Complete Report for Printing
Get Report as PDF File
|
Jeffery A. Foran, Ph.D. on The Draft Baseline Human Health and Ecological Risk Assessment
for the Lower Fox River and Green Bay 10 December 2001
1.0 Risk Assessment Review and Analysis 1.1. Human Health Risk Assessment - Overview PCBs, as well as other contaminants in the Fox River and Green Bay pose significant risks to human health. PCB exposure occurs from a variety of sources and routes including consumption of contaminated fish, consumption of contaminated wildlife, consumption of water, inhalation of aerosols containing PCBs and other contaminants, and dermal contact with contaminated water via recreational and occupational activities. The health effects of exposure to PCBs have been well documented (ATSDR 2000) and occur in two fundamental categories – cancer and non-cancer effects. PCBs are suspected of causing a variety of cancers in humans who have been exposed occupationally. There are also indications that some subgroups of women exposed to PCBs in the environment may be at increased risk for breast cancer. There is conclusive evidence that PCBs cause cancer in a variety of non-human animals and in a variety of organ systems. Combination of information from cancer studies of humans and non-human animals has led the U.S. EPA to classify PCBs as probable human carcinogens. Non-cancer effects of exposure to PCBs include an array of adverse health outcomes including effects on various human organs and systems such as eyes (ocular effects), kidneys (renal effects), and hormones (endocrine effects), developmental effects, neurological effects, immunological effects, reproductive effects, and genotoxic effects. A recent body of scientific evidence has also raised significant concern with a variety of non-cancer effects in the fetus and in young children exposed to PCBs. A thorough discussion of the adverse health effects of exposure to PCBs can be found in the ATSDR’s Toxicological Profile for Polychlorinated Biphenyls (ATSDR 2000), and at www.foxriverwatch.com. The Fox River/Green Bay Baseline Human Health Risk Assessment (FR/GB BLHHRA) indicates that many residents of the region are subjected to significant cancer and non-cancer risks associated with exposure to PCBs. Of particular concern are the extremely high cancer risks that occur in individuals who consume fish from the system. Cancer risks in recreational and high-intake fish consumers are greater than 1X10-3 (one excess cancer attributable to PCB exposure in every 1000 exposed individuals). This cancer rate is approximately equal to the cancer rate experienced by individuals who smoke two or three packs of cigarettes a day. It is also 100 to 1000 times greater than cancer risks commonly determined to be "acceptable" by state and federal agencies, and more than one 10 times greater than cancer risks that have triggered stringent regulation of pollutant sources by the U.S. EPA. These risk levels, while disturbing in their own right, should be of additional concern because of the large number individuals who face these risks. The BLHHRA estimates that there are upwards of 14,000 highly exposed recreational anglers in the Fox River/Green Bay region. Many family members of these anglers are also likely exposed to PCBs at similar levels. Additionally, 12,000 individuals are considered high-intake consumers from under-represented groups including low-income minority anglers, Hmong anglers, and members of the Oneida band living in the region. Therefore, assuming that for every highly exposed recreational angler there is one highly exposed family member, the total population facing cancer risks in excess of 1X10-3 approaches 40,000 individuals. Fish consumers are not the only individuals who face elevated cancer risks from PCB exposure. Hunters, through consumption of contaminated wildlife, face cancer risks approaching 1X10-4, a level deemed "unacceptable" by both state and federal regulatory agencies. Other exposures (drinking water, recreational exposure, occupational – marine workers) are also associated with cancer risks, although these risks are relatively low compared with risks associated with consumption of contaminated fish and wildlife. The risk of adverse, non-cancer effects in individuals exposed to PCBs through fish consumption or other routes is also significant. Risks for non-cancer effects are typically assessed quantitatively via a Hazard Index (HI) approach. Simply stated, Hazard Indices of less than 1 indicate that there is a relatively low risk of experiencing non-cancer effects from PCB exposure, while Hazard Indices greater than 1 indicate an increasing risk of non-cancer effects. Stated another way – the lower the HI, the lower the likelihood of an adverse effect, the greater the HI, the greater the likelihood of an adverse effect. As with cancer risks, high intake and recreational fish consumers face the highest Hazard Indices, ranging from 10 to nearly 100. Hunters who consume their catch also face hazard indices greater than 10, while other exposure routes (drinking water, etc.) result in hazard indices of less than 1 but greater than 0.1. 1.2 Human Health Risk Assessment – Analysis Human health risk assessments require information on human exposure to one or more contaminants, and information on the toxicity of specific contaminants such as PCBs. The FR/GB BLHHRA relies heavily on published information on human exposure to and toxicity of PCBs. This approach is both appropriate and necessary, since conducting new exposure and toxicity evaluations is immensely time consuming and cost prohibitive. At the same time, the approach requires selection of data and information from numerous studies, many of which provide different quantitative evaluations of exposure and toxicity. In these cases, the assessment must evaluate the quality of toxicity and exposure data, and choose which data to rely on for the analysis. The FR/GB BLHHRA cites many of the pertinent studies of PCBs that provide information on toxicity and exposure. It also attempts to choose data that reflect the range of toxicity and exposure estimates. 1.2.1 Exposure The BLHHRA evaluates a variety of studies of fish consumption behaviors in recreational anglers and subsistence (high-intake) fish consumers. These studies provide a range of fish consumption rates, and the BLHHRA has chosen a subset of rates from these studies. Unfortunately, the BLHHRA does not rely on a full range of fish consumption rates, nor does it incorporate the "high-end" consumption rates into the risk assessment for cancer and non-cancer effects. The BLHHRA uses fish consumption estimates to calculate cancer and non-cancer risks for recreational anglers that range from 4,086 g/yr (central tendency estimate - CTE) to 13,393 g/yr (reasonable maximum estimate - RME), and consumption estimates for high-intake fish consumers that range from 6,129 g/yr (CTE) to 20,203 g/yr (Sections 5.4.3, pages 5-22 to 5-24). However, West et al. (1993), as cited in the BLHHRA, reports fish consumption rates in recreational anglers as high as 28,490 g/yr (RME), and rates in high-intake fish consumers that range from 15,695 g/yr (CTE) to 40,150 g/yr (RME). West’s high-end fish consumption rates for recreational and high-intake fish consumers are more two times greater than "high-end" rates chosen for the BLHHRA. Similarly, the BLHHRA incorporates assumptions about how a fish are cleaned and cooked. Cleaning and cooking may reduce the quantities of PCBs in fish; thus, human exposure to PCBs may be reduced with appropriate cleaning and cooking practices. However, as cited in the BLRA (Volume 1, Section 5.2, page 5-6), many individuals do not clean and cook their fish in ways that reduce PCBs in fish tissue; thus, these individuals will be exposed to higher PCB concentrations. Despite this information, the BLHHRA uses a PCB "reduction factor" of 50% based on the assumption that individuals practice appropriate cleaning and cooking procedures. Finally, the BLHHRA acknowledges (BLRA, Volume 1, Section 5.2, page 5-8) but then disregards that fact that at least some individuals who fish and consume their catch also hunt and consume their game, drink contaminated water, and are exposed to PCBs via recreational and occupational activities. These would clearly be the highest exposed individuals, but are not accounted for in the development of quantitative estimates of exposure and health risks. 1.2.2. Toxicity The Baseline Human Health Risk Assessment uses a standard approach to the assessment of PCB toxicity. It follows U.S. EPA guidance for the evaluation, selection, and use of toxicity studies in the risk assessment. It also appropriately considers concurrent exposure to PCBs and other toxicants such as dioxin, through use of toxicity equivalency factors (TEF) and additivity assumptions (for toxicity) in risk calculations. The BLHHRA appropriately acknowledges the extensive animal evidence as well as less extensive human epidemiological data that support conclusions of human cancer risk. However, the BLHHRA improperly states (BLRA, Volume 1, Section 5.6.2, page 5-60): "It is also important to note that some studies have concluded that PCBs are not carcinogenic in humans based upon negative epidemiological studies." Negative human epidemiological studies are incapable of proving that PCBs are not human carcinogens. In fact, most scientific studies in general are incapable of proving a negative assertion. The BLHHRA acknowledges appropriately the significant limitations of the Kimbrough study. But on a broader scale, negative epidemiological studies, which are quite common, are virtually never used to "prove" that a substance is not a human carcinogen. Human epidemiological studies typically lack adequate power to identify adverse effects occurring in populations at relatively low levels or frequencies. This is due to the very large sample or population size required to provide adequate statistical power to detect rare or uncommon events. Therefore, it is completely inappropriate to declare that a negative epidemiological study proves or concludes that PCBs don’t cause human cancer, and the language on page 5-60 of the BLHHRA should be modified accordingly. The BLHHRA describes the use of the reference dose (RfD) in Section 5.7.1, page 5-80. This description is not consistent with the U.S. EPA definition of the RfD (upon which the BLHHRA relies heavily), and as such is misleading. The description of the RfD should state: Finally, the BLHHRA is lacking in that it does not address the potential for, and in some cases evidence of synergism when assessing the risks of concurrent exposure to multiple toxicants. For example, research indicates that PCBs and mercury, and PCBs and DDE act synergistically in affecting a variety of biological functions such as neurological development and survival (Bemis and Seegal 1999, Wren et al. 1987). PCB co-occurs with mercury and DDE throughout the Fox River/Green Bay system, but the BLHHRA does not address the potential for synergistic toxicity among these contaminants. 1.3. Ecological Risk Assessment – Overview The goal of the Baseline Ecological Risk Assessment (BLERA) is to determine whether there are ecological risks in the Fox River/Green Bay system at levels that warrant remedial action of stressors causing those risks. A standard, although somewhat simplistic, approach (U.S. EPA 1997) was used to conduct the BLERA for the Fox River/Green Bay system. This approach is driven by the questions posed in the problem formulation stage of the RA. These questions take the following form: For each measurement and/or assessment endpoint (e.g., fish survival andMeasurement and assessment endpoints were developed for a variety of species, populations, and communities including water column and benthic invertebrates; benthic and pelagial fish; insectivorous, piscivorous, and carnivorous birds; and piscivorous mammals. Exposure to and effects of site contaminants were assessed at lower levels of biological organization (e.g., benthic insects) via Sediment Effects Concentrations, and at higher levels of biological organization via modeling. Toxicity Reference Values (TRVs) for each level of biological organization were established from the chemical-specific No-Observed-Adverse-Effect-Concentration (NOAEC) and the Lowest-Observed-Adverse-Effect-Concentration (LOAEC). For example, a NOAEC TRV of 0.05 ug/L total PCBs was used for aquatic invertebrates, while a Sediment Effect Concentration of 31.6 ug/kg dry wt. total PCBs was used for benthic invertebrates. Similarly, a NOAEC TRV of 0.76 mg/kg total PCBs was used for pelagic fish species. TRVs were established for the following contaminants: PCBs (total and specific congeners), mercury, arsenic, lead, DDT and metabolites, dieldrin, and dioxins (2,3,7,8 TCDD/TCDF). To assess risk for each assessment endpoint, the concentration of a contaminant in the ambient environment or in a biological medium (e.g., fish tissue) was compared with safe levels of the contaminant in the medium or in tissue (determined, for example, by the NOAEC TRV). The ratio of the two concentrations is the Hazard Quotient. There is no risk where the HQ based on the NOAEC is less than one. Potential risk for an assessment/measurement endpoint exists where the LOAEC HQ is less than and the NOAEC is greater than 1. Risk increases as the LOAEC HQ increases above 1. Significant ecological risks occur at virtually all levels of biological organization and for all assessment/measurement endpoints throughout the Fox River/Green Bay system. Hazard Quotients are elevated above 1 for: Fish exposed to PCBs, mercury, DDD/DDE; Birds exposed to PCBs, DDE, mercury, dieldrin; Mammals exposed to PCBs and dieldrin. The magnitude of ecological risks is considerable, ranging higher than 350 for mink exposed to PCB in the lower Fox River and Green Bay. Other highly elevated risks include: Mink exposed to PCBs in Little Lake Butte des Morts (HQ > 170)Hazard quotients for fish-eating birds are about 10 times lower than mink HQs, but still elevated about 1 indicating significant risks throughout the Fox River/Green Bay system. 1.4. Ecological Risk Assessment – Analysis The Baseline Ecological Risk Assessment (BLERA) provides an overview of the risks to ecological receptors in the Fox River/Green Bay system associated with exposure to selected chemicals. The report acknowledges that the Hazard Quotient approach used to assess risk can be overly simplistic and potentially unrepresentative of actual risks experienced in the field. Therefore, field validation of HQ-based risk estimates was conducted, and confirmed that adverse ecological effects have indeed occurred in the Fox River and Green Bay. The HQ-based approach to risk assessment for chemicals of concern is relatively thorough and generally follows U.S. EPA guidelines for the conduct of ecological risk assessments. However, the BLERA falls far short of a comprehensive assessment and, as such, is likely not conservative in that it ignores the issue of concurrent impacts of multiple chemical and non-chemical stressors. The U.S. EPA as well as many non-EPA scientists have acknowledged the importance of considering multiple stressors in ecological risk assessment (Foran and Ferenc 1999, Ferenc and Foran 2000). There is ample evidence that non-chemical stressors (e.g., disease, thermal stress, habitat alteration, and many others) influence an organism’s response to chemical stressors (and vice versa) in ways that may render organisms significantly more susceptible to chemical stressors than predicted from chemical-specific, single-stressor assessments. The consultant’s report itself acknowledges this issue (Draft Baseline Human Health Ecological Risk Assessment, Volume 1, Section 6.3.1, Page 6-39) by stating: "tests using field-collected species are confounded by the presence of multiple contaminants and potentially non-optimal health…and may be affected by both contaminant and non-contaminant stressors." But rather than acknowledge the important influence of non-chemical stressors ("non-optimal health") in assessing risks for chemicals of concern in the Fox River/Green Bay system, the report dismisses this critically important concept by relying on laboratory-based assessment of chemical risk. The result of this simplification is to underestimate risk associated with exposure to Chemicals of Concern in the Fox River/Green Bay system. It is likely then that risk-based cleanup levels will not be protective of ecological receptors, where cleanup levels are derived from assessments that fail to account for multiple chemical and non-chemical stressors. 1.5. Sediment Quality Thresholds Sediment Quality Thresholds (SQT) are levels (concentrations) of PCBs in the sediment that will not pose a risk to exposed humans or ecological receptors. SQTs were developed only for PCBs, based on human health and ecological risk assessments, as exposure to PCBs poses the greatest risks to human health and ecological receptors. While the report acknowledges that SQTs are not necessarily cleanup levels, they do provide a benchmark to assess the magnitude or extent of risk remaining once cleanup levels have been identified, and they provide goals or benchmarks that indicate PCB sediment concentrations below which risks to humans and ecological receptors are acceptable and/or negligible. SQTs are established via modeling that assesses the propensity of PCBs to accumulate in tissues of important ecological receptors (e.g., fish), the degree to which humans or fish-consuming wildlife who consume fish will be exposed to PCBs, and the risks faced by humans and fish-consuming wildlife. SQTs for PCBs are as low as 1 ug/kg (parts per billion or ppb in sediments) for high-intake fish consumers based on an acceptable cancer risk level of 1X10-6, 28 ug/kg for high-intake fish consumers based on a hazard index of 1, and as low as 24 ug/kg (ppb) for mink based on a NOAEC HQ of 1. 1.6. Conclusions 1.6.1 Human Health The Baseline Human Health Risk Assessment (BLHHRA) identifies extremely elevated cancer and non-cancer risks in large populations of high-intake and recreational fish consumers and in hunters. However, the assessment does not incorporate high-end assumptions associated with fish consumption, it does not address cumulative exposure to contaminants via different activities (fishing, hunting, recreational/occupational activities, etc.), and it assumes, incorrectly, that all fish consumers practice cleaning and cooking procedures that reduce contaminant levels by up to 50%. Incorporating high-end consumption estimates, removing assumptions of contaminant loss from cooking and cleaning, and incorporating concurrent exposure from non-fish sources (e.g., hunting) results in estimates of health risks that are approximately three to four times (3-4X) greater than risk estimates provided in the BLHHRA for high-intake and recreational fish consumers. Further, the assessment of PCB toxicity used in the BLHHRA, while progressive in its incorporation of additivity assumptions, is also not conservative. The BLHHRA fails to address synergism associated with concurrent exposure to PCBs and DDE, and PCBs and mercury. Therefore, despite the highly elevated risk estimates presented in the BLHHRA, the assessment is not conservative and may underestimate total human health risks associated with exposure to contaminants in the Fox River/Green Bay system. 1.6.2. Ecological Risk Assessment The Baseline Ecological Risk Assessment also identifies elevated risks to all levels of biological organization in the Fox River/Green Bay system. Highest risks occur in fish-eating mammals (mink) in the Lower Fox River and Zone 2 of Green Bay. Despite the highly elevated ecological risk estimates throughout the system, the BLERA is not conservative, and likely underestimates risk to components of the Fox River/Green Bay ecosystem. Underestimation of risk is primarily due to a lack of consideration of the influence of non-chemical stressors (e.g., disease, thermal stress, habitat modification, etc.) on an organism’s susceptibility to chemical toxicity. It has been well documented that non-chemical stressors increase susceptibility to chemical stressors (and vice versa); therefore, adverse impacts likely occur in the Fox River/Green Bay system at contaminant levels below those deemed safe or acceptable in the BLERA. The implications of lack of conservatism in both the human health and ecological risk assessments are discussed in the following section on Sediment Quality Thresholds. 1.6.3. Sediment Quality Thresholds Sediment Quality Thresholds (SQTs) are used to predict concentrations of PCBs in sediments that will not pose an unacceptable risk to humans and ecological receptors. SQTs are risk-based numbers and as such, are only protective when based on human health or ecological risk estimates that are adequately protective themselves. As the human health and ecological risk assessments developed for the Fox River/Green Bay BLRA lack appropriate conservatism (they underestimate risk), SQTs based on these assessments are themselves under protective. As acknowledged in the BLRA, SQTs are not cleanup levels themselves. However, they serve as benchmarks for cleanup activities and as assessment tools for the efficacy of remedial actions. In this capacity, SQTs must be based on fully protective assessments of human health and ecological risk. 2.0. Feasibility Study Review and Analysis The Feasibility Study (FS) "developed and evaluated a range of remedial alternatives…to manage the risk associated with the presence of industrial contaminants discharged to the river." Remedial Action Objectives (RAO) for the system "lay the foundation for remedial expectations…and provide metrics to measure long-term success. RAOs for the Fox River/Green Bay remedial action plan include: Achieve surface water quality criteria to the extent practicable; Protect ecological receptors (i.e., healthy invertebrate, bird, fish, mammal populations); Reduce transport of PCBs from the river into Green Bay and Lake Michigan; Minimize contaminant releases during remediation. RAOs are critically important as they provide metrics to measure long-term success of proposed remedial actions. To that end, we evaluated the proposed cleanup (or non-cleanup) options as they were presented and assessed in the FS, against the RAOs for the Fox River and Green Bay (Section 3.0 of these comments). Remedial Action Objectives will be achieved when PCBs and other pollutants are removed or isolated so that they no longer contaminate system components including sediments and fish (among others). To that end, the Feasibility Study (FS, Chapter 5) evaluated action (cleanup) levels that determine the quantities of PCBs to be removed from the Fox River and Green Bay. Action levels, which are developed from risk-based Sediment Quality Thresholds (these comments - sections 1.5 and 1.6.3 above), "are designed to meet project expectations and RAOs." Action levels "represent safe thresholds in surface sediment that are protective of both human and ecological receptors" (FS Section 5.1, page 5-2). The FS evaluated an array of action levels, including those that purportedly bracket risk-based SQTs. However, risk-based SQTs are as low as 24ug/kg (hereafter - ppb) for wildlife (ecological effects) and as low as 11 ppb for human health risks, approximately an 10 times lower than the lowest action level (125 ppb) evaluated for the Fox River, and over 50 times lower than the lowest action level (500 ppb) evaluated for Green Bay (FS Section 5.5). Clearly, the Feasibility Study excluded evaluation of action levels that would be protective of human health and wildlife. As a result, action levels that are necessary to achieve Remedial Action Objectives were not considered in the selection of cleanup options (remedial alternatives) for the Remedial Action Plan. Action levels as low as 125 ppb were evaluated in the FS for the Fox River. However, action levels only as low as 500 ppb were evaluated for Green Bay. The FS concludes that, at an action level of 500ppb, PCBs will not reach concentrations in Green Bay sediments after a 100-year waiting (recovery) period that will meet RAOs or be protective of human health and wildlife. Unfortunately, the FS draws this conclusion without evaluating whether action levels of 250ppb or 125ppb in Green Bay would achieve RAOs. Failure to evaluate action levels below 500ppb for Green Bay appears to be based on cost and technology considerations. As such, the FS inappropriately excludes action levels that are potentially protective of human health and wildlife. While it may not be feasible, because of cost or technological constraints, to achieve PCB sediment levels below 500ppb in the near term, these lower action levels should be evaluated in the FS for their efficacy in achieving RAOs and in protecting human health and wildlife in the longer term. Technology may change considerably in the next few years, and while not feasible presently, action levels below 500ppb may become feasible as technology advances, or as new cleanup alternatives emerge. As it is written presently, the FS effectively writes off cleanup options for Green Bay that may achieve RAOs in the longer term, including the 100-year period that was assessed in the FS. Therefore, the FS evaluation of cleanup options for Green Bay is fundamentally flawed and must be revised to include consideration of PCB action levels as low as 125ppb. 3.0. Proposed Cleanup (Action) Levels for the Fox River and Green Bay As a result of the Feasibility Study’s assessment of action levels, remedial technologies, and associated cleanup costs, the WDNR and the U.S. EPA have proposed the use of a PCB action (cleanup) level of 1ppm for portions of the Fox River (Little Lake Butte des Morts – OU 1; Little Rapids to De Pere - OU 3; De Pere to Green Bay – OU 4). WDNR and EPA have proposed no cleanup for the Fox River from Appleton to Little Rapids (OU 2), and no cleanup for any portion of Green Bay, including its heavily contaminated Zone 2. 3.1. Sediment/PCB Removal in the Fox River (OU 1, 3, and 4) The WDNR and the U.S. EPA have selected a PCB cleanup (action) level of 1ppm for OU 1, 3, and 4 of the Fox River. This cleanup level is many times higher than Sediment Quality Thresholds that are protective of human health and wildlife. For example, it is 90 times higher than PCB sediment concentrations that are fully protective of human health (as estimated in the BLHHRA), and over 40 times higher than PCB sediment concentrations that are fully protective of wildlife (as estimate in the BLERA). The U.S. EPA and the WDNR suggest that use of a 1ppm PCB cleanup level will, after a waiting period (nearly 30 years in OU 1, over 40 years in OU 3, and nearly 60 years in OU 4), result in sediment concentrations that are protective of human health and wildlife. However, the WDNR and U.S. EPA draw these conclusions by relying on faulty assumptions about PCB degradation during post-cleanup waiting or recovery periods, and average post-cleanup PCB sediment concentrations. 3.1.1. Waiting Period/Natural Recovery WDNR and the U.S. EPA indicate that after removing PCBs to a concentration of 1ppm, PCB sediment concentrations protective of human health will not be achieved for reach- and receptor-specific waiting periods as long as 29 years in OU 1, 42 years in OU3, and 59 years in OU 4 (Table 3, page 24 of 35, of the Proposed RAP for the Fox River and Green Bay). These recovery periods are based on the assumption that PCBs will continue to degrade or be transported out of the Fox River system after PCB-contaminated sediment cleanup to 1ppm. This assumption is grossly inconsistent with the Feasibility Study, and with the vast scientific literature on PCBs, both of which conclude that natural degradation of PCBs in sediments does not and will not occur in the Fox River or Green Bay. Therefore, it is conceivable that, after PCB removal to 1ppm in portions of the Fox River, actual sediment concentrations may never reach levels that are protective of human health and wildlife, or that achieve Remedial Action Objectives for the Fox River and Green Bay. 3.1.2. Surface Weighted Average Concentrations. The conclusion that sediment concentrations will meet SQTs (after a waiting period) is reached by developing a model-based assessment of post-cleanup sediment concentrations called the Surface Weighted Average Concentration (SWAC). The SWAC describes an average PCB sediment concentration throughout a river stretch. It does not reflect variability in PCB sediment concentrations and, therefore, does not address true, post-cleanup sediment concentrations within a stretch. In fact, true PCB concentrations may be as high as 1ppm in some parts of a river stretch. In these cases, PCBs will continue to pose significant threats to human health and wildlife in a river stretch, even after cleanup to 1ppm. 3.2. Sediment PCB Removal in Fox River OU 2. The Wisconsin DNR and the U.S. EPA have recommended that no PCB cleanup occur in Fox River OU 2 (Appleton to Little Rapids). Rather, the proposed alternative for this reach is Monitored Natural Recovery (MNR). The WDNR and the U.S. EPA suggest that MNR may take 70 years or more to reduce PCB sediment concentrations to levels that are protective of human health and wildlife and that meet project RAOs. MNR is based on the faulty assumption that PCBs will degrade naturally or be transported from the Fox River over a period of time and, as such, do not require removal to protect human health and wildlife. As indicated previously, the Feasibility Study and the vast scientific literature on PCBs conclude that natural degradation of PCBs in sediments does not and will not occur in the Fox River or Green Bay. Therefore, the no cleanup alternative for OU 2 may never achieve PCB sediment concentrations that are protective of human health and wildlife, or that achieve Remedial Action Objectives for the Fox River and Green Bay. 3.3. Sediment Cleanup Levels for Green Bay The Wisconsin DNR and the U.S. EPA have proposed no cleanup (natural recovery) for all sections of Green Bay, including the highly contaminated inner bay, referred to as Zone 2. In fact, Zone 2 of Green Bay contains over 31,000 kg of PCBs – more than the total mass of PCBs in the entire Fox River. The WDNR and EPA support the no cleanup alternative by suggesting that the PCB mass in the bay is distributed over a very large area, is contained in a very large volume of sediment, and by suggesting that PCB concentrations in Green Bay sediment are "typically low." Further, only two percent of the sediment in Green Bay is contaminated with PCBs at concentrations greater than 1ppm, and less than 0.2 percent is contaminated with PCBs at concentrations greater than 5ppm. Finally, the WDNR and EPA admit that, with the no cleanup alternative, PCB concentrations will not reach levels in Green Bay sediments protective of human health and wildlife within the 100-year time frame evaluated in the feasibility study. In contrast to the conclusions of WDNR and EPA, cleanup of PCBs from Green Bay sediments would have substantial benefits to human health and wildlife. Health and ecological risks are highest for the lower Fox River (De Pere to Green Bay) and for Green Bay, with cancer risks for high-intake consumers exceeding 1X10-3 in these regions. Over 30,000 kg of PCBs reside in a relatively restricted area of lower Green Bay, and cleanup of contaminated sediments to an action level of 1ppm would remove nearly 30,000 kg of PCBs from Green Bay. Cleanup to lower levels would remove virtually all PCBs and, concurrently, protect human health and wildlife by achieving project RAOs. 3.4. Conclusions Project-specific Remedial Action Objectives (RAO), as described in the Feasibility Study, "lay the foundation for remedial expectations…and provide metrics to measure long-term success. RAOs for the Fox River/Green Bay remedial action plan include: Achieve surface water quality criteria to the extent practicable;The WDNR and the U.S. EPA have proposed approaches for the removal of PCB-contaminated sediment from portions of the Fox River that will not achieve RAOs for any stretch of the River or for Green Bay, within an acceptable time frame (upwards of 100 years). In fact, the proposed approaches for removal of PCB-contaminated sediment will result in unacceptably high human health and ecological risks for many future generations of human and non-human residents of the Fox River and Green Bay system. 4.0 Literature Cited Agency for Toxic Substances and Disease Registry (ATSDR). 2000 Toxicological Profile for Polychlorinated Biphenyls. U.S. Dept. of Health and Human Services, Public Health Service, Washington, D.C. 765pp. Bemis, J.C. and R.F. Seegal. 1999. PCBs and methylmercury act synergistically to reduce rat brain dopamine content in vitro. Ennviron Health Perspect. 107:879-885. Ferenc, S.A. and J.A. Foran. 2000. Multiple stressors in ecological risk and impact assessment: Approaches to risk estimation. SETAC Press, Pensacola, FL. 251 pp. Foran, J.A. and S. A. Ferenc. 1999. Multiple Stressors in Ecological Risk and Impact Assessment. SETAC Press, Pensacola, FL. 100pp U.S. Environmental Protection Agency (EPA). 1997. Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessments. Interim Final. Report # EPA540-R-97-006. US EPA, Office of Solid Waste and Emergency Response, Edison, NJ. Wren, C.D., D.B. Hunter, J.F. Leatherland, et al. 1987. The effects of PCBs and methylmercury, singly and in combination on mink. II: Reproductive and kit development. Arch Environ Contam Toxicol. 16:449-454. |
 |
|
||||
 |
|
| CONTENT BY: Rebecca
Leighton Katers
WEB DESIGN BY: DataScouts WEB HOSTING BY: Doteasy |
|
|
|
