Brain tumor risk among United States nuclear workers.

This review of ten carefully conducted cohort mortality studies of U.S. workers in the nuclear industry published during the past decade finds a significantly increased brain cancer risk. There is a high degree of consistency between these studies, as eight out of ten cohorts, individually, show comparable increased risks. A sensitivity analysis that selects the studies of highest quality yields similar increased risk estimates from brain cancer, no matter how the studies are grouped. Those index studies that provide radiation dose exposure information show stable excess brain cancer risks of 15% at cumulative doses of less than 5 rem. There are no obvious environmental or geographical confounders likely to explain this consistently observed excess brain cancer risk. Occupational chemical exposures may contribute to this excess brain cancer risk among nuclear workers, but the only apparent common factor in ten cohorts with quite diverse work environments is the potential for exposure to ionizing radiation. Overall, these index studies of more than 78,000 workers followed for an average of 21 years, with more than 1.6 million person years of observation, establish that there is a statistically significant 15% excess risk of brain cancer for workers in the U.S. nuclear industry who have low-dose average cumulative radiation exposures.