 2002

Inhalation rate (m3/d) 2.1 9.3 14.5 15.8 15.8 15.8 Richardson, 1997; Allan and Richardson,1998

Water ingestion rate (L/d) 0.3 0.6 0.8 1.0 1.5 1.5 Richardson, 1997

Time spent outdoors (hr/d) -- 1 -- 1 -- 1 1.5 1.5 8 Richardson, 1997

Skin surface area (cm2) Hands

Arms (upper and lower) Legs (upper and lower)

TOTAL

320 550 910 1780

430 890 1690 3010

590 1480 3070 5140

800 2230 4970 8000

890 2500 5720 9110

890

2500 5720 9110

Richardson, 1997

Soil loading to exposed skin (g/cm2/event

Hands Surfaces other than hands

1 x 10-4 1 x 10-5

1 x 10-4 1 x 10-5

1 x 10-4 1 x 10-5

1 x 10-4 1 x 10-5

1 x 10-4 1 x 10-5

1 x 10-3 1 x 10-4

Kissel et al., 1996, 1998

Food ingestion2 (g/day) Root vegetables

Other vegetables Fish

83 72 0

105 67 56

161 98 90

227 120 104

188 137 111

NA

Richardson, 1997

Canadian Native Populations (characteristics not listed should be assumed to be equivalent to those for the general population)

Receptor characteristic Infant Toddler Child Teen Adult Source

Age 0 – 6 mo. 7 mo.- 4 yr 5 – 11 yr 12 – 19 yr $ 20 yr Health Canada, 1994

Food ingestion2 (g/day) Fish

Wild game

0 0

95 85

170 125

200 175

220 270

Richardson, 1997

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[In Table 3 above: 1 – Data not available; however, time spent outdoors may be assumed to be equivalent to that of adults if the infant, toddler or child is assumed to be accompanied by a parent or guardian during outdoor activity. 2 – Data are for “eaters only”; those reporting zero (0) intake were excluded from the estimate.]

TABLE 4 Exposure Duration and Frequency Assumptions for

Preliminary Quantitative Risk Assessments

Agricultural Land

Residential Land

Commercial Land

Industrial Land

Construction Worker

Hours per day on site 24 24 8 8 8

Days per week on site 7 7 5 5 5

Weeks per year on site 52 52 52 48 2

Dermal exposure events per day 1 1 1 1 1

Meals of contaminated foods consumed per day

1 1 1 1 NA1

Life expectancy (years) for amortization of carcinogen exposures2

56/75 56/75 56/75 56/75 56/75

1 – Not applicable 2 – If cancer risks are estimated for adults only, the 56-year duration of adulthood (20 to 75 years, inclusive) should be used; if cancer risks are estimated on the basis of lifetime average daily intake, then average life expectancy of 75 years should be used. 2.5.3 Exposure Equations The preferred exposure equations to be employed for a limited number of exposure pathways are presented in Table 5. Additional equations may also be included where the assessor determines that other exposure pathways beyond those listed in Table 5 are required. In those cases, the Problem Formulation section of the PQRA report should provide an adequate explanation of the need to include those additional pathways. The source of any additional equations must be fully referenced. Inhalation exposures will be derived on the basis of the time spent in the contaminated environment (1.5 hours per day if outdoors; 22.5 hours per day if indoors; see Table 3). However, soil ingestion exposures are considered to be independent of the time spent outdoors. Although it is unlikely that ingested soil would be delivered as a single bolus dose, it is equally

14

unlikely that intake would be distributed uniformly throughout the day. Therefore, for purposes of conservatism, 100% of the daily unintentional intake of contaminated soil should be assumed. 2.5.4 Airborne Respirable Dust Levels It is anticipated that this pathway of exposure will generally be insignificant relative to direct ingestion of soil and water, and to dermal absorption. However, exposures corresponding to this pathway should be calculated if deemed appropriate by the assessor. When included, the concentration of a specific contaminant in the respirable airborne dust should be assumed to be equal to the concentration in surface soil (maximum or average, as appropriate). When this pathway is included, an average airborne concentration of respirable (≤ 10 µm aerodynamic diameter) particulate matter should be assumed to be 0.76 µg/m3 (based on U.S. EPA, 1992). For situations where significant vehicle traffic on contaminated unpaved surfaces is a concern, such traffic can generate considerably greater suspended dust levels. Dust levels from unpaved roads vary according to climatic conditions, traffic levels, and the texture and nature of the road surface material (Claiborn et al., 1995). A reasonable dust level created by vehicle traffic on unpaved roads is 250 µg/m3 (down-wind side of the road; Claiborn et al., 1995). 2.5.5 Models Models may be necessary to estimate the concentrations of contaminants of potential concern in groundwater, surface water, indoor or ambient air, produce and vegetation, fish, wild game or other environmental media through which receptors may potentially be exposed. Necessary modelling should be kept to a level of complexity consistent with the “screening” nature of the risk assessment. Estimates of the concentrations of volatile COPCs in indoor air should be derived from the methods presented by Williams et al. (1996) and the CCME (1996 - Appendix G). Likewise, estimating COPC concentrations in groundwater and in surface water may be obtained from the methods described by the CCME (1996). For estimating COPC concentrations in vegetation, methods presented by the CCME (1996 – produce check) or the Oak Ridge National Laboratory (ORNL) (1998) may be used. For estimating COPC concentrations in fish and wildlife, simple bioaccumulation/biomagnification factors may be employed where available on a chemical-by-chemical basis, or more sophisticated modelling may be used, as deemed appropriate by the risk assessor. Not withstanding the guidance above, other modelling methods may be used as long as they are generally accepted. Any models employed should be fully referenced to permit peer review, including a rationale for the specific model selected.

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TABLE 5 Recommended General Equations to Be Used to Estimate Doses

Note: Presented below are generalized equations; actual equations presented by individual contractors may vary according to the manner in which different variables are presented, the units used, and the precise presentation of exposure frequency, exposure duration and averaging times.

INADVERTENT INGESTION OF CONTAMINATED SOIL

The predicted intake of each contaminant via soil ingestion is calculated as:

LEBWDDDAF IR C = day)(mg/kg Dose GITSS

×××××× 321/

Where: CS = concentration of contaminant in soil (mg/kg) D2 = weeks per year exposed/52 weeks IRS = receptor soil ingestion rate (kg/d) D3 = total years exposed to site (to be employed for assessment of carcinogens only) AFGIT = absorption factor from the gastrointestinal tract (unitless) BW = body weight (kg) D1 = days per week exposed/7 days LE = life expectancy (yr) (to be employed for assessment of carcinogens only)

INHALATION OF CONTAMINATED SOIL PARTICLES

The predicted intake of each contaminant via inhalation of dust entrained into the air is calculated as:

LEBW DDDDAF IR P C = day)(mg/kg Dose InhAAirS

×××××××× 4321/

Where: CS = concentration of contaminant in soil (mg/kg) D2 = days per week exposed/7 days PAir = particulate concentration in air (kg/m3) D3 = weeks per year exposed/52 weeks IRA = receptor air intake (inhalation) rate (m3/h) D4 = total years exposed to site (to be employed for assessment of carcinogens only) AFInh = inhalation absorption factor (unitless) BW = body weight (kg) D1 = hours per day exposed (h/day) LE = life expectancy (yr) (to be employed for assessment of carcinogens only)

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TABLE 5 (continued) Recommended General Equations to Be Used to Estimate Doses

INHALATION OF CONTAMINANT VAPOURS

The predicted intake of each contaminant via inhalation of vapours is calculated as:

LEBW DDDDAF IR C

= day)(mg/kg Dose InhAa

××××××× 4321/

Where: Ca = concentration of contaminant in air (mg/m3) D3 = weeks per year exposed/52 weeks IRA = receptor air intake (inhalation) rate (m3/h) D4 = total years exposed to site (to be employed for assessment of carcinogens only) AFInh = inhalation absorption factor (unitless) BW = body weight (kg) D1 = hours per day exposed (h/day) LE = life expectancy (yr) (to be employed for assessment of carcinogens only) D2 = days per week exposed/7 days Note: Ca may be directly measured or may be estimated from soil-borne or groundwater-borne concentrations of volatile COPCs using methods discussed in the text.

INGESTION OF CONTAMINATED DRINKING WATER

The predicted intake of each contaminant via ingestion of contaminated drinking water is calculated as:

LEBWDDDAF IR C = day)(mg/kg Dose GITSW

×××××× 321/

Where: CW = concentration of contaminant in drinking water (mg/L) D2 = weeks per year exposed/52 weeks IRS = receptor water intake rate (L/d) D3 = total years exposed to site (to be employed for assessment of carcinogens only AFGIT = absorption factor from the gastrointestinal tract (unitless) BW = body weight (kg) D1 = days per week exposed/7 days LE = life expectancy (yr) (to be employed for assessment of carcinogens only)

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TABLE 5 (continued) Recommended General Equations to Be Used to Estimate Doses

DERMAL CONTACT WITH CONTAMINATED SOIL

The predicted intake of each contaminant via dermal contact with soil is calculated as:

LEBWDDDEF AF ) SL SA C ( = day)(mg/kg Dose SkinHHS

×××××××× 321/

Where: CS = concentration of contaminant in soil (mg/kg) D1 = days per week exposed/7 days SAH = skin surface area exposed (cm2) D2 = weeks per year exposed/52 weeks SLH = soil loading to exposed skin (kg/cm2-event) D3 = total years exposed to site (to be employed for assessment of carcinogens only) AFSkin = dermal absorption factor (unitless) BW = body weight (kg) EF = exposure frequency (events/d) LE = life expectancy (yr) (to be employed for assessment of carcinogens only)

INGESTION OF CONTAMINATED PRODUCE, FISH, GAME OR OTHER FOOD

The predicted intake of each contaminant via ingestion of contaminated produce, fish and/or game is calculated as:

LEBWDDRAF IR C

= day)(mg/kg Dose iGITFoodFoodIi

××

××××∑365

]][[/ 2

Where: CFood I = concentration of contaminant in food I (mg/kg) D2 = total years exposed to site (to be employed for assessment of carcinogens only) IRFood i = receptor ingestion rate for food i (kg/d) BW = body weight (kg) RAFGITi = relative absorption factor from the gastrointestinal tract for contaminant i (unitless) 365 = total days per year (d/yr) Di = days per year during which consumption of LE = life expectancy (yr) (to be employed for assessment of carcinogens only) food i will occur (d/yr)

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2.5.6 Relative Absorption Factors and Exposure via Multiple Pathways Few, if any, toxicological reference values (TRVs) exist specifically for the dermal exposure pathway. Therefore, dermal exposures will routinely be added to the oral dose, following adjustment for relative bioavailability or absorption, for subsequent comparison to the oral TRV. For some contaminants of potential concern, separate TRVs are available for oral and inhalation exposures. In these cases, the exposures via these pathways should be determined separately for comparison to pathway-specific TRVs. In cases where only an oral TRV is available, exposures by all routes (oral, dermal, inhalation) should be summed for comparison to the oral TRV. For COPCs where multiple exposure pathways will be summed for comparison to a single TRV, it will be necessary to apply relative absorption factors (RAFs) in exposure calculations. Oral exposures should always be assumed to have a relative absorption of 100% (RAF = 1). Where inhalation exposures are being summed with oral exposures, the inhalation RAF will generally default to 1 unless there is good evidence that respiratory absorption is significantly less that 100%. Where dermal exposures are being summed with oral exposures, the RAF values presented in Table 6 should be applied, unless more appropriate information has been identified and justified (with proper citations). For contaminants not listed in Table 6, other sources such as the Risk Assessment Information System (RAIS; http://risk.lsd.ornl.gov/rap_hp.shtml), Toxicological Profiles published by the Agency for Toxic Substances and Disease Registry (ATSDR; http://www.atsdr.cdc.gov/toxpro2.html), or other authoritative sources should be consulted. Where alternate data sources are consulted, they must be clearly cited and fully referenced. For other forms of dermal exposures, such as those involving submersion in water, dermal absorption in units of µg/cm2-hour may be required. The source of such equations and assumptions, if required, should be clearly cited and fully referenced.

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TABLE 6 Relative Dermal Absorption Factors (RAFDermal) Recommended for

Preliminary Quantitative Risk Assessments (after Ontario Ministry of Environment and Energy (OMEE), 1996b)

CHEMICAL AFDERMAL CHEMICAL AFDERMAL

ACENAPHTHENE 0.2 DICHLOROETHYLENE, CIS-1,2- 0.1

ACENAPHTHYLENE 0.18 DICHLOROETHYLENE, TRANS-1,2- 0.1

ACETONE 0.1 DICHLOROPHENOL, 2,4- 0.4

ALDRIN 0.25 DICHLOROPROPANE, 1,2- 0.2

ANTHRACENE 0.29 DICHLOROPROPENE, 1,3- 0.2

ANTIMONY 0.1 DIELDRIN 0.25

ARSENIC 0.03 DIETHYL PHTHALATE 0.02

BARIUM 0.1 DIMETHYL PHTHALATE 0.07

BENZENE 0.08 DIMETHYLPHENOL, 2,4- 0.26

BENZO(A)ANTHRACENE 0.2 DINITROPHENOL, 2,4- 0.26

BENZO(A)PYRENE 0.2 DINITROTOLUENE, 2,4- 0.13

BENZO(B)FLUORANTHENE 0.2 ENDOSULFAN 0.2

BENZO(G,H,I)PERYLENE 0.18 ENDRIN 0.25

BENZO(K)FLUORANTHENE 0.2 ETHYLBENZENE 0.2

BERYLLIUM 0.03 ETHYLENE DIBROMIDE (DIBROMOETHANE, 1,2-) 0.1

BIPHENYL, 1,1- 0.08 FLUORANTHENE 0.2

BIS(2-CHLOROETHYL)ETHER 1 FLUORENE 0.2

BIS(2-CHLOROISOPROPYL)ETHER 1 HEPTACHLOR 0.2

BIS(2-ETHYLHEXYL)PHTHALATE 0.02 HEPTACHLOR EPOXIDE 0.2

BROMODICHLOROMETHANE 0.1 HEXACHLOROBENZENE 0.13

BROMOFORM (TRIBROMOMETHANE) 0.11 HEXACHLOROBUTADIENE 0.2

BROMOMETHANE 0.1 HEXACHLOROCYCLOHEXANE, GAMMA (GAMMA-HCH) 0.2

CADMIUM 0.14 HEXACHLOROETHANE 1

CARBON TETRACHLORIDE 0.1 INDENO(1,2,3-CD)PYRENE 0.2

CHLORDANE 0.05 LEAD 0.006

CHLOROANILINE, P- 0.1 MERCURY 0.05

CHLOROBENZENE 0.1 METHOXYCHLOR 0.2

CHLOROFORM 0.1 METHYL ETHYL KETONE 0.1

CHLOROPHENOL, 2- 0.26 METHYL ISOBUTYL KETONE 0.1

CHROMIUM(III) 0.04 METHYL MERCURY 0.2

CHROMIUM(VI) 0.09 METHYL TERT BUTYL ETHER 0.1

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CHEMICAL AFDERMAL CHEMICAL AFDERMAL

CHRYSENE 0.2 METHYLENE CHLORIDE (DICHLORMETHANE) 0.1

COBALT 0.1 METHYLNAPHTHALENE, 2- 0.1

COPPER 0.1 MOLYBDENUM 0.1

CYANIDE 0.3 NAPHTHALENE 0.1

DIBENZO(A,H)ANTHRACENE 0.09 NICKEL 0.35

DIBROMOCHLOROMETHANE 0.1 P,P'-DDD 0.2

DICHLOROBENZENE, 1,2- (O-DCB) 0.1 P,P'-DDE 0.2

DICHLOROBENZENE, 1,3- (M-DCB) 0.1 P,P'-DDT 0.2

DICHLOROBENZENE, 1,4- (P-DCB) 0.1 PENTACHLOROPHENOL 0.11

DICHLOROBENZIDINE, 3,3'- 0.54 PETROLEUM HYDROCARBONS (PHC; CCME F1 – F4) 0.2 a

DICHLOROETHANE, 1,1- 0.13 PHENANTHRENE 0.18

DICHLOROETHANE, 1,2- 0.1 PHENOL 0.26

DICHLOROETHYLENE, 1,1- 0.1 PYRENE 0.2

SELENIUM 0.002 TRICHLOROETHANE, 1,1,2- 1

SILVER 0.25 TRICHLOROETHYLENE 0.1

STYRENE 0.2 TRICHLOROPHENOL 2,4,6- 0.26

TETRACHLOROETHYLENE 0.1 TRICHLOROPHENOL, 2,4,5- 0.26

THALLIUM 0.01 VANADIUM 0.1

TOLUENE 0.12 VINYL CHLORIDE (CHLOROETHYLENE) 0.16

TRICHLOROBENZENE, 1,2,4- 0.08 XYLENES (MIXED ISOMERS) 0.12

TRICHLOROETHANE, 1,1,1- 0.1 ZINC 0.02

a – see CCME, 2000 2.5.7 Carcinogens For carcinogenic substances, only exposure in adult receptors need be determined, consistent with the methods employed by the CCME (1996) and Health Canada (1995) to derive soil quality guidelines for carcinogenic substances. The variability between adult exposure and lifelong average exposure is much smaller than the uncertainty inherent in the derivation of cancer slope factors. Therefore, the more complex lifelong average daily intake need not be determined for a preliminary quantitative risk assessment, unless preferred by the assessor. When establishing health-based guidelines for soil quality, neither the CCME (1999) nor Health Canada (1995, for example) amortized shorter-than-lifetime exposures over average life expectancy. During the derivation of guidelines for industrial properties, for example, exposure was averaged to account for anticipated occupational exposures of 8 hours per day, 5 days per

21

week, 48 weeks per year (CCME, 1996), but career-long exposure (say, 35 years) was not averaged over life expectancy. However, it is generally assumed that exposure to low doses or concentrations of a carcinogenic substance – i.e., relatively low environmental levels -- require a concurrent increase in exposure duration to initiate cancer. Also, cancer potency values (TD05, TC05, slope factor, unit risk) are typically derived on the assumption of lifelong exposure. The validity and defensibility of exposure amortization for carcinogenic substances is under review by Health Canada. Until that review is complete, shorter-than-lifetime carcinogen exposures should be amortized over the average life expectancy (75 years) if the cancer risk is based on lifetime average daily exposure, or over 56 years (the duration of adulthood) if cancer risk is based on estimates in adults only. Recommended exposure durations for various land uses are presented in Table 4. 2.6 Hazard Assessment Health Canada TRVs should be applied where available (these are presented in a companion document [Health Canada, 2003]). For substances with no Health Canada TRVs, reference doses (RfDs), reference concentrations (RfCs), acceptable daily intakes (ADIs), or minimum risk levels (MRLs) should be obtained from the following agencies, in order of preference:

1) U.S. EPA Integrated Risk Information System (IRIS); http://www.epa.gov/iriswebp/iris/index.html

2) World Health Organization (WHO); various sources including: http://www.inchem.org/; http://jecfa.ilsi.org/index.htm; http://www.who.dk/air/activities/20020620_1 )

3) Netherlands National Institute of public Health and the Environment (RIVM); http://www.rivm.nl/bibliotheek/rapporten/711701025.pdf

4) Agency for Toxic Substances and Disease Registry (ATSDR) (U.S.); http://www.atsdr.cdc.gov/toxpro2.html

For each contaminant of potential concern, the source of each TRV and the pathway(s) to which it is being applied should be identified. In some cases, assessors may believe that the TRVs presented by Health Canada (2003) are inadequate or inappropriate for application at the site in question. In these cases, the assessor should discuss his/her concerns with the Client and, where deemed appropriate, alternate TRVs may be employed. However, it is imperative that the PQRA report contain a clear description of the inadequacies of the TRVs presented by Health Canada, along with a convincing rationale

22

(with citations) to support the use of an alternate value. For these cases, risks should be characterized using the prescribed TRV and the assessor’s preferred value. 2.7 Risk Characterization

2.7.1 Non-carcinogens: Single-Substance Exposures For substances presenting risks other than cancer, a Hazard Quotient (HQ; analogous terms include “exposure ratio” and “hazard ratio”) will be derived as the ratio of the estimated exposure (for each critical receptor) to the tolerable daily intake (TDI) or tolerable concentration (TC), as follows:

Hazard Quotients for individual exposure pathways should be presented where there are pathway-specific TRVs. Where exposures via multiple pathways are being summed for comparison to a single TRV (for example, it is common to sum oral and dermal exposures for comparison to the oral TDI), it is necessary only to display the HQ for the summed exposure. For purposes of preliminary quantitative risk assessment, exposures associated with a HQ # 0.2 will be deemed negligible. This is consistent with the CCME (1996) and the OMEE (1996a), and has become accepted common practice. 2.7.2 Carcinogens: Single-Substance Exposures For substances deemed to be carcinogenic, the estimated exposure (amortized as appropriate) will be multiplied by the appropriate slope factor or unit risk to derive a conservative estimate of the potential incremental lifetime cancer risk (ILCR) associated with that exposure. The ILCR is derived as:

Hazard Quotient = Estimated Exposure (µg/kg/day) Tolerable Daily Intake (µg/kg/day)

OR, in the case of air-borne contaminants with a tolerable air concentration in (µg/m3)-1:

Hazard Quotient = Air Concentration (µg/m3) x Fraction of Time Exposed

Tolerable Air Concentration (µg/m3)

ILCR = Exposure (µg/kg/d) x Cancer Slope Factor (µg/kg/d)-1 OR, in the case of air-borne contaminants with a unit risk value in (µg/m3)-1: ILCR = Air Concentration (µg/m3) x Fraction of Time Exposed x Cancer Unit

Risk (µg/m3)-1

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Where pathway-specific slope factors or unit risks exist, the risks via inhalation and the risks via oral + dermal exposure should be estimated separately. In other cases, the cancer risks posed by simultaneous inhalation/dermal/oral exposure will be estimated. Cancer risks will be deemed to be “essentially negligible” (de minimus) where the estimated ILCR is # 1-in-100,000 (≤ 1 x 10-5). The rationale for this essentially negligible risk level is presented in Appendix B. 2.7.3 Exposure to Mixtures For simultaneous exposure to multiple chemicals of potential concern, non-cancer Hazard Quotients should be assumed to be additive, and should be summed for those substances determined by the risk assessor to have similar target organs/effects/mechanisms of action. For the purposes of PQRAs, exposures associated with this total HQ # 0.2 will be deemed negligible. For carcinogens with the same target organ and form of cancer, the risks should be assumed to be additive and thus should be summed. The total cancer risk in such cases will be deemed to be “essentially negligible” where the estimated total ILCR is # 1-in-100,000 (1 x 10-5). 2.8 Non-standard Assumptions and Toxicological Reference Values In those situations where assessors have introduced exposure pathways, equations, assumptions and/or TRVs that are different from, or in addition to, those presented in this guidance document, the implications for exposure and risk estimates must be summarized and discussed.

• Were exposures increased, decreased, or essentially unchanged compared to the prescribed procedures?

• Were the resulting risks increased, decreased, or essentially unchanged compared to the prescribed procedures?

• Do the prescribed methods predict negligible risks while the alternate methods suggest that a risk exists? Or vice versa?

2.9 Uncertainties The uncertainties in the exposure and risk estimates should be discussed. Issues to be addressed should include, but not be limited to:

• the quality and quantity of data; • use of maximum COPC concentrations (where appropriate); • factors, assumptions, and models that would likely lead to an overestimation of

exposures and risks; and

24

• factors, assumptions, and models that might lead to an underestimation of risks. 2.10 Conclusions and Discussion The overall conclusions with respect to the risks posed by the contaminated site should be summarized in this section of the PQRA report. Any other issues that, in the opinion of the assessor, require discussion but have not been presented in other sections, should also be included here. 2.11 Recommendations List all recommendations that may stem from the results of the PQRA. 2.12 References The report should be thoroughly referenced to enable peer reviewers to identify and obtain all documents and authoritative sources cited in the report. A complete list of those references is required. 3. REFERENCES The following are the references to the guidance provided in this document: Allan, M., and G.M. Richardson. 1998. Probability density functions describing 24-hour inhalation rates

for use in human health risk assessments. Human and Ecological Risk Assessment 4(2): 379-408. Canadian Council of Ministers of the Environment (CCME). 1993a. Guidance Manual on Sampling,

Analysis and Data Management for Contaminated Sites, Volume I: Main Report. Report CCME EPC-NCS62E. CCME, Winnipeg. December 1993.

Canadian Council of Ministers of the Environment (CCME). 1993b. Guidance Manual on Sampling,

Analysis, and Data Management for Contaminated Sites, Volume II: Analytical Method Summaries. CCME, Winnipeg.

Canadian Council of Ministers of the Environment (CCME). 1996. A Protocol for the Derivation of

Environmental and Human Health Soil Quality Guidelines. Report CCME EPC-101E, CCME. March 1996.

Canadian Council of Ministers of the Environment (CCME). 1999. Canadian Environmental Quality

Guidelines (and updates). CCME, Winnipeg. Canadian Council of Ministers of the Environment (CCME). 2000. Canada-Wide Standards for

Petroleum Hydrocarbons (PHCs) in Soil: Scientific Rationale (Supporting Technical Document). CCME, Winnipeg. Available online at: http://www.ccme.ca/assets/pdf/phc_scirat_final_e.pdf

Canadian Council of Ministers of the Environment (CCME). 2001. Canada-Wide Standards for

Petroleum Hydrocarbons (PHCs) in Soil. CCME, Winnipeg. Available online at: http://www.ccme.ca/assets/pdf/phcs_in_soil_standard_e.pdf

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Canada Mortgage and Housing Corporation (CMHC). 1997. Evaluation of Site-specific Risk Assessment for Contaminated Lands. Contract report submitted by Golder Associates Ltd. March 4, 1997.

Claiborn, C., et al. 1995. Evaluation of PM10 emission rates from paved and unpaved roads using tracer

techniques. Atmos. Environ. 29(10): 1075-1089. Health Canada. 1994. Human Health Risk Assessment for Priority Substances: Canadian Environmental

Protection Act Assessment Report. Health Canada, Ottawa. 36 pp. Health Canada. 1995. Canadian Soil Quality Guidelines for Contaminated Sites - Human Health Effects:

Inorganic Arsenic. Final Report. Air and Waste Section, Environmental Health Directorate, Health Canada, Ottawa. Available online at: http://www.hc-sc.gc.ca/ehp/ehd/catalogue/bch_pubs/contaminated_sites_arsenic.pdf

Health Canada. 2004. Federal Contaminated Site Risk Assessment in Canada, Part II: Health Canada

Toxicological Reference Values (TRVs). Safe Environments Programme, Health Canada, Ottawa. Kissel, J.C., K.Y. Richter, and R.A. Fenske. 1996. Field measurement of dermal soil loading attributable

to various activities: implications for exposure assessment. Risk Anal. 16(1): 115-125. Kissel, J.C., et al. 1998. Investigation of dermal contact with soil in controlled trials. J. Soil Contam.

7(6): 737-752. Massachusetts Department of Environmental Protection (MADEP). 2002. Technical Update: Calculation

of Enhanced Soil Ingestion Rate. Office of Research and Standards, MADEP, Boston, MA. Available online at: http://www.state.ma.us/dep/ors/files/soiling.doc

Oak Ridge National Laboratory (ORNL). 1998. Empirical Models for the Uptake of Inorganic Chemicals

from Soil to Plants. Report BJC/OR-133, ORNL. Ontario Ministry of Environment and Energy (OMEE). 1996a. Guidance on Site-Specific Risk Assessment

for Use at Contaminated Sites in Ontario. Standards Development Branch, OMEE, Toronto. Ontario Ministry of Environment and Energy (OMEE). 1996b. Rationale for the Development and

Application of Generic Soil, Groundwater and Sediment Criteria for Use at Contaminated Sites in Ontario (including all appendices). ISBN: 0-7778-4504-5 (disk copy). Standards Development Branch, OMEE, Toronto.

Richardson, G.M. 1997. Compendium of Canadian Human Exposure Factors for Risk Assessment.

Ottawa: O'Connor Associates Environmental Inc. Risklogic Scientific Services Inc. 2003. Preliminary Screening-Level Risk Assessment (SLRA):

Development of a Standardized Statement of Work and a Site Checklist to Aid SLRA for Fisheries and Oceans Canada - Final Report. Contract report prepared for the Office of Environmental Coordination, Fisheries and Oceans Canada, Ottawa.

United States Environmental Protection Agency (U.S. EPA). 1992. Risk Assessment Guidance for

Superfund: Volume I – Human Health Evaluation Manual (Part B, Development of Risk-based Preliminary Remediation Goals). EPA/540/R-92/003, U.S. EPA, Washington, DC.

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United States Environmental Protection Agency (U.S. EPA). 1997. Exposure Factors Handbook, Volume I: General Factors; Volume II: Food Ingestion Factors; Volume III: Activity Factors. EPA/600/P-95/002Fa, U.S. EPA, Washington, DC. August 1997.

United States Environmental Protection Agency (U.S. EPA). 2002. Preliminary Remediation Goals

(PRGs): EPA Region 9 PRGs Table. U.S. EPA. Dated 10/01/02. Available online at: http://www.epa.gov/region09/waste/sfund/prg/files/02table.pdf

Williams, D.R., J. Paslawski, and G.M. Richardson. 1996) Development of a screening relationship to

describe migration of contaminant vapours into buildings. J. Soil Contam. 5(2): 141-156.

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APPENDIX A Screening Contaminants of Potential Concern for Local or Regional Background (Natural)

Soil, Groundwater and Surface Water Concentrations Before a site is considered contaminated, on-site concentrations of contaminants, particularly natural elements, should be compared to data from local or regional surveys of soil quality, groundwater quality, or surface water quality in uncontaminated areas. If possible, such surveys should be conducted at the time of the site environmental assessment, although the collection of background samples at that time is generally a rare occurrence. However, the results of many regional soil surveys are available in the open scientific literature. Soil survey data are also available from provincial ministries of natural resources, which have conducted surveys and compiled soil survey data for purposes of mineral exploration and mineral mapping. Similarly, the Geological Survey of Canada (GSC) has compiled data from numerous large-scale and small-scale soil surveys for purposes of mineral exploration and mapping across Canada. These GSC surveys are publicly available as GSC Open Files, which can be searched and reviewed with the assistance of the local GSC office or library. If it is found that concentrations of contaminants of potential concern at the site are representative of background levels, the site may not be considered contaminated despite the fact that generic guidelines are exceeded. Many contaminants, particularly metals, are naturally occurring, and natural levels can exceed Canadian Council of Ministers of the Environment (CCME) guidelines and other generic guidelines without representing industrial or anthropogenic contamination. A prime example is arsenic. The CCME soil quality guideline for arsenic is 12 ppm. This guideline was derived on the basis of a “national” natural background concentration of 10 ppm arsenic in agricultural soils from southern Ontario and the Prairies, with an additional 2 ppm which represented the additional contamination (above background) associated with a 1-in-1-million cancer risk (Health Canada, 1995). Although natural levels of arsenic in those agricultural soils are only 10 ppm, the regional background of arsenic established for Ontario is 17 ppm (Ontario Ministry of Environment and Energy (OMEE), 1997b), and in various regions of British Columbia it ranges up to 25 ppm (British Columbia Ministry of Water, Land and Air Protection (BCMWLAP), undated). In Sydney, Nova Scotia, local sampling determined that the local urban background concentration of arsenic ranged up to 200 ppm (JDAC Environment Ltd., 2002). In Yellowknife, NWT, the natural soil-borne levels of arsenic average approximately 150 ppm, with natural levels occasionally exceeding 1500 ppm (Richardson, 2002). Yellowknife is situated on a geologic anomaly known as a greenstone belt. Greenstone belts and other geologic deposits are rich in mineral deposits, of which arsenic is a natural contaminant.

28

Soils derived from such geologic deposits will have naturally high concentrations of those elements. In fact, prospecting for mineral deposits is often accomplished by surveying soils for anomalously high arsenic levels (see Richardson, 2002). Therefore, arsenic and other metals can be present in soils at levels far in excess of national or provincial guideline values, but such levels do not represent anthropogenic or industrial pollution. When setting national guidelines, the CCME derives guideline values by determining the tolerable or essentially negligible concentration of a contaminant above the background (natural) level (CCME, 1996a). The CCME also recognizes that natural levels in soil vary spatially, and recommends that local soil quality objectives be established that incorporate local or regional background concentrations if they are significantly different from the background value used in the derivation of the national generic guideline for a particular contaminant (CCME, 1996b). In some cases, it may be appropriate to use “urban” background concentrations, rather than those associated with more rural areas. This may be particularly true for carcinogens where risk assessment and risk management are targeted at incremental risks above background levels. If the local urban environment and/or adjacent properties have elevated concentrations from sources other than the subject property, and those elevated concentrations are accepted and not slated for remediation or risk management, then these urban background levels may constitute the appropriate background concentrations for risk assessment and risk management purposes. However, professional judgment will be required to determine the most suitable basis for defining background concentrations. The Ontario Ministry of Environment and Energy presents the main elements of a background approach and Ontario-specific criteria (OMEE, 1997 – Table F). Similar guidance is also provided by the BC Ministry of Water, Land and Air Protection (BCMWLAP, undated). REFERENCES British Columbia Ministry of Water, Land and Air Protection (BCMWLAP) (undated). Protocol 4:

Determining Background Soil Quality. Section 53, Contaminated Sites Regulation, Waste Management Act. Government of British Columbia, Victoria, BC. Available online at: http://wlapwww.gov.bc.ca/epd/epdpa/contam_sites/policy_procedure_protocol/protocols/background_soil.html

Canadian Council of Ministers of the Environment (CCME). 1996a. A Protocol for the Derivation of

Environmental and Human Health Soil Quality Guidelines. Report CCME EPC-101E, CCME. March 1996.

Canadian Council of Ministers of the Environment (CCME). 1996b. Guidance Manual for Developing

Site-specific Soil Quality Remediation Objectives for Contaminated Sites in Canada. CCME, Winnipeg, Manitoba. March 1996.

29

Health Canada. 1995. Canadian Soil Quality Guidelines for Contaminated Sites, Human Health Effects: Inorganic Arsenic. Air and Waste Section, Environmental Health Directorate, Health Canada, Ottawa. Unpublished report. February 1995.

JDAC Environment Ltd. 2002. Background Surface Soil Concentrations, Urban Reference Area, Human

Health Risk Assessment North of Coke Ovens (NOCO) Area – Sydney, NS. Contract report submitted to Public Works and Government Services Canada.

Ontario Ministry of Environment and Energy (OMEE). 1997. Guideline for Use at Contaminated Sites in

Ontario. OMEE, Toronto. Revised February 1997. Richardson, G.M. 2002. Determining Natural (Background) Arsenic Soil Concentrations in Yellowknife

NWT, and Deriving Site-Specific Human Health-Based Remediation Objectives For Arsenic in The Yellowknife Area. Final report, submitted by Risklogic Scientific Services Inc. to the Yellowknife Arsenic Soils Remediation Committee (YASRC), Yellowknife. April 2002.

30

APPENDIX B Essentially Negligible Cancer Risk for Contaminated Site Risk Assessment

When assessing risks posed by exposure to carcinogenic substances, regulatory agencies such as Health Canada and the United States Environmental Protection Agency (U.S. EPA) assume that any level of exposure (other than zero) is associated with some hypothetical cancer risk. As a result, it is necessary for regulatory agencies to specify a level of carcinogenic risk that is considered acceptable, tolerable, or essentially negligible. In the 1970s, the U.S. Food and Drug Agency (FDA) was the first agency to address this issue, adopting a risk level of 1-in-1-million (10-6) as the incremental cancer risk for carcinogenic residues in foods that was considered to be “essentially zero” (Kelly, 1991). The origin of this “essentially zero” risk level was purely arbitrary. Since then, the 10-6 risk level has become commonplace in the regulation and management of environmental contaminants, with the strongest endorsement coming from the U.S. EPA, which employs 10-6 as its primary risk benchmark for “acceptable” exposure to carcinogens within the general population. Although a 1-in-1-million (10-6) cancer risk is the most frequently used risk level for the management of risks posed by environmental (including soil) contamination, many agencies and provinces, including the U.S. EPA, identify a range of increased cancer incidence risks; generally, from 1-in-10,000 (or 1 x 10-4) to 1-in-1,000,000 (or 1 x 10-6) is considered an acceptable risk range depending on the situation and circumstances of exposure (Graham, 1993; Kelly, 1991; Lohner, 1997; Travis, 1987; U.S. Environmental Protection Agency (U.S. EPA), 1991). In contrast, many industrial standards for workplace environments (such as those of the American Conference of Governmental Industrial Hygienists [ACGIH], 2002) offer a protection to only the 1 x 10-3 level or higher of risk (e.g., a risk of 1 x 10-2, or 1-in-100, is a 1 percent chance). This higher cancer risk is “accepted” in workplace environments because it is often technologically or financially infeasible to reduce exposures to even lower levels, and the nature of exposure is generally deemed to be informed and “voluntary” in the workplace. The U.S. Supreme Court has upheld the industry basis for such standards (Graham, 1993). In establishing generic Canadian soil quality guidelines, the Canadian Council of Ministers of the Environment (CCME) (1996) prescribed the 10-6 level of risk as being essentially negligible. This was established as the lowest common denominator amongst provincial and federal agencies participating in the CCME guidelines derivation process. However, the CCME (1996) acknowledges that the designation of negligible cancer risk is an issue of policy rather than of science, allowing different agencies to establish such a policy consistent with their respective

31

environmental regulatory agendas. To that end, Health Canada, when publishing human health soil quality guidelines in support of the CCME process, applied the concentration of carcinogenic substances in soil associated with risks ranging from 1-in-10,000 (10-4) to 1-in-10,000,000 (10-7) (see Health Canada, 1995, for example). Health Canada (formerly Health and Welfare Canada [HWC], 1989), as the federal advisor on environmental health issues, has established that a cancer risk in the range of 1-in-1-100,000 (10-5) to 1-in-1-1,000,000 (10-6) is “essentially negligible” for carcinogenic substances in drinking water. Although published Health Canada advice on this issue has been restricted to exposures via drinking water, the 10-5 risk level has been widely accepted by federal agencies and others involved with contaminated site risk assessment. This level of risk was deemed essentially negligible for risk assessments being conducted in Sydney, Nova Scotia, for soil-borne carcinogenic contaminants associated with the Sydney Tar Ponds, for example (JDAC Environment Ltd., 2002). The Atlantic Provinces (NS, NB, PEI, and Nfld./Lab.) have implemented a common approach to contaminated site risk assessment known as Atlantic Risk-Based Corrective Action (RBCA) (Atlantic Partnership in RBCA Implementation [Atlantic PIRI], 1999). Within that common risk assessment / risk management framework, an acceptable or essentially negligible cancer risk level of 10-5 has been adopted. The background incidence of cancer in Canada and the U.S. is high, relative to a 10-5 or 10-6 risk level. The lifetime probability of developing cancer in the U.S. and Canada is approximately 0.4, or 40% (National Cancer Institute of Canada [NCIC], 2001; National Cancer Institute [NCI], 1999). Thus, an excess or incremental cancer risk of 1 x 10-5 increases a person’s lifetime cancer risk from 0.40000 to 0.40001. Some unknown proportion of this “background” cancer incidence is believed to be associated with exposure to environmental pollutants. However, a 10-5 incremental (i.e., over and above background) cancer risk represents only a 0.0025% increase over background cancer incidence; an increase that would be undetectable using available epidemiological data and statistics, particularly in smaller populations that may reside near contaminated sites. Hypothetical incremental cancer rates associated with carcinogenic substances at contaminated sites are estimated from cancer “slope factors” or “unit risks” derived from human epidemiological studies and animal cancer bioassays. Generally, the incidence of cancer for occupationally exposed adults or laboratory animals (both of which are exposed to dose levels far in excess of exposure levels in the general population or in populations residing near contaminated sites) is plotted against the exposure dose (often standardized for exposure

32

duration, particularly for occupational studies), and a dose-response curve is fitted to those data. This dose-response curve is then extrapolated from the study exposure range down to a dose of zero, with the assumption that there is no threshold below which cancer will not occur. In the U.S. (Crump, 1996), low-dose extrapolation is achieved through application of the linearized multistage model, a statistical model that can describe both linear and non-linear dose-response patterns, and that produces an upper confidence bound on the linear low-dose slope of the dose-response curve. Health Canada often applies this same methodology for the derivation of the TC05 (the concentration in air or water found to induce a 5% increase in the incidence of, or deaths due to, tumours considered to be associated with exposure; see Health Canada [1996]) or the TD05 (the dose found to induce a 5% increase in the incidence of, or deaths due to, tumours considered to be associated with exposure). Health Canada may also apply a model-free low-dose extrapolation method (Krewski et al., 1989), making no a priori judgments regarding the shape of the dose-response curve in the low-dose range. The model-free approach can also provide an upper bound estimate on the slope of the dose-response curve in the low-dose range. These upper bounds on the dose-response curve become the slope factors or unit risks employed for the estimation of hypothetical cancer rates. As such, it is believed (but not proven) that the slope factor or unit risk for carcinogenic substances will overestimate the true cancer incidence associated with low-dose exposure to environmental pollutants, such as from contaminated sites (Kelly, 1991). Given the conservatism (safety) margin associated with the derivation of cancer slope factors and unit risks, and the negligible impact of a 1-in-100,000 incremental risk level for contaminated site exposures, a cancer risk level of 1-in-100,000 (1 x 10-5) is recommended for the purposes of assessing and managing federal sites contaminated with carcinogenic substances. REFERENCES American Conference of Governmental Industrial Hygienists (ACGIH). 2002. TLVs and BEIs. ACGIH,

Cincinnati, OH. Atlantic Partnership in RBCA Implementation (Atlantic PIRI). 1999. Atlantic RBCA Reference

Documentation, Version 1.0. Atlantic PIRI. April 1999. Canadian Council of Ministers of the Environment (CCME). 1996. A Protocol for the Derivation of

Environmental and Human Health Soil Quality Guidelines. Report CCME EPC-101E, CCME. March 1996.

Crump, K.S. 1996. The linearized multistage model and the future of quantitative risk assessment. Hum.

Exp. Toxicol. 15(10): 787-798. Graham, J. 1993. The legacy of one in a million in risk in perspective. Harvard Center for Risk

Analysis. Risk in Perspective 1:1-2.

33

Health Canada. 1995. Canadian Soil Quality Guidelines for Contaminated Sites. Human Health Effects: Inorganic Arsenic. Air and Waste Section, Environmental Health Directorate, Ottawa. Final Report. March 1995.

Health and Welfare Canada (HWC). 1989. “Derivation of Maximum Acceptable Concentrations and

Aesthetic Objectives for Chemicals in Drinking Water.” In: Guidelines for Canadian Drinking Water Quality - Supporting Documentation. Health and Welfare Canada. Prepared by the Federal-Provincial Subcommittee on Drinking Water of the Federal-Provincial Advisory Committee on Environmental and Occupational Health. Ottawa, Ontario.

JDAC Environment Ltd. 2002. Human Health Risk Assessment – North of Coke Ovens (NOCO) Area,

Sydney, NS. Contract report submitted to Public Works and Government Services Canada. Kelly, K.E. 1991. The Myth of 10-6 as a Definition of “Acceptable Risk”. Presented at the 84th Annual

Meeting and Exhibition of the Air and Waste Management Association, Vancouver, BC, June 16-21.

Krewski, D., D. Gaylor, and M. Szyszkowicz. 1991. A model-free approach to low-dose extrapolation.

Environ. Health Perspect. 90: 279-285. Lohner, T.W. 1997. Is 10-6 an appropriate de minimus cancer risk goal? Risk Policy Report, April 18,

1997, pp. 31-33. National Cancer Institute (NCI). 1999. SEER Cancer Statistics Review, 1973-1996. NCI, National

Institutes of Health, Bethesda, MD. National Cancer Institute of Canada (NCIC). 2001. Canadian Cancer Statistics 2001. NCIC, Toronto,

Canada. Available online at: http://66.59.133.166/stats/maine.htm Travis, C.C., et al. 1987. Cancer risk management: a review of 132 federal regulatory agencies.

Environmental Science Technology 21: 415-420. U.S. Environmental Protection Agency (U.S. EPA). 1991. Risk Assessment Guidance for Superfund:

Volume 1 Human Health Evaluation Manual (Part B, Development of Risk-based Preliminary Remediation Goals). Publication 9285.7-01B. Office of Emergency and Remedial Response, U.S. EPA, Washington, DC.

Health Canada

SantéCanada

FEDERAL CONTAMINATEDSITE RISK ASSESSMENT INCANADA

PART II:HEALTH CANADATOXICOLOGICAL REFERENCEVALUES (TRVS)

Contaminated Sites Program

FEDERAL CONTAMINATED SITE RISK ASSESSMENT IN CANADA

PART II: HEALTH CANADA TOXICOLOGICAL REFERENCE VALUES (TRVS)

September 2004

Prepared by:

Environmental Health Assessment Services Safe Environments Programme

Our mission is to help the people of Canada maintain and improve their health. Health Canada Published by authority of the Minister of Health Également disponible en français sous le titre : Partie II : Les valeurs de référence toxicologiques de Santé Canada This publication can be made available in/on computer diskette/large print/audio-cassette/braille upon request. Her Majesty the Queen in Right of Canada, 2004 Cat. H46-2/04-368E ISBN 0-662-38245-5

i

PREFACE

Federal Contaminated Site Risk Assessment in Canada: Part II: Health Canada Toxicological Reference Values (TRVs) was prepared in support of the Federal Contaminated Sites Accelerated Action Plan (FCSAAP), a program designed to ensure improved and continuing federal environmental stewardship as it relates to contaminated sites located on federally owned or operated properties. This document is a companion to Federal Contaminated Site Risk Assessment in Canada: Part I: Guidance on Human Health Preliminary Quantitative Risk Assessment (PQRA) and was prepared by the Environmental Health Assessment Services Division, Safe Environments Programme, Health Canada. As the practice of risk assessment advances, and as the FCSAAP proceeds, new and updated information on toxicological reference values and other aspects of risk assessment will be published. As a result, it is anticipated that revisions to this document will be necessary from time to time to reflect this new information. Health Canada should be consulted at the address below to confirm that the version of the document in your possession is the most recent edition and that the most recent TRVs are being used. Questions, comments, criticisms, suggested additions or revisions to this document should be directed to:

Contaminated Sites Program Environmental Health Assessment Services Safe Environments Programme Health Canada 2720 Riverside Drive Sir Charles Tupper Building, 4th Floor, PL 6604M Ottawa, ON K1A 0K9 Fax: (613) 941-8921 E-mail: cs-sc@hc-sc.gc.ca See also: http://www.hc-sc.gc.ca/hecs-sesc/ehas/contaminated_sites.htm

ii

TABLE OF CONTENTS Preface................................................................................................................................................i Abbreviations and Acronyms ............................................................................................................iii Health Canada Toxicological Reference Values (TRVs) ..................................................................1 Notes ..................................................................................................................................................4 References..........................................................................................................................................4

iii

ABBREVIATIONS AND ACRONYMS DWQG Drinking water quality guidelines

FCSAAP Federal Contaminated Sites Accelerated Action Plan

JECFA Joint Expert Committee on Food Additives

JMPR Joint Meeting on Pesticide Residues

PCB Polychlorinated biphenyl

PCDD Polychlorinated dibenzo-dioxin

PCDF Polychlorinated dibenzo-furan

PQRA Preliminary quantitative risk assessment

SFinh Inhalation slope factor

SForal Oral slope factor

TC Tolerable concentration

TC05 Tumorigenic concentration: concentration (air, water) found to induce a 5% increase in the incidence of, or deaths due to, tumours considered to be associated with exposure

TD05 Tumorigenic dose: dose found to induce a 5% increase in the incidence of, or deaths due to, tumours considered to be associated with exposure

TDI Tolerable daily intake

TRV Toxicological reference value

URInh Inhalation unit risk

WHO/FAO World Health Organization / Food and Agriculture Organization

1

HEALTH CANADA TOXICOLOGICAL REFERENCE VALUES (TRVS)

Non-Carcinogenic Toxicological

Reference Values Carcinogenic Toxicological Reference Values

Name Health

Canada TDI a

(mg/kg-d)

Health Canada

TC (mg/m3)

Oral slope factor from

TD05 b

(mg/kg-d)-1

Inhalation slope factor from TC05

c

(mg/kg-d)-1

Inhalation unit risk from

TC05 c

(mg/m3)-1

Oral slope factor from

DWQG a

(mg/kg-d)-1

Aldicarb 0.001

Aldrin + dieldrin 0.0001

Aniline 0.007 b

Arsenic 2.8 2.80E+01 6.40E+00 1.7 h

Atrazine + metabolites 0.0005

Azinphos-methyl 0.0025

Barium 0.016

Bendiocarb 0.004

Benzene 1.46E-02 3.30E-03 3.10E-01

Benzo(a)pyrene 1.37E-01 3.10E-02 2.30

Benzo(b)fluoranthene 8.20E-03 1.90E-03

Benzo(j)fluoranthene 6.80E-03 1.60E-03

Benzo(k)fluoranthene 5.50E-03 1.30E-03

Bis(2-ethyl-hexyl) phthalate 0.044 b

Bis(Chloro-methyl) ether 4.13E+01 9.43E+00

Boron 0.0175

Bromoxynil 0.0005

Cadmium 0.0008 4.29E+01 9.80E+00

Carbaryl 0.01

Carbofuran 0.01

Carbon tetrachloride 4.90E-02

Chloramine, mono 0.048

Chlorobenzene 0.43 b 0.01 b

Chlorpyrifos 0.01

Chromium, hexavalent 0.001 3.31E+02 7.58E+01

Chromium, total 0.001 4.76E+01 1.09E+01

Copper 0.03 d

Cyanazine 0.0013

Cyanide, free 0.02 d

DDT 0.01 e

Diazinon 0.002

Dibutyl phthalate 0.063 b

Dicamba 0.0125

2

Non-Carcinogenic Toxicological

Reference Values Carcinogenic Toxicological Reference Values

Name Health

Canada TDI a

(mg/kg-d)

Health Canada

TC (mg/m3)

Oral slope factor from

TD05 b

(mg/kg-d)-1

Inhalation slope factor from TC05

c

(mg/kg-d)-1

Inhalation unit risk from

TC05 c

(mg/m3)-1

Oral slope factor from

DWQG a

(mg/kg-d)-1

Dichlorobenzene, 1,2- 0.43 b

Dichlorobenzene, 1,4- 0.11 b 0.095 b

Dichlorobenzidine, 3,3'- 6.76E-02

Dichloroethane, 1,2- 8.06E-03 7.50E-02 h

Dichloroethylene, 1,1 0.003

Dichloromethane 0.05 b 9.90E-05 2.30E-05 7.90E-05

2,4-D 0.01

Dichorophenol, 2,4- 0.1

Diclofop-methyl 0.001

Dimethoate 0.002

Dinoseb 0.001

Diquat 0.008

Diuron 0.0156

Fluoride, inorganic 0.122

Glyphosate 0.03

Hexachlorobenzene 0.0005 b 8.3E-01

Indeno(1,2,3-cd)pyrene 1.6E-02 3.8E-03

Lead 0.0036

Malathion 0.02

Mercury, inorganic (ionic) 0.0003 d

Methoxychlor 0.1

Methyl methacrylate 0.05 b 0.052 b

Methyl tertiary- butyl ether 0.01 b 0.037 b

Metolachlor 0.005

Metribuzin 0.0083

Monochlorobenzene 0.0089

Nickel chloride 0.0013 b

Nickel oxide 0.00002 b

Nickel subsulphide 0.000018 b

Nickel sulfate 0.05 b 0.0000035b

Nickel, metallic 0.000018 b

Nickel, oxidic/sulphidic/ soluble 5.5E+00 1.3E+00

Nickel, soluble 3.1E+00 7.1E-01

Nickel, sulphidic

3

Non-Carcinogenic Toxicological

Reference Values Carcinogenic Toxicological Reference Values

Name Health

Canada TDI a

(mg/kg-d)

Health Canada

TC (mg/m3)

Oral slope factor from

TD05 b

(mg/kg-d)-1

Inhalation slope factor from TC05

c

(mg/kg-d)-1

Inhalation unit risk from

TC05 c

(mg/m3)-1

Oral slope factor from

DWQG a

(mg/kg-d)-1

Nitrilotriacetic acid (NTA) 0.01

Paraquat (as dichloride) 0.001

Parathion 0.005

Pentachlorobenzene 0.001 b

Pentachlorophenol 0.006

Phenol 0.06 d

Phorate 0.0002

Picloram 0.02

PCBs 0.001 f

PCDD/PCDF 1.00E-08 b

PCDD/PCDF 2.0E-09 g

Simazine 0.0013

Styrene 0.12 b 0.092 b

Terbufos 0.00005

Tetrachlorobenzene, 1,2,3,4- 0.0034 b

Tetrachlorobenzene, 1,2,3,5- 0.00041 b

Tetrachlorobenzene, 1,2,4,5- 0.00021 b

Tetrachloroethylene 0.014 b 0.36 b

Tetrachlorophenol, 2,3,4,6- 0.01

Toluene 0.22 b 3.8 b

Trichlorobenzene, 1,2,3- 0.0015 b

Trichlorobenzene, 1,2,4- 0.0016 b 0.007 b

Trichlorobenzene, 1,3,5- 0.0015 b 0.0036 b

Trichloroethylene 2.5E-04 2.7E-03 6.1E-04

Trichlorophenol,2,4,6- 2.0E-02

Trifluralin 0.0048

Uranium (non-radiological) 0.0006 d

Vinyl chloride 2.60E-01

Xylene, mixed isomers 1.5 b 0.18 b

4

NOTES a – From Canadian Guidelines for Drinking Water Quality, Supporting Documentation (Health Canada, 2002), unless otherwise indicated.

b – For non-carcinogens, TDI and TC values taken directly from Health Canada (1996); for carcinogens, oral slope factor derived as: SForal = 0.05/TD05; TD05 from Health Canada (1996).

c – Inhalation unit risk derived as: URInh = 0.05/TC05; inhalation slope factor derived as: SFInh = 0.05/(TC05 x 16 m3/day/70.7 kg); TC05 from Health Canada (1996); inhalation rate from Allan and Richardson (1998) and Richardson (1997); adult body weight from Richardson (1997).

d – From CCME Soil Quality Guidelines and supporting documentation on health-based guidelines prepared by Health Canada.

e – WHO/FAO Joint Meeting on Pesticide Residues (JMPR) (the Food Directorate, Health Canada, generally endorses and applies the TDIs for pesticide residues derived by the JMPR).

f – Grant, D.L. (1983) (this TDI is still applied by Health Canada for the assessment of PCB exposure from foods and other sources).

g – Officially, the Health Canada TDI for PCDD/PCDF is 10 pg/kg-d (Health Canada, 1996); however, the WHO/FAO Joint Expert Committee on Food Additives and Contaminants (JECFA) recently proposed a revised TDI of 2 pg/kg-d. The Food Directorate, Health Canada, generally endorses and applies the TDIs for food contaminants derived by the JECFA, and it is anticipated that this revised TDI will be implemented. Therefore, it is recommended that preliminary quantitative risk assessments (PQRAs) for PCDDs/PCDFs in Canada employ this more conservative TDI.

h – Although the TRV from the Canadian Drinking Water Quality Guidelines Supporting Documentation is presented, it is recommended that the comparable TRV from the more recent assessment (Health Canada, 1996) be employed for risk characterization. REFERENCES Allan, M., and G.M. Richardson. 1998. Probability density functions describing 24-hour inhalation rates

for use in human health risk assessments. Human and Ecological Risk Assessment 4(2): 379-408. Grant, D.L. 1983. “Regulation of PCBs in Canada.” In: PCBs: Human and Environmental Hazards.

Edited by F.M. D’Itri and M.A. Kamrin. Toronto: Butterworth Publishers; pp. 383-392. Health Canada. 1996. Health-Based Tolerable Daily Intakes/Concentrations and Tumorigenic

Doses/Concentrations for Priority Substances. Report no. 96-EHD-194. Ottawa, Ontario. Health Canada. 2002. Guidelines for Canadian Drinking Water Quality, Supporting Documentation.

Ottawa, Ontario. Available online at: http://www.hc-sc.gc.ca/hecs-sesc/water/dwgsup.htm Richardson, G.M. 1997. Compendium of Canadian Human Exposure Factors for Risk Assessment.

Ottawa: O'Connor Associates Environmental Inc.

Health Canada

SantéCanada

FEDERAL CONTAMINATEDSITE RISK ASSESSMENT INCANADA

PART III:GUIDANCE ON PEER REVIEW OF HUMAN HEALTH RISK ASSESSMENTS FORFEDERAL CONTAMINATED SITESIN CANADA

Contaminated Sites Program

FEDERAL CONTAMINATED SITE RISK ASSESSMENT IN CANADA

PART III: GUIDANCE ON PEER REVIEW OF HUMAN HEALTH RISK

ASSESSMENTS FOR FEDERAL CONTAMINATED SITES IN CANADA

September 2004

Prepared by:

Environmental Health Assessment Services Safe Environments Programme

Our mission is to help the people of Canada maintain and improve their health. Health Canada Published by authority of the Minister of Health Également disponible en français sous le titre : Partie III : Le guide sur l’examen par les pairs des évaluations des risques pour la santé humaine des lieux contaminés fédéraux au Canada This publication can be made available in/on computer diskette/large print/audio-cassette/braille upon request. Her Majesty the Queen in Right of Canada, 2004 Cat. H46-2/04-369E ISBN 0-662-38246-3

i

PREFACE

This guidance document has been prepared to assist in the peer review of federal contaminated site human health risk assessments submitted to Health Canada. These assessments range from basic preliminary quantitative risk assessments (PQRAs) to complex site-specific risk assessments (SSRAs). Federal Contaminated Site Risk Assessment in Canada: Part III: Guidance on Peer Review of Human Health Risk Assessments was prepared by the Environmental Health Assessment Services Division, Safe Environments Programme, Health Canada, in support of the Federal Contaminated Sites Accelerated Action Plan (FCSAAP). The FCSAAP is a program designed to provide improved and continuing federal environmental stewardship as it relates to contaminated sites located on federally owned or managed properties. Also in support of the FCSAAP are three additional guidance documents for conducting PQRAs and SSRAs of federal contaminated sites: 1) Federal Contaminated Site Risk Assessment in Canada: Part I: Guidance on Human Health Preliminary Quantitative Risk Assessment (PQRA); 2) Federal Contaminated Site Risk Assessment in Canada: Part II: Health Canada Toxicological Reference Values (TRVs); and 3) a guidance document for conducting complex site-specific risk assessments, which is currently being prepared by Health Canada and will be published when completed. Questions, comments, criticisms, suggested additions or revisions to this document should be directed to:

Contaminated Sites Program Environmental Health Assessment Services Safe Environments Programme Health Canada 2720 Riverside Drive Sir Charles Tupper Building, 4th Floor, PL 6604M Ottawa, ON K1A 0K9 Fax: (613) 941-8921 E-mail: cs-sc@hc-sc.gc.ca See also: http://www.hc-sc.gc.ca/hecs-sesc/ehas/contaminated_sites.htm

ii

TABLE OF CONTENTS

Preface ................................................................................................................................................i Abbreviations and Acronyms ............................................................................................................iii 1. Introduction ...............................................................................................................................1 2. References.................................................................................................................................1 Table 1 Contaminants Commonly Associated with Various Industrial Operations ...............4 Appendix A Guidance on Checklist for Peer Review of Human Health Risk

Assessments for Federal Contaminated Sites in Canada ...........................................5 Appendix B Checklist for Peer Review of Human Health Risk Assessments for Federal Contaminated sites in Canada............................................................................................................21

iii

ABBREVIATIONS AND ACRONYMS ATSDR Agency for Toxic Substances and Disease Registry

CAEAL Canadian Association of Environmental Analytical Laboratories

CCME Canadian Council of Ministers of the Environment

COPC Chemical of potential concern

ESA Environmental site assessment

FCSAAP Federal Contaminated Sites Accelerated Action Plan

IRIS Integrated Risk Information System

MOEE Ontario Ministry of Environment and Energy

PAHs Polycyclic aromatic hydrocarbons

PCBs Polychlorinated biphenyls

PCE Tetrachloroethylene = perchloroethylene

PHCs Petroleum hydrocarbons

PQRA Preliminary quantitative risk assessment

PRGs Preliminary remediation goals

RAIS Risk Assessment Information System

SSRA Site-specific risk assessment

TCE Trichloroethylene

TRV Toxicological reference value

U.S. EPA United States Environmental Protection Agency

VOCs Volatile organic chemicals

1

1. INTRODUCTION

A checklist has been formulated to assist in conducting peer reviews of human health risk assessments of federal contaminated sites submitted to Health Canada. It is intended that the peer review will be completed directly on the checklist provided in Appendix B, by responding “yes” or “no” to each question and, where appropriate, adding a short explanation or cross-reference as to where the information may be found in the risk assessment report. As well, the checklist has been designed such that an answer of “no” to any question requires a suitable explanation. If that explanation is not contained within the report, follow-up and resolution by the report author and/or the initiating department may be required before the report is deemed complete and acceptable. The guidance outlined in Appendix A is intended to supplement the checklist by providing explanations of some of the key checklist questions/items, as well as references for sources of additional information. In addition to Health Canada’s guidance for conducting a preliminary quantitative risk assessment (PQRA) (Health Canada, 2003a), information on preparing risk assessments may be found in documents produced by the Canadian Council of Ministers of the Environment (CCME) (1996), the Ontario Ministry of Environment and Energy (MOEE) (1996a), and the U.S. Environmental Protection Agency (U.S. EPA) (1989). 2. REFERENCES

Agency for Toxic Substances and Disease Registry (ATSDR). 2003. Toxicological Profiles. Public Health Service, U.S. Department of Health and Human Services. Atlanta, GA. Available online at: http://www.atsdr.cdc.gov/toxpro2.html

Baes, C.F. III, et al. 1984. A Review and Analysis of Parameters for Assessing Transport of

Environmentally Released Radionuclides through Agriculture. ORNL-5786, Oak Ridge National Laboratory, Oak Ridge, Tennessee.

Canadian Council of Ministers of the Environment (CCME). 1993. Guidance Manual on Sampling,

Analysis, and Data Management for Contaminated Sites, Volumes I and II. CCME, Winnipeg, Manitoba. December 1993.

Canadian Council of Ministers of the Environment (CCME). 1996. A Protocol for the Derivation of

Environmental and Human Health Soil Quality Guidelines. Report CCME EPC-101E, CCME, Winnipeg, Manitoba. March 1996.

Canadian Council of Ministers of the Environment (CCME). 2000. Canada-Wide Standards for

Petroleum Hydrocarbons (PHCs) in Soil: Scientific Rationale, Supporting Technical Document. CCME, Winnipeg, Manitoba. December 2000.

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Canadian Council of Ministers of the Environment (CCME). 2001. Canada-Wide Standards for Petroleum Hydrocarbons (PHC) in Soil: User Guidance. CCME, Winnipeg, Manitoba. April 2001.

Canadian Council of Ministers of the Environment (CCME). 2002. Canadian Environmental Quality

Guidelines. CCME, Winnipeg, Manitoba. Canadian Council of Ministers of the Environment (CCME). 2003. Canada-Wide Standards for

Petroleum Hydrocarbons in Soil: Spreadsheet Model. Version 2003/03/12. CCME. Available online at: http://www.ccme.ca/initiatives/standards.html?category_id=9#142

Health Canada. 1996a. Health-Based Tolerable Daily Intakes/Concentrations and Tumorigenic

Doses/Concentrations for Priority Substances. Environmental Health Directorate (Health Canada) Report 96-EHD-194. Ottawa: Supply and Services Canada. 15pp.

Health Canada. 1996b. CEPA Supporting Documentation: Health-Based Tolerable Daily

Intakes/Concentrations and Tumorigenic Doses/Concentrations for Priority Substances. Environmental Health Directorate, Health Canada, Ottawa. August 1996.

Health Canada. 2004. Federal Contaminated Site Risk Assessment in Canada: Part I: Guidance on

Human Health Preliminary Quantitative Risk Assessment (PQRA). Environmental Health Assessment Services Division, Health Canada, Ottawa. September 2004.

Health Canada. 2004. Federal Contaminated Site Risk Assessment in Canada: Part II: Health Canada

Toxicological Reference Values (TRVs). Environmental Health Assessment Services Division, Health Canada, Ottawa. September 2004.

Health Canada. 2003c. Guidelines for Canadian Drinking Water Quality, Supporting Documentation.

Environmental Health Directorate, Health Canada, Ottawa. Available online at: http://www.hc-sc.gc.ca/hecs-sesc/water/dwgsup.htm

Oak Ridge National Laboratory (ORNL). 1998. Empirical Models for the Uptake of Inorganic Chemicals

from Soil by Plants. Published by Bechtel Jacobs Company. Prepared for U.S. Department of Energy. Report BJC/OR-133, ORNL, Oak Ridge, Tennessee. September 1998.

Oak Ridge National Laboratory (ORNL). 2003. Risk Assessment Information System (RAIS). ORNL,

Oak Ridge, Tennessee. Available online at: http://risk.lsd.ornl.gov Ontario Ministry of Environment and Energy (OMEE). 1993. Ontario Typical Range of Chemical

Parameters in Soil, Vegetation, Moss Bags and Snow. Phytotoxicity Section, Standards Development Branch, OMEE, Toronto, Ontario. ISBN-0-7778-1979-1. Version 1.0a, revised April 1994.

Ontario Ministry of Environment and Energy (OMEE). 1996a. Guidance on Site-Specific Risk Assessment

for Use at Contaminated Sites in Ontario. Standards Development Branch, OMEE. ISBN 0-7778-4058-03. Toronto, Ontario. May 1996.

Ontario Ministry of Environment and Energy (OMEE). 1996b. Guidance on Sampling and Analytical

Methods for Use at Contaminated Sites in Ontario. Standards Development Branch, OMEE. ISBN-0-7778-4056-1. Toronto, Ontario. December 1996.

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Ontario Ministry of Environment and Energy (OMEE). 1996c. Rationale for the Development and Application of Generic Soil, Groundwater and Sediment Criteria for Use at Contaminated Sites in Ontario. Standards Development Branch, OMEE. ISBN 0-7778-2818-9. Toronto, Ontario. December 1996.

Richardson, G.M. 1997. Compendium of Canadian Human Exposure Factors for Risk Assessment.

Ottawa: Published by O'Connor Associates Environmental Inc. Stevens, J.B. 1992. Disposition of toxic metals in the agricultural food chain. 2. Steady-state bovine

tissue biotransfer factors. Environ. Sci. Technol. 26(10): 1915-21. Travis, C.C., and A.D. Arms. 1988. Bioconcentration of organics in beef, milk, and vegetation. Environ.

Sci. Technol. 22(3): 271-4. United States Environmental Protection Agency (U.S. EPA). 1989. Risk Assessment Guidance for

Superfund: Volume 1: Human Health Evaluation Manual (Part A). EPA/540/1-89/002. Interim Final. U.S. EPA, Office of Emergency and Remedial Response, Washington, DC. December 1989.

United States Environmental Protection Agency (U.S. EPA). 1996. Soil Screening Guidance: Technical

Background Document. EPA/540/R-95/128. U.S. EPA, Office of Solid Waste and Emergency Response, Washington, DC.

United States Environmental Protection Agency (U.S. EPA). 1997. Exposure Factors Handbook, Volume

I: General Factors; Volume II: Food Ingestion Factors; Volume III: Activity Factors. EPA/600/P-95/002Fa. U.S. EPA, Washington, DC. August 1997.

United States Environmental Protection Agency (U.S. EPA). 2000. User’s Guide for the Johnson and

Ettinger (1991) Model for Subsurface Vapor Intrusion into Buildings (Revised). U.S. EPA, Office of Emergency and Remedial Response, Washington, DC. December 2000. Available online at: http://www.epa.gov/superfund/programs/risk/airmodel/johnson_ettinger.htm

United States Environmental Protection Agency (U.S. EPA). 2001. Johnson and Ettinger (1991) Model

for Subsurface Vapor Intrusion into Buildings. Version 2.3. U.S. EPA, Office of Emergency and Remedial Response, Toxics Integration Branch, Washington, DC. Available online at: http://www.epa.gov/superfund/programs/risk/airmodel/johnson_ettinger.htm

United States Environmental Protection Agency (U.S. EPA). 2002. Child-Specific Exposure Factors

Handbook. Interim Report. EPA-600-P-00-002B. U.S. EPA, Office of Research and Development, National Center for Environmental Assessment, Washington, DC. September 1, 2002.

United States Environmental Protection Agency (U.S. EPA). 2003. Integrated Risk Information System

(IRIS). U.S. EPA, National Center for Environmental Assessment, Cincinnati, OH. Available online at: http://www.epa.gov/iris/index.html

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TABLE 1 Contaminants Commonly Associated with Various Industrial Operations

INDUSTRIAL OPERATION POTENTIAL CONTAMINANTS

Agricultural operations Pesticides, metals (as components of pesticides)

Battery recycling, disposal Metals, pH changes

Coal gasification PAHs, PHCs

Dry cleaning Tetrachloroethylene (PCE) and degradation products (trichloroethylene, 1,1-dichloroethylene, cis- and trans-1,2-dichloroethylene, vinyl chloride)

Electrical equipment/transformers PCBs, PHCs (mineral oils)

Electroplating Metals, pH changes

Machine shops, metal fabrication Metals, VOCs, degreasing solvents (trichloroethylene = TCE) and degradation products (1,1-dichloroethylene, cis- and trans-1,2-dichloroethylene, vinyl chloride)

Mining, smelting, ore processing Metals, pH changes

Petroleum production, distribution, processing, storage

PHCs, benzene, toluene, ethylbenzene, xylenes (BTEX), PAHs, lead, methyl tert butyl ether (MTBE)

Road salt storage Sodium adsorption ratio (SAR), electrical conductivity (EC), chloride, sodium

Wood preservation Pentachlorophenol, PAHs, PHCs, arsenic, chromium, copper

Note: The above list is not intended to be exhaustive of all industrial operations or contaminants.

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APPENDIX A Guidance on Checklist for Peer Review of Human Health Risk Assessments for

Federal Contaminated Sites in Canada

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Appendix A: Guidance on Checklist for Peer Review of Human Health Risk Assessments for Federal Contaminated Sites in Canada

Report title: ___________________________________________________________________

Report author: ___________________________________________________________________

Report date: ___________________________________________________________________

Reviewed by: ___________________________________________________________________

Date reviewed: ___________________________________________________________________

QUERY SUPPLEMENTARY EXPLANATION

1. PROBLEM FORMULATION

• Is the purpose of the risk assessment clear? (i.e., why is the risk assessment being conducted?)

The risk assessment report should contain a clear explanation of the purpose for conducting the risk assessment (e.g., contamination found in soil, etc.). As described in the Health Canada (2003a) PQRA guidance document, PQRAs and complex site-specific risk assessments (SSRAs) are not independent, but represent opposite ends of a continuum of complexity in risk assessment. The purpose of the risk assessment should support the selected level of complexity of the risk assessment.

• Is the scope of the risk assessment clear? (e.g., on-site versus offsite, current versus future land use, all types of receptors, etc.)

Sometimes, for a valid reason, the scope may be narrowed and this should be explained (e.g., remediation of a specific chemical is planned and, therefore, is not part of the scope).

• Is Health Canada the only regulatory agency to be satisfied with the risk assessment? (i.e., is the site to remain under federal control or is provincial approval also required?)

If there is a potential for offsite effects, or if the site is being divested by a federal department, then the requirements of another regulatory jurisdiction (e.g., provincial) may need to be addressed in addition to the requirements of Health Canada.

• Does the risk assessment address current land use and conditions only? If “no”, consult Health Canada for additional guidance.

In general, for federal contaminated sites, only current land use and conditions will be addressed.

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QUERY SUPPLEMENTARY EXPLANATION

1.1 Site Characterization

• Note that some of the information requested below may be provided in a supplemental (environmental site assessment or ESA) report rather than the risk assessment report. If so, indicate the title of the report(s) here.

The results of site investigations should be summarized in the risk assessment report, including a description of the sampling methodologies; the number, location, and depth of the samples collected; and the analytes for which the samples were tested. A site location map, presenting key site features (buildings, surface water, etc.), and a site plan, presenting all sample locations, should be included in the risk assessment report.

• Does the report include a description of historical land uses?

The risk assessment report should describe the past, current, and, if applicable, the proposed future use of the site. The historical land use information should be used to identify potential chemicals of concern (see Section 1.4, below).

• If groundwater on the site, or in the vicinity of the site (within 500m), is used as a source of potable water, was the groundwater tested?

The source of potable water for the site and the surrounding area should be documented, and groundwater should be tested if used as a source of drinking water.

• Are all relevant site characteristics documented (e.g., soil type, direction of groundwater flow, distance to nearest surface water body)?

Regional information concerning the topography, geology, and hydrogeology of the area should be provided.

• Does the report include a site plan? A description of the area surrounding the site, including the land use and occupation (if applicable), should also be provided.

• If the report refers to groundwater monitoring wells, are borehole logs and details of the monitoring well installations provided?

• Is depth to groundwater reported?

If there are potential exposure pathways due to affected groundwater or due to volatilization of organic chemicals from soil or groundwater, then the risk assessment report or a referenced ESA report should include borehole logs, descriptions of monitoring well installations, measurements of the depth to groundwater, a contour of groundwater flow direction, etc.

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QUERY SUPPLEMENTARY EXPLANATION

1.2 Sample Collection

• Have all relevant media been tested (e.g., soil, groundwater)?

• Make a note here if any other media were tested as well

(e.g., surface water, sediment, soil gas, indoor air, outdoor air, vegetation and/or other biota).

Based on the historical land use information, chemicals of potential concern are identified and tested in soil and, possibly, groundwater, surface water, sediment, soil gas, indoor air, outdoor air, vegetation and/or other biota.

• Is there a description of the sampling methodologies? • Did the sampling methodologies follow a standard method,

such as from the CCME, the U.S. EPA, province, etc.?

The CCME (1993) and MOEE (1996b) have developed guidance documents that provide information on sampling methodologies and chemical analysis of samples. Proper sampling techniques are important to make sure the sample is representative of the medium sampled, to reduce the likelihood of chemical loss during sampling (for volatile organic chemicals), and to prevent contamination of samples. If field screening methods were used during the sample collection (e.g., headspace vapour measurements), then these methods should be described in the risk assessment report.

• Were sufficient samples collected from the appropriate locations that you are confident that the likely maximum concentration has been found? (i.e., were all ‘hot spots’ and known/suspected areas of contamination sampled?)

A variety of methods could have been used to select sampling locations, including random, systematic (grid), targeted (at known or suspected ‘hot spots’ or in locations of frequent/continuous receptor occupation), etc. The soil sampling conducted at a contaminated site during typical ESAs is usually targeted at zones of known or suspected contamination. In most cases, the sampling will not be random, and areas with elevated concentrations will typically receive more frequent sampling than areas without contamination. Therefore, the maximum concentrations determined from such targeted sampling will likely exceed the true average, on-site concentrations of contaminants in soil. The peer reviewer should be comfortable that the likely maximum or near-maximum concentration has been reasonably defined.

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QUERY SUPPLEMENTARY EXPLANATION

1.3 Sample Analyses

• Were the chemical analyses completed by a laboratory that was certified by CAEAL or other organization for the analyses?

The Canadian Association of Environmental Analytical Laboratories (CAEAL) certifies laboratories for specific analytical methods. The risk assessment should state whether the data were analyzed by a laboratory certified for the tests conducted.

• Does the report or referenced ESA report include laboratory Certificates of Analysis?

• Does the report include a description of quality assurance and quality control measures employed?

The risk assessment should provide a description of quality control and quality assurance measures employed in sampling and analysis (e.g., were duplicate samples tested, was a field blank tested, did the laboratory test spiked samples, etc.).

• If on-site contaminants are known to degrade (e.g., TCE → vinyl chloride), were analyses conducted for those degradation products?

In many cases, particularly for TCE, the degradation products can be as toxic or more toxic than the parent compound. It is important that degradation products be investigated where appropriate.

1.4 Identification of Chemicals of Potential Concern (COPCs)

• Did the list of contaminants that were selected for analysis include all those typically associated with the historical uses of the site?

Table 1 lists contaminants typically associated with a variety of land uses and industrial operations. The risk assessment report should include analyses for contaminants expected to be present in association with the current or previous land use.

• Were all COPCs screened using CCME guidelines? • If no, list the agencies from which other screening

guidelines were obtained (province, the U.S. EPA, etc.).

For further consideration in the risk assessment, chemicals are often screened by comparing the available analytical results with guidelines such as those in the CCME Canadian Environmental Quality Guidelines (CCME, 2002). The risk assessment should document the comparison of the analytical results with the guidelines and clearly indicate the chemicals selected for further analysis. The measured background concentrations in soil reported in MOEE (1993) may also be used to screen for chemicals of concern.

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QUERY SUPPLEMENTARY EXPLANATION

• For guidelines from agencies other than the CCME, were the selected guidelines appropriate for the samples, chemical analyses, and land uses at the site?

In many cases, the land use of the site in question will not precisely match an agricultural, residential, commercial or industrial land use as defined by the CCME or the provinces when they set the guidelines. The peer reviewer must be comfortable that the guidelines selected for screening are for the most appropriate default land use category. Also, U.S. EPA preliminary remediation goals (PRGs) are often used for screening in instances when no CCME or provincial guideline exists. PRGs are derived on the basis of 100% of the toxicological reference value (TRV) for non-carcinogens, whereas the CCME, Ontario and some other provinces derive their guidelines on the basis of only 20% of the TRV. When U.S. EPA PRGs are employed, they should be divided by 5 (i.e., reduced so that they are based on 20% of the TRV) in order to be comparable to CCME and provincial policies on procedures for guidelines derivation.

• Are the units of measurement the same as those of the guidelines?

It is important that the units of measurement be the same as those of the guidelines or that the units are converted properly. Errors are often made when concentrations in mg/kg are compared to guidelines in units of µg/kg, or vice versa.

• Are degradation products identified as COPCs even if not detected?

In general, for sites where tetrachloroethylene and/or trichloroethylene are identified, their degradation products (even if not detected) should be included as chemicals of potential concern when future land use is being evaluated in the risk assessment, because they may be produced in the future. When current land use is the focus of the risk assessment, but it is anticipated that the land use will not change for the foreseeable future, then consideration of degradation products may also be relevant.

• Were COPCs screened using the maximum measured on-site concentrations?

For consistency, Health Canada (2003a) specifies that maximum concentrations should be used for screening of COPCs. However, where sufficient data exist, some other statistic (mean, upper confidence limit of the mean, specified percentile value, etc.) may be applied, at the discretion of the risk assessor. The peer reviewer should be comfortable that the selected statistic, if not the maximum value, is justified and supported by a statistical analysis and by sufficient sample size for the site in question.

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QUERY SUPPLEMENTARY EXPLANATION

• If a statistic other than the maximum concentration was used for COPC screening, is a statistical analysis of the data presented?

If the risk assessment uses concentrations other than the maximum measured concentrations for the analysis, then any statistical evaluation of the data must be fully documented.

• If a statistic other than the maximum concentration was used for COPC screening, is the selected statistic (mean, upper confidence limit of the mean, specified percentile value, etc.) appropriate and defensible given sample size and other factors?

Peer reviewers must use their judgement. The peer reviewer should be comfortable that the selected statistic, if not the maximum value, is justified and supported by a statistical analysis and by sufficient sample size for the site in question.

2. EXPOSURE ASSESSMENT

• Is the use of the property (for purposes of the risk assessment) clearly explained?

The risk assessment should clearly describe the present and proposed future use (if different from the present use) of the property.

• If there is a potential for offsite exposures are offsite land uses and receptors identified?

If there is a potential for offsite migration of chemicals, then offsite land uses should also be described.

• Were exposure calculations conducted using the maximum measured on-site concentration(s)?

If the risk assessment uses concentrations other than the maximum measured concentrations for the analysis, then any statistical evaluation of the data must be fully documented.

• If the maximum concentration was not used, was the selected statistic (mean, upper confidence limit of the mean, specified percentile value, etc.) appropriate and defensible given sample size and other factors?

The statistical analysis should be consistent with the number of samples collected. It is not uncommon that limited data are overanalyzed.

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QUERY SUPPLEMENTARY EXPLANATION

2.1 Receptors and Pathways

• Have all relevant receptor age groups been identified (infant, toddler, child, teen, adult)?

Health Canada (2003a) and the CCME (1996) define five age groups for receptors: adults (20 to 70 years of age), teens (12 to 19 years of age), children (5 to 11 years of age), toddlers (7 months to 4 years of age) and infants (0 to 6 months of age).

• If all relevant receptor age groups have not been identified, has the most sensitive age group been identified?

In some cases, a risk assessment will focus only on what has been defined as the most sensitive age group or receptor group. For example, toddlers are often considered the most sensitive age group due to having the greatest intake per unit of body weight of any age group. Other sensitive age groups may be identified for toxicological reasons. For example, exposure to methyl mercury is a concern for women of child-bearing age, to protect against teratogenic effects.

• Have all potentially sensitive receptor population groups been identified (e.g., the elderly, First Nations communities)?

The risk assessment should also identify the presence of any potentially sensitive receptors. For example, exposure to methyl mercury or other bioaccumulative substance, is a concern for subsistence fishing populations (First Nations communities; sports fishers who consume their catch) due to high intake rates relative to the general population.

• Have all relevant exposure pathways been considered? • For those pathways that were excluded, was their exclusion

adequately justified?

Health Canada (2003a) provides a checklist of potential exposure pathways to be considered in a risk assessment. These pathways may include direct contact with soil (incidental ingestion of soil, dermal contact with soil, inhalation of suspended particulate matter), ingestion of groundwater, inhalation of vapours (indoors and/or outdoors) arising from contaminated soil and/or groundwater, contact with surface water (ingestion, dermal absorption), and ingestion of food. The risk assessment should clearly state the pathways that are of concern and provide justification for any pathways that are eliminated. Health Canada (2003a) also presents the equations for estimating the dose via each pathway.

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QUERY SUPPLEMENTARY EXPLANATION

• Were all receptor exposure characteristics (body weight, inhalation rate, etc.) drawn from accepted Canadian sources (Health Canada, Compendium of Canadian Human Exposure Factors for Risk Assessment (Richardson, 1997), the CCME, etc.)?

• If an alternate source of receptor characteristics was used,

was this because no Canadian data or value has been published?

• If alternate sources for exposure characteristics were used,

was the source/citation clearly documented? • If alternate sources for exposure characteristics were used,

are the assumptions used appropriate and adequately justified?

The physical and behavioural characteristics of each receptor group should be documented, with references, in the risk assessment. Preferred sources of this information for Canadian risk assessments are: Health Canada (2003a), CCME (1996) and Richardson (1997). For characteristics not included in these documents, the U.S. EPA Exposure Factors Handbook (U.S. EPA, 1997) and the U.S. EPA Child-Specific Exposure Factors Handbook (U.S. EPA, 2002) may be used.

• Were assumptions regarding exposure duration and exposure frequency appropriate and adequately justified?

Often the exposure frequency and duration must be assumed; these assumptions should be clearly noted in the risk assessment to assess their validity. Typical assumptions for a PQRA are provided in the Health Canada (2003a) guidance document. However, in many cases the risk assessor will have to apply his/her professional judgement in defining such assumptions. The peer reviewer should consider whether such assumptions are reasonable.

• Does the report include sample calculations? • Can those calculations be reproduced? (i.e., check the

math)

It is very important for peer reviewers to confirm the accuracy of mathematical calculations. Errors occur far more often than you might imagine.

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QUERY SUPPLEMENTARY EXPLANATION

• Are all equations dimensionally consistent and are all units correct (i.e., are the dimensions and the units the same on both sides of the ‘equal’ sign)?

Dimensionally consistent means that the dimensions (and units) are the same on both sides of the ‘equal’ sign (e.g., a dose in mg/kg/d on one side and a concentration in mg/kg on the other side are not dimensionally consistent). It serves as a quick check that the equations are correct; that the equation actually produces the units indicated for the equation product. Unit-related problems are the most common mistakes in risk assessments.

2.2 Environmental Fate Modelling

• Are models used to predict the environmental fate of any COPC? (e.g., is a model used to estimate the groundwater concentration from the soil concentration? Is a model used to predict the rate of migration of a COPC in groundwater? Is an equation used to predict the indoor air concentration of a volatile substance from the concentration in soil or groundwater?- etc.)

• If yes, are the names, sources and citations for the model(s)

identified? • Has the model(s) been peer reviewed or published by an

authoritative source (such as the CCME, Environment Canada, the U.S EPA, etc.)? (i.e., is the model ‘generally accepted’?)

• If a unique model was created from first principles, seek

comment and assistance from an appropriate expert to determine its validity and applicability.

In general, a simple model is more appropriate for application in a simple (preliminary quantitative) risk assessment. Be wary of instances when a complex model and complex treatment of data are applied to a relatively simple situation or to very limited input information. If a model is used for calculation of chemical concentrations in one medium from measured concentrations in soil (or groundwater in the case of indoor air), questions to be considered include: What is the reference for the model? Has it been peer reviewed? Is it readily available? Is the complexity of the model appropriate for the situation, number of samples and risk assessment complexity? Why was this particular model selected? Is a complex model applied to a preliminary quantitative (simple) risk assessment? Does the model attempt to make too much out of very limited input data (i.e., does it suggest greater precision in the model results than the input data could conceivably deliver)? Are model results given with far more significant digits than the available data can justify?

• Is the selected model(s) designed for the type of application to which it was applied?

Is the model intended for use for the type of chemicals considered in the risk assessment (e.g., many models are intended only to be applied to non-ionizing organic chemicals and extrapolation to other chemicals may not be appropriate)?

• Are all model assumptions and equations explained?

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QUERY SUPPLEMENTARY EXPLANATION

• Are intermediate results included (e.g., predicted concentrations at relevant locations) and do they make sense?

Intermediate calculations (e.g., concentrations at specific locations) should be presented so that, even if the calculations are not readily reproduced by hand, the sensibility of the calculations may be evaluated.

Environmental fate models are most likely to be used to evaluate the transport of vapours from soil or groundwater to indoor or outdoor air, to predict down-gradient concentrations in groundwater, to predict concentrations in adjacent surface water, or to predict concentrations in produce, meat, or milk that are consumed. Readily available references for each of these types of models are discussed below. Vapour Transport Modelling CCME (1996) and CCME (2000) both present dilution factors for soil gas to indoor air (the ratio of the chemical concentration in soil gas to the concentration in indoor air). Both approaches are acceptable, but CCME (2000) provides a more complex approach, providing dilution factors for: a) residential buildings with and without basements; b) commercial/industrial buildings; c) coarse and fine-grained soils; and d) as a function of the depth or distance of contamination from the building. The dilution factors presented in either CCME (1996) or CCME (2000) may be used as a screening tool to estimate concentrations of a volatile contaminant in indoor air from the concentration in soil gas. Dilution factors presented in CCME (2000) were derived using a model known as the Johnson and Ettinger model; the model is readily available from the U.S. EPA (2000, 2001). Site-specific application of the Johnson and Ettinger model permits inclusion of site characteristics (e.g., soil permeability, depth to groundwater, etc.) that may result in lower predicted indoor air concentrations. Alternate models may be used, but the equations and assumptions should be documented and intermediate calculations (e.g., the dilution factor and the predicted indoor air concentrations) should be provided to permit an evaluation of whether the results are reasonable (by comparison, for example, to the results in CCME (2000)).

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QUERY SUPPLEMENTARY EXPLANATION

Vapour Transport Modelling (continued) Volatilization from soil or groundwater to outdoor air is generally of less concern compared to volatilization to indoor air; however, at sites where there is no indoor air exposure, outdoor air may be a concern. This is particularly true for construction workers involved with short-term excavation activities to install underground utilities, or during remediation. The U.S. EPA (1996) provides a simple model for estimating chemical concentrations in outdoor air as a result of contaminated soil or groundwater. Groundwater Modelling Commercial or proprietary models for predicting the migration of contaminants in groundwater may be used and the assumptions, equations, and results should be clearly documented in the risk assessment report. The CCME provides two approaches to calculating contaminant concentrations in groundwater, as part of the development of the guidelines for petroleum hydrocarbons (PHCs) (CCME, 2000, 2001). The first approach is a simple steady-state mixing dilution model and is the same as the approach in CCME (1996). The second approach is a dynamic advective-dispersive model, which accounts for retardation by organic matter, anaerobic biodegradation, and dispersion. A spreadsheet is available from the CCME (2003) to perform the calculations for these approaches and may be used to assist in evaluating the results in a risk assessment report. Uptake into Produce, Meat, or Milk Estimating chemical concentrations in produce, meat, or milk is generally highly uncertain. CCME (1996) presents simple equations, derived by Travis and Arms (1988), for estimating concentrations of organic chemicals in produce, meat, and milk. Baes et al. (1984) and ORNL (1998) present uptake factors for inorganic contaminants in plants. Stevens (1992) presents tissue biotransfer factors for estimating the concentration of metals in beef as a result of the rate of intake of metal in the diet.

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QUERY SUPPLEMENTARY EXPLANATION

3. HAZARD ASSESSMENT

• Were all toxicological reference values (TRVs) drawn from Health Canada?

• If no, was it because Health Canada had no TRV for the

subject COPC?

Health Canada (2003b) provides a list of TRVs for a large number of chemicals and is the preferred source for risk assessments prepared for Health Canada. If alternate values are used in the risk assessment, then a reference should be provided and their selection justified. For chemicals not listed in the Health Canada (2003b) TRV document, TRVs may be obtained from another peer reviewed source. Health Canada (2003a) lists the following sources of information, in order of preference: U.S. Environmental Protection Agency (U.S. EPA, 2003) online database known as the “Integrated Risk Information System” (IRIS): http://www.epa.gov/iris/index.html World Health Organization (WHO); information available at various sources including: http://www.inchem.org/; http://jecfa.ilsi.org/index.htm Netherlands National Institute of Public Health and the Environment (RIVM): http://www.rivm.nl/bibliotheek/rapporten/711701025.pdf U.S. Agency for Toxic Substances and Disease Registry (ATSDR, 2003): http://www.atsdr.cdc.gov/toxpro2.html

• Are the selected TRVs clearly stated, with references, for each chemical and for each pathway?

• Are the health effects associated with each COPC and the basis for the TRVs described?

The risk assessment should include a description of the health effects for each chemical of concern and the basis for the selected TRV (refer to Health Canada, 2003c, 1996a, 1996b).

• If dermal absorption is a pathway evaluated, are dermal absorption factors drawn from Health Canada advice?

• If no, were the sources of dermal absorption factors

referenced?

Oral and dermal exposures are often summed, for comparison to an oral TRV. In such cases, a dermal absorption factor should be applied, since dermal absorption is usually much lower than oral absorption. These factors are listed in the Health Canada (2003a) guidance document and also in MOEE (1996c). For chemicals not listed in either of these references, the Risk Assessment Information System (RAIS) (ORNL, 2003; http://risk.lsd.ornl.gov) is an online database containing dermal absorption factors as well as TRVs.

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QUERY SUPPLEMENTARY EXPLANATION

• Has 100% oral bioavailability been assumed? (If a variable representing bioavailability is not included, then 100% is implicitly assumed).

• If no, then were the values based on tests of on-site soil?

Absorption factors for ingestion are usually 100% in preliminary quantitative risk assessments. Oral bioavailability is commonly measured in vitro as bioaccessibility (% solubility in simulated gastric fluid), which depends upon the properties of the soil and the site-specific characteristics of the contaminant. In complex risk assessments, direct assays of contaminant bioaccessibility may be conducted to directly measure potential bioavailability. Therefore, if a value for oral bioavailability of less than 100% is used, ideally it is based on site-specific measurements of bioaccessibility.

• If no bioaccessibility tests of on-site soil were conducted, did the study or literature from which the oral bioavailability value was obtained investigate sites with the same source of contamination? (same industry or industrial process, etc.)

The form of the chemical may vary depending upon its source. For metals, for example, the bioavailability is relatively low for mine tailings, but is relatively high for deposits from ore roasting/processing. The bioavailability value should be based on a similar source of the contaminant.

• If no tests of on-site soil were conducted, did the study or literature from which the oral bioavailability value was obtained investigate sites with the same soil characteristics? (similar grain size [fine or coarse], same type of soil [sand, silt, clay, etc.], similar organic carbon content, etc.)

Bioaccessibility and bioavailability tend to increase as soil grain size decreases or as soil organic matter content decreases.

• If inhalation was a pathway evaluated, was absorption by this pathway assumed to be 100%? (if a variable representing inhalation bioavailability is not included, then 100% is implicitly assumed).

Absorption factors for inhalation are usually 100% in preliminary quantitative risk assessments.

• If inhalation absorption was less than 100%, was the source of the inhalation absorption factor referenced and is it appropriate to the contaminant?

All absorption factors less than 100% must be fully explained and referenced.

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QUERY SUPPLEMENTARY EXPLANATION

4. RISK CHARACTERIZATION

• Are the results of the risk assessment clear? The risk assessment report should provide a clear statement of the predicted risks and hazard quotients for each chemical and for each exposure pathway.

• For chemicals and pathways affecting the same target organ, are the hazard quotients summed for non-cancer effects?

Hazard quotients should be summed for chemicals that affect the same target organ. Generally, oral and dermal exposures will be summed.

• Are all non-cancer hazard quotients less than 0.2 (or other level defined as acceptable)?

The definition of an acceptable hazard quotient depends upon the jurisdiction. Health Canada considers hazard quotients of 0.2 or less as acceptable. If any other agency has been identified as having jurisdiction (for example, provinces for offsite areas), then the acceptable hazard quotient may be different and should be documented in the risk assessment.

• For carcinogens, have risks been summed for chemicals and pathways causing the same form of cancer?

Risks for chemicals that produce the same form of cancer should be summed. Generally, oral and dermal exposures will be summed.

• Are all cancer risks less than 1 x 10-5 (or other level defined as essentially negligible)?

Health Canada considers risks of one in one hundred thousand (1 x 10-5) or less as essentially negligible. If any other agency has been identified as having jurisdiction (for example, provinces for offsite areas), then the negligible risk level may be different and should be documented in the risk assessment.

• Is the uncertainty of the results discussed? The risk assessment should provide an evaluation of the uncertainty in the results. This evaluation may be largely a qualitative discussion for preliminary risk assessments, or may be quantitative in complex risk assessments. In either case, the report should indicate the variables and assumptions for which the results are most sensitive.

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QUERY SUPPLEMENTARY EXPLANATION

5. RISK MANAGEMENT

• If any non-cancer hazard quotients exceed 0.2 or any cancer risks exceed 1 x 10-5, are remedial or risk management measures proposed?

• If yes, are the proposed measures consistent with the

spatial scale of the site and the magnitude of the risks? (i.e., do the risk management options appear to be ‘over-kill’?)

If the calculated risks or hazard quotients exceed the levels considered acceptable by Health Canada (or other jurisdiction, if applicable), then the risk assessment report may provide recommendations for remediation (i.e., calculation of remedial criteria) and/or a detailed description of risk management measures to control exposures to acceptable levels.

• If ongoing monitoring or risk management measures are recommended, is the responsible department or agency clearly identified, if other than the Client department that solicited the risk assessment?

6. OVERALL COMMENTS

• Is the risk assessment report acceptable? • If no, list all concerns, outstanding issues, required

explanations, and/or data requirements. Use separate sheets as necessary.

Following review of the risk assessment, is the risk assessment report acceptable? Are there any outstanding issues that require clarification or more information? Are there any follow-up actions to be taken?

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APPENDIX B Checklist for Peer Review of Human Health Risk Assessments for

Federal Contaminated Sites in Canada

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Appendix B: Checklist for Peer Review of Human Health Risk Assessments for Federal Contaminated Sites in Canada

Report title: ___________________________________________________________________

Report author: ___________________________________________________________________

Report date: ___________________________________________________________________

Reviewed by: ___________________________________________________________________

Date reviewed: ___________________________________________________________________

QUERY YES NO N/A EXPLANATION/REFERENCE TO SECTION IN RISK ASSESSMENT REPORT

1. PROBLEM FORMULATION

• Is the purpose of the risk assessment clear? (i.e., why is the risk assessment being conducted?)

• Is the scope of the risk assessment clear? (e.g., on-site versus offsite, current versus future land use, all types of receptors, etc.)

• Is Health Canada the only regulatory agency to be satisfied with the risk assessment? (i.e., is the site to remain under federal control or is provincial approval also required?)

• Does the risk assessment address current land use and conditions only?

• If “no”, consult Health Canada for additional guidance.

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QUERY YES NO N/A EXPLANATION/REFERENCE TO SECTION IN RISK ASSESSMENT REPORT

1.1 Site Characterization

• Note that some of the information requested below may be provided in a supplemental (environmental site assessment, or ESA) report rather than the risk assessment report. If so, indicate the title of the report(s) here.

• Does the report include a description of historical land uses?

• If groundwater on the site, or in the vicinity of the site (within 500m), is used as a source of potable water, was the groundwater tested?

• Are all relevant site characteristics documented (e.g., soil type, direction of groundwater flow, distance to nearest surface water body)?

• Does the report include a site plan?

• If the report refers to groundwater monitoring wells, are borehole logs and details of the monitoring well installations provided?

• Is depth to groundwater reported?

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QUERY YES NO N/A EXPLANATION/REFERENCE TO SECTION IN RISK ASSESSMENT REPORT

1.2 Sample Collection

• Have all relevant media been tested (e.g., soil, groundwater)?

• Make a note here if any other media were tested as well

(e.g., surface water, sediment, soil gas, indoor air, outdoor air, vegetation and/or other biota).

• Is there a description of the sampling methodologies?

• Did the sampling methodologies follow a standard method, such as from the CCME, the U.S. EPA, province, etc.?

• Were sufficient samples collected from the appropriate locations such that you are confident that the likely maximum concentration has been found? (i.e., were all ‘hot spots’ and known/suspected areas of contamination sampled?)

1.3 Sample Analyses

• Were the chemical analyses completed by a laboratory that was certified by CAEAL or other organization for the analyses?

• Does the report or referenced ESA report include laboratory Certificates of Analysis?

• Does the report include a description of quality assurance and quality control measures employed?

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QUERY YES NO N/A EXPLANATION/REFERENCE TO SECTION IN RISK ASSESSMENT REPORT

• If on-site contaminants are known to degrade (e.g., TCE → vinyl chloride), were analyses conducted for those degradation products?

1.4 Identification of Chemicals of Potential Concern (COPCs)

• Did the list of contaminants that were selected for analysis include all those typically associated with the historical uses of the site?

• Were all COPCs screened using CCME guidelines? • If no, list the agencies from which other screening

guidelines were obtained (province, the U.S. EPA, etc.).

• For guidelines from agencies other than the CCME, were the selected guidelines appropriate for the samples, chemical analyses, and land uses at the site?

• Are the units of measurement the same as those of the guidelines?

• Are degradation products identified as COPCs even if not detected?

• Were COPCs screened using the maximum measured on-site concentration?

• If a statistic other than the maximum concentration was used for COPC screening, is a statistical analysis of the data presented?

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QUERY YES NO N/A EXPLANATION/REFERENCE TO SECTION IN RISK ASSESSMENT REPORT

• If a statistic other than the maximum concentration was used for COPC screening, is the selected statistic (mean, upper confidence limit of the mean, specified percentile value, etc.) appropriate and defensible given sample size and other factors?

2. EXPOSURE ASSESSMENT

• Is the use of the property (for purposes of the risk assessment) clearly explained?

• If there is a potential for offsite exposures, are offsite land uses and receptors identified?

• Were exposure calculations conducted using the maximum measured on-site concentration(s)?

• If the maximum concentration was not used, was the selected statistic (mean, upper confidence limit of the mean, specified percentile value, etc.) appropriate and defensible given the sample size and other factors?

2.1 Receptors and Pathways

• Have all relevant receptor age groups been identified (infant, toddler, child, teen, adult)?

• If all relevant receptor age groups have not been identified, has the most sensitive age group been identified?

• Have all potentially sensitive receptor population groups been identified (e.g., elderly; First Nations communities)?

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QUERY YES NO N/A EXPLANATION/REFERENCE TO SECTION IN RISK ASSESSMENT REPORT

• Have all relevant exposure pathways been considered?

• For those pathways that were excluded, was their exclusion adequately justified?

• Were all receptor exposure characteristics (body weight, inhalation rate, etc.) drawn from accepted Canadian sources (e.g., Health Canada, Compendium of Canadian Human Exposure Factors for Risk Assessment (Richardson, 1997), the CCME, etc.)?

• If an alternate source for receptor characteristics was used, was this because no Canadian data or value has been published?

• If alternate sources for exposure characteristics were used, was the source/citation clearly documented?

• If alternate sources for exposure characteristics were used, are the assumptions appropriate and adequately justified?

• Were assumptions regarding exposure duration and exposure frequency appropriate and adequately justified?

• Does the report include sample calculations?

• Can those calculations be reproduced? (i.e., check the math)

• Are all equations dimensionally consistent and are all units correct (i.e., are the dimensions and the units the same on both sides of the ‘equal’ sign)?

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QUERY YES NO N/A EXPLANATION/REFERENCE TO SECTION IN RISK ASSESSMENT REPORT

2.2 Environmental Fate Modelling

• Are models used to predict the environmental fate of any COPC? (e.g., is a model used to estimate the groundwater concentration from the soil concentration? Or to predict the rate of migration of a COPC in groundwater? Is an equation used to predict the indoor air concentration of a volatile substance from the concentration in soil or groundwater? Etc.)

• If yes, are the names, sources and citations for the model(s) identified?

• Has the model(s) been peer reviewed or published by an authoritative source (e.g., the CCME, Environment Canada, the U.S. EPA, etc.)? (i.e., is the model ‘generally accepted’?)

• If a unique model was created from first principles, seek

comment and assistance from an appropriate expert to determine its validity and applicability.

• Is the selected model(s) designed for the type of application to which it was applied?

• Are all model assumptions and equations explained?

• Are intermediate results included (e.g., predicted concentrations at relevant locations) and do they make sense?

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QUERY YES NO N/A EXPLANATION/REFERENCE TO SECTION IN RISK ASSESSMENT REPORT

3. HAZARD ASSESSMENT

• Were all toxicological reference values (TRVs) drawn from Health Canada?

• If no, was it because Health Canada had no TRV for the subject COPC?

• Are the selected TRVs clearly stated, with references, for each chemical and each pathway?

• Are the health effects associated with each COPC and the basis for the TRVs described?

• If dermal absorption is a pathway evaluated, are dermal absorption factors drawn from Health Canada advice?

• If no, were the sources of dermal absorption factors referenced?

• Has 100% oral bioavailability been assumed? (If a variable representing bioavailability is not included, then 100% is implicitly assumed).

• If no, were the values based on tests of on-site soil?

• If no bioaccessibility tests of on-site soil were conducted, did the study or literature from which the oral bioavailability value was obtained investigate sites with the same source of contamination? (same industry or industrial process, etc.)

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QUERY YES NO N/A EXPLANATION/REFERENCE TO SECTION IN RISK ASSESSMENT REPORT

• If no tests of on-site soil were conducted, did the study or literature from which the oral bioavailability value was obtained investigate sites with the same soil characteristics? (similar grain size [fine or coarse], same type of soil [sand, silt, clay, etc.], similar organic carbon content, etc.)

• If inhalation was a pathway evaluated, was absorption by this pathway assumed to be 100%? (if a variable representing inhalation bioavailability is not included, then 100% is implicitly assumed).

• If inhalation absorption was less than 100%, was the source of the inhalation absorption factor referenced and is it appropriate to the contaminant?

4. RISK CHARACTERIZATION

• Are the results of the risk assessment clear?

• For chemicals and pathways affecting the same target organ, are the hazard quotients summed for non-cancer effects?

• Are all non-cancer hazard quotients less than 0.2 (or other level defined as acceptable)?

• For carcinogens, have risks been summed for chemicals and pathways causing the same form of cancer?

• Are all cancer risks less than 1 x 10-5 (or other level defined as essentially negligible)?

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QUERY YES NO N/A EXPLANATION/REFERENCE TO SECTION IN RISK ASSESSMENT REPORT

• Is the uncertainty of the results discussed?

5. RISK MANAGEMENT

• If any non-cancer hazard quotients exceed 0.2 or any cancer risks exceed 1 x 10-5, are remedial or risk management measures proposed?

• If yes, are the proposed measures consistent with the spatial scale of the site and the magnitude of the risks? (i.e., do the risk management options appear to be ‘over-kill’?)

• If ongoing monitoring or risk management measures are recommended, is the responsible department or agency clearly identified, if other than the Client department that solicited the risk assessment?

6. OVERALL COMMENTS

• Is the risk assessment report acceptable? • If no, list all concerns, outstanding issues, required

explanations, and/or data requirements. Use separate sheets as necessary.

NOTES:

• N/A = not applicable • The above checklist should be completed in conjunction with the report entitled Guidance on Peer Review of Human Health Risk Assessments

for Federal Contaminated Sites in Canada.

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• The checklist has been designed such that an answer of NO to any question requires follow-up and suitable explanation or resolution by the report author and/or the initiating department before the report should be defined as complete and acceptable.