Strontium-90 Radiation Standards for Environmental Cleanup. W. C. Griffith, Consortium for Risk Evaluation with Stakeholder Participation, University of Washington, Seattle, WA; S. B. Curtis, Fred Hutchinson Cancer Research Center, Seattle, WA; and S. M. Bartell and E. M. Faustman, Consortium for Risk Evaluation with Stakeholder Participation, University of Washington, Seattle, WA
Standards for exposure to ionizing radiation from internally deposited radionuclides were developed using simple and consistent models that can be applied for all radionuclides, chemical forms, types of radiation, and combinations of target tissues—even for cases where little or no data is available. The simple models for these standards should be reviewed based on the best scientific information when their application leads to long-term effort at high cost for environmental cleanup. Strontium-90 contamination is used as an example based on cleanup of contaminated groundwater at the Hanford Nuclear Reservation by the U.S. Department of Energy. The health effects of soluble Sr-90 have not been studied in human populations and are inferred to be bone cancers and leukemia based on extrapolation from other types of radiation exposures. The scientific evidence suggests that the standard can be modified based upon a threshold dose response for bone cancer based on evidence for people exposed to other radionuclides and laboratory animal studies. The scientific evidence for leukemia suggests that the standards do not need to be modified, the risks should be extrapolated based on a linear-quadratic dose response developed from studies of the atomic bomb survivors. The modification would increase Sr-90 standards by 56%. Although this is a relatively modest change in standards it could lead to substantial cost savings because of the extent of the effected areas at Hanford.
Supported (not endorsed) by CRESP by Department of Energy Cooperative Agreement #DE-FCO1-95EW55084.
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