Development and Validation of Models for Evaluating Health and Ecological Risks to Native American Pueblos in the Vicinity of Los Alamos National Laboratory. A. M. Dorries, L. Naranjo, Jr., and O. B. Meyers, Los Alamos National Laboratory, Los Alamos, New Mexico; and J. L. Lewis, Radian Corporation, 1821 Carlisle NE, Albuquerque, NM 87110
The United States Department of Energy's Los Alamos National Laboratory (LANL) in northern New Mexico is evaluating risks to human health and the environment that may have resulted from development of the atomic bomb and subsequent nuclear weapons' development and research activities. The remediation of LANL is being carried out under the federal Resource Conservation and Recovery Act, which requires public involvement and acceptance of the remediation plan. LANL is bordered by several Native American Pueblos, and the tribes have expressed concerns about the adequacy of standard exposure assessment assumptions in assessing past, present and future risks to the tribes as a result of laboratory activities. To address these concerns and ensure the accuracy of the assessment, tribal members have been working with laboratory employees and contractors to develop appropriate scenarios and to ensure the appropriate site-specific data are gathered for model input parameters. A four-phase approach to model development is being followed. Initially, the existing laboratory exposure scenarios are reviewed with a representative of the tribes to determine which assumptions would need to be modified to reflect differences in lifestyles at the pueblos. Second, the revised scenario is transmitted to the tribal councils to request input from tribal members on 1) the appropriateness of the assumptions, and 2) the specific data necessary to adequately develop distributions for input parameters. Third, based on the responses from individual pueblos, necessary site-specific data will be collected for media deemed important potential contaminant sources by each pueblo. Finally, probability distributions reflecting pueblo-specific parameters will be developed to model exposures. The first stage of development has been completed and has resulted in modifications including incorporation of additional pathways related to traditional ceremonial activities, ranching, and hunting; broadening of recreational scenarios to reflect a higher contact time with potentially contaminated soils; modification of dietary inputs to reflect the use of indigenous plants, game animals, and traditional domestic plants. Preliminary examination of the model suggests that plant uptake factors will be the primary drivers in the risk assessments. Therefore, plants cultivated by the pueblos are being raised at the laboratory to allow evaluation of site-specific plant uptake factors for known contaminants. The incorporation of extensive site-specific parameters into the stochastic models used in the human health and ecological risk assessments will not only provide a degree of confidence in the validity of the results for the site, but will also allow assessment of the impact of the site- and culturally-tuned models by comparing predicted risks and clean-up levels resulting from use of default and tuned models. This presentation will present the model, discuss the process involved in its development, and address the impact of the refinements to the extent possible. A companion presentation (Naranjo et al.) will detail the input of tribal members in development of sampling plans that sample appropriate media and locations to ensure the appropriate data are obtained for the risk assessment.