Savannah River Site Health Effects Subcommittee (SRSHES) Meeting

Final Meeting Minutes
January 10, 2002

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Since the last meeting, the workgroup reviewed the scenarios proposed by CDC, appointed lead reviewers, selected locations, identified required actions and made recommendations. For all six scenarios, location templates will need to be completed and scenario assumptions will need to be reviewed. Mr. Lockridge asked SRSHES to provide comments on the scenarios as soon as possible because the workgroup is attempting to complete these tasks within the next two weeks and submit an initial draft to CDC. Other actions that will be required are outlined in the appropriate scenario.

The rural family would have lived in the closest downwind area where farms could have been located in 1955. Adults as well as infants born in 1955 and 1964 will be considered since 1964 was the year of the highest radioiodine release. Reasonable and high default consumption values will be used. Persons would have spent a lot of time outdoors, extensively worked in the soil, consumed fresh milk from a backyard cow, and had crops irrigated from the Savannah River. The workgroup selected farms near the junction of Route 125 and the SRS southeast boundary as the scenario location and made two recommendations: include resuspension of soil contaminants in the breathing zone for the “working in soil” assumption; and include a nursing mother for one of the existing two infants.

The urban/suburban family would have lived just downwind of the site boundary where urban/suburban families could have lived in 1955. Adults, infants and consumption values will be the same as those for the rural family. Persons would have worked at the nearest downwind industrial location in 1955 and consumed fresh milk from the nearest dairy or rural neighbor. The workgroup selected Augusta, Georgia as the scenario location and made two recommendations: assume the adult worked onsite at SRS instead of the “nearest industrial location” and assume the onsite work location was associated with higher radiological exposures, such as SRS Canyons.

The houseboat family would have lived at the nearest docking location downwind where persons could have lived on houseboats in 1955. Adults, infants and consumption values will be the same as those for the rural family. Persons would always have been outdoors, in contact with the Savannah River, and obtained food from local farms or grocery stores. The workgroup selected New Ellenton, South Carolina as the scenario location and identified two additional actions that will be required. The plausibility of the houseboat scenario will need to be confirmed with the Citizen’s Advisory Board (CAB). A location will need to be identified if the scenario is plausible, but the houseboat family should be replaced with a site construction worker living in a trailer if the scenario is not realistic. The workgroup recommended that Savannah River activities of the outdoors person be increased if the houseboat scenario is deleted. These key elements would include eating fish and living on the water.

The migrant worker family would have lived in the nearest downwind location where migrant workers could have lived and worked in 1955. Adults, infants and consumption values will be the same as those for the rural family. Persons would always have been outdoors and in contact with the soil; had crops irrigated by the Savannah River; and obtained food from local farms or grocery stores. The workgroup will identify a Georgia location near the SRS site boundary at a later date and will conduct additional research on SRS migrant workers and their lifestyles from 1955-1992. A delivery person scenario has the same assumptions as the urban/suburban family, but spends eight hours per week onsite. The workgroup selected Barnwell, South Carolina as the scenario location and has identified a factory worker who made routine deliveries to SRS and spent eight hours per week on site.

The outdoors person would have lived in camps at the nearest downwind location that was appropriate for the season, i.e., hunting or fishing. Consumption values will be the same as those for the rural family. Persons would always have been outdoors; spent eight hours per day on the Savannah River in the summer; spent eight hours per day onsite during hunting or fishing season; and obtained food from nearby grocery stores. The workgroup selected Jackson, South Carolina as the scenario location and recommended that the individual who obtained food from nearby grocery stores be replaced with the “poacher”. This individual would have legally or illegally obtained fish, deer, game birds, turtles and other meats from hunting and fishing onsite.

In addition to specific recommendations for each scenario, the workgroup also made general observations about the overall process. First, chemical source terms and scenarios should be evaluated with the same level of rigor in terms of health effects in offsite populations. The dose reconstruction scenarios are only radiological. Second, synergistic effects of radiological and chemical scenarios should be considered. Third, modifications suggested by the workgroup to better represent onsite workers should be considered. Fourth, limitations of computer models that may impact the scenarios should be clearly stated. For example, the rural family scenario would need to be evaluated if the model has no soil resuspension capacity.

The workgroup noted that it could provide further assistance to CDC after the radiological dose scenarios are completed. These activities would include developing and reviewing chemical scenarios; reviewing and ranking dominant radionuclides by risk; and reviewing screening analysis results in terms of community presentation. However, the workgroup acknowledged the need to first participate in a tutorial of the risk-ranking process.

Discussion.
Ms. Elizabeth Donnelly of NCEH joined the meeting by conference call and reminded SRSHES that the default values for the scenarios are based on the International Atomic Energy Agency (IAEA) model. However, she indicated that SRSHES is welcome to select another data source. Ms. Kato raised the possibility of including a gestating female working onsite in one of the scenarios. Mr. Lockridge confirmed that this suggestion and additional scenarios proposed by SRSHES will be included in the workgroup’s report to CDC. Two members expressed support for the workgroup’s modifications to the scenarios. Ms. Guess noted that some onsite workers lived near the plant with their families and may have transported exposures home.

Dr. Hinton pointed out that data from the Savannah River Ecology Laboratory show resuspension as important pathways for both ingestion and inhalation. He confirmed that he would provide this information to the workgroup. He inquired whether the final scenarios would be reviewed by outside experts before being piloted. Dr. Robert Whitcomb of NCEH remarked that the scenarios will undergo CDC’s usual peer review process for dose reconstruction research. After the scenarios are completed, CDC anticipates that the radionuclide-screening phase will be completed in one year. Ms. Perry offered to identify points of contact who can assist the workgroup in gathering historical data. She raised the possibility of assigning values to combine scenarios. For example, a delivery person could also be an outdoors person.

Dr. Markiewicz offered to provide existing data that may be of use to the workgroup. An expert review panel held multiple meetings to discuss pathways, limitations, risk ranking and other key elements of the Oak Ridge dose reconstruction project. The majority of the technical presentations were videotaped. For chemical screening and risk ranking, ATSDR developed a one-page flowchart outlining the screening process for past and present exposures. Ms. Todorov confirmed that after data from the exposure scenarios are incorporated into risk models, NCEH will explain the risk ranking process to the workgroup. Since age, race/ethnicity and other factors can cause heavy-metal effects to vary among individuals, Mr. Graves raised the possibility of including a minority, child and adult in each scenario.

Dr. Whitcomb pointed out that a child and adult are represented in each scenario, but race/ethnicity will play a more important role after the screening process has been completed. The default consumption values incorporated into each scenario will attempt to maximize potential outcomes and rank health effects for radionuclides released at SRS in order of importance. The risk-based screening criteria proposed by CDC will be shared with SRSHES. Dr. Whitcomb clarified that doses will not be generated during the screening process.

Ms. Donnelly added that attempts are not being made to determine dose in this phase of the project because the screening calculations are extremely conservative. For example, an assumption is made for each scenario that the wind blows 25% of the time toward the scenario site. Dr. Hinton disagreed with this approach since screening level calculations require dose to be estimated before risk. SRSHES commended the workgroup because the comprehensive presentation reflects an extensive amount of time and energy devoted to enhancing the scenarios.