OCCUPATIONAL EXPOSURE TO IONIZING-RADIATION AND MORTALITY AMONG WORKERS OF THE FORMER SPANISH NUCLEAR-ENERGY BOARD

Objectives-Firstly, to ascertain whether mortality among workers of th e former Spanish Nuclear Energy Board (Junta de Energia Nuclear-JEN) w as higher than that for the Spanish population overall; and secondly, if this were so, to ascertain whether this difference was associated w ith exposure to ionising radiation. Methods-A retrospective follow up of a cohort of 5657 workers was carried out for the period 1954-92. Co hort mortality was compared with that for the Spanish population overa ll, with standardised mortality ratios (SMRs) adjusted for sex, age, a nd calendar period. Also, Poisson models were used to analyse mortalit y from lung cancer in the cohort by level of exposure to ionising radi ation.Results-Workers' median and mean cumulative exposures were 3.04 and 11.42 mSv, respectively. Mean annual exposure was 1.33 mSv. Excess mortality due to bone tumours was found for the cohort as a whole (si x deaths observed; SMR 2.95; 95% confidence interval (95% CI) 1.08 to 6.43). Among miners, excess mortality was found for non-malignant resp iratory diseases (SMR 2.94; 95% CI 2.27 to 3.75), and for lung cancer bordering on statistical significance (SMR 1.50; 95% CI 0.96 to 2.23; P = 0.055). Relative risks of dying of lung cancer from ionising radia tion in the dose quartiles 2, 3, and 4 versus the lowest dose quartile , were 1.00, 1.64, and 0.94, respectively. Conclusions-Excess mortalit y from lung cancer was found among JEN miners. Nevertheless, no clear relation was found between mortality from lung cancer and level of exp osure to ionising radiation in the JEN cohort. Continued follow up of the cohort is required to confirm excess mortality from bone tumours.