Sister chromatid exchanges and chromosome aberration frequencies in plutonium workers

Peripheral blood lymphocytes from controls and from a small population of plutonium workers with internal plutonium depositions, cumulative chronic external irradiation, and occupational exposure to single or multiple chemicals, were analysed for the frequency of sister chromatid exchanges (SCE) and chromosome aberrations. SCE are sensitive to some chemical mutagens, while chromosome aberrations are induced by moderate to high doses of ionizing radiation, and therefore these different cytogenetic end-points are complementary. We analysed the frequency data from workers grouped by internal systemic burdens of plutonium (less than 148, 148-740 and greater than 740 Bq) and to those exposed to five chemicals in the workplace: perchloroethylene, beryllium, carbon tetrachloride, benzene, and trichloroethylene. A significant increase in chromosome aberrations compared with the control frequency was observed only in cells of workers with greater than 740 Bq of internalized plutonium. Based on prior studies, the lack of a dose-response indicator from internal plutonium was not unexpected because of the small sample and the low frequency of aberrations induced at the lower plutonium burdens. There were no significant increases in the SCE mean frequencies when analysed by estimated internal plutonium or from exposure to any of the chemicals.