draft human health risk assessment (hhra) synthesis

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.


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.


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).


� 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.


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.


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


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


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


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.


� 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.


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


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.


� 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:


� 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.


� 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


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


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


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.


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


presented in Table 2. A summary of the data used in the 1999 SBHHRA is presented in

Appendix A, Table A-7.


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.


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


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


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.


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



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.


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


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.


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.


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.


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


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.


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


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


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


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


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


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


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


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)


� 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.


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.


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.


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.


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)


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.


Table 1


(Continued)


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.


Table 1


(Continued)


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.


Table 2


(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


(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


(Continued)



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


(Continued)



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


(Continued)



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


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



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



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


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









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


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


Reach 3 NA 0.0019 NA 0.0019


Reach 4 0.0027 0.00097 0.0027 0.00094


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


Reach 7 NA 0.00061 NA 0.00059


Reach 8 0.00034 0.00023 0.00033 0.00022


Reach 9 0.0016 0.00067 0.0016 0.00065


Reach 10 NA 0.00044 NA 0.00043


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


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


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


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


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


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


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


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


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


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


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


≤ 1 -

Recreational Angler – Adult Above range Arsenic, pesticides, PCBs

>1 Antimony, arsenic, mercury, thallium


Subsistence Angler – Adult Above range Arsenic, pesticides, PCBs

>1 Antimony, arsenic, mercury, thallium,

zinc



4 Surface Water Exposure – Most Conservative NA - ≤ 1 -


Table 21, continued





Sediment Exposure – Most Conservative Within range Arsenic,PAHs, beryllium

≤ 1 -

Recreational Angler - Adult Within range Cadmium, bis(2-ethylhexyl)phthalate,

PCBs

≤ 1 -


Subsistence Angler - Adult Above range Cadmium, bis(2-ethylhexyl)phthalate,

pesticides, PCBs

>1 Mercury, zinc



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



6 Surface Water Exposure – Most Conservative NA - ≤ 1c -


≤ 1 -

6, cont’d. Recreational Angler - Adult Within range Arsenic, pesticides, >1 Thallium

Table 21, continued





PCBs


Subsistence Angler - Adult Above range Arsenic, bis(2-ethylhexyl)phthalate,

pesticides, PCBs

>1 Mercury, thallium



7 Surface Water Exposure – Most Conservative NA - ≤ 1 -

Sediment Exposure – Most Conservative Within range Arsenic, PAHs ≤ 1 -






7 – Heard Pond Surface Water Exposure – Most Conservative NE - ≤ 1c -

Sediment Exposure – Most Conservative Within range Arsenic ≤ 1 -




Ethnic Angler – Adult NE - ≤ 1 -

Ethnic Angler – Child NE - ≤ 1 -

Table 21, continued





8 Surface Water Exposure – Most Conservative NE - ≤ 1 -







9 Surface Water Exposure – Most Conservative NE - ≤ 1 c -


Recreational Angler - Adult Above range Methylene chloride, PAHs, PCBs

>1 Mercury


Subsistence Angler - Adult Above range Methylene chloride, PAHs, pesticides,

PCBs

>1 Mercury



10 Surface Water Exposure – Most Conservative NE - ≤ 1d -





Table 21, continued





10, cont’d. Ethnic Angler – Adult 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 -



Subsistence Angler - Adult NE - >1 Antimony, mercury, selenium, thallium



Charles River Surface Water Exposure – Most Conservative NE - ≤ 1 -

Sediment Exposure – Most Conservative NE - ≤ 1 -






Sudbury Reservoir

Surface Water Exposure – Most Conservative NE - ≤ 1c -

Sediment Exposure – Most Conservative NE - ≤ 1 -

Table 21, continued





Sudbury Reservoir, cont’d.

Recreational Angler - Adult Within range Arsenic, pesticides, PCBs

≤ 1 -


Subsistence Angler - Adult Above range Arsenic, pesticides, PCBs

>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


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


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:


1999

2006

Reach

1

Reach

3

Reach 8

0

0.5

1

1.5

2

2.5

Haz

ard

Quo

tient


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


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:


1999

2006

Reach

1

Reach 3

Reach

8 0

2

4

6

8

10

12

Haz

ard

Quo

tient


Figure 9 Comparison of Mercury Hazard Quotients – Ethnic Angler Fish Ingestion -

Adult

Notes:


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).


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


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


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


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


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


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


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


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


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





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


Largemouth Bass 11 4 -Yellow Bullhead 1 1 3


Largemouth Bass 11 3 -Yellow Bullhead 9 2 -



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 -


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 -


Yellow Perch 13 3 13 Sudbury Reservoir Brown Bullhead 2 1 -


Yellow Perch 14 3 13

Appendix Tables A-10 - 06 Samples

Table A-11

2006 HHRA Hazard Quotient Summary*


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