There have been few systematic studies of the non-malignant health effects of alpha-particle radiation in humans. Animal studies and a report on
plutonium-exposed workers from Russia suggest an association between high doses to the lung from
plutonium exposure and the development of fibrotic
lung disease. Prompted by a case of lung
fibrosis in a retired
plutonium worker, we tested the hypothesis that
plutonium inhalation increases the risk for developing chest radiograph abnormalities consistent with
pulmonary fibrosis. We conducted a retrospective study of nuclear weapons workers that included estimating absorbed doses to the lung with an internal dosimetry model. Our study population consisted of 326
plutonium-exposed workers with absorbed lung doses from 0 to 28 Sv and 194 unexposed workers. We compared the severity of chest radiograph interstitial abnormalities between the two groups using the International Labour Organization profusion scoring system. There was a significantly higher proportion of abnormal profusion scores among
plutonium-exposed workers (17.5%) than among unexposed workers (7.2%), P < 0.01. Lung doses of 10 Sv or greater conferred a 5.3-fold risk (95% CI 1.2-23.4) of having an abnormal chest X ray consistent with
pulmonary fibrosis when compared with unexposed individuals after controlling for the effects of age, smoking and
asbestos exposure. This study shows that
plutonium may cause lung
fibrosis in humans at absorbed lung doses above 10 Sv.