Mortality of workers at the Hanford site: 1945-1986

Updated analyses of mortality of workers at the Hanford site provide little evidence of a positive correlation of cumulative occupational radiation dose and mortality from leukemia and from all cancer except leukemia. Estimates of the excess relative risk per 10 mSv were negative for both disease categories, but these estimates are consistent both with no risk and with estimates obtained through extrapolation from high-dose data. For all cancer except leukemia, the upper limit for a two-sided 90% confidence interval was about 1.5 times the prediction of the BEIR V model, but several times the estimate recommended by the ICRP 60 committee. For leukemia, the comparable upper limit was very close to that predicted by either BEIR V or ICRP 60. The all-cancer risk estimate, from a recent report on updated analyses of data for Oak Ridge National Laboratory workers, was strongly rejected based on the Hanford data. Of 24 specific cancer categories evaluated, only cancer of the pancreas and Hodgkin's disease showed positive correlations with radiation dose that approached statistical significance with one-tailed p values of 0.07 and 0.04, respectively; these correlations are interpreted as probably spurious. For multiple myeloma, for which a correlation was reported previously, the p value was 0.10. However, a significant correlation (p < .05) was obtained when analyses were expanded to include deaths with multiple myeloma listed on the death certificate but not considered to be the underlying cause, when analyses were expanded to include deaths occurring in Washington State during the time period 1987-1989, or when a 2-y latency period (instead of 10-y) was assumed.