Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
DRAFT
HUMAN HEALTH RISK ASSESSMENT SYNTHESIS
Nyanza Superfund Site Operable Unit IV
Sudbury River Mercury Contamination
Prepared for:
U.S. Environmental Protection Agency
Contract No. GS-10F-0090N EPA Order No. 3Z-0066-NBSX
May 2006
Avatar Work Order Number 0023.001.02.0804
1. Introduction................................................................................................................. 1 1.1 Objectives of HHRA Synthesis Report............................................................... 1 1.2 Site History ......................................................................................................... 2 1.3 Site Description................................................................................................... 3
1.3.1 Sudbury River Reach Descriptions............................................................. 4 1.3.2 Sudbury River Reference Area Descriptions.............................................. 5
1.3.2.1 Reach 1 – Headwaters of the Sudbury River .......................................... 6 1.3.2.2 Charles River .......................................................................................... 6 1.3.2.3 Sudbury Reservoir .................................................................................. 6
1.4 Chronology of HHRA Evaluations..................................................................... 7 1.4.1 1992 Final RI Report for Operable Unit III ................................................ 8 1.4.2 Task Force and OU IV Formation .............................................................. 8 1.4.3 1999 Report............................................................................................... 10 1.4.4 2003-2005 Supplemental Investigation .................................................... 10 1.4.5 2006 Report............................................................................................... 11
1.5 Report Overview............................................................................................... 11 2. Summary of 1992 Human Health Risk Assessment Presented within the OU III RI (NUS)................................................................................................................................ 13
2.1 Introduction and Background ........................................................................... 13 2.1.1 Sampling Program Summary.................................................................... 14 2.1.2 Conceptual Model..................................................................................... 15 2.1.3 Exposure Points ........................................................................................ 17
2.2 Direct Contact Pathway risk Results................................................................. 17 2.2.1 Cancer Risk............................................................................................... 17 2.2.2 Noncancer Hazard..................................................................................... 17
2.3 Indirect Pathway risk results............................................................................. 18 2.3.1 Cancer Risk............................................................................................... 18 2.3.2 Noncancer Hazard..................................................................................... 18
3. Summary of 1999 (Weston) Report.......................................................................... 19 3.1 Introduction and Background ........................................................................... 19
3.1.1 Sampling Program Summary.................................................................... 19 3.1.2 Conceptual Model..................................................................................... 20 3.1.3 Exposure Points ........................................................................................ 20
3.2 Direct Contact Results ...................................................................................... 22 3.3 Indirect Pathways Results ................................................................................. 23
4. Summary of 2006 (Avatar) Report ........................................................................... 23 4.1 Introduction and Background ........................................................................... 23
4.1.1 Sampling Program Summary.................................................................... 23 4.1.2 Sampling Program Summary.................................................................... 23 4.1.3 Conceptual Model..................................................................................... 24 4.1.4 Exposure Points ........................................................................................ 24
4.2 Results............................................................................................................... 26 5. Integration and Comparison of all HHRAs .............................................................. 27
5.1 Data Summaries ................................................................................................ 27 5.1.1 Surface Water............................................................................................ 27 5.1.2 Sediment ................................................................................................... 27
i H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
5.1.3 Fish Tissue ................................................................................................ 28 5.2 Direct Contact ................................................................................................... 28 5.3 Indirect Pathways.............................................................................................. 29
5.3.1 Site (Reaches 2 through 10) versus Reference Concentrations ................ 30 5.3.1.1 Reach 1 Reference Area Statistical Comparisons................................. 31 5.3.1.2 Charles River Statistical Comparisons.................................................. 31 5.3.1.3 Sudbury Reservoir Statistical Comparisons.......................................... 31 5.3.1.4 Site versus Reference Area Semi-quantitative Comparisons................ 32
5.3.2 Trends in Fish Concentrations .................................................................. 32 6. Summary and Conlusions ......................................................................................... 33 7. References................................................................................................................. 35
ii H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
1. INTRODUCTION
1.1 OBJECTIVES OF HHRA SYNTHESIS REPORT
Since the inclusion of the Nyanza Chemical Waste Dump Superfund Site on the National
Priorities List (NPL) in 1982, three human health risk assessments (HHRAs) have been
performed to evaluate the risk to chemical exposure in the Sudbury River (one for various
contaminants, the other two for mercury only). These evaluations were undertaken to
determine the potential for adverse health effects to occur in individuals potentially
exposed to chemical contaminants originating from the Site. Assumed exposures
included direct contact from living adjacent to the Sudbury River and from using the river
for recreational purposes.
As part of the phased Remedial Investigation (RI) of the Site, each of the three HHRAs
were based on the objectives of the individual phases of the RI and the data collected to
meet those objectives. In large part, the principal differences among each of the risk
assessments are due to investigations of: 1) different chemicals of potential concern; 2)
different areas of the river; 3) different media sampled; and 4) different exposure
pathways. To provide a complete perspective of the evaluation of risk associated with
contamination of the Sudbury River, this synthesis report has been developed to meet the
following objectives:
� Summarize the results of all of the risk assessments in one concise report.
� Qualitatively compare results among reports.
� Note general trends in risks.
The intention of this report is to integrate all of the available HHRA results. Although
qualitative evaluations are performed to make comparisons among risks from various
sampling efforts and associated risk assessments, risks will not be recalculated based on
newly collected data or updated exposure factors. For example, health risks from a child
exposed to contaminated sediments while wading were developed in the 1992 RI.
Additional sediment data were collected in 2003-2005 and many default exposure
parameters have been updated since the 1992 RI. Exposure doses and subsequent risks
1 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
are not recalculated using the most recent concentrations and exposure data for the child
wader.
1.2 SITE HISTORY
The Nyanza Chemical Waste Dump Superfund Site (hereafter Nyanza Site) was occupied
from 1917 through 1978 by several companies that manufactured textile dyes and dye
intermediates. Additional products manufactured on-site included various colloidal
solids and acrylic polymers. During the period of operation, large volumes of chemical
waste were disposed in burial pits, below ground containment structures, and various
lagoons scattered throughout the “Hill” section of the site. Wastes contained in these
disposal areas included partially treated process water, chemical sludge, solid process
wastes (chemical precipitate and filter cakes), solvent recovery distillation residue,
numerous organic and inorganic chemicals (including mercury), and off-specification
products. Process chemicals that could not be reused or recycled, such as phenol,
nitrobenzene, and mercuric sulfate, were also disposed of on-site or discharged into the
Sudbury River mainly through a small stream referred to as Chemical Brook.
Mercury and chromium were used as catalysts in the production of textile dyes from 1917
to 1978. Approximately 2.3 metric tons (2,300 kg) of mercury were used per year from
1940 to 1970 (JBF Scientific Corp., 1972), with a total of 45 to 57 metric tons of mercury
released to the Sudbury River during this period (JBF Scientific Corp., 1973). From
1970 until the facility closed in 1978, wastes were treated on-site and wastewater was
discharged to Ashland’s town sewer system. These revised treatment practices reduced
the quantity of mercury released to the Sudbury River to between 23 and 30 kg per year
or about 0.2 metric tons during that eight-year period.
Nyanza, Inc. was cited for several waste disposal violations by the Massachusetts
regulatory agencies from 1972 to 1977. In 1981, most of the property was acquired by
MCL Development Corporation, which leased a large portion of the site. In 1982, the
Nyanza Site was placed on the National Priorities List (NPL) by the U.S. EPA. Four
other small property owners currently operate or lease facilities to various light industries
and commercial concerns.
2 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
1.3 SITE DESCRIPTION
The Nyanza Site is located in Ashland, Massachusetts approximately 35 km west of
Boston. The Nyanza Site, which covers approximately 35 acres, is situated in an
industrial area 0.4 km south of the Sudbury River. Surface water runoff and groundwater
discharged from the site drains into Trolley Brook, Chemical Brook, and the Eastern
Wetland (Figure 1). Trolley Brook, which drains the Eastern Wetlands, and Chemical
Brook are the primary site drainages. Trolley Brook merges with Chemical Brook and
continues through a culvert that discharges to Outfall Creek, a small man-made channel
approximately 60 m long. Outfall Creek flows to the Lower Raceway, which joins the
Sudbury River 240 m downstream from the site. The study area consists of an
approximately 60 km stretch of river that begins in the river’s headwaters and extends to
where the Sudbury and the Assabet Rivers converge to form the Concord River (Figure
2).
The Sudbury River flows in a northerly direction through rolling, hilly terrain and
consists of a series of impoundments, flowing reaches, and extensive wetland areas. A
majority of the land surrounding the study area is suburban residential, consisting of
several closely spaced urban centers connected by arterial commuting routes. The
watershed area of the Sudbury River is approximately 165 square miles.
The Sudbury River, from its source to its confluence with the Assabet River to form the
Concord River, is designated by the Massachusetts Department of Environmental
Protection as a Class B Inland Water (MADEP, 2000). As such, the waters of the
Sudbury are designated as habitat for fish, other aquatic life and wildlife, and for primary
(e.g., wading and swimming) and secondary recreation (e.g., fishing and boating). In
addition, they are designated as a suitable source of irrigation and other agricultural uses
water, industrial cooling and process uses, and public water supply with appropriate
treatment. A fish advisory has been posted for the Sudbury River since 1986 due to the
potential risk associated with unsafe levels of mercury in fish.
3 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
1.3.1 Sudbury River Reach Descriptions
In an effort to refine the extent of contamination and the associated risk potential to both
human and ecological receptors, the Sudbury River was divided into ten reaches (i.e.,
river segments), which were based on changes in river configuration, impounding
structures, and stream junctures (Figure 2). The following discussion presents a brief
description of each reach.
� Reach 1— this reference area extends from the headwaters of the Sudbury River in Cedar Swamp to the Pleasant Street impoundment.
� Reach 2—extends from the Pleasant Street Impoundment to the Union Street Bridge (Route 135) in Ashland. Reach 2 is directly impacted by site discharges in and downstream of Mill Pond, the only impoundment located in this reach. Trolley Brook, Chemical Brook, Outfall Creek, Lower Raceway and the Eastern Wetlands drain into the Sudbury River within (but are not considered part of) Reach 2. In addition, contaminated groundwater underlying the Site discharges to Mill Pond.
� Reach 3—extends from the Union Street Bridge to the Reservoir No. 2 dam. Reach 3 contains Reservoir No. 2 (47 ha, mean depth 3.1 m, maximum depth 4.9 m) and receives discharge from Cold Spring Brook. Reservoir No. 2 is the first major sediment depositional area downstream of the site. This reservoir was developed in 1879 to supply water to Boston.
� Reach 4—extends from the Reservoir No. 2 dam to the Reservoir No. 1 dam. Reach 4 contains Reservoir No. 1 (49 ha, mean depth 2.2 m, maximum depth 4.0 m) which is the second major impoundment downstream from the site. Reservoir No. 1 receives discharge from the Framingham Reservoir No. 3 reference impoundment; in turn, Reservoir No. 3 receives source water from the Sudbury Reservoir. Neither the Sudbury Reservoir nor Reservoir No. 3 receives surface drainage from the site. Reaches 3 and 4 are similar in that they consist primarily of impounded areas with slow moving water.
� Reach 5—extends from the Reservoir No. 1 dam at Winter Street to the Massachusetts Turnpike (Interstate 90) overpass, where the Sudbury River widens. The upper portion of this reach is typically narrow with high stream velocity and only minor depositional areas. In the lower portion of this reach, the river broadens as a result of water retention in Saxonville Pond and the water velocity diminishes. Sediment deposition is expected to occur in this portion of the reach.
� Reach 6—extends from the Turnpike overpass to the Saxonville Dam. This reach includes a small section of flowing river and a ponded depositional area behind the Saxonville Dam (Saxonville Pond).
4 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
� Reach 7—extends from the Saxonville Dam downstream to the Route 20 overpass in Wayland. Reach 7 has a low stream gradient (<1 foot drop per mile) resulting in a slow, meandering river with increased potential for deposition. Includes Heard Pond, which, although not an impoundment of the Sudbury River, lies within the Sudbury’s floodplain and at times of high water receives overflow from the river.
� Reach 8—extends from the Route 20 overpass to the Route 117 overpass, before the Fairhaven Bay inlet. This reach includes the Great Meadows National Wildlife Refuge (GMNWR). The river channel within Reach 8 meanders through an extensive wooded and emergent wetland complex that has a high depositional potential.
� Reach 9—extends from the inlet area to Fairhaven Bay to the Fairhaven Bay outlet. Fairhaven Bay is a large pond-like feature in the Sudbury River (27 ha, mean depth 1.5 m, maximum depth 3.4 m) that is the last major depositional area before the Sudbury/Assabet River confluence.
� Reach 10—extends from the Fairhaven Bay outlet to the Sudbury/Assabet River confluence. This portion of the Sudbury River has a flow regime similar to that of Reach 8, with slightly less meander.
1.3.2 Sudbury River Reference Area Descriptions
Portions of the Sudbury River lie within the Boston-Sudbury Lowland and Eastern
Plateau hydrologic provinces of eastern Massachusetts (Motts and O’Brien, 1981).
Reference areas located within these provinces were used to provide data on background
levels of mercury for the field investigations.
In establishing reference areas for the Sudbury River, several areas were ultimately
chosen to represent three types of riverine characteristics:
1) a lotic environment characterized by shallow water (i.e., < 3 ft) segments of moderate to fast flowing water;
2) a lotic environment characterized by somewhat deeper water segments (i.e., > 3 ft) of relatively slow flowing water; and
3) a lacustrine environment characterized by a reservoir.
As such, the primary reference areas included Reach 1 (headwaters of the Sudbury
River), the Charles River in the vicinity of Millis, and the Sudbury Reservoir west of
Framingham, respectively.
5 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
1.3.2.1 Reach 1 – Headwaters of the Sudbury River
Reach 1 extends from the headwaters of the Sudbury River in Cedar Swamp to a small
dam (referred to as the Pleasant Street Impoundment), just upstream of Mill Pond in
Ashland. Reach 1 contains several sampling locations, including Whitehall Reservoir
(233 ha, mean depth 2.0 m, maximum depth 9.8 m). The flowing portion of Reach 1
serves as a reference area for Reaches 2, 5, 7, and 10.
1.3.2.2 Charles River
The Charles River reference area lies within the Boston-Sudbury Lowland hydrologic
province. This province represents a small irregularly-shaped area of low relief in eastern
Massachusetts. It consists mainly of broad plains interrupted by numerous low hills and
ridges. The lowland in the vicinity of the site and reference areas is drained by the
Charles and Sudbury Rivers. The surficial geology of the region consists mostly of
stratified drift surrounding drumlins and isolated till-covered bedrock hills.
Glaciolacustrine sediments occupy much of the lowland around the Sudbury River (Motts
and O’Brien, 1981). The habitat of the Charles River near Millis is similar to that of the
Sudbury River especially in the vicinity of the GMNWR. Flow characteristics, open
water, emergent wetlands and adjacent scrub-shrub areas are similar and are expected to
support fish and wildlife species that have been observed in the Great Meadows and other
meandering portions of the Sudbury River watershed. The Charles River was selected to
serve as a reference for portions of the slower flowing areas of the Sudbury River,
including GMNWR (Reach 8) and Reach 9.
1.3.2.3 Sudbury Reservoir
The Sudbury Reservoir is a man-made impoundment located with the Eastern Plateau
province. This province is characterized as low-lying region, sloping gently seaward.
Elevations in this province are generally less than 500 ft above sea level. In addition to
the Sudbury River, this region is drained by the Concord, Charles, and Assabet Rivers,
among others. Surface waters reflect poorly-integrated drainage due to disruption by
glaciation. Surface topography in the province reflects stratified drift of sand and gravel
deposits (Motts and O’Brien, 1981). The Sudbury Reservoir was selected to serve as a
reference for the impounded areas of the Sudbury River, including Mill Pond (Reach 2), 6
H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
Reservoirs 1 and 2 (Reaches 4 and 3, respectively), and the Saxonville Pond (Reach 6).
Although lacking the substantial industrial, commercial and residential development
surrounding many of the Sudbury River reservoirs, it is, nevertheless, expected to provide
a suitable reference area for ambient mercury levels in fish and other media.
1.4 CHRONOLOGY OF HHRA EVALUATIONS
As noted previously, three HHRAs have been performed for the Sudbury River:
1) 1992: Final Remedial Investigation Report: Nyanza Operable Unit III-
Sudbury River Study (OU III RI; NUS, 1992);
2) 1999: Nyanza Chemical Waste Dump Superfund Site, Supplemental Baseline
Human Health Risk Assessment (Weston, 1999a); and
3) 2006: Human Health Risk Assessment, Nyanza Superfund Site, Operable Unit
IV – Sudbury River Mercury Contamination (Avatar, 2006).
The rationale for the performance of each HHRA, the commencement of investigations
subsequent to the 1992 RI/FS, and how the three HHRA documents relate to one another
are presented below. Summaries of all the studies conducted, their objectives, and the
media sampled are presented in Tables 1 and 2.
To expedite remediation, the RI/FS for the Nyanza Site was originally divided into the
following three Operable Units (OUs):
� OU I — addressed on-site surficial soil, sediment and sludges.
� OU II - “Nyanza II - Groundwater Study” — addressed groundwater contamination from the site and determined the presence of off-site migration.
� OU III - “Nyanza III - Sudbury River” — originally addressed contamination of the Sudbury River by discharges of wastewater and sludge from the site; OU III has since been more narrowly focused on addressing mercury contamination in soils and surface water in the continuing source areas, which are the Eastern Wetlands, Trolley Brook, Outfall Creek, and the Lower Raceway.
7 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
1.4.1 1992 Final RI Report for Operable Unit III
In 1987, Operable Unit III was delineated to characterize surface water and sediment
contamination within the Sudbury River and its tributaries. A number of field
investigations were performed including the collection of surface water and sediment
samples throughout the Study Area, the collection of fish and invertebrate biota, the
performance of a soil boring program in the areas adjacent to the Nyanza Site, and the
collection of monthly water quality samples.
A Remedial Investigation and Feasibility Study (RI/FS) of Operable Unit (OU) III, the
Sudbury River, was conducted from October 1989 through February 1992. The RI was
conducted to assess the contaminants in the Sudbury River basin in the vicinity and
downriver of the Nyanza Chemical Waste Dump Site. The goals of this RI/FS were to:
1) Determine the nature and extent of the contamination in the Sudbury River;
2) Evaluate public health and ecological risk associated with potential exposure
to the contamination;
3) Provide data to develop general response objective and cleanup standards
focusing on sediment cleanup; and
4) Provide data to develop and evaluate remedial alternatives to mitigate the
defined risks.
As a result of the findings presented in the OU III RI (NUS, 1992), EPA determined that
the potential risks to both human and ecological receptors could be attributed principally
to mercury contamination in the Sudbury River.
1.4.2 Task Force and OU IV Formation
To further evaluate the nature, extent, and potential impacts of the mercury contamination
in the Sudbury River, EPA organized a multi-disciplinary task force. The Sudbury River
Task Force included representatives from EPA-New England, the U.S. Fish and Wildlife
Service (USFWS), the U.S. Geological Survey (USGS), the Army Corps of Engineers
(ACOE), the National Oceanic and Atmospheric Administration (NOAA), and the
8 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
Framingham Advocates for the Sudbury River, as well as members of several academic
and private research concerns.
Based on a review and information gaps evaluation of the 1992 assessment related to the
nature and extent of contamination in the Sudbury River, the Task Force was directed to
develop information necessary to produce a scientifically defensible risk assessment
associated with mercury contamination in the Sudbury River.
The primary objectives of the Sudbury River Task Force were to:
1) Establish the extent of mercury contamination within the Sudbury River;
2) Determine the contribution of the Nyanza Site to any identified mercury
contamination; and
3) Provide information necessary to refine remediation objectives for the
protection of ecological resources and human health.
To facilitate the Task Force investigations, EPA established Operable Unit IV – Sudbury
River specifically to address mercury contamination within the river proper. New, more
accurate collection and analytical methods were used by the Task Force to obtain
mercury concentration data.
It should be noted that methods used to analyze and differentiate mercury compounds in
natural systems, such as those employed to generate data for the OUIII RI, have
historically been subject to sample contamination (Gill and Bruland, 1990; Spry and
Wiener, 1991). Porcella (1990) found that historical surface water mercury
measurements may be as much as 10,000 times higher than more recent tests indicate.
Samples collected as part of the Task Force studies tended to follow clean-sampling
protocols (Gill and Bruland, 1990; Porcella et al., 1992; Bloom, 1995) for all aspects of
sample collection, preservation and transport, thereby reducing the probability of sample
contamination.
In addition, due to differences in handling techniques and analytical procedures for fish
tissue, it was determined that fish tissue analyses conducted for the OU III RI lacked the
analytical precision of more recently collected data (e.g., the detection limits for OU III 9
H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
RI data were not sufficiently low to detect mercury at the concentrations present in fish
because of sample dilution necessary to correct for matrix interference). Questions were
also raised regarding the ability to meet data quality objectives in the analytical
procedures. Therefore, the Task Force studies incorporated analytical techniques
(Bloom, 1989, 1992; Bloom and Fitzgerald, 1988; Liang et al., 1994) capable of detecting
mercury compounds at much lower concentrations than previously used.
1.4.3 1999 Report
The 1999 Supplemental Baseline HHRA (Weston, 1999a) incorporated the data collected
from the Sudbury River identified by the data needs assessment of the Task Force. The
objectives were to further characterize and where appropriate, quantify the potential
human health risk associated with chemical contamination of the Sudbury River resulting
from previous manufacturing and waste disposal practices at the Nyanza Chemical Waste
Dump Superfund Site.
The 1999 assessment was based on the current and potential designated uses projected for
the Sudbury River (MADEP, 1996) at that time, and as such, was limited to an evaluation
of the potential risk associated with exposure to mercury resulting from:
� fish consumption;
� recreational use of the Sudbury River (e.g., swimming); and
� ingestion of water as a drinking water source.
The 1999 report concluded that potential human exposure to mercury in surface water
and sediment in the Sudbury River was well-below any level of concern. However,
exposure to mercury through the catch and consumption of fish from Reach 3 (Reservoir
2) and Reach 8 (Great Meadows National Wildlife Refuge) posed an unacceptable level
of risk to subsistence anglers, i.e., individuals who obtain all of their dietary protein from
fish caught from these areas of the Sudbury River.
1.4.4 2003-2005 Supplemental Investigation
A subsequent evaluation of the 1999 Supplemental Assessment by EPA concluded that
there were insufficient fish tissue data for a number of reaches to adequately assess the
10 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
risk associated with fish consumption for the entire 60 km of the Sudbury River,
beginning at the headwaters (upgradient of the Nyanza site) and extending to the
confluence of the Sudbury and Assabet Rivers. Therefore, in July 2003, the U.S. Fish &
Wildlife Service (USFWS) collected several species of game and panfish from each of 10
reaches (Sec. 1.3.1) of the Sudbury River for total mercury and methylmercury analyses.
Additional media collected for mercury analysis for use in the ecological risk assessment
and to better understand the mechanism of uptake and transfer of mercury in fish
included other biological tissue (e.g., crayfish, several size classes of fish below the
edible range), sediment, and surface water.
1.4.5 2006 Report
Whereas the 1992 and 1999 HHRAs included data from some wetlands and surface water
drainages of the Nyanza Site and the Sudbury River, the 2006 HHRA consisted entirely
of the Sudbury River proper, Heard Pond, and reference areas that could provide
information regarding background conditions. The 2003-2005 Supplemental
Investigation data were used in the 2006 HHRA to address the following objectives:
1) Evaluate and identify the human health risk associated with consumption of
fish from each of the reaches of the Sudbury River; and
2) Evaluate the exposure and the consequent risk for those reaches that were not
previously assessed.
The 2006 HHRA documented the potential mercury exposure and consequent risk to
individuals who catch and eat fish from the Sudbury River.
1.5 REPORT OVERVIEW
The remainder of this synthesis report describes the risks calculated in each HHRA report
and integrates the results. A summary of the remaining sections is provided below.
� Section 2 – Summary of 1992 Report: Presents the objectives of the 1992 HHRA, briefly describes the sampling program upon which the risks were based, presents the conceptual model of exposure with which risk was evaluated, and summarizes the results of the HHRA.
11 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
� Section 3 – Summary of 1999 Report: Presents the objectives of the 1999 HHRA, briefly describes the sampling program upon which the risks were based, presents the conceptual model of exposure , and summarizes the results of the HHRA.
� Section 4 – Summary of 2006 Report: Presents the objectives of the 2006 HHRA, briefly describes the sampling program upon which the risks were based, presents the conceptual model of exposure, and summarizes the results of the HHRA.
� Section 5 – Integration and Comparison of All HHRAs: For side-by-side comparisons, this section presents:
� 1) Exposure Point Concentrations (EPCs) for each medium used in each of the reports;
� 2) hazards and risks from direct and indirect pathways;
� 3) comparisons of 2003-2005 supplemental data with appropriate risk-based benchmarks; and
� 4) “updated” noncancer hazards for mercury calculated using the risk-ratio approach to facilitate comparisons of risks calculated for fish ingestion between various fish data collection efforts.
12 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
2. SUMMARY OF 1992 HUMAN HEALTH RISK ASSESSMENT PRESENTED WITHIN THE OU III RI (NUS)
2.1 INTRODUCTION AND BACKGROUND
NUS Corporation performed an RI, which included a baseline public health risk
assessment, from October 1989 through February 1992 for the Sudbury River Study Area
OU III (NUS, 1992). The objective of the risk assessment was to estimate the current and
potential future risks to the public resulting from exposure to the organic and inorganic
chemicals detected in surface water, sediment, and fish tissue. In addition to the ten
reaches that were defined for the Sudbury River, Heard Pond, and reference areas, risks
were estimated for several additional locations within the Study Area. These areas
included:
� The Eastern Wetlands � Chemical and Trolley Brooks � The Raceway � The Cold Spring Brook Culvert
Since the focus of this Synthesis Report is the risk associated with the contamination in
the Sudbury River Proper, the results associated with the aforementioned additional areas
are not presented in this report.
In this 1992 investigation, all potential site-related contaminants, as well as other
chemicals not thought to be site-related but detected in the Sudbury River, were
considered in the risk assessment to determine the contribution of site-related risks to the
overall Sudbury River Study Area risks. The Nyanza Site-specific contaminants
evaluated in the assessment of risk associated with the Sudbury River included:
� Trichloroethene (TCE) � Benzidine � 1,2-,1,3-, and 1,4-Dichlorobenzene � Antimony � Chlorobenzene � Arsenic � Nitrobenzene � Cadmium � 1,2,4-Trichlorobenzene � Chromium � Aniline � Lead � Naphthalene � Mercury and associated methyl � Phenols mercury
13 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
Other contaminants were also identified although they were not directly related to
activities associated with the Site. These contaminants are listed below. It is likely that
the presence of these contaminants were related to a number of active or inactive
landfills, other potential oil/hazardous material release sites, wastewater discharge sites,
and non-point sources such as runoff from roads.
� Vinyl Chloride � 1,1-Dichloroethene � 1,2-Dichloroethene � Methylene Chloride � Bis(2-ethylhexyl)phthalate � 2-Methylnaphthalene � Acenaphthylene � Phenanthrene � Fluoranthene � Pyrene � Benzo(a)anthracene � Chrysene � Benzo(b)fluoranthene � Benzo(k)fluoranthene � Benzo(a)pyrene � Indeno(1,2,3-cd)pyrene � Dibenz(a,h)anthracene � Benzo(g,h,i)perylene
2.1.1 Sampling Program Summary
� DDT, DDD, and DDE � PCBs � Chlordane � Endosulfan I, II � Endosulfan Sulfate � Dieldrin � Aldrin � Heptachlor � Barium � Beryllium � Copper � Manganese � Nickel � Silver � Selenium � Thallium � Vanadium � Zinc
There were two separate sampling programs conducted by NUS in support of the
Remedial Investigation: Phase I and Phase II. The Phase I sampling program occurred
between September and December of 1989. It entailed the following field activities:
� Sampling and analysis of surface water and sediment from selected locations in the Sudbury River.
� Sampling and analysis of surface water and sediment from selected locations in the Chemical Brook Culvert.
� Monthly water sampling from selected locations in the Sudbury River and Trolley Brook to define seasonal fluctuations in water chemistry.
� Sampling and analysis of fish from selected locations in the Sudbury River.
� Surveying benthic biota in the Study Area.
14 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
� Assessing wetlands in the Study Area.
� Surveying bathymetry and sediment thickness in Reservoirs No. 1 and No. 2 by the USGS.
� Sampling and analysis of sediment within the Eastern Wetlands.
Following completion of the Phase I investigation, a number of data gaps were identified.
A Phase II work plan was then developed. The Phase II field activities were performed
from September 1990 through June 1991 and included:
� Expanding the Study Area to delineate the downstream extent of the mercury contamination in the Sudbury River sediments.
� Additional sampling and analysis of surface water and sediment from selected locations in the Sudbury River to fill data gaps.
� Sampling and analysis of sediment within the Eastern Wetlands.
� Sampling and analysis of sediment from selected locations within the bordering wetlands of the Sudbury River.
� Sampling and analysis of sediment from selected locations within the Raceway that parallels the Sudbury River.
� Sampling and analysis of additional fish from selected locations in the Sudbury River to fill data gaps.
� Sampling and analysis of caddis fly larvae at selected locations in the Sudbury River.
� Inspecting the Chemical Brook Culvert by remote video camera to identify areas of sediment deposition.
� Additional sampling and analysis of sediment from the Chemical Brook Culvert.
Appendix A, Table A-1 of this synthesis report presents a summary of the samples, by
medium and location that were collected as part of Phase I and Phase II.
2.1.2 Conceptual Model
The 1992 RI report described multiple sources that may contribute to the contamination
issues within the Sudbury River Study Area including:
15 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
� Nyanza Site Source Area.
� Twelve active or inactive landfill sites.
� Potential oil/hazardous materials release sites.
� Wastewater discharge sites.
� Non-point source(s).
There are four primary mechanisms by which contaminants appear to be migrating from
source areas to potential human receptors. First, surface runoff from contaminated soils
(the Nyanza site) may transport contaminants to surface water and sediment of the
Sudbury River. This mechanism is viewed as the primary contaminant flow path to the
River. Second, the contaminants that enter the River may be transported through the
surface water in the dissolved phase or adsorb to sediment. Contaminants in the surface
water and sediment may be exchanged between these media through adsorption and
desorption processes. Finally, contaminant transport may result from the discharge of
contaminated groundwater to surface water where chemicals may occur in the dissolved
phase or may also sorb to sediments and particulate organic matter in the water column.
Based on the contaminant occurrence and distribution, contaminant fate and transport,
and the known land and water use information, receptor populations and exposure routes
evaluated in the 1992 HHRA are noted below.
� Resident – adult: exposed through dermal contact and incidental ingestion of sediment.
� Resident – teen: exposed through dermal contact and incidental ingestion of sediment.
� Resident – child: exposed through dermal contact and incidental ingestion of sediment.
� Recreational swimmer/wader – adult: exposed through dermal contact and incidental ingestion of surface water and sediment.
� Recreational swimmer/wader – teen: exposed through dermal contact and incidental ingestion of surface water and sediment.
� Recreational swimmer/wader – young child: exposed through dermal contact and incidental ingestion of surface water and sediment.
16 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
� Recreational angler – adult: exposed through ingestion of filleted fish tissue.
� Subsistence angler – adult: exposed through ingestion of filleted fish tissue.
2.1.3 Exposure Points
Surface water (unfiltered) and sediment (0-6 inch depth) EPCs were calculated on a
reach-specific basis. Fish EPCs were calculated on a reach-specific basis using all of the
fillet data available for that reach (i.e., all species grouped into one data set). Consistent
with EPA guidance at the time, risks were calculated based on the maximum (analogous
to the current reasonable maximal exposure case) and average (analogous to the central
tendency exposure case) concentrations. Fish length was not used as a discriminatory
factor in reducing data sets. It is not known whether the fillet data were analyzed skin-on
or skin-off.
2.2 DIRECT CONTACT PATHWAY RISK RESULTS
Based on the receptors and exposure routes identified in the Conceptual Site Model, risks
(cancer and noncancer) were calculated for the following direct contact pathways:
incidental ingestion and dermal contact with surface water and sediment.
2.2.1 Cancer Risk
Appendix A, Table A-2 presents a summary of the cancer risks based on the surface
water contact exposure pathways. None of the cancer risks estimated for the surface
water exposure scenarios exceeded 2E-05. Appendix A, Table A-3 presents a summary
of the cancer risks based on the sediment contact exposure pathways. The cancer risks
from the sediment exposure scenarios based on the maximum contaminant concentrations
in downstream sediments ranged from 7E-06 to 9E-05. In most cases, the cancer risks
associated with “other Sudbury River contaminants” exceeded those estimated for the
Nyanza Site contaminants.
2.2.2 Noncancer Hazard
Appendix A, Table A-2 presents a summary of the total HIs based on the surface water
contact exposure pathways. Based on this assessment, direct contact with surface water
in the Reach 3 (Reservoir 2; HI = 3.8) represents the only noncancer risk for recreational
17 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
direct contact. The only chemical with a HI greater than 1 was selenium. Appendix A,
Table A-3 presents a summary of the total hazard indices (HIs) based on the sediment
contact exposure pathways. None of the river reaches for which the recreational
sediment exposure was evaluated represented a noncancer hazard.
2.3 INDIRECT PATHWAY RISK RESULTS
Based on the sports and subsistence angler (hereafter referred to as the recreational and
subsistence anglers, respectively) identified in the Conceptual Site Model, risks (cancer
and noncancer) were calculated for the ingestion of fish pathway. Risks from the RME
case only (based on the maximum concentration) are presented below.
2.3.1 Cancer Risk
Appendix A, Table A-4 presents a summary of the cancer risks based on the ingestion of
fish exposure pathway by a recreational angler. The cancer risks ranged from 6.9E-05
(Sudbury Reservoir) to 7.6E-04 (Reach 3). Cancer risks estimated for Reach 2 - Mill
Pond, Reach 6, and Reach 9 also exceeded 1E-04 for the recreational angler. The
primary contaminants contributing to the cancer risks include arsenic, several pesticides,
and PCBs. In all cases, the cancer risks associated with “other Sudbury River
contaminants” exceed those estimated for the Nyanza Site contaminants. Appendix A,
Table A-5 presents a summary of the cancer risks based on the ingestion of fish exposure
pathway by a subsistence angler. The cancer risks based on RME (and although not
presented herein, CTE) exposure all exceeded 1E-04. The maximum cancer risk is 5.5E-
03 (Reach 3). Cancer risks estimated for Reach 2 - Mill Pond and Reach 9 also exceeded
1E-03 for the subsistence angler.
2.3.2 Noncancer Hazard
Appendix A, Table A-4 presents a summary of the total HIs based on the ingestion of fish
exposure pathway by a recreational angler. The HIs calculated for the recreational angler
for all contaminants ranged from 0.58 (Reach 1 – Southville Pond) to 17 (Reach 3).
Reach 1 - Cedar Swamp Pond, Reach 2 - Mill Pond, Reach 4, Reach 6, and Reach 9 also
had total HIs greater than one. Appendix A, Table A-5 presents a summary of the total
HIs based on the ingestion of fish exposure pathway by a subsistence angler. The HIs for
18 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
all River reaches for the RME (and although not presented herein, CTE) exceeded one.
The total HIs ranged from 4.2 (Reach 1 – Southville Pond) to 120 (Reach 3).
In general, exposure to mercury in fish was the primary contributor to the health hazard
associated with fish consumption (Appendix A, Table A-6). In most cases, mercury
contributed over 50% of the total noncancer risk. At two areas (Reach 1 - Southville
Pond and Mill Pond), the reasonable maximum exposure to mercury in fish accounted for
over 95% of the total noncancer risk associated with fish consumption. The only areas
where mercury was not the primary driver of the total HIs were Reaches 3 and 6. At
these two areas, mercury contributed roughly 25% of the total HI. Other metals
(antimony, arsenic, and thallium) were the primary contributors to the total HIs at these
areas.
3. SUMMARY OF 1999 (WESTON) REPORT
3.1 INTRODUCTION AND BACKGROUND
The 1999 Supplemental Baseline Human Health Risk Assessment (SBHHRA; Weston,
1999a) supplemented the OU III RI (NUS, 1992). The objectives of this assessment were
to further characterize and where appropriate, quantify the potential human health risk in
the newly established Operable Unit IV – Sudbury River associated with mercury
contamination of the Sudbury River. Toward that end, the Supplemental Baseline HHRA
incorporated the additional data collected by the Task Force, and was limited to an
evaluation of the potential risk associated with exposure to mercury resulting from: 1)
fish consumption; 2) recreational use of the Sudbury River (e.g., swimming); and 3)
ingestion of water as a drinking water source.
3.1.1 Sampling Program Summary
The 1999 SBHHRA incorporated the data collected for the OU III RI and from a number
of studies conducted between 1992 and 1996. These chemical analysis methodologies
and sampling locations for the latter data were not selected specifically to support risk
assessment, but were specific to the studies conducted by the Sudbury River Task Force.
A brief summary of the studies conducted, their objectives, and the media sampled is
19 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
presented in Table 2. A summary of the data used in the 1999 SBHHRA is presented in
Appendix A, Table A-7.
3.1.2 Conceptual Model
The sources and fate and transport of the contamination are the same as those presented
in the 1992 HHRA conceptual model (see Subsection 2.2). The receptor populations and
exposure routes evaluated in the 1999 HHRA are noted below.
� Resident: exposed through ingestion of tap water (qualitative evaluation only).
� Recreational swimmer/wader – young child: exposed through dermal contact and incidental ingestion of surface water and sediment (qualitative evaluation only).
� Recreational swimmer/wader – teen: exposed through dermal contact and incidental ingestion of surface water and sediment (qualitative evaluation only).
� Recreational angler – adult (female of childbearing age): exposed through ingestion of filleted fish tissue
� Recreational angler – child: exposed through ingestion of filleted fish tissue.
� Subsistence angler – adult (female of childbearing age) exposed through ingestion of filleted fish tissue.
� Ethnic angler – adult (female of childbearing age): exposed through ingestion of whole body fish tissue.
3.1.3 Exposure Points
In the SBHHRA, two sets of summary tables each were prepared for surface water and
sediments. One summary table is based on the OU III RI data (hereafter referred to as
NUS data) and a second summary table is based on OU IV Task Force data. Because of
questions regarding the ability of the OU III RI surface water and fish data to meet
analytical procedure data quality objectives, only Task Force data were used to assess
risks from fish ingestion and the ingestion of surface water as a drinking water source in
the 1999 SBHHRA. OU III RI data were used to assess risks from exposure to surface
water and sediments from swimming and wading. Mercury levels in surface water and
sediment collected from 1989 to 1991 and corresponding risks in these media were 20
H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
compared with mercury levels in surface water and sediment collected as part of the
Task Force effort from 1992 through 1996.
Consistent with EPA guidance, the EPCs for the reasonable maximum exposure (RME)
and central tendency exposure (CTE) evaluations were calculated for each data set for
each river reach based on the 95% upper confidence limit (UCL) of the mean
concentration, using the appropriate equation for data distribution as recommended in
Calculating the Concentration Term (EPA, 1992). That is, UCLs were calculated based
on data distributions as follows:
� Normal distribution: Student’s t-test
� Lognormal distribution: H-UCL
� Neither normal nor lognormal distribution: Default to H-UCL.
If the 95% UCL concentration exceeded the maximum detected concentration for a
chemical, the maximum detected concentration was used as the EPC.
Surface water (unfiltered) and sediment (0-6 cm depth) EPCs were calculated on a reach-
specific basis. EPCs were calculated on a reach-specific basis using all of the fillet or
whole body fish data available for that reach (i.e., species contribution weighted
incidentally based on the number of fish per species analyzed in that reach). Fish length
was not used as a discriminatory factor in reducing data sets. Fillet concentrations were
based on the combined results from analyses of fish fillet and whole body less gut or
stomach. Although not explicitly stated in text, from the reports that describe the
methodology of the fish collection, it is assumed that the fillet data were analyzed skin-
on.
In summary, a total of 10 reaches (one upstream of the site and 9 adjacent to or
downstream of the Nyanza Site) were evaluated in the SBHHRA . For some reaches of
the river, however, the scenarios of exposure are limited due to the absence of a particular
type of data. For example, fillet fish tissue data collected by the Task Force are only
available for Reaches 1, 3, and 8. For risk associated with the consumption of fish from
21 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
other reaches, a qualitative comparison was made of the current data with those collected
as part of the OU III RI.
3.2 DIRECT CONTACT RESULTS
The risks due to mercury from water consumption and recreational activities were
addressed qualitatively either through a comparison with toxicological benchmarks or
through a comparison with the risk assessment conducted previously in the OU III
Remedial Investigation. Qualitative comparisons for these pathways did not reveal any
potential risks. Appendix A, Table A-8 shows reach-specific HQs based on a
comparison of surface water concentrations with MCLs and RBCs.
Based on a comparison of the mercury levels recorded in the Task Force studies with the
1992 RI surface water levels and their attendant risk, the use of similar scenarios of
exposure to those used in the 1992 RI resulted in noncancer risks (HQ) to a child ranging
from 1.3E-04 (Reaches 2 and 8) to 3.8E-05 (Reach 10). For the teen, the risk (HQ)
associated with exposure to mercury in surface water during recreational activities ranges
from 2.0E-04 to 6.2E-05. Methylmercury HQs for the child ranged from 5.9E-06 (Reach
8) to 1.4E-06 (Reach 10) and for the teen ranged from 7.2E-06 to 1.8E-06. Based on the
results of the surface water data collected by the Task Force from 1992 through 1996,
direct contact exposure to mercury in surface water is well-below a level for health
concerns for children and teens.
Based on a comparison of the mercury levels recorded in the Task Force studies with the
1992 RI sediment levels and their attendant risk, the use of similar scenarios of exposure
to that used in the 1992 RI resulted in a range of noncancer hazards (HQ) for a child of
0.12 (Reach 2) to 0.0025 (Reach 10). For the teen, the noncancer hazards (HQ)
associated with exposure to sediments during recreational activities ranged from 0.073 to
0.0015. Based on the results of the sediment data collected by the Task Force from
1992 through 1996, direct contact exposure to mercury in sediment is well-below a level
for health concerns for children and teens.
22 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
3.3 INDIRECT PATHWAYS RESULTS
The risk of exposure to mercury in fish was evaluated using the fish tissue data collected
by the Task Force from Reaches 1 (reference area), 3 (Reservoir 2), and 8 (Great
Meadows National Wildlife Refuge) between 1992 and 1996. The risk to the adult
recreational angler was only marginally above the toxicity threshold (i.e., HQ >1.0) for
Reaches 3 and 8. Doses for the child recreational angler were below the toxicity
threshold. Exposure to mercury through fish consumption by subsistence and ethnic
anglers posed a potential risk to human health (Appendix A, Table A-9). Although HQs
were presented for the RME case only, note that the HQs were below 1 under the CTE
case. Risks to the subsistence angler and an ethnic subsistence angler were substantially
above an HQ of 1. Based on the results of the fish tissue data collected by the Task Force
from 1992 through 1996, direct contact exposure to mercury from the ingestion of fish is
above a level of concern for subsistence and ethnic anglers.
4. SUMMARY OF 2006 (AVATAR) REPORT
4.1 INTRODUCTION AND BACKGROUND
4.1.1 Sampling Program Summary
As noted previously, the 2006 Human Health Risk Assessment for the Nyanza Chemical
Waste Dump Superfund Site, Operable Unit IV- Sudbury River documented the potential
mercury exposure and consequent risk to individuals who catch and eat fish from the
Sudbury River. The 2006 report represented an addendum to the 1999 report, and was
initiated because EPA concluded that there were insufficient fish tissue data for a number
of reaches to adequately assess the risk. The objectives of the 2006 risk assessment were
to evaluate and identify the human health risk associated with mercury exposure from the
consumption of fish from each of the ten reaches of the Sudbury River including Heard
Pond and additional reference areas.
4.1.2 Sampling Program Summary
The large fish collection program from the 2003-2005 Supplemental Investigation
provided the fish tissue data used in the 2006 risk assessment. In support of human
23 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
health risk assessment, this program focused on collecting and analyzing fish greater than
or equal to 15 cm total length, both fillet and whole body samples. Fish tissue collected
as part of the 2003-2005 supplemental investigation was analyzed for total mercury, with
a subset analyzed for methylmercury.
Species targeted included largemouth bass (Micropterus salmoides), yellow perch (Perca
flavescens), and brown bullhead (Ameiurus nebulosus). The targeted number of samples
were collected from each of the 9 site-impacted reaches and 3 reference areas. A
summary of the fish that were collected for use in the 2006 HHRA are presented in
Appendix A, Table A-10.
4.1.3 Conceptual Model
The sources and fate and transport of the contamination is the same as that presented in
the 1992 HHRA conceptual model (see Subsection 2.2). The receptor populations and
exposure routes evaluated in the 2006 HHRA are noted below.
� Recreational angler – adult: exposed through ingestion of filleted fish tissue (skin on).
� Recreational angler – child: exposed through ingestion of filleted fish tissue (skin on).
� Subsistence angler – adult: exposed through ingestion of filleted fish tissue (skin on).
� Ethnic angler – adult: exposed through ingestion of whole body fish tissue.
� Ethnic angler – child: exposed through ingestion of whole body fish tissue.
4.1.4 Exposure Points
For the scenarios evaluated in the 2006 HHRA, EPCs were calculated for two different
data sets (fillet data and whole body data) per species per reach. To be consistent with
legal size requirements, the following criteria were placed on the data (MDFW, 2005):
� Small and Largemouth Bass ≥30.48 cm (12 inches) and
� All other species – no size limit.
24 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
The fillet data set consisted of all fillets meeting the above criteria. The whole body fish
data sets consisted of all whole body fish greater than 15 cm and of “reconstructed”
whole body concentrations also from fish greater than 15 cm. Many of the larger fish
were filleted and oftentimes analyzed with the associated offal sample. To obtain a
“reconstructed” whole body concentration, the procedures below were followed.
� When only the fillet from an individual fish was analyzed, it was assumed that the fillet concentration represented the whole body fish concentration.
� When both fillet and offal concentrations were available, the following equation was used to “reconstruct” the whole body fish concentration:
C × W + C × Wf f o oCwb = Wf + Wo
Where:
Cwb = Concentration in whole body
Cf = Concentration in fillet
Wf = Weight of fillet
Co = Concentration in offal
Wo = Weight of offal
Note: If a fillet was split and analyzed as a primary and duplicate sample (instead of
analyzing both the left and right fillets together as a primary), the fillet concentration was
determined using the averaging technique noted above and the fillet weight equaled the
sum of the primary and duplicate samples.
For the 2006 HHRA, it was conservatively assumed that all total mercury detected in fish
tissue was methylmercury since numerous references (e.g., Huckabee et al., 1979; Bloom
et al., 1990; EPA, 1996) and site-specific paired analyses indicated that at least 89% of
the mercury contained in fish exists as methylmercury.
Consistent with EPA guidance, the EPCs for the reasonable maximum exposure (RME)
and central tendency exposure (CTE) evaluations were calculated for each data set for 25
H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
each river reach based on the 95% upper confidence limit (UCL) of the mean
concentration, using the appropriate equation for data distribution recommended by the
EPA’s ProUCL program (Version 3.0; 2004). If the 95% UCL concentration exceeded
the maximum detected concentration for a chemical, or if the 95% UCL was not able to
be calculated by ProUCL, the maximum detected concentration was used as the EPC.
EPCs were calculated on a reach- and species-specific basis. However, a species-
weighted EPC was used to calculate doses and risks for each reach. Weighting was
reach-specific and based on the number of species for which there are data, assuming that
anglers at the site eat an equal portion of each species collected at that particular reach.
For example, if there were three species (largemouth bass, brown bullhead, and yellow
perch) within a data set for a reach, the EPC was calculated as follows:
EPC + EPC + EPClargemouth bass brown bullhead yellow perchEPC for use in dose and risk calculations = 3
This approach was selected because the study on which the recreational ingestion rates
are based (Ebert et al., 1993) developed ingestion rates from a composite of fish species
similar to those collected in the Sudbury River, and not for an individual fish species.
4.2 RESULTS
This section presents a reach by reach summary of the hazard quotients and background
comparisons for the RME scenarios (Appendix A, Table A-11). Exposure to mercury
levels in fish caught and consumed from Reaches 2, 3, and 9 represented a potential risk
to individuals for all fish consumption scenarios evaluated. For Reaches 4, 6, 8, and 10,
exposure to mercury levels in fish caught and consumed from each reach represented a
potential risk to individuals for all fish consumption scenarios evaluated except for the
adult recreational angler scenario. For Reaches 5 and 7 (excluding Heard Pond),
exposure to mercury levels in fish caught and consumed from each reach represented a
potential risk to individuals for all fish consumption scenarios evaluated except for the
adult and child recreational angler scenarios. As for Heard Pond, the exposure to
mercury levels in fish caught and consumed from Heard Pond represented a potential risk
only to the child of the ethnic angler and the subsistence angler.
26 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
5. INTEGRATION AND COMPARISON OF ALL HHRAS
A graphical presentation of the site conceptual model, incorporating all exposure
scenarios evaluated among the three risk assessments is presented in Figure 3. The
remainder of this section presents a synthesis of the exposure data and results.
5.1 DATA SUMMARIES
The details of the data used in each risk assessment report were presented in the previous
sections. In this section, EPCs used in each report are presented in Table 3 through Table
6. Note that because of the time elapsed between reports, EPC derivation methodologies
were different for each. In addition, since mercury was the only contaminant evaluated in
the 1999 and 2006 HHRAs, this discussion is limited to total mercury concentrations.
Total mercury was selected as the comparison point because: 1) the majority of mercury
in surface water and sediment occurs in the nonmethylated form; and 2) although the
majority of mercury in fish tissue is in the methylated form, methylmercury analyses
were only run on a subset of data; therefore total mercury concentrations may be used to
obtain a more robust data set assuming that the toxicological information applied is for
methylmercury. In addition, as mercury does not have any toxicity values relating to its
potential for carcinogenicity, only noncancer hazard quotients (HQs) are presented.
5.1.1 Surface Water
Table 3 presents the EPCs associated with surface water data sets from the sampling
programs supporting each risk assessment. Although surface water was not evaluated in
the 2006 HHRA, the 2003-2005 supplemental investigation included surface water
investigations. EPCs (and the sample counts for the data sets from which they were
derived) used in the 2006 ERA are presented for comparative purposes.
5.1.2 Sediment
Table 4 presents the EPCs associated with sediment data sets from the sampling
programs supporting each risk assessment. Although sediment was not evaluated in the
2006 HHRA, the 2003-2005 supplemental investigation included sediment investigations.
EPCs (and the sample counts for the data sets from which they were derived) used in the
2006 ERA are presented for comparative purposes. 27
H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
5.1.3 Fish Tissue
Tables 5 and 6 present the EPCs associated with fillet and whole body fish data sets,
respectively, from the sampling programs supporting each risk assessment.
5.2 DIRECT CONTACT
As part of the 1992 RI, the risk due to exposure to mercury in surface water and
sediments was evaluated for the bordering wetlands only. For the 1999 HHRA, a risk
ratio approach was applied to the reaches of the Sudbury River proper with the minimum
and maximum mercury EPCs to obtain a range of swimming/wading risks. The
maximum HQs for this pathway were 0.0002 (teen receptor) and 0.12 (child receptor) for
surface water and sediments, respectively. Because of the low potential for human health
hazards estimated for exposure to surface water and sediment in the Sudbury River, the
direct contact pathways were not reevaluated in the 2006 risk assessment. Because of
this, a side-by-side presentation of risks is not possible for the swimming/wading
scenario.
To ensure that the latest data do not indicate the potential for adverse health effects from
direct contact exposure to mercury in surface water and sediments in the Sudbury River,
a separate evaluation was performed. Instead of using the risk-ratio approach (which
would be based on outdated exposure and toxicity assumptions) to quickly estimate HQs
for the swimmer/wader scenario, a more conservative approach was used. As noted in
the 1999 HHRA, residential exposure scenarios provide greater exposure to contaminants
than the swimmer/wader scenarios.
For instance, assuming surface water was used, untreated, as the household water supply
would result in higher risks than exposure to mercury from incidentally ingesting surface
water and dermally contacting the water while swimming. Therefore, comparing surface
water concentrations to tap water risk-based concentrations (RBCs) calculated for a target
hazard quotient of 1.0 and maximum contaminant levels (MCLs) provides a highly
conservative estimate of recreational exposure risks. Likewise, assuming that the
concentrations in sediment were equivalent to those in soil, the incidental ingestion and
dermal contact a resident has with soils around their house would result in higher risks
28 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
than exposure to sediments while wading/swimming. Therefore, comparing sediment
concentrations to residential soil screening levels (SSLs) and RBCs (both calculated for a
target hazard quotient of 1.0) provides a highly conservative estimate of recreational
exposure risks.
Ratios of the mercury concentration to the RBCs, MCL, and SSL for direct contact
surface water and sediment exposures are presented in Tables 7 and 8, respectively based
on the aforementioned approach. Note that although this approach was used in the 1999
HHRA for surface water exposures, benchmark values have changed and updated risks
based on the current benchmarks are presented. In addition, total and methylmercury
data were considered. Figures 4 and 5 graphically present the HQs for total mercury
only.
Based on these comparisons, it is not expected that exposure to mercury while swimming
or wading in the Sudbury River will result in adverse health effects.
5.3 INDIRECT PATHWAYS
The same general equation for determining chronic daily intakes of COPCs from the
ingestion of fish was used by all the risk assessments:
Cfish × IR × FI× EF× EDCDI (mg/kg − day) = BW × AT
Where:
CDI = Chronic daily intake (mg/kg-day)
Cfish = Concentration in fish
IR = Ingestion rate
FI = Fraction ingested from contaminated source
EF = Exposure frequency
ED = Exposure duration
BW = Body weight
AT = Averaging time
29 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
However, because of the availability of new human metrics, the values for the exposure
parameters were different among the RAs for some of the parameters. Tables 9 through
11 present comparisons of the fish ingestion exposure parameters used in each risk
assessment.
Tables 12 through 14 present a side-by-side presentation of hazard quotients for the fish
ingestion pathway calculated in each HHRA for recreational, subsistence, and ethnic
anglers. These hazard quotients are also presented in Figures 6 through 9 for receptors
and reaches where comparisons can be made. Note that in the 1992 RA, the RfD for total
mercury (3E-04) was used to assess fish ingestion; whereas, in the 1999 and 2006 RAs, it
was assumed that all of the mercury present in fish was methylated and the
methylmercury RfD (1E-04) was used.
Because of the differences in exposure parameter values made among HHRAs, the risk
ratio approach (using the results from the 2006 HHRA) was applied to the 1999 EPCs to
obtain more comparable HQ values (Tables 15 through 17). Note that because of the
potential issue with the data quality from the 1992 report, the table presents HQs only for
the 1999 and 2006 HHRAs.
5.3.1 Site (Reaches 2 through 10) versus Reference Concentrations
Statistical comparisons of mercury concentrations in fillet and whole body samples
collected from potentially affected reaches of the Sudbury River and from appropriate
reference areas were made on a species- and tissue-specific basis. This discussion
encompasses data from the 2003-2005 Supplemental Investigation sampling only. Recall
that the individual reaches of the Sudbury River were assigned reach-specific reference
areas based on similarity of habitat conditions within the stream (Subsection 1.3.2) and
statistical comparisons of fish collected from these areas were made accordingly:
� Reach 1 Reference Area – Reaches 2, 5, 7, and 10
� Charles River – Reaches 8 and 9
� Sudbury Reservoir – Reaches 3, 4, 6, and Reach 7 – Heard Pond 30
H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
Comparisons were made for data sets with like distributions using the Equal Variance t-
test or Aspin-Welch Unequal Variances test as appropriate and for data sets with unlike
or nonparametric distributions using the Kolmogorov-Smirnov Test for Different
Distributions. All were performed at α = 0.05. Table 18 presents the results of these
evaluations.
5.3.1.1 Reach 1 Reference Area Statistical Comparisons
Insufficient sample numbers were available with which to develop a statistical
comparison of mercury concentrations in bullhead fillet and largemouth bass fillet and
whole body tissues collected from the Reach 1 reference area with mercury
concentrations in similar tissues in Reaches 2, 5, 7 and 10. For those sufficiently sized
data sets for which comparisons could be made, the mercury concentrations in whole
body bullhead, yellow perch fillet, and yellow perch whole body tissues collected from
Reaches 5 and 7 were not statistically different from the mercury concentrations in these
species and tissues collected from Reach 1. Mercury concentrations in yellow perch
whole body tissue collected from Reach 2 and bullhead whole body tissue collected from
Reach 10 were also not statistically different from the mercury levels in these species and
tissues from Reach 1.
5.3.1.2 Charles River Statistical Comparisons
Comparing reaches associated with the Charles River reference location, both fillet and
whole body bullhead concentrations were not statistically different from those found in
the similar samples collected from Reaches 8 and 9. However, mercury concentrations in
the fillet and whole body samples of largemouth bass and yellow perch from Reaches 8
and 9 were statistically greater than similar samples collected from the Charles River.
5.3.1.3 Sudbury Reservoir Statistical Comparisons
Comparing reaches associated with the Sudbury Reservoir reference location, both fillet
and whole body bullhead concentrations were not statistically different from those found
in the similar samples collected from Reach 4. However, mercury concentrations in the
fillet and whole body samples of largemouth bass and yellow perch from Reaches 4 were
31 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
statistically greater than similar samples collected from the Sudbury Reservoir. For
Reaches 3 and 6, the mercury concentrations in all tissue types and species were
statistically greater than those found in similar samples collected from the Sudbury
Reservoir. Mercury concentrations in bullhead whole body tissue collected from Reach
7 – Heard Pond were not statistically different from the mercury levels in this species and
tissue from the Sudbury Reservoir. However, mercury concentrations in the fillet and
whole body samples of largemouth bass and yellow perch, as well as fillet samples of
bullhead from Reach 7 – Heard Pond, were statistically lower than similar samples
collected from the Sudbury Reservoir. This was the only case where a statistically
significant difference was the result of the reference area concentrations being greater
than the reach. Graphical presentations of site versus background concentrations for fillet
and wholebody fish are found in Figures 10 and 11.
5.3.1.4 Site versus Reference Area Semi-quantitative Comparisons
In addition to the statistical comparisons of mercury levels in tissues, a comparison was
performed of the risk of mercury exposure from fish caught and consumed from
potentially site-affected reaches of the Sudbury River with fish caught and consumed
from reference areas. The ratios of site-impacted versus reference area HQs are
presented in Table 19. From these tables, it can be observed that the differences between
the site and reference hazard quotients range from a factor of 0.9 to 3.8. Note that, in
general, the only difference in the calculation of risk between the potentially site-
impacted reaches and reference areas occurs in the EPC; therefore, differences in
concentrations are, by extension, the differences in the potential risk.
5.3.2 Trends in Fish Concentrations
In the 1999 HHRA, a comparison of mercury levels in fish and the attendant risk
indicated a substantial decrease in mercury between 1989/1990 and 1993-1995. It is not
clear; however, if this trend is an accurate representation or is, rather, a function of
possibly poor data quality of the initial fish sampling. The possible reduction in mercury
levels over time as well as an incomplete sampling of the potentially affected portions of
the river (i.e., river reaches missing fish concentration data), gave rise to the 2003
Supplemental Investigation, and subsequently, this risk assessment. A graphical 32
H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
comparison of the mercury concentrations from the data set used in the 1999 HHRA
(collected 1993-1995) and those used the 2006 HHRA (collected 2003-2004) are
presented in Figures 12 and 13.
A comparison of the fillet data using data sets comprised of all species between years
indicates that concentrations of mercury in Reach 3 (Reservoir 2) and Reach 8
(GMNWR) have remained approximately unchanged over the last 10 years; whereas the
mercury concentrations in the Reach 1 reference area appear to have increased over this
period. This similarity holds when comparing mercury EPCs (Table 20), with Reaches 3
and 8 being approximately the same between the 1999 and 2006 HHRAs and the EPC for
Reach 1 used in the 2006 HHRA being approximately 3.7 times higher than that used in
the 1999 HHRA. Note that the fillet data used in the 1999 HHRA were actually
concentrations determined from fillet and “whole body less gut or stomach” samples.
Because mercury contamination is more likely to sequester in the muscle portions, the
inclusion of other fish parts (such as the head and fins) in the sample will likely yield
lower concentrations than what is in the fillet.
For the whole body samples (Figure 13), the mercury levels in whole body tissues using
data sets composed of all species in Reaches 1 and 3 appear to be higher for the more
recent data, whereas the mercury concentrations in the whole body tissues of fish
collected from Reach 8 appear approximately the same as those of 10 years prior. When
comparing EPCs from Reaches 1, 3, and 8, the concentrations in the 2006 HHRA are
approximately twice those used in the 1999 HHRA. Note that for the whole body data
set used in this HHRA, if both fillet and offal concentrations were not available with
which to “reconstruct” a whole body concentration, the fillet concentration was used as a
conservative estimate of the whole body concentration. This also will artificially inflate
the mercury concentrations. It is not known to what degree this conservative assumption
inflates the concentrations.
6. SUMMARY AND CONLUSIONS
In summary, all of the exposure pathways evaluated for the Sudbury River proper and
their associated risks and hazards are presented in Table 21. Note that the information in
33 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
the table represents the most up-to-date results as presented in this report. That is, any
hazards attributable to mercury are based on results presented in the 2006 HHRA or
extrapolations from the data used in the 2006 ERA; whereas risk/hazards for all other
chemicals are based on the results presented in the 1992 report.
Of the chemicals for which risks of greater than 1E-06 or hazard quotients greater than
unity (i.e., 1), only antimony, arsenic, and mercury are considered site-related (see
Section 2.1). Of these, only arsenic had toxicity values for which to estimate cancer risk.
Arsenic risks fell either below or within the 1E-06 to 1E-04 range for all site-related
reaches and exposures except for the Reach 3 recreational and subsistence angler
exposures and Reach 4 subsistence angler exposure. Arsenic was not detected in the
upstream reference impoundments, but recreational and subsistence angler arsenic risks
from fish ingestion exposure were calculated for the Sudbury Reservoir as 8.6E-06 and
6.3E-05.
Site-related chemicals (other than mercury) with noncancer hazards greater than unity
were antimony and arsenic from recreational and subsistence angler fish ingestion
exposures in Reach 3. Antimony HQs were 7.1 and 52 for recreational and subsistence
anglers, respectively. Antimony was detected in the Reach 1 – Cedar Swamp Pond
reference area, with exposure yielding 0.38 and 2.8 HQs for the recreational and
subsistence anglers, respectively. Arsenic HQs were 1.1 and 7.9 for recreational and
subsistence anglers, respectively. Arsenic was not detected in the upstream reference
impoundments, but arsenic recreational and subsistence angler HQs were calculated for
the Sudbury Reservoir as 0.037 and 0.27.
For mercury, only noncancer hazards could be estimated. HQs were greater than unity
only for the fish ingestion exposure scenarios. The maximum HQs per scenario/receptor
were as follows:
� Recreational Angler – Child: 3.5 (Reach 2)
� Recreational Angler – Adult: 1.8 (Reach 2)
� Subsistence Angler – Adult: 9.1 (Reach 3)
� Ethnic Angler – Child: 15 (Reach 3)
34 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
� Ethnic Angler – Adult: 8.0 (Reach 3)
A summary of the mercury hazards due to fish ingestion is presented by reach in Table
22. As can be noted from the table, HQs are greater than unity for all site-related reaches
for at least one recreational angler receptor except from Reach 5 and Reach 7 (including
Heard Pond). HQs are greater than unity for all subsistence and ethnic angler exposures
for all site-related and reference reaches.
These results indicate the need for a routine monitoring of mercury in fish in the Sudbury
River to evaluate the need for continued fish advisories resulting from mercury
contamination.
7. REFERENCES
Avatar Environmental. 2006. Supplemental Baseline Human Health Risk Assessment, Nyanza Superfund Site, Operable Unit IV, Sudbury River Mercury Contamination.
Bloom, N.S. 1995. Mercury as a Case Study of Ultra-Clean Sample Handling and Storage in Aquatic Trace-Metal Research. Environ. Lab. March/April, P. 20-25.
Bloom, N.S., 1992. On the Chemical Form of Mercury in Edible Fish and Marine Invertebrate Tissue. Can. J. Fish. Aquat. Sci. 49:1010-1017.
Bloom, N.S. and S.W. Effler. 1990. Seasonal Variability in the Mercury Speciation of Onandaga Lake, New York. Water Air Soil Poll. 56:251-265.
Bloom, N.S. 1989. Determination of Program Levels of Methyl Mercury by Aqueous Phase Ethylation, Followed by Cryogenic Gas Chromatography with Cold Vapour Atomic Flourescence Detection. Can. J. Fish. Aqua. Sci. 46:1131-1140.
Bloom, N.S., Colman, J.A. and L. Barber. 1997. Artifact formation of methyl mercury during aqueous distillation and alternative techniques for the extraction of methyl mercury from environmental samples. Fresenius J. Anal. Chem. 358: 371-377.
Bloom, N.S. and Fitzgerald, W.F. 1988. Determination of Volatile Mercury Species at the Pilogram Level by Low-Temperature Gas Chromatography with Cold-Vapor Atomic Flourescence Detection. Analytica Chimica Asta 208:151-161.
Camp, Dresser, and McKee, Inc. (CDM). 1982. Remedial Action Master Plan Draft. June 23, 1982.
35 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
Colman, J.A. and R.F Breault. 2000. Sampling for mercury at subnanogram per litre concentrations for load estimation in rivers. Can. J. Fish. Aquat. Sci. 57: 1073-1079.
Colman, J.A., M.C. Waldron, R.F Breault, and R.M. Lent. 1999. Distribution and transport of total mercury and methylmercuy in mercury-contaminated sediments in reservoirs and wetlands of the Sudbury River, east-central Massachusetts. U.S. Geol. Surv. Water-Resour. Invest. Rep. 99-4060.
Ebasco Services, Inc. 1995. Final Extent of Contamination Report for Pre-Design Investigations, Nyanza Chemical Waste Dump Superfund Site Operable Unit III, Ashland, Massachusetts. Prepared under USACE Contract No. DACW33-91-D-0005. May 22, 1995.
Ebert, E., N. Harrington, K. Boyle, J. Knight, and R. Keenan. 1993. Estimating Consumption of Freshwater Fish Among Maine Anglers. North Amer. J. Fisheries Management. 13: 737-745.
EPA (United States Environmental Protection Agency). 2004. ProUCL – Version 3.0 Prepared by Lockheed Martin Environmental Services.
EPA (United States Environmental Protection Agency). 2002. Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites. OSWER 9355.4-24. Office of Solid Waste and Emergency Response, Washington, DC. December.
EPA (United States Environmental Protection Agency). 1996. Drinking Water Regulations and Health Advisories. Office of Water. October 1996. EPA 882-B-96-002.
EPA Region 3 (U.S. Environmental Protection Agency, Region 3). 2005. Risk-Based Concentration Table. October 2005.
Frazier, B.E., J.G. Wiener, R.G. Rada, and D.R. Engstrom. 1997. Stratigraphy and Historic Accumulation of Mercury in Recent Depositional Sediments in the Sudbury River. Draft Final Report - Submitted to U.S. EPA Region 1.
Gill, G.A. and K.W. Bruland. 1990. Mercury Speciation in Surface Freshwater Systems in California and Other Areas. Environ. Sci.Tech. 24(9): 1392-1400.
Haines, T.A., T.W. May, R.T. Finleyson, S.E. Mierzykowski and M.W. Powell. 1997. Factors Affecting Food Chain Transfer of Mercury in the Vicinity of the Nyanza Site, Sudbury River, Massachusetts. Draft Final Report-submitted to U.S. EPA, Region 1.
Huckabee, J.W., J.W. Elwood, and S.G. Hildebrand. 1979. Accumulation of Mercury in Freshwater Biota . p. 277-300. In J.O. Nriagu (Ed.) Biogeochemistry of Mercury in the Environment. Elsevoer/North-Holland Biomedical Press, New York.
36 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
JBF (JBF Scientific Corporation). 1973. An Investigation of Mercury Problems in Massachusetts. Boston Massachusetts Water Resources Commission, Division of Water Pollution Control.
JBF (JBF Scientific Corporation). 1972. Control of Mercury Contamination in Freshwater Sediments. EPA-R2-72-077. Washington, D.C., U.S. Environmental Protection Agency, Office of Research and Monitoring.
Liang, L., N.S. Bloom, and M. Horvet. 1994. Simultaneous determination of mercury speciation in biological materials by GC/CVAFS after ethylation and room temperature precollection. Clin. Chem. 40:602-607.
MADEP (Massachusetts Department of Environmental Protection). 2000. Massachusetts Surface Water Quality Standards. 314 CMR 4.00. May 12, 2000.
MDFW (Massachusetts Division of Fisheries and Wildlife). 2005. Abstracts of the 2005 Massachusetts Fish and Wildlife Laws.
Motts, W.S., and A. O’Brien. 1981. Geology and Hydrology of Wetlands in Massachusetts. Publication No. 123, Water Resources Research Center, University of Massachusetts at Amherst, Mass.
Nail, G.H. and D.D. Abraham. 1997. Sudbury River Sediment Transport Model: Draft Final Report. New England Division, Corps of Engineers.
Naimo, T.J., J.G. Wiener, W.G. Cope and N.S. Bloom. 1997. Bioavailability of Sediment-Associated Mercury to Hexagenia Mayflies in a Contaminated Floodplain River. Draft Final Report-submitted to U.S. EPA, Region 1.
NUS (NUS Corporation). 1992. Final Remedial Investigation Report (Volumes I to IV): Nyanza Operable Unit III-Sudbury River Study, Middlesex County, Massachusetts.
NUS (NUS Corporation). 1984. Operable Unit I Remedial Investigation/Feasibilty Study. Sudbury River, Middlesex County, Massachusetts.
Porcella, D.B., C.J. Watras and N.S. Bloom. 1992. Mercury Species in Lake Water. pp 127-138. In the Deposition and Fate of Trace Metals in Our Environment. Gen. Tech. Rep. NL-150. U.S. Forest Service, North Central Forest Experimental Station, St. Paul, Minn.
Porcella, D. 1990. Mercury in the Environment. Electric Power Research Institute Journal 15(3):46-49.
Salazar, S.M., N. Beckvar, M.H. Salazar and K. Finkelstein. 1996. An In-situ Assessment of Mercury Contamination in the Sudbury River, Massachusetts, Using Bioaccumulation and Growth in Transplanted Freshwater Mussels (Elliptio complanata). NOAA Tech. Memo NOS ORCA 89.
37 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
Spry, D.J. and J.G. Wiener. 1991. Metal Bioavailability and Toxicity to Fish in Low-Alkalinity Lakes in Critical Review. Environ. Pollut. 71:243-304.
Waldron, M.C., J.A. Colman, and R.F. Breault. 2000. Distribution, hydrologic transport, and cycling of total mercury and methyl mercury in a contaminated river-reservoir-wetland system (Sudbury River, eastern Massachusetts). Can. J. Fish. Aquat. Sci. 57: 1080-1091.
Weston (Roy F. Weston, Inc.). 1999a. Draft: Nyanza Chemical Waste Dump Superfund Site, Supplemental Baseline Human Health Risk Assessment.
Weston (Roy F. Weston, Inc.). 1999b. Draft: Nyanza Chemical Waste Dump Superfund Site, Supplemental Baseline Ecological Risk Assessment.
38 H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Nyanza HHRA Synthesis Report.doc 5/5/2006 1:03:28 PM
TABLES
Table 1 Chronology of Primary Evaluations and Investigations Conducted at
the Nyanza Superfund Site Ashland, Massachusetts
Investigation Investigator and Date Key Findings
Waste disposal violations
Massachusetts Departments of Public Health (DPH) and Massachusetts Department of Water Pollution Control, 1972-1977
Identified several waste disposal violations.
Investigation of Mercury Problems in Massachusetts
JBF Scientific Corp. 1972 Identified elevated levels of mercury in water, sediments and biota in the Sudbury River, and qualitatively linked mercury contamination in the Sudbury River to the Nyanza Site.
Environmental Site Investigation
Camp, Dresser and McKee, 1974 Determined on- and off-site contamination sources and developed a groundwater contamination control plan.
Sudbury River Fish Monitoring Study
U.S. Fish and Wildlife Service (USFWS) 1977-1987
Detected elevated mercury concentrations in several fish species and sediment collected in the Sudbury River.
Preliminary Site Assessment
Massachusetts Department of Environmental Quality and Engineering (DEQE) 1980
Performed a site assessment and review of previous studies that identified off-site migration of several metal (including mercury) and organic contaminants.
Environmental Investigations of Sudbury River
Massachusetts DEQE Metropolitan District Commission (MDC), 1980-1987
Identified metal and organic contamination in surface water, sediment, and fish collected in the Sudbury River near the site.
Remedial Action Master Plan
Camp, Dresser and McKee 1982 Remedial action plan emphasizing on-site source control is developed.
Operable Unit I (on-site surficial soil, sediment, and sludge) RI/FS
NUS Corporation, 1984 Characterized the extent of on-site inorganic and organic contamination and recommended source removal and stabilization activities. ROD based on findings signed in 1985.
H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Word Tables.doc 5/04/05
Table 1
Chronology of Primary Evaluations and Investigations Conducted at the Nyanza Superfund Site Ashland, Massachusetts
(Continued)
Investigation Investigator and Date Key Findings
Sludge Removal EPA Region 1 Environmental The “vault”, or major source of organic groundwater Action Service Division (ESD), 1987 contamination is removed. E.C. Jordan begins RI/FS
activities on Operable Unit II (groundwater). On-site sludges were excavated, solidified and buried on Mejunko Hill, then covered with a cap.
Off-site EPA, 1991 Activities involved in the groundwater study included Groundwater installation of monitoring wells, topographic and Control, OU II geophysical studies, aquifer testing, and groundwater,
surface water, sediment, and subsurface sampling. As a result, it was concluded that a contaminated groundwater plume containing VOCs and metals was traveling north, east, and northeast toward the Sudbury River. It was concluded that there were minimal human health risks due to groundwater in basements or drinking water. The minimal risk is attributed to the lack of known public or private drinking wells. It was concluded that if individuals began to utilize the groundwater for future household use or if groundwater was not properly addressed, potential human health and environmental risks exists.
Sudbury River NUS Corporation, 1992 Following Phase I sampling, surface water had minimal Study, OU III contamination; mercury, chromium, and lead
contamination found in sediments; and mercury, PCB, and pesticide contamination found in fish. Following Phase II activities, minimal surface water contamination confirmed Phase I findings, high levels of mercury contamination found in sediments downstream of site, high mercury levels in fish found in entire river stretch, and PCB and pesticide contamination found not related to Nyanza site.
H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Word Tables.doc 5/04/05
Table 1
Chronology of Primary Evaluations and Investigations Conducted at the Nyanza Superfund Site Ashland, Massachusetts
(Continued)
Investigation Investigator and Date Key Findings
Final Extent of Contamination Report for Pre-Design Investigations, OU III
Ebasco Services, Inc., 1995 Determined the extent of mercury contamination in the Continuing Sources Area soils and excluded both TCL and TAL chemicals in surface water. Most soil mercury levels below 1-foot depth were less than 1.0 ppm. Mercury contamination in soils in the Eastern Wetlands was present to depths of at least 0.5 feet. Trolley Creek had mercury contamination as high as 126 ppm at depths of 2 to 3 feet. Study estimated that approximately 18,750 cubic yards of soil would require excavation. Surface water sampling was limited; however, no VOC, SVOC, pesticides or PCB’s were present. Mercury in surface waters was detected at levels ranging from 0.22 to 16.9 ppb.
Additional On-site Investigations
Camp, Dresser and McKee, 1996 Identified additional on-site source areas in support of remedial design.
Ecological Task Task Force Members, 1997 Following initial site investigations of the Sudbury Force Findings River, it was concluded that additional studies were
necessary. Sediments and fish were contaminated with mercury and other heavy metals.
Baseline Human Roy F. Weston, Inc. 1999a Evaluation showed human health effects from mercury Health Risk due to fish consumption. Risks to recreational anglers Assessment and subsistence fishermen due to exposure from fish
consumption were above a hazard quotient of 1. Routine monitoring of mercury in fish in the Sudbury River was recommended to evaluate the need for continued fish advisories due to mercury contamination.
Baseline Ecological Roy F. Weston, Inc., 1999b Evaluation showed sediment contamination effects on Risk Assessment benthic communities within Sudbury River and nearby
wetlands and tributaries; methylation of inorganic mercury occurring in wetlands, bioaccumulation of methylmercury occurring within study area, and reproductive/developmental and neurotoxic/behavioral effects occurring on avian receptors. Recommended need for continued monitoring and data collection and potential remediation.
Supplemental Avatar Environmental, 2006 HQs ranged from 0.3 (Child of a recreational angler – Baseline Human Heard Pond) to 15 (Child of an ethnic angler – Reach Health Risk 3). HQs for site-impacted areas were 0.5 to 4.5 times Assessment those found in the background areas.
H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Word Tables.doc 5/04/05
Table 1
Chronology of Primary Evaluations and Investigations Conducted at the Nyanza Superfund Site Ashland, Massachusetts
(Continued)
Investigation Investigator and Date Key Findings
Kingfisher Study Biodiversity Research Institute (BRI), 2006
Results pending.
Marsh Bird Study BRI, 2006 Results pending.
Hooded Merganser Study
BRI, 2006 Results pending.
Tree Swallow Study BRI, 2006 Results pending.
Mink and Otter Study
BRI, 2006 Results pending.
Supplemental Baseline Ecological Risk Assessment
Avatar Environmental, 2006 Results pending.
Table 2
OU IV Mercury Assessment Studies at the Nyanza Superfund Site Ashland, Massachusetts
Title Researchers
and Date Affiliation Objectives
Distribution and transport of total Colman, J.A., U.S. Determine the effect of Hg contaminated-mercury and methylmercury in M.C. Waldron, Geological Sudbury River sediment on net MeHg mercury-contaminated sediments R.F Breault, Survey generation as determined by the presence, in reservoirs and wetlands of the and R.M. Lent, distribution, and correlation of ∑ Hg and Sudbury River, east-central 1999 MeHg in the bed sediments. Massachusetts
Sampling for mercury at sub- Colman, J.A. U.S. Collect and analyze Hg water concentrations at nanogram per liter concentrations and R.F Geological subnanogram/liter concentrations of stream for load estimation in rivers. Breault, 2000 Survey cross-sections so that constituent load
estimates could be calculated.
Artifact formation of methyl Bloom, N.S., Frontier Geo- Determine the relative proportion of methyl mercury during aqueous Colman, J.A. Sciences, Inc., mercury generated during standard pre-distribution and alternative for the and L. Barber, U.S. extraction distillation procedures and identify extraction of methyl mercury 1997 Geological method modifications that may result in the environmental samples Survey, Duke
University elimination or reduction in pre-extraction methyl mercury production.
Sudbury River Sediment Transport Nail, G.H. and U.S. Army Determine the extent of mercury contamination Model D.D. Abraham,
1997 Corps of Engineers
in existing river sediment, and the potential for resuspension and movement of these sediments.
Distribution, hydrologic transport, Waldron, U.S. Determine occurrence and distribution of Hg in and cycling of total mercury and M.C., Colman, Geological the water column. methyl mercury in a contaminated J.A. and R.F. Survey Determine current sources of Hg in the river-reservoir-wetland system Breault, 2000 Sudbury River. (Sudbury River, eastern Massachusetts) Determine how Hg from the Superfund site
move downstream through the system. Determine if the reservoirs affect Hg transport and sedimentation. Determine if contaminated sediment beds sites of elevated MeHg production. Determine how much the wetland associated reaches contribute to the river’s MeHg load. Determine if transport of MeHg from ∑Hg contaminated sites is an important source of MeHg to food chains at downstream sites.
H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Word Tables.doc 5/04/05
Table 2
OU IV Mercury Assessment Studies at the Nyanza Superfund Site Ashland, Massachusetts
(Continued)
Title Researchers and
Date Affiliation Objectives
Estimating historical mercury concentrations and assessing fish exposure to mercury in a contaminated reservoir on the Sudbury River, East-Central Massachusetts, using a constant settling-velocity model and accumulation rates of mercury in sediment cores
J.A. Colman, 1997 U.S. Geological Survey
Estimate historical mercury concentrations in the first reservoir downstream from the Nyanza Superfund site for use in assessing exposure of fish to mercury.
Factors affecting food chain transfer of mercury in the vicinity of the Nyanza Site, Sudbury River, Massachusetts
Haines, T.A., May, T.W., Finlayson, R.T., Merzykowski, S.E. and M.W. Powell, 1997
U.S. Geological Survey-Biological Resources Division, University of Maine, U.S. Fish and Wildlife Service
Characterize total mercury content of the most important predator fish species in reference and contaminated sites in the Sudbury River, considering both impounded and free-flowing reaches and three seasons (spring, summer and fall). Characterize total and methyl mercury concentrations in invertebrates and forage fish in reference and contaminated sites in the Sudbury River, in order to assist in the determination of the importance of food chain pathways of mercury in the continuing contamination of fish and wildlife resources in the river. Construct a computer model that represents the major pathways of methyl mercury into the food chain leading to predatory fish and develop forecast models that predict biota mercury accumulation from environmental variables and can be used to evaluate remediation strategies.
Table 2
OU IV Mercury Assessment Studies at the Nyanza Superfund Site Ashland, Massachusetts
(Continued)
Title Researchers and Date
Affiliation Objectives
Bioavailability of sediment associated mercury in Hexagenia mayflies in a contaminated floodplain river
Naimo, T.J. Wiener, J.G., Cope, W.G., and N.S. Bloom, 1997
U.S. Geological Survey, Biological Resources Division,
Frontier Geosciences
Determine if Hexagenia mayfly nymphs exposed to mercury-contaminated surficial sediment from the Sudbury River accumulate MeHg. Determine if the accumulation of MeHg in mayflies is a function of the ∑Hg concentration in sediment. Assess which contaminated areas on the Sudbury River have the greatest potential for MeHg transfer into the benthic food chain.
An in-situ assessment of mercury contamination in the Sudbury River, Massachusetts, using bioaccumulation and growth in transplanted mussels
Salazar, S.M., Beckvar, N, Salazar, M.H. and K., Finkelstein, 1996
National Oceanic and Atmospheric Administration E.V.S. Consultants
Demonstrate the extent of bioavailable mercury within the downstream reaches of the Sudbury River resulting from operations at the Nyanza site. Identify areas that could act as sources of mercury for transport downstream. Determine the effect of mercury exposure on a resident species.
Stratigraphy and historic accumulation of mercury in recent depositional sediments in the Sudbury River
Frazier, B.E., Wiener, J.G., Rada, R.G., and D.E. Engstrom, 1997
University of Wisconsin-La Cross U.S. Geological Survey, Biological Resources Division
Determine the vertical distribution of mercury in sediments from the Sudbury River. Estimate the recent inputs of mercury to depositional environments in the Sudbury River, as reflected by the temporal pattern in accumulation rates of mercury in the sediments.
Science Museum of Minnesota
Table 2
OU IV Mercury Assessment Studies at the Nyanza Superfund Site Ashland, Massachusetts
(Continued)
Title Researchers and Date
Affiliation Objectives
Kingfisher Study Biodiversity Research Institute (BRI), in review
Not Applicable Determine the extent to which mercury has accumulated in the blood and feathers of adult kingfisher foraging the Sudbury River for comparison with existing data on effects levels (i.e., critical residue levels); Determine the extent to which mercury has accumulated in the eggs of kingfisher for comparison with existing data on effects levels; Obtain data on the ambient levels of mercury in eggs and in blood and feathers of adult kingfisher inhabiting reference surface waters including Sudbury Reservoir and the Charles River; Evaluate the bioaccumulation and trophic dynamics of mercury transfer from sediment to kingfisher and other piscivorous birds for use in establishing remedial measures if necessary.
Marsh Bird Study BRI, 2006; see Appendix A
Not Applicable Determine the extent to which mercury has accumulated in the blood and feathers of adult marsh birds inhabiting the floodplains of the Sudbury River for comparison with existing data on effects levels (i.e., critical residue levels); Determine the extent to which mercury has accumulated in the eggs of marsh birds for comparison with existing data on effects levels; Obtain data on the ambient levels of mercury in eggs and in blood and feathers of marsh birds inhabiting reference floodplains including Sudbury Reservoir and the Charles River; Evaluate the bioaccumulation and trophic dynamics of mercury transfer from sediment and floodplain soils to marsh birds for use in establishing remedial measures if necessary.
Table 2
OU IV Mercury Assessment Studies at the Nyanza Superfund Site Ashland, Massachusetts
(Continued)
Title Researchers and Date
Affiliation Objectives
Hooded Merganser Study BRI, 2006; see Appendix A
Not Applicable Determine the extent to which mercury has accumulated in the blood and feathers of adult mergansers inhabiting the Sudbury River for comparison with existing data on effects levels (i.e., critical residue levels); Determine the extent to which mercury has accumulated in the eggs of mergansers for comparison with existing data on effects levels; Obtain data on the ambient levels of mercury in eggs and in blood and feathers of adult mergansers inhabiting reference surface waters including Sudbury Reservoir and the Charles River; Evaluate the bioaccumulation and trophic dynamics of mercury transfer from sediment to mergansers for use in establishing remedial measures if necessary.
Tree Swallow Study BRI, 2006; see Appendix A
Not Applicable Determine the extent to which mercury has accumulated in the blood and feathers of adult tree swallows for comparison with existing data on effects levels (i.e., critical residue levels); Determine the extent to which mercury has accumulated in the eggs of tree swallows for comparison with existing data on effects levels; Obtain data on the ambient levels of mercury in eggs and in blood and feathers of adult tree swallows inhabiting reference surface waters including Sudbury Reservoir and the Charles River; Evaluate the bioaccumulation and trophic dynamics of mercury transfer from sediment to tree swallows for use in establishing remedial measures if necessary.
Table 2
OU IV Mercury Assessment Studies at the Nyanza Superfund Site Ashland, Massachusetts
(Continued)
Title Researchers and Date
Affiliation Objectives
Mink and Otter Study BRI, 2006; see Appendix A
Not Applicable Determine the extent to which mercury has accumulated in the blood and fur of mink and otter inhabiting the Sudbury River for comparison with existing data on effects levels (i.e., critical residue levels); Obtain data on the ambient levels of mercury in blood and fur in mink and otter inhabiting reference surface waters including Sudbury Reservoir and the Charles River; Evaluate the bioaccumulation and trophic dynamics of mercury transfer from sediment to mink and otter for use in establishing remedial measures if necessary.
Table 3 Total Mercury EPC Comparison - Unfiltered Surface Water
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Exposure Area EPC (mg/L)
1999 2005 (n) Reach 1 Reach 2 Reach 3 Reach 4 Reach 5 Reach 6 Reach 7 Reach 8 Reach 9 Reach 10 Charles River Sudbury Reservoir
2.53E-06 2.00E-05 1.00E-05
NA NA NA
1.00E-05 2.00E-05
NA 6.07E-06
NA NA
2.26E-06 4.18E-05 5.89E-06 2.70E-06 1.59E-06
NA 1.04E-05 1.11E-05
NA NA
2.19E-06 NA
(4) (3) (1) (1) (1) -
(10) (14)
--
(16) -
EPC = Exposure point concentration mg/L = Milligrams per liter NA = Not available
Note: Mercury not detected in Sudbury River proper or reference area samples used in 1992 HHRA.
Table 4 Total Mercury EPC Comparison - Sediment
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Exposure Area EPC (mg/kg)
1992a 1999b 2005c (n) Reach 1 NA 2.04E-01 2.26E+00 (4) Reach 1 and Sudbury Reservoir 1.59E+00 NA NA -Reach 2 3.06E+01 1.90E+01 7.27E+00 (3) Reach 3 5.46E+01 1.91E+01 1.88E+01 (1) Reach 4 7.30E+00 1.20E+01 9.13E+00 Reach 5 4.10E+00 NA 1.61E+00 (1) Reach 6 1.76E+01 7.30E+00 5.24E+00 -Reach 7 5.50E+00 1.01E+00 5.29E-01 (10) Reach 8 2.10E+00 1.72E+00 6.66E-01 (14) Reach 9 3.90E+00 1.81E+00 1.46E+00 -Reach 10 5.30E-01 4.00E-01 8.13E-01 -Charles River NA NA 1.85E-03 (7) Sudbury Reservoir NA NA 6.96E-04 (6)
EPC = Exposure point concentration mg/kg = Milligrams per kilogram NA = Not available a 0-6 in. sample depth b 0-6 cm sample depth c 0-5 cm sample depth
Table 5 Total Mercury EPC Comparison - Fish Fillets
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Exposure Area EPC (mg/kg)
1992a 1999b 2005c
Reach 1 NA 1.44E-01 5.16E-01 Reach 1 - Cedar Swamp Pond 9.60E+00 NA NA Reach 1 - Southville Pond 8.90E-01 NA NA Reach 2 NA NA 8.31E-01 Reach 2 - Mill Pond 1.98E+00 NA NA Reach 3 7.60E+00 8.63E-01 9.36E-01 Reach 4 4.19E+00 NA 5.78E-01 Reach 5 NA NA 4.63E-01 Reach 6 1.80E+00 NA 6.00E-01 Reach 7 NA NA 5.05E-01 Reach 7 - Heard Pond NA NA 1.18E-01 Reach 8 NA 6.87E-01 6.91E-01 Reach 9 3.20E+00 NA 6.85E-01 Reach 10 NA NA 7.19E-01 Charles River NA NA 3.46E-01 Sudbury Reservoir 1.18E+00 NA 2.53E-01
EPC = Exposure point concentration mg/kg = Milligrams per kilogram NA = Not available a Concentrations from "fish flesh". Not noted if fillet or whole body, or skin off or on. b Concentrations from fillet or whole body less gut or stomach. Assumed skin on. c Concentrations from skin-on fillets.
Table 6 Total Mercury EPC Comparison - Whole Body Fish
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Exposure Area EPC (mg/kg)
1999 2005a
Reach 1 1.23E-01 2.88E-01 Reach 2 NA 4.12E-01 Reach 3 4.21E-01 8.23E-01 Reach 4 NA 4.91E-01 Reach 5 NA 3.96E-01 Reach 6 NA 5.08E-01 Reach 7 NA 4.57E-01 Reach 7 Heard Pond NA 1.01E-01 Reach 8 2.82E-01 4.73E-01 Reach 9 NA 5.53E-01 Reach 10 NA 6.25E-01 Charles River NA 3.14E-01 Sudbury Reservoir NA 2.17E-01
NA = Not available Note: Scenarios with the consumption of whole body fish not evaluated in 1992 report. a Includes both whole body and reconstructed whole body samples.
Table 7 Updated Direct Contact Mercury Potential Hazards - Surface Water
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Exposure Area
Concentration to RBC or MCL Tap Water RBCa MCLb
1999 2006 1999 2006 Reach 1
Total Mercury Methylmercury
Reach 2 Total Mercury Methylmercury
Reach 3 Total Mercury Methylmercury
Reach 4 Total Mercury Methylmercury
Reach 5 Total Mercury Methylmercury
Reach 6 Total Mercury Methylmercury
Reach 7 Total Mercury Methylmercury
Reach 8 Total Mercury Methylmercury
Reach 9 Total Mercury Methylmercury
Reach 10 Total Mercury Methylmercury
Charles River Total Mercury Methylmercury
Sudbury Reservoir Total Mercury Methylmercury
0.00023 0.000082
0.0018 0.000092
0.00091 0.000074
NC NC
NC NC
NC NC
0.00091 0.000039
0.0018 0.00016
NC NC
0.00055 0.000063
NC NC
NC NC
0.00021 0.000085
0.0038 0.00011
0.00054 0.00010
0.00025 0.000039
0.00015 0.000034
NC NC
0.00095 0.000079
0.0010 0.000077
NC NC
NC NC
0.00020 0.000099
NC NC
0.0013 0.00015
0.010 0.00017
0.0050 0.00014
NC NC
NC NC
NC NC
0.0050 0.000071
0.010 0.00029
NC NC
0.0030 0.00012
NC NC
NC NC
0.0011 0.00016
0.021 0.00020
0.0029 0.00018
0.0014 0.000071
0.00080 0.000063
NC NC
0.0052 0.00014
0.0055 0.00014
NC NC
NC NC
0.0011 0.00018
NC NC
NC = Not calculated. Surface water concentrations not available. a Value of 1.1E-02 mg/L for total mercury (mercuric chloride value) was used; value of 3.7E-03 mg/L for methylmercury was used (EPA, 2005). b Value of 2.0E-03 mg/L was used; the MCL for mercury (inorganic) was used for both total mercury and methylmercury (EPA, 1996).
Table 8 Updated Direct Contact Mercury Potential Hazards - Sediment
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Exposure Area
Concentration to SSL or RBC SSLa Residential RBCb
1999 2006 1999 2006 Reach 1
Total Mercury 0.0089 0.099 0.0087 0.10 Methylmercury
Reach 2 NA 0.00057 NA 0.00055
Total Mercury 0.83 0.32 0.81 0.31 Methylmercury
Reach 3 NA 0.0019 NA 0.0019
Total Mercury 0.84 0.82 0.81 0.80 Methylmercury
Reach 4 0.0027 0.00097 0.0027 0.00094
Total Mercury 0.53 0.40 0.51 0.39 Methylmercury
Reach 5 NA 0.00035 NA 0.00034
Total Mercury NA 0.071 NA 0.069 Methylmercury
Reach 6 NA 0.00053 NA 0.00052
Total Mercury 0.32 0.23 0.31 0.22 Methylmercury
Reach 7 NA 0.00061 NA 0.00059
Total Mercury 0.044 0.023 0.043 0.023 Methylmercury
Reach 8 0.00034 0.00023 0.00033 0.00022
Total Mercury 0.075 0.029 0.073 0.028 Methylmercury
Reach 9 0.0016 0.00067 0.0016 0.00065
Total Mercury 0.079 0.064 0.077 0.062 Methylmercury
Reach 10 NA 0.00044 NA 0.00043
Total Mercury 0.018 0.036 0.017 0.035 Methylmercury
Charles River NA 0.00043 NA 0.00042
Total Mercury NA 0.014 NA 0.014 Methylmercury
Sudbury Reservoir NA 0.00024 NA 0.00024
Total Mercury NA 0.014 NA 0.013 Methylmercury NA 0.000091 NA 0.000089
NA = Not available a Value of 2.3E+01 mg/kg for total mercury (mercuric chloride value) was used; value of 7.6E+00 mg/kg for methylmercury was used. Calculated using latest SSL ingestion and dermal equation with exposure assumptions (EPA, 2006). b Value of 2.3E+01 mg/kg for total mercury (mercuric chloride value) was used; value of 7.8E+00 mg/kg for methylmercury was used.
Table 9 Exposure Parameter Value Comparisona - Recreational Angler
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Parameter
Recreational Angler Adult Child
1992 1999 2006 1999 2006 Fish Ingestion Rateb (g/day) 54 25 All Waters - 32
Flowing - 14 Standing - 18
4.7 All Waters - 13 Flowing - 6.1 Standing - 6.9
Fraction Ingested (unitless) 0.25 0.5 0.5 0.5 0.5 Exposure Frequency (days/year) 350 350 350 350 350 Exposure Duration (years) 30 20 30 10 6 Body Weight (kg) 70 64 70 25 15 Averaging Time (noncancer; days) 10950 7300 10950 3650 2190
aRME case only. bFor the 2006 RA, all waters includes Reaches 2 and 9; flowing waters includes Reaches 1,5,7,8, and 10, and Charles River; standing waters includes Reaches 3,4,6, Heard Pond, and Sudbury Reservoir.
Table 10 Exposure Parameter Value Comparison* - Subsistence Angler
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Parameter Adult
1992 1999 2006 Fish Ingestion Rate (g/day) 132 170 142.4 Fraction Ingested (unitless) 0.75 1 0.5 Exposure Frequency (days/year) 350 350 350 Exposure Duration (years) 30 20 30 Body Weight (kg) 70 64 70 Averaging Time (noncancer; days) 10950 7300 10950
*RME case only.
Table 11 Exposure Parameter Value Comparison* - Ethnic Angler
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Parameter Adult Child
1999 2006 2006 Fish Ingestion Rate (g/day) 170 142.4 56.96 Fraction Ingested (unitless) 1 0.5 0.5 Exposure Frequency (days/year) 350 350 350 Exposure Duration (years) 20 30 6 Body Weight (kg) 64 70 15 Averaging Time (noncancer; days) 7300 10950 2190
*RME case only.
Table 12 Mercury Fish Ingestion Hazard Quotient Comparison - Recreational Angler
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach
Hazard Quotients Adult Child
1992 1999 2006 1999 2006 Reach 1 NA 0.27 0.50 0.13 1.0 Reach 1 - Cedar Swamp Pond 5.9 NA NA NA NA Reach 1 - Southville Pond 0.6 NA NA NA NA Reach 2 NA NA 1.8 NA 3.5 Reach 2 - Mill Pond 1.2 NA NA NA NA Reach 3 4.7 1.6 1.2 0.78 2.1 Reach 4 2.6 NA 0.70 NA 1.3 Reach 5 NA NA 0.40 NA 0.90 Reach 6 1.1 NA 0.70 NA 1.3 Reach 7 NA NA 0.50 NA 1.0 Reach 7 - Heard Pond NA NA 0.10 NA 0.3 Reach 8 NA 1.3 0.70 0.62 1.3 Reach 9 2.0 NA 1.5 NA 2.8 Reach 10 NA NA 0.70 NA 1.4 Charles River NA NA 0.33 NA 0.67 Sudbury Reservoir 0.7 NA 0.31 NA 0.56
NA = Not available
Table 13 Mercury Fish Ingestion Hazard Quotient Comparison - Subsistence Angler
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach Hazard Quotients*
1992 1999 2006 Reach 1 NA 3.7 5.0 Reach 1 - Cedar Swamp Pond 43 NA NA Reach 1 - Southville Pond 4.0 NA NA Reach 2 NA NA 8.1 Reach 2 - Mill Pond 9.0 NA NA Reach 3 34 22 9.1 Reach 4 19 NA 5.6 Reach 5 NA NA 4.5 Reach 6 8.1 NA 5.9 Reach 7 NA NA 4.9 Reach 7 - Heard Pond NA NA 1.2 Reach 8 NA 18 6.7 Reach 9 14 NA 6.7 Reach 10 NA NA 7.0 Charles River NA NA 3.4 Sudbury Reservoir 5.3 NA 2.5
NA = Not available * Only adult exposures evaluated.
Table 14 Mercury Fish Ingestion Hazard Quotient Comparison - Ethnic Angler
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach Hazard Quotients*
1999 2006 Reach 1 3.1 2.8 Reach 2 NA 4.0 Reach 3 11 8.0 Reach 4 NA 4.8 Reach 5 NA 3.9 Reach 6 NA 5.0 Reach 7 NA 4.5 Reach 7 - Heard Pond NA 1.0 Reach 8 7.2 4.6 Reach 9 NA 5.4 Reach 10 NA 6.1 Charles River NA 3.1 Sudbury Reservoir NA 2.1
NA = Not available * Only adult exposures presented since child evaluated only in 2006 HHRA.
Table 15 Comparison of Estimated* Mercury Fish Ingestion Hazard Quotients with 2006 HHRA Results - Recreational Angler
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach
Hazard Quotients Adult Child
1999 2006 1999 2006 Reach 1 0.1 0.5 0.3 1.0 Reach 1 - Southville Pond NA NA NA NA Reach 1 - Cedar Swamp Pond NA NA NA NA Reach 2 NA 1.8 NA 3.5 Reach 2 - Mill Pond NA NA NA NA Reach 3 1.1 1.2 1.9 2.1 Reach 4 NA 0.7 NA 1.3 Reach 5 NA 0.4 NA 0.9 Reach 6 NA 0.7 NA 1.3 Reach 7 NA 0.5 NA 1.0 Reach 7 - Heard Pond NA 0.1 NA 0.3 Reach 8 0.7 0.7 1.3 1.3 Reach 9 NA 1.5 NA 2.8 Reach 10 NA 0.7 NA 1.4 Charles River NA 0.3 NA 0.7 Sudbury Reservoir NA 0.3 NA 0.6
NA = Not available * 1999 HQs estimated using risk ratio approach. Note: shading indicates a hazard index > 1.0.
Table 16 Comparison of Estimateda Mercury Fish Ingestion Hazard Quotients with 2006 HHRA Results - Subsistence Angler
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach Hazard Quotientsb
1999 2006 Reach 1 1.4 5.0 Reach 1 - Southville Pond NA NA Reach 1 - Cedar Swamp Pond NA NA Reach 2 NA 8.1 Reach 2 - Mill Pond NA NA Reach 3 8.4 9.1 Reach 4 NA 5.6 Reach 5 NA 4.5 Reach 6 NA 5.9 Reach 7 NA 4.9 Reach 7 - Heard Pond NA 1.2 Reach 8 6.7 6.7 Reach 9 NA 6.7 Reach 10 NA 7.0 Charles River NA 3.4 Sudbury Reservoir NA 2.5
NA = Not available a 1999 HQs estimated using risk ratio approach. b Only adult exposures evaluated. Note: shading indicates a hazard index > 1.0.
Table 17 Comparison of Estimateda Mercury Fish Ingestion Hazard Quotients with 2006 HHRA Results - Ethnic Angler
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach Hazard Quotientsb
1999 2006 Reach 1 1.2 2.8 Reach 2 NA 4.0 Reach 3 4.1 8.0 Reach 4 NA 4.8 Reach 5 NA 3.9 Reach 6 NA 5.0 Reach 7 NA 4.5 Reach 7 - Heard Pond NA 1.0 Reach 8 2.7 4.6 Reach 9 NA 5.4 Reach 10 NA 6.1 Charles River NA 3.1 Sudbury Reservoir NA 2.1
NA = Not available a 1999 HQs estimated using risk ratio approach. b Only adult exposures presented since child evaluated only in 2006 HHRA. Note: shading indicates a hazard index > 1.0.
TABLE 18
REACHES DOWNSTREAM FROM SITE VERSUS REFERENCE CONCENTRATION STATISTICAL
COMPARISONS
Reach
Site Impacted Reaches Compared with Reference Concentrations Bullhead Largemouth Bass Yellow Perch
Fillet WB Fillet WB Fillet WB Reach 1 Reference Area
2 NA NA NA NA S (A) NS (E)
5 NA NS (K) NA NA NS (K) NS (E)
7 NA NS (E) NA NA NS (E) NS(A)
10 NA NS (K) NA NA S (E) S (K)
Charles River Reference Area
8 NS (E) NS (E) S (A) S (A) S (A) S (A)
9 NS (A) NS (A) S (A) S (A) S (A) S (A)
Sudbury Reservoir Reference Area
3 S (A) S (K) S (K) S (K) S (A) S (K)
4 NS (E) NS (K) S (K) S (K) S (A) S (K)
6 S (A) S (K) S (K) S (K) S (A) S (K)
Reach 7 – Heard Pond S* (E) NS (K) S* (K) S *(K) S* (A) S* (A)
Notes:
Variances tested using Variance-Ratio Equal-Variance Test and Modified-Levene Equal Variance Test. All tests run at (α = 0.05).
A = Aspin-Welch Unequal Variance Test E = Equal Variance t-Test K = Kolmogorov-Smirnov Test for Different Distributions. NA = Not available. Insufficient sample count to complete comparison. NS = Not statistically significantly different from reference. S = Statistically significantly different from reference. Site impacted reach has mean greater than reference unless otherwise indicated.
*Reference area has greater mean.
Shading indicates site impacted reach has mean greater than reference area.
Table 19
2006 HHRA Site Versus Background Mercury Hazard Quotient Comparison Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach Ratio of Site-Impacted to Reference HQ
Recreational and Subsistence Angler Ethnic Angler Reach 1 Reference Area
2 3.4/3.7/1.6* 1.4 5 0.9 1.4 7 1.0 1.6
10 1.4 2.2 Charles River Reference Area
8 2.0 1.5 9 4.2/4.5/2.0* 1.8
Sudbury Reservoir Reference Area 3 3.7 3.8 4 2.3 2.3 6 2.4 2.3
*Recreational angler - child/Recreational angler - adult/Subsistence angler
Excel TablesTable 19 - 06 Site to Bkgd 5/5/2006
Table 20 Mercury EPC Comparison
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach/Tissue Type Exposure Point Concentrations (mg/kg wet weight)
1999 HHRA 2006 HHRA 2006:1999 Reach 1
Fillet 0.14 0.52 3.7 Whole Body 0.12 0.29 2.4
Reach 3 Fillet 0.86 0.94 1.1 Whole Body 0.42 0.82 2.0
Reach 8 Fillet 0.69 0.69 1.0 Whole Body 0.28 0.47 1.7
Table 21
Reach-Specific Summary of Risks/Hazards for Each Scenarioa
Reach Exposure Scenario/Receptor Cancer Riskb Chemicals Exceeding
1E-06 Noncancer Hazard Quotient or Index
Chemicals Exceeding 1.0
Site Impacted
2 Surface Water Exposure – Most Conservative Within range Arsenic, beryllium ≤ 1 -
Sediment Exposure – Most Conservative Within range Arsenic, PAHs, beryllium
≤ 1 -
Recreational Angler – Adult Above range PCBs >1 Mercury
Recreational Angler – Child NE - >1 Mercury
Subsistence Angler – Adult Above range Pesticides/PCBs >1 Mercury
Ethnic Angler – Adult NE - >1 Mercury
Ethnic Angler – Child NE - >1 Mercury
3 Surface Water Exposure – Most Conservative Below range - >1 Selenium
Sediment Exposure – Most Conservative Within range Arsenic, PAHs, beryllium
≤ 1 -
Recreational Angler – Adult Above range Arsenic, pesticides, PCBs
>1 Antimony, arsenic, mercury, thallium
Recreational Angler – Child NE - >1 Mercury
Subsistence Angler – Adult Above range Arsenic, pesticides, PCBs
>1 Antimony, arsenic, mercury, thallium,
zinc
Ethnic Angler – Adult NE - >1 Mercury
Ethnic Angler – Child NE - >1 Mercury
4 Surface Water Exposure – Most Conservative NA - ≤ 1 -
H:\Projects\Nyanza\Reports & Documents\HH RA Synthesis\Word Tables.doc 5/04/05
Table 21, continued
Reach-Specific Summary of Risks/Hazards for Each Scenarioa
Reach Exposure Scenario/Receptor Cancer Riskb Chemicals Exceeding
1E-06 Noncancer Hazard Quotient or Index
Chemicals Exceeding 1.0
Sediment Exposure – Most Conservative Within range Arsenic,PAHs, beryllium
≤ 1 -
Recreational Angler - Adult Within range Cadmium, bis(2-ethylhexyl)phthalate,
PCBs
≤ 1 -
Recreational Angler – Child NE - >1 Mercury
Subsistence Angler - Adult Above range Cadmium, bis(2-ethylhexyl)phthalate,
pesticides, PCBs
>1 Mercury, zinc
Ethnic Angler – Adult NE - >1 Mercury
Ethnic Angler – Child NE - >1 Mercury
5 Surface Water Exposure – Most Conservative Below range - ≤ 1 -
Sediment Exposure – Most Conservative Within range Arsenic, PAHs ≤ 1 -
Recreational Angler - Adult NE - ≤ 1 -
Recreational Angler – Child NE - ≤ 1 -
Subsistence Angler - Adult NE - >1 Mercury
Ethnic Angler – Adult NE - >1 Mercury
Ethnic Angler – Child NE - >1 Mercury
6 Surface Water Exposure – Most Conservative NA - ≤ 1c -
Sediment Exposure – Most Conservative Within range Arsenic, PAHs, beryllium
≤ 1 -
6, cont’d. Recreational Angler - Adult Within range Arsenic, pesticides, >1 Thallium
Table 21, continued
Reach-Specific Summary of Risks/Hazards for Each Scenarioa
Reach Exposure Scenario/Receptor Cancer Riskb Chemicals Exceeding
1E-06 Noncancer Hazard Quotient or Index
Chemicals Exceeding 1.0
PCBs
Recreational Angler – Child NE - >1 Mercury
Subsistence Angler - Adult Above range Arsenic, bis(2-ethylhexyl)phthalate,
pesticides, PCBs
>1 Mercury, thallium
Ethnic Angler – Adult NE - >1 Mercury
Ethnic Angler – Child NE - >1 Mercury
7 Surface Water Exposure – Most Conservative NA - ≤ 1 -
Sediment Exposure – Most Conservative Within range Arsenic, PAHs ≤ 1 -
Recreational Angler - Adult NE - ≤ 1 -
Recreational Angler – Child NE - ≤ 1 -
Subsistence Angler - Adult NE - >1 Mercury
Ethnic Angler – Adult NE - >1 Mercury
Ethnic Angler – Child NE - >1 Mercury
7 – Heard Pond Surface Water Exposure – Most Conservative NE - ≤ 1c -
Sediment Exposure – Most Conservative Within range Arsenic ≤ 1 -
Recreational Angler - Adult NE - ≤ 1 -
Recreational Angler – Child NE - ≤ 1 -
Subsistence Angler - Adult NE - >1 Mercury
Ethnic Angler – Adult NE - ≤ 1 -
Ethnic Angler – Child NE - ≤ 1 -
Table 21, continued
Reach-Specific Summary of Risks/Hazards for Each Scenarioa
Reach Exposure Scenario/Receptor Cancer Riskb Chemicals Exceeding
1E-06 Noncancer Hazard Quotient or Index
Chemicals Exceeding 1.0
8 Surface Water Exposure – Most Conservative NE - ≤ 1 -
Sediment Exposure – Most Conservative Within range Arsenic ≤ 1 -
Recreational Angler - Adult NE - ≤ 1 -
Recreational Angler – Child NE - >1 Mercury
Subsistence Angler - Adult NE - >1 Mercury
Ethnic Angler – Adult NE - >1 Mercury
Ethnic Angler – Child NE - >1 Mercury
9 Surface Water Exposure – Most Conservative NE - ≤ 1 c -
Sediment Exposure – Most Conservative Within range Arsenic ≤ 1 -
Recreational Angler - Adult Above range Methylene chloride, PAHs, PCBs
>1 Mercury
Recreational Angler – Child NE - >1 Mercury
Subsistence Angler - Adult Above range Methylene chloride, PAHs, pesticides,
PCBs
>1 Mercury
Ethnic Angler – Adult NE - >1 Mercury
Ethnic Angler – Child NE - >1 Mercury
10 Surface Water Exposure – Most Conservative NE - ≤ 1d -
Sediment Exposure – Most Conservative Within range Arsenic ≤ 1 -
Recreational Angler - Adult NE - ≤ 1 -
Recreational Angler – Child NE - >1 Mercury
Subsistence Angler - Adult NE - >1 Mercury
Table 21, continued
Reach-Specific Summary of Risks/Hazards for Each Scenarioa
Reach Exposure Scenario/Receptor Cancer Riskb Chemicals Exceeding
1E-06 Noncancer Hazard Quotient or Index
Chemicals Exceeding 1.0
10, cont’d. Ethnic Angler – Adult NE - >1 Mercury
Ethnic Angler – Child NE - >1 Mercury
Reference
1 Surface Water Exposure – Most Conservative Within range 1,1-Dichloroethylene ≤ 1 -
Sediment Exposure – Most Conservative Within range Arsenic, beryllium ≤ 1 -
Recreational Angler - Adult NE - ≤ 1 -
Recreational Angler – Child NE - ≤ 1 -
Subsistence Angler - Adult NE - >1 Antimony, mercury, selenium, thallium
Ethnic Angler – Adult NE - >1 Mercury
Ethnic Angler – Child NE - >1 Mercury
Charles River Surface Water Exposure – Most Conservative NE - ≤ 1 -
Sediment Exposure – Most Conservative NE - ≤ 1 -
Recreational Angler - Adult NE - ≤ 1 -
Recreational Angler – Child NE - ≤ 1 -
Subsistence Angler - Adult NE - >1 Mercury
Ethnic Angler – Adult NE - >1 Mercury
Ethnic Angler – Child NE - >1 Mercury
Sudbury Reservoir
Surface Water Exposure – Most Conservative NE - ≤ 1c -
Sediment Exposure – Most Conservative NE - ≤ 1 -
Table 21, continued
Reach-Specific Summary of Risks/Hazards for Each Scenarioa
Reach Exposure Scenario/Receptor Cancer Riskb Chemicals Exceeding
1E-06 Noncancer Hazard Quotient or Index
Chemicals Exceeding 1.0
Sudbury Reservoir, cont’d.
Recreational Angler - Adult Within range Arsenic, pesticides, PCBs
≤ 1 -
Recreational Angler – Child NE - ≤ 1 -
Subsistence Angler - Adult Above range Arsenic, pesticides, PCBs
>1 Mercury
Ethnic Angler – Adult NE - >1 Mercury
Ethnic Angler – Child NE - >1 Mercury
NA = Not applicable. Medium samples not available. NE = Not evaluated. No carcinogenic COPCs detected.
aHazards attributable to mercury are based on results presented in the 2006 HHRA or extrapolations from the surface water and sediment data collected during the 2003-2005 supplemental investigation; whereas risk/hazards for all other chemicals are based on the results presented in the 1992 report.
bCancer risk range = 1E-06 to 1E-04.
cMercury not detected in surface water samples collected for the 1992 HRHA and surface water samples not collected subsequently from this reach.
dMercury not detected in surface water samples collected for the 1992 HRHA and not collected from this reach during the 1993-1995 supplemental investigation. Results based on data presented in 1999 HHRA.
FIGURES
Legend:
Brooks/Streams Wetlands Scale: 1” ≅ 700’
Nyanza Chemical Dump Superfund Site Middlesex County, Massachusetts
FIGURE 1 NYANZA FACILITY MAP
F:\Projects\Nyanza\Reports & Documents\HHRA Synthesis\Figure 1-1.ppt
������
�������
�����
��������
�
S ry i er
p �r
S ry
i e r
In ian �r�
S ry i er
a et i
er
C nc r
i er
C ar
e
i er
S ry i er ater e
� 20 0 20 40 Inset -cale in Miles E H a en
� n �
ON O �air a en
E H
�ay
�arrar � n
� N O�N
i i �a e
SE ON E E S E H
�
S B
Car in Mi � n �BO O H
�ri t ear � n Mi a er � � N � n E H� n
�S ry e er ir E
� ey E S � n � ���� E H� N H �Sa� n i e
�� � n
NO HBO O H
�a e E H C c it ate� �
e ��� SO HBO O H E H N � � e ���
�i � n �ES BO O H �� e ���Ce ar SH� N S�amp E H� n Mi E H � a ac m � � n � n
E H SHE BO N
p int n e er ir e t r an e er ir e er ir ite a
e er ir
�� HO � N ON
� ����
LEGEND: Target Areas River Reaches 4000 0 4000 8000 Nyanza S perf n Site OU IV Township Boundary S ry i er Merc ry C ntaminati nPrimary 1 6 -cale in Feet-econdary 2 7County Boundary 1 0 1 23 8Watershed Boundary FIGURE 2
4 9 i -cale in Miles REACHES AND SUDBURY RIVER -udbury River Watershed 10 -ource:5Hydrography Office of Geographic and Environmental Information (MassGI-), TARGET AREAS Commonwealth of Massachusetts Executive Office of Environmental Affairs.
I C:\NYANZA\APRs\location.apr I Target Areas 11x17 I c:\nyanza\exports\out\hhra synthesis figure 2 050206.eps I 9:41 AW, 5/2/2006 I
SOURCE
PRIMARY RELEASE/
TRANSPORT MECHANISMS
PRIMARY RECEIVING
MEDIA
PRIMARY EXPOSURE
MEDIA
SECONDARY EXPOSURE
MEDIA
EXPOSURE ROUTES
Residential (Direct Contact)
Recreational (Direct Contact)
EXPOSURE SCENARIOS
Surface Runoff
Nyanza Site
Facility Fish Sudbury
River
SECONDARY RELEASE/
TRANSPORT MECHANISMS
• Surface water flow downstream
• Flooding and runoff • Sediment re-suspension and downstream transport
Surface Water
Sediment
Ingestion Riverbank Soil Erosion
••
Ingestion
•• •
•• •
Dermal Contact
•• •
•• •Ingestion
Dermal Contact
Discharge of Wastes into Chemical
Brook
Fish Consumption
Child Adult
••
Child Adult
••
Child Adult Recreational Subsistence Ethnic
Adult Child Child Teen Teen Adult
= Incomplete exposure pathway.
= Pathway/receptor was only evaluated in the 1992 HHRA. •
= Pathway/receptor was evaluated quantitatively in the 1992 HHRA and qualitatively in the 1999 HHRA. •
= Pathway/receptor was only evaluated in the 1999 and 2006 HHRAs. •
= Pathway/receptor was evaluated in all three HHRAs. •
= Pathway/receptor was evaluated qualitatively in the 2006 HHRA. •
= Pathway/receptor was evaluated quantitatively in the 2006 HHRA. •
Note: Pertains to exposures in Sudbury River proper only.
Nyanza Superfund Site Sudbury River Mercury Contamination
Figure 3 Conceptual Site Model
Human Health Risk Assessment Synthesis Document
2006 Reach 1 Reach 2 Reach 3 Reach 7 Reach 8
0
0.001
0.002
0.003
0.004
Haz
ard
Quo
tient
Nyanza Superfund Site OUIV Sudbury River Mercury Contamination
Figure 4 Comparison of “Updated” Direct Contact Total Mercury Hazard Quotients –
Surface Water
Notes:
Associated with Table 7. Shows only reaches where data available for both years.
Shows HQs derived from Tap Water RBC.
1999
Notes: Reach 1 – Headwaters to Pleasant Street Impoundment; Reach 2 - Pleasant Street Impoundment to Union Street Bridge; Reach 3 -Reservoir No. 2; Reach 7 - Saxonville Dam to Route 20 overpass; Reach 8 -Route 20 overpass to the Route 117 overpass (includes Great Meadows National Wildlife Refuge).
2006 1999 1992
Reach
1 Rea
ch2
Reach
3 Rea
ch 4 Rea
ch 5 Rea
ch 6 Rea
ch7
Reach
8 Rea
ch9
Reach 10
0
0.1 0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Haz
ard
Quo
tient
Nyanza Superfund Site OUIV Sudbury River Mercury Contamination
Figure 5 Comparison of 1992 and “Updated” 1999 and 2006 Direct Contact Total
Mercury Hazard Quotients – Sediment
Notes: Reach 1 – Headwaters to Pleasant Street Impoundment; Reach 2 - Pleasant Street Impoundment to Union Street Bridge; Reach 3 -Reservoir No. 2; Reach 4 - Reservoir No. 1; Reach 5 - Reservoir No. 1 dam to Massachusetts Turnpike overpass; Reach 6 - Turnpike overpass to the Saxonville Dam; Reach 7 - Saxonville Dam to Route 20 overpass; Reach 8 - Route 20 overpass to the Route 117 overpass (includes Great Meadows National Wildlife Refuge); Reach 9 - Fairhaven Bay; Reach 10 - Fairhaven Bay outlet to the Sudbury/Assabet River confluence.
Notes:
Associated with Table 8. Shows only Reaches/reference areas where data available for at least 2 years.
Shows HQs derived from 1992 child receptor and “Updated” 1999 and 2006 HQs based on SSL.
HQs for Reach 1 from the 1992 report include data from the Sudbury Reservoir.
1992 1999 2006
Reach
1 Rea
ch 3 Rea
ch 4 Rea
ch6
Reach 8
Reach
9 Sud
buryRes
.
0
1
2
3
4
5
Haz
ard
Quo
tient
Nyanza Superfund Site OUIV Sudbury River Mercury Contamination
Figure 6 Comparison of Mercury Hazard Quotients – Recreational Angler
Fish Ingestion - Adult
Notes: Reach 1 – Headwaters to Pleasant Street Impoundment; Reach 3 -Reservoir No. 2; Reach 4 - Reservoir No. 1; Reach 6 - Turnpike overpass to the Saxonville Dam; Reach 8 - Route 20 overpass to the Route 117 overpass (includes Great Meadows National Wildlife Refuge); Reach 9 - Fairhaven Bay.
Notes:
Associated with Table 12. Shows only Reaches/reference areas where data available for at least 2 years.
1999
2006
Reach
1
Reach
3
Reach 8
0
0.5
1
1.5
2
2.5
Haz
ard
Quo
tient
Nyanza Superfund Site OUIV Sudbury River Mercury Contamination
Figure 7 Comparison of Mercury Hazard Quotients – Recreational Angler
Fish Ingestion - Child
Notes:
Associated with Table12. Shows only Reaches/reference areas where data available for at least 2 years.
Notes: Reach 1 – Headwaters to Pleasant Street Impoundment; Reach 3 -Reservoir No. 2; Reach 8 - Route 20 overpass to the Route 117 overpass (includes Great Meadows National Wildlife Refuge).
1992
1999 2006
Reach 1
Reach 3
Reach
4 Rea
ch 6
Reach
8 Rea
ch9
Sudbury R
es.
0 5
10
15
20
25
30
35
Haz
ard
Quo
tient
Nyanza Superfund Site OUIV Sudbury River Mercury Contamination
Figure 8 Comparison of Mercury Hazard Quotients – Subsistence Angler
Fish Ingestion - Adult
Notes: Reach 1 – Headwaters to Pleasant Street Impoundment; Reach 3 -Reservoir No. 2; Reach 4 - Reservoir No. 1; Reach 6 - Turnpike overpass to the Saxonville Dam; Reach 8 - Route 20 overpass to the Route 117 overpass (includes Great Meadows National Wildlife Refuge); Reach 9 - Fairhaven Bay.
Notes:
Associated with Table 13. Shows only Reaches/reference areas where data available for at least 2 years.
1999
2006
Reach
1
Reach 3
Reach
8 0
2
4
6
8
10
12
Haz
ard
Quo
tient
Nyanza Superfund Site OUIV Sudbury River Mercury Contamination
Figure 9 Comparison of Mercury Hazard Quotients – Ethnic Angler Fish Ingestion -
Adult
Notes:
Associated with Table 14. Shows only Reaches/reference areas where data available for at least 2 years.
Notes: Reach 1 – Headwaters to Pleasant Street Impoundment; Reach 3 -Reservoir No. 2; Reach 8 - Route 20 overpass to the Route 117 overpass (includes Great Meadows National Wildlife Refuge).
Nyanza Superfund Site OUIV Sudbury River Mercury Contamination
Figure 10 Distribution of Total Mercury (ΣHg) Concentrations in Fish Fillets
Legend:
y
Maximum
Minimum
75th Percentile
Median 25th Percentile
0.00E+00
5.00E-01
1.00E+00
1.50E+00
2.00E+00 ΣH
g C
once
ntra
tion
(mg/
kg w
et w
eigh
t)
2.5E-01
7.5E-01
Charles River
Sudbury Reservoir
Reach 1
Reach 2
Reach 3
Reach 4
Reach 5
Reach 6
Reach 7
Reach 8
Reach 9
Reach 10
Reach 7 - HP
Background
Notes: Reach 1 – Headwaters to Pleasant Street Impoundment; Reach 2 - Pleasant Street Impoundment to Union Street Bridge; Reach 3 -Reservoir No. 2; Reach 4 - Reservoir No. 1; Reach 5 - Reservoir No. 1 dam to Massachusetts Turnpike overpass; Reach 6 - Turnpike overpass to the Saxonville Dam; Reach 7 - Saxonville Dam to Route 20 overpass; Reach 7 – HP = Heard Pond; Reach 8 - Route 20 overpass to the Route 117 overpass (includes Great Meadows National Wildlife Refuge); Reach 9 - Fairhaven Bay; Reach 10 - Fairhaven Bay outlet to the Sudbury/Assabet River confluence.
0.00E+00
5.00E-01
1.00E+00
1.50E+00
2.00E+00 ΣH
g C
once
ntra
tion
(mg/
kg w
et w
eigh
t)
2.5E-01
7.5E-01
Charles River
Sudbury Reservoir
Reach 1
Reach 2
Reach 3
Reach 4
Reach 5
Reach 6
Reach 7
Reach 8
Reach 9
Reach 10
Reach 7 - HP
Background
Nyanza Superfund Site OUIV Sudbury River Mercury Contamination
Figure 11 Distribution of Total Mercury (ΣHg) Concentrations in Wholebody Fish
Legend:
y
Maximum
Minimum
75th Percentile
Median 25th Percentile
Notes: Reach 1 – Headwaters to Pleasant Street Impoundment; Reach 2 - Pleasant Street Impoundment to Union Street Bridge; Reach 3 -Reservoir No. 2; Reach 4 - Reservoir No. 1; Reach 5 - Reservoir No. 1 dam to Massachusetts Turnpike overpass; Reach 6 - Turnpike overpass to the Saxonville Dam; Reach 7 - Saxonville Dam to Route 20 overpass; Reach 7 – HP = Heard Pond; Reach 8 - Route 20 overpass to the Route 117 overpass (includes Great Meadows National Wildlife Refuge); Reach 9 - Fairhaven Bay; Reach 10 - Fairhaven Bay outlet to the Sudbury/Assabet River confluence.
ΣHg
Con
cent
ratio
n (m
g/kg
wet
wei
ght)
0.00E+00
5.00E-01
1.00E+00
1.50E+00
2.00E+00
Reach 1 Reach 1 Reach 3 Reach 3 Reach 8 Reach 8 1993/1994 2003 1993/1994 2003 1993/1994 2003
Legend: 75th Percentile
25th Percentile y
Maximum
Minimum
Median
Nyanza Superfund Site OUIV Sudbury River Mercury Contamination
Figure 12 Distribution of Total Mercury (ΣHg) Concentrations in Fish Fillets – 1993-1994 and
2003 Data Sets
Note: Reach 1 – Reference Area – Headwaters to Pleasant Street Impoundment Reach 3 – Reservoir 2 Reach 8 – Great Meadows National Wildlife Refuge
ΣHg
Con
cent
ratio
n (m
g/kg
wet
wei
ght)
0.00E+00
5.00E-01
1.00E+00
1.50E+00
2.00E+00
2.50E+00
2.50E-01
7.50E-01
Reach 1 Reach 1 Reach 3 Reach 3 Reach 8 Reach 8 1993/1994 2003 1993/1994 2003 1993/1994 2003
Legend: 75th Percentile
25th Percentile y
Maximum
Minimum
Median
Nyanza Superfund Site OUIV Sudbury River Mercury Contamination
Figure 13 Distribution of Total Mercury (ΣHg) Concentrations in Whole Body Fish – 1993-
1994 and 2003 Data Sets
Note: Reach 1 – Reference Area – Headwaters to Pleasant Street Impoundment Reach 3 – Reservoir 2 Reach 8 – Great Meadows National Wildlife Refuge
APPENDIX A
Table A-1
Summary of the Data Collected for Use in the 1992 HHRA Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach
# Samples Collected for Mercury Analysis
Surface Water Sediment Fish - Fillets
Species Number Reach 1 - Cedar Swamp Pond - - Largemouth Bass
Yellow Perch 7 10
Reach 1 - Southville Pond - - Largemouth Bass 7 Reach 2 7 9 -Reach 2 - Mill Pond - - Largemouth Bass
Yellow Perch 20 10
Reach 3 5 22 Largemouth Bass Yellow Perch
Bullhead
34 16 7
Reach 4 1 12 Largemouth Bass Yellow Perch
Bullhead
30 21 9
Reach 5 1 6 -Reach 6 3 20 Largemouth Bass
Yellow Perch Bullhead
23 20 4
Reach 7 4 13 -Reach 7 - Heard Pond - 1 -Reach 8 - 5 -Reach 9 - 2 Largemouth Bass
Yellow Perch 20 10
Reach 10 - 5 -
Table A-2
Summary of Hazard Indices and Cancer Risks from Direct Contact Exposure to Surface Water* 1992 Final Remedial Investigation Report
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach Hazard Index Cancer Risk Reach 1 and Sudbury Reservoir 0.0086 1.7E-06 Reach 2 0.15 1.3E-05 Reach 3 3.8 4.7E-09 Reach 4 0.0025 ---Reach 5 0.0049 6.8E-07 Reach 6 0.0019 ---Reach 7 0.0037 ---
Note: shading indicates a hazard index > 1.0 and/or a cancer risk ≥ 1E-06. * Based on most conservative exposure. I.e., child recreational noncancer and lifetime cancer risk.
Table A-3
Summary of Hazard Indices and Cancer Risks from Direct Contact Exposure to Sediment* 1992 Final Remedial Investigation Report
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach Hazard Index Cancer Risk Reach 1 and Sudbury Reservoir 0.23 1.8E-05 Reach 2 0.39 6.6E-05 Reach 3 0.69 9.0E-05 Reach 4 0.33 3.0E-05 Reach 5 0.15 1.4E-05 Reach 6 0.38 4.2E-05 Reach 7 0.41 4.1E-05 Reach 7 - Heard Pond 0.11 7.1E-06 Reach 8 0.33 2.0E-05 Reach 9 0.48 4.2E-05 Reach 10 0.092 8.0E-06
Note: shading indicates a hazard index > 1.0 and/or a cancer risk ≥ 1E-06. * Based on most conservative exposure. I.e., child recreational noncancer and lifetime cancer risk.
Table A-4
Summary of Hazard Indices and Cancer Risks from Fish Ingestion - Recreational Angler Exposure 1992 Final Remedial Investigation Report
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach Hazard Index Cancer Risk Reach 1
Cedar Swamp Pond 6.9 ---Southville Pond 0.58 ---
Reach 2 Mill Pond 1.2 3.1E-04
Reach 3 17 7.6E-04 Reach 4 3.0 8.8E-05 Reach 6 4.7 1.0E-04 Reach 9 2.2 3.6E-04 Sudbury Reservoir 0.93 6.9E-05
Note: shading indicates a hazard index > 1.0 and/or a cancer risk ≥ 1E-06.
Table A-5
Summary of Hazard Indices and Cancer Risks from Fish Ingestion - Subsistence Angler Exposure 1992 Final Remedial Investigation Report
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach Hazard Index Cancer Risk Reach 1
Cedar Swamp Pond 51 ---Southville Pond 4.2 ---
Reach 2 Mill Pond 9.1 2.2E-03
Reach 3 120 5.5E-03 Reach 4 22 6.4E-04 Reach 6 34 7.5E-04 Reach 9 16 2.6E-03 Sudbury Reservoir 8.9 5.0E-04
Note: shading indicates a hazard index > 1.0 and/or a cancer risk ≥ 1E-06.
Table A-6
Summary of the Contribution of Mercury to the Hazard Indices for Recreational and Subsistence Anglers 1992 Final Remedial Investigation Report
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach
Recreational Angler Subsistence Angler
Total HI Mercury HQ Percent
Contribution Total HI Mercury HQ Percent
Contribution Reach 1
Cedar Swamp Pond 6.9 5.9 86% 51 43 84% Southville Pond 0.6 0.55 95% 4.2 4.0 95%
Reach 2 Mill Pond 1.2 1.2 100% 9.1 9.0 99%
Reach 3 17.0 4.7 28% 120 34 28% Reach 4 3.0 2.6 87% 22 19 86% Reach 6 4.7 1.1 23% 34 8.1 24% Reach 9 2.2 2.0 91% 16 14 88% Sudbury Reservoir 0.9 0.73 78% 8.9 5.3 60%
Table A-7
Summary of the Data Used in the 1999 HHRA Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach
# Samples Collected
Surface Water Sediment Fish
Species Fillet* Whole Body Reach 1 18 15 Black Crappie
Bluegill Largemouth Bass
17 10 17
5 20 -
Reach 1 - Whitehall Reservoir 34 20 -Reach 2 16 3 -Reach 2 - Mill Pond 10 - -Reach 3 36 19 Bullhead
Largemouth Bass Yellow Perch
10 29 9
--
20 Reach 4 - 13 -Reach 6 - 3 -Reach 7 11 1 -Reach 8 23 16 Black Crappie
Bluegill Largemouth Bass
11 10 30
5 20 -
Reach 9 - 34 -Reach 10 1 2 -
*Concentrations from fillet or whole body less gut or stomach. Not noted if skin off or on.
c
Table A-8
Comparison of Surface Water Exposure Point Concentrations with Risk-Based Concentrations and Maximum Contaminant Levels Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Chemical
Lower of the 95% UCL and the Maximum
Concentration (µg/L)
for Tap Watera
(µg/L)
Risk-Based Concentration (RBC) Ratio of Water
Concentration and RBC
Maximum Contaminant Level (MCL) b
(µg/L)
Ratio of Water Concentration
and MCL Reach 1
Mercury 2.53E-03 1.10E+01 c 2.30E-04 2.00E+00 1.27E-03 Methylmercury 3.00E-04 3.70E+00 8.11E-05 NA NC
Reach 2 Mercury 2.00E-02 1.10E+01 c 1.82E-03 2.00E+00 1.00E-02 Methylmercury 3.34E-04 3.70E+00 9.03E-05 NA NC
Reach 3 Mercury 1.00E-02 1.10E+01 c 9.09E-04 2.00E+00 5.00E-03 Methylmercury 2.71E-04 3.70E+00 7.32E-05 NA NC
Reach 7 Mercury 1.00E-02 1.10E+01 c 9.09E-04 2.00E+00 5.00E-03 Methylmercury 1.42E-04 3.70E+00 3.84E-05 NA NC
Reach 8 Mercury 2.00E-02 1.10E+01 c 1.82E-03 2.00E+00 1.00E-02 Methylmercury 5.79E-04 3.70E+00 1.57E-04 NA NC
Reach 10 Mercury 6.07E-03 1.10E+01 c 5.52E-04 2.00E+00 3.04E-03 Methylmercury 2.31E-04 3.70E+00 6.24E-05 NA NC
a U.S. EPA Region III, 1998. Risk-based Concentration Tables . April, 1998. b U.S. EPA, 1996. Drinking Water Regulations and Health Advisories.
Mercuric chloride value.
human health\7_98\Appendix Tables 5/5/2006 12:42 PM
Table A-9
1999 HHRA Hazard Quotient Summary* Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Exposure Area Recreational Angler Subsistence Angler Ethnic Angler
Child Adult Adult Adult Reach 1 Reach 3 Reach 8
0.13 0.78 0.62
0.27 1.6 1.3
3.7 22 18
3.1 11 7.2
* Mercury was the only COPC.
Table A-10
Summary of the Available for Use in the 2006 HHRA Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach Species # Samples Collected
Fillet Offal Whole Body 1 Largemouth Bass 11 3 -
White Sucker - - 8 Yellow Bullhead 2 2 2
Yellow Perch 14 3 5 2 Brown Bullhead - - 3
Largemouth Bass 10 6 -White Sucker - - 4 Yellow Perch 5 2 5
3 Brown Bullhead 7 3 -Largemouth Bass 10 4 -Yellow Bullhead 3 1 -
Yellow Perch 13 3 13 4 Brown Bullhead 5 1 -
Largemouth Bass 10 3 -Yellow Bullhead 5 3 5
Yellow Perch 15 4 13 5 Brown Bullhead 10 2 -
Largemouth Bass 11 4 -Yellow Bullhead 1 1 3
Yellow Perch 14 3 3 6 Brown Bullhead 1 1 -
Largemouth Bass 11 3 -Yellow Bullhead 9 2 -
Yellow Perch 14 3 13 7 Brown Bullhead 4 2 -
Largemouth Bass 13 4 -Yellow Bullhead 6 1 -
Yellow Perch 14 4 13 7 - Heard Pond Largemouth Bass 10 3 -
Yellow Bullhead 10 3 -Yellow Perch 10 3 13
8 Bluegill - - 5 Brown Bullhead 7 4 -
Largemouth Bass Yellow Bullhead
11 6 -7 2 -
Yellow Perch 17 7 30 9 Brown Bullhead 10 3 -
Largemouth Bass 11 3 -Yellow Perch 14 3 13
10 Brown Bullhead 7 1 -Largemouth Bass 11 3 -Yellow Bullhead 4 2 -
Yellow Perch 14 3 13 Charles River Brown Bullhead 2 2 -
Largemouth Bass 10 3 -Yellow Bullhead 8 1 -
Yellow Perch 13 3 13 Sudbury Reservoir Brown Bullhead 2 1 -
Largemouth Bass 9 2 -Yellow Bullhead 7 2 -
Yellow Perch 14 3 13
Appendix Tables A-10 - 06 Samples
Table A-11
2006 HHRA Hazard Quotient Summary*
Operable Unit IV - Nyanza Chemical Dump Superfund Site - Middlesex County, Massachusetts
Reach
Site Impacted RME Hazard Quotient
Recreational Angler Subsistence Angler Ethnic Angler
Child Adult Adult Child Adult
Reach 2 3.5 1.8 8.1 7.5 4.0
Reach 3 2.1 1.2 9.1 15 8.0
Reach 4 1.3 0.7 5.6 8.9 4.8
Reach 5 0.9 0.4 4.5 7.2 3.9
Reach 6 1.3 0.7 5.9 9.3 5.0
Reach 7 1.0 0.5 4.9 8.3 4.5
Reach 7 - Heard Pond 0.3 0.1 1.2 1.8 1.0
Reach 8 1.3 0.7 6.7 8.6 4.6
Reach 9 2.8 1.5 6.7 10 5.4
Reach 10 1.4 0.7 7.0 11 6.1
*Mercury was the only COPC.
Appendix TablesA-11 - 06 Results 5/5/2006