Low Dose Radiation and Solid Tumors Mortality Risk

Background US nuclear capable shipyard workers have increased potential for occupational radiation exposure. Objective The aim of the study is to examine solid tumor mortality risks at low doses. Method 437,937 workers working from 1957 to 2004 at eight US shipyards were studied. Results Radiation workers with a median life-time dose at 0.82 mSv had a significantly lower solid tumor mortality risk (relative risk [RR]: 0.96, 95% confidence interval [CI]: 0.94-0.98) than nonradiation workers. Among 153,930 radiation workers, the RRs of solid tumors increased with increasing dose categories without statistical significance. The dose category >0-<25 mSv had significantly lower RR (0.95, 95% CI: 0.91-0.99) versus 0 dose and the excess relative risk was 0.05/100 mSv (95% CI: 0.01-0.08). Conclusions Solid tumor risk might increase with radiation dose, but not linearly at low doses. Actual mortality risk may be dependent on dose received.