Radiation Standards

U.S. regulatory standards to protect the public from radiation lack a conclusively verified scientific basis. In the absence of conclusive data, scientists have assumed that even the smallest radiation exposure carries a risk. Some scientists say that this "linear, no-threshold hypothesis" is too conservative. The National Academy of Sciences plans to conclude its study on the risks of low-level radiation in 2001. The Department of Energy began a 10-year research project on the effects of low-level radiation on human cells, in part to help verify or disprove the linear model. The Environmental Protection Agency (EPA) and the Nuclear Regulatory Commission (NRC) have sometimes differed over how restrictive U.S. radiation protection standards should be, particularly about the proposed disposal of high-level nuclear waste in a repository at Yucca Mountain and the cleanup and decommissioning of nuclear facilities. For example, EPA applies community drinking water limits for radioactive substances to groundwater at nuclear sites; some limits are equivalent to fractions of a millirem a year. NRC includes groundwater and other potential contamination sources under a less restrictive limit of 25 millirem a year for all means of exposure, which conforms with internationally recommended radiation protection guidance. Although the National Academy of Sciences has criticized EPA's approach, it recognizes that EPA has the authority to set a separate standard for Yucca Mountain. As for nuclear cleanup and decommissioning sites where both agencies have jurisdiction, little progress has been made to finalize a memorandum of understanding between the two, and Congress may need to help resolve the agencies' disagreement. Costs per site could be immense, and the tighter the restriction, the higher the cost of cleanup. GAO summarized this report in testimony before Congress; see: Radiation Standards: Scientific Basis Inconclusive, and EPA and NRC Disagreement Continues, by Ms. Gary L. Jones, Associate Director for Energy, Resources, and Science Issues, before the Subcommittee on Energy and Environment, House Committee on Science. GAO/T-RCED-00-252, July 18 (15 pages).

GAO noted that: (1) U.S. regulatory standards to protect the public from the potential health risks of nuclear radiation lack a conclusively verified scientific basis, according to a consensus of recognized scientists; (2) scientists have assumed that even the smallest radiation exposure carries a risk; (3) this assumption extrapolates better-verified high-level radiation effect to lower, less well-verified levels and is the preferred theoretical basis for the U.S. radiation standards; (4) some say that the model is overly conservative and that below certain exposure levels, there is no risk of cancer from radiation; (5) others say that the model may underestimate the risk; (6) interest among scientists in obtaining a more conclusive understanding of the effects of low-level radiation has been evident in recent federally funded initiatives, including a reassessment by the National Academy of Sciences of the latest research evidence on the risks of low-level radiation; (7) also, a 10-year DOE research program, begun in fiscal year 1999, has been specifically addressing the effects of low-level radiation within human cells, in part to help verify or disprove the linear model; (8) although GAO recommended as far back as 1994 that EPA and NRC take the lead in pursuing an interagency consensus on acceptable radiation risks to the public, they continue to disagree on two major regulatory applications: (a) the proposed disposal of high-level nuclear waste in a repository at Yucca Mountain; and (b) the cleanup and decommissioning of nuclear facilities; (9) centrally at issue between the two agencies is groundwater protection; (10) EPA applies community drinking water limits for radioactive substances to groundwater at nuclear sites while NRC includes groundwater and other potential contamination sources under a less restrictive limit of 25 millirem a year for all means of exposure, an approach that conforms to internationally recommended radiation protection guidance; (11) as applied in proposed standards for nuclear waste disposal at Yucca Mountain, EPA's groundwater approach has been criticized as technically unsupported by the National Academy of Sciences, which Congress mandated to recommend standards for the repository; (12) the costs of implementing different radiation standards vary, depending on the standards' restrictiveness; and (13) comprehensive estimates of overall costs to comply with current and prospective standards were unavailable.

Recommendations

Our recommendations from this work are listed below with a Contact for more information. Status will change from "In process" to "Open," "Closed - implemented," or "Closed - not implemented" based on our follow up work.

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