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.