Radiation Standards: Scientific Basis Inconclusive, and EPA and NRC Disagreement Continues, Report to the Honorable Pete Domenici, U.S. Senate [open pdf - 913KB]
"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. In the absence of more conclusive data, scientists have assumed that even the smallest radiation exposure carries a risk. This assumption (called the 'linear, no-threshold hypothesis' or model) extrapolates better-verified high-level radiation effects to lower, less well-verified levels and is the preferred theoretical basis for the current U.S. radiation standards. However, this assumption is controversial among many scientists. Some say that the model is overly conservative and that below certain exposure levels, there is no risk of cancer from radiation. […] 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, begun in the summer of 1998 and planned to conclude in 2001. 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."
Government Accountability Office: http://www.gao.gov/