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Technical Review of the Work Plan to Develop Health-based Cleanup Goals for Winston-Thomas Facility in Bloomington, Indiana May 1997 by Jana S. Hammonds, M.S. F. Owen Hoffman, Ph.D. SENES Oak Ridge, Inc. Center for Risk Analysis 102 Donner Drive Oak Ridge, Tennessee 37830 Table of Contents 1.0 Introduction 2.0 Comments/Concerns Regarding the Work Plan to Develop Health-based PCB Cleanup Goals for the Winston-Thomas Facility in Bloomington, Indiana 2.1 Methodology 2.2 Site Characterization 2.3 Comprehensibility of Exposure Scenarios 2.4 Adequacy of Exposure Pathways and Parameters 2.5 Ecological Risk 3.0 Summary 4.0 References 1.0 Introduction The purpose of this report is to present a technical review of the Work Plan to Develop Health-Based PCB Cleanup Goals for the Winston Thomas Facility in Bloomington, Indiana. To aid in this effort, various background documents pertaining to the Winston Thomas PCB contamination were compiled and studied. Furthermore, comments from other agencies and contractors pertaining to this work plan were also included.The goal of the subject document, as stated in the cover letter, is to provide a methodology "to develop a health based cleanup goal, then use this goal to guide remedy design, thereby having a remedy which will be protective of human health and the environment." However, the methodology proposed falls short of this goal in several aspects. These aspects can be covered in several categories: 1) general methodology, 2) site characterization, 3) comprehensibility of exposure scenarios, 4) adequacy of exposure pathways and parameters, and 5) ecological risk. The following section of this report outlines various comments pertaining to each of the stated categories. 2.0 Comments/Concerns Regarding the Work Plan to Develop Health-based PCB Cleanup Goals for the Winston-Thomas Facility in Bloomington, Indiana 2.1 Methodology The general principle of back calculating to a "protective" concentration is technically acceptable. However, the proposed methodology does not appear to be comprehensive or conservative. Point estimates of exposure parameters, toxicity parameters, and an acceptable risk level are used to determine a single estimate of concentration for the health-based cleanup goal (HBCG). If values for these parameters were derived conservatively (i.e., so as to not under-estimate risk), then the analysis would be similar to a screening level risk assessment. However, the pathways proposed in this document are not comprehensive and actual exposed population groups may receive risk higher than estimated(see Section 2.3 and 2.4). A more defensible way of calculating a "protective" concentration is to evaluate the uncertainty in each parameter (such as exposure time, surface area, ingestion rates, etc.). By including parameter uncertainty, various combinations of parameters can easily be analyzed to determine a subjective probability distribution of concentration results. From these concentration results, subjective confidence bounds can be obtained (Hammonds et al., 1994; NCRP, 1996). For instance, by including uncertainty in each of the parameters, a statement such as "there is 95% confidence that a level of xx ppm in soil will be below concentrations deemed protective of human health in current and future exposure conditions" can be obtained. A detailed discussion of the advantages (and disadvantages) of probabilistic risk assessment (i.e., risk assessment with an uncertainty analysis included) is beyond the scope of this report; however, some advantages are mentioned below. The probabilistic approach Is consistent with the definition of risk Is capable of disclosing all the available information about variability and uncertainty; Allows all to see the full range of variability and uncertainty when uncertainty and variability are properly propagated through the model, instead of being misled into thinking that exposure and risk are point values; Is a written rational that defends the selected probability distribution in a risk assessment; Gives direct and indirect measures of the value of information through the use of a sensitivity analysis; Ultimately saves money; and Outputs a distribution of potential risk values from which a subjectiveconfidence interval or Bayesian interval can be used indecision-making (Burmaster, 1996; NCRP, 1996). For the reasons listed above, a probabilistic approach instead of the deterministic approach should be used to obtain HBCGs. Probabilistic risk assessments are the state-of-the-art approach and will play an increasingly critical role in the development, refinement, and execution of regulatory monitoring and decision-making activities in the years ahead (IAEA, 1989; Hammonds et al., 1994; MacIntosh et al., 1992; 1994; Power and McCarty, 1996; NCRP, 1996). 2.2 Site Characterization The cover letter of this report states that the HBCGs will be based on surface soil contamination only. However, this does not adequately address many concerns associated with the site. For example, Figure 1-1 of this report presents a map of the area including and surrounding the Winston Thomas Facility. From this map, it appears that all contamination is east of Clear Creek. However, a contamination map provided by the City of Bloomington Utilities Engineering indicates that PCB contamination exists on the west side of the creek as well. Because PCB contamination exists in surface soils near the creek, the surface water will be contaminated simply due to runoff during rain events. The surface water could also be contaminated from ground water depending on the hydrogeology of the region. Because the surface water is most likely contaminated the fish, waterfowl, and other aquatic species in and around the creek will also be contaminated. Therefore, the aquatic medium must be considered in the definition of exposure.   Furthermore, page 2-1 indicates that PCBs were found in some wells, but the source of the PCB contamination is inconclusive. Because the PCB contamination source was inconclusive, ChemRisk has excluded the route of exposure from the analysis. However, for a screening level or "protective" assessment, it is inappropriate to exclude groundwater as a potential route of exposure without more evidence. A "buffer zone material" is referred to on page 1-1. What does this include? 2.3 Comprehensibility of Exposure Scenarios The document proposes to "derive two on-site soil HBCGs as part of the risk-based cleanup program considered for this site. In the first case, an HBCG will be based on current land use assuming that the security fence remains in place. In the second case, an HBCG will be derived assuming that future land use is commercial and that the security fence is removed." For the current and the future land use evaluations, the only pathways included are incidental ingestion of surface soil, dermal contact with surface soil, and inhalation of airborne particulates derived from surface soil. However, these pathways do not appear to encompass all possible routes of exposure. Because Clear Creek is most likely contaminated, pathways such as ingestion of fish, ingestion of waterfowl, and swimming (which should include dermal contact and incidental ingestion of surface water) should be considered for evaluation in the current and future land use scenarios. To establish probable PCB concentrations in the surface water, data should be collected (if not currently available) and/or predictions of water concentrations could be made based on surface soil contamination. In addition, the ingestion of drinking water should be included as a potential pathway of concern. Site specific information should be obtained to establish the number of wells being used, the frequency of their use, and the number of people using them. The hydrogeology of the area should be evaluated to determine the potential for the groundwater contamination reaching the city water supply. Finally, exposure to subsurface soils should also be included. During future events such as construction activities, workers can be directly exposed to the subsurface soils. Page 3-1 states "Exposures related to the excavation of subsurface soils will not be evaluated separately under the future land use scenario. To do so would require a specific plan detailing the number, size, depth of any excavations as well as specific information concerning the nature and extent of subsurface contamination." This is inappropriate. To adequately characterize the contamination of the site, information should be obtained regarding possible concentration levels of PCBs at varying depths of soil. It should not be assumed that the surface soil concentrations are conservative estimates for what is buried beneath, especially when it is stated that future construction activities could occur. If larger concentrations exist beneath the surface (which is often the case), then excluding this pathway may not be protective of human health. 2.4 Adequacy of Exposure Pathways and Parameters In reference to the lawn care worker scenario in the future land use evaluation, Page 3-2 states "Because this scenario is identical to the maintenance worker scenario under current conditions, it will not be necessary to derive a separate HBCG for this scenario." However, the lawn care worker would be exposed much more that the typical maintenance worker. A lawn care worker could be actively stirring up dust which would increase his inhalation exposure and could be performing landscaping activities which would increase his dermal exposure and risk of inadvertent ingestion of contaminated soil. In addition, the exposure frequency seems to be underestimated when compared to the following statement from Langley (1997): "Mowing crews (usually 4-6 persons) frequent the site during the 8 month mowing season and are on site for 3-5 consecutive 8 hour days." This statement needs to be verified and, if confirmed, adjustments should be made to the HBCG evaluation. Another scenario under consideration in the future land use evaluation is the potential for children to play outside (page 3-2). For this scenario, it is assumed that children below the age of eight would not be playing outside because of required supervision from an adult. However, if the property is developed as commercial property, the possibility of a corporation to have a day care facility with pre-school children exists. Page 3-5 states "For chronic noncarcinogenic effects, the pathway-specific period of exposure is averaged over the exposure duration i.e., adult exposure is averaged over 25 years and exposure to the eight to 18 year old is averaged over ten years." When studying the potential health effects of noncarcinogens, however, we are often concerned with the potential of high exposures occurring during a shorter period of time. This concern results because of the scientific theory that exposure to noncarcinogens will not lead to a detrimental health effect unless a certain exposure/threshold level is exceeded. Age dependency in the rate of exposure must be considered for noncarcinogenic assessments. During one year, someone may eat a lot of fish or exhibit activities that may differ substantially from a 25 year average. Likewise, during a year the body weight can be much lower for a young child than for a child averaged from 8 to 18 years. Therefore, when evaluating the risk from noncarcinogens, two scenarios could be evaluated: 1) excessive habits over a one year exposure with an appropriate body weight (the weight of the child most at risk) and 2) more realistic exposure or consumption over a period of years. For the exposed skin surface area on page 3-7, the potential of someone swimming in Clear Creek should be considered. Much more surface area would be exposed for someone wearing a swimsuit. Furthermore, the head and neck were included in the estimate for maintenance/lawn care workers but were not included in the individuals trespassing on the property. The head and neck would be exposed for both groups. Therefore, an adjustment of the surface area is necessary. Finally, page 3-7 states that "default soil ingestion rates of 100 mg/day for adults and 200 mg/day for young children have previously been recommended by the USEPA." But the value used for the adult and the adolescent is 50 mg/day. A more transparent justification of selecting this lower ingestion rate is needed than is currently provided (the reference is given). 2.5 Ecological RiskAs stated in the cover letter, the intent of the HBCGs is to be protective of human health and the environment. However, ecological risk is not considered in this analysis, and it is invalid to assume that conditions which are protective of human health are also protective of the ecosystem. To ensure that the environment is not harmed, an ecological risk assessment should be performed. It may be sufficient to conduct such an assessment at a screening level to determine the need for a more refined analysis. 3.0 Summary Although most HBCGs are calculated using point estimates, webelieve that it is more appropriate to include uncertainty in theseestimates. Because uncertainty is not addressed, the results maybe misleading. In addition, because all potential routes ofexposure and exposure scenarios are not included, the current HBCGswould not necessarily be protective of human health, and there isdefinitely no basis presented for why this evaluation would be protective of theenvironment (or ecosystem). Based on our review of the work plan and our currentunderstanding of the facility and the current and potential activities, a moredetailed investigation of legitimate pathways of concern is needed anduncertainty estimates should be included before this analysis would bescientifically defensible. 4.0 References Burmaster, D.E. 1996. Benefits and costs of using probabilistic techniques in human health risk assessments-with an emphasis on site-specific risk assessments. Human and Ecological Risk Assessment 2(1):35-43. Hammonds, J.S., Hoffman, F.O., and Bartell, S.M. 1994. An Introductory Guide to Uncertainty Analysis in Environmental and Health Risk Assessment. Oak Ridge National Laboratory. ES/ER/TM-35/R1. International Atomic Energy Agency (IAEA). 1989. Evaluating the Reliability of Predictions Made Using Environmental Transfer Models. Safety Series No. 100, IAEA, Vienna, Austria. Langley, J.N. 1997. CBU comments on "Work Plan to Develop Health-Based PCB Cleanup Goals for Winston Thomas Facility, Bloomington, Indiana" by ChemRisk for Westinghouse, December 19, 1996. MacIntosh, D.L., Suter, G.W., II, and Hoffman, F.O. 1994. Uses of probabilistic exposure models in ecological risk assessments of contaminated sites. Risk Analysis 14(4):405-419. MacIntosh, D.L., Suter, G.W., II, and Hoffman, F.O. 1992. Model of the PCB and Mercury Exposure of Mink and Great Blue Heron Inhabiting the Off-Site Environment Downstream from the U.S. Department of Energy Oak Ridge Reservation. ORNL/ER-90, Oak Ridge National Laboratory, Oak Ridge, Tennessee. MacIntosh, D.L., Suter, G.W., II, and Hoffman, F.O. 1994. Uses of probabilistic exposure models in ecological risk assessments of contaminated sites. Risk Analysis 14(4):405-419. National Council on Radiation Protection and Measurements (NCRP). 1996. A Guide for Uncertainty Analysis in Dose and Risk AssessmentsRelated to Environmental Contamination. NCRP Commentary No. 14,NCRP, Bethesda, Maryland. Power, M., and McCarty, L.S. 1996. Probabilistic risk assessment: betting on its future.Human and Ecological Risk Assessment 2(1):30-34.

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