Debate Continues on Radiation Standards
SCIENCE POLICY: NRC Pulled Into Radiation Risk Brawl
Science, Volume 285, Number 5425, p 177
A festering feud over possible health risks of low radiation levels has blistered into public view. But instead of assailing each other, two bitter foes are unloading on the National Research Council (NRC) for assembling what they claim is a biased panel to weigh radiation risks. In response, the NRC last month canceled the panel's first meeting and agreed to review its composition. "We're just taking a breather," says radiation biologist Evan Douple, director of the NRC Board on Radiation Effects Research.
The nasty decades-long dispute centers on the risk posed by ionizing radiation from sources such as medical isotopes and spent nuclear fuel. A range of federal agencies have set exposure standards for the general public and for workers--standards based on accepted risk levels that the government tasks the NRC to review every several years. Billions of dollars are at stake: Stricter standards could increase the amount that agencies and industries must spend to clean up radioactive waste and protect workers.
Arriving at safe levels of radiation exposure is hard because little data exist on how low doses--less than 10 Roentgen equivalent man (rem) a year--affect health. (Annual U.S. exposure from all sources is 360 millirem). For years researchers have derived estimates mainly from cancer rates among 50,000 Japanese atom bomb survivors who received acute doses of more than 500 millirem. Current exposure regulations are based on the Linear No-Threshold (LNT) model, which uses a straight line to extrapolate the Japanese data to zero: It assumes no safe cutoff, and that doubling the dose doubles the risk.
The bone of contention is whether the LNT reflects reality. Some experts believe that population studies in regions with high background exposure--from radon or uranium deposits--suggest that radiation is harmless below a certain dose. Others point to data--including cellular studies--hinting that low doses may pose an even greater cancer risk, proportionally, than higher doses. At the request of several agencies, the NRC organized the latest panel on the Biological Effects of Ionizing Radiation to look at what model best fits the data.
But the 16-person committee that the NRC unveiled on 10 June, chaired by Harvard epidemiologist Richard Monson, drew an angry response. The panel "is completely skewed" toward people who favor relaxed standards, claims Dan Hirsch of the Committee to Bridge the Gap, a nuclear watchdog group in Santa Cruz, California. His organization and 73 other groups and individuals claim in a 22 June letter that most panelists have published studies or opinions suggesting the need for looser standards.
Other groups say the panel contains the opposite bias and ignores researchers who believe the LNT model is too restrictive. A nonprofit called Radiation, Science, and Health Inc., which insists low doses are harmless, claims that panelist Geoffery Howe, a Columbia University epidemiologist, has "obfuscat[ed] data so as to support the LNT." Bridge the Gap, meanwhile, finds fault for a different reason, claiming Howe advocates "the premise that low doses of radiation are substantially less harmful than officially presumed." Howe told Science he considers the LNT model "a reasonable assumption not proven."
NRC hopes to announce any revisions to the panel within a few weeks, Douple says. But that may not quell the fire: If the NRC makes "minor cosmetic changes that do not alter the imbalance of the panel," Hirsch says, his group may file a lawsuit under the Federal Advisory Committee Act.
Revisions to the act in 1997 opened panel memberships to public debate in the first place.
�1999 by The American Association for the Advancement of Science.
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