Lung Carcinogenesis Induced by Inhaled High-fired Oxides of Beryllium and Plutonium

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Abstract
The carcinogenicity of inhaled, submicron-sized, high-fired 239 Pu dioxide and beryllium oxide particles was examined in over 600 rats following single nose-only exposure to initial alveolar depositions of 1.0-91 .mu.g Be and of 4-180 nCi 239Pu. The alveolar half-life of Be in the lung was 325 days. Only 1 of 184 rats exposed to Be-only developed a lung tumor during the 2 yr observation period following exposure. None of 128 unexposed rats developed lung tumors. The incidences of lung tumors were 10% at an initial alveolar deposition of 5 nCi 239Pu, 37% at 45 nCi and 53% at 180 nCi. The alveolar clearance of 239Pu was decreased and the translocation of 239Pu to thoracic lymph nodes was increased in rats given PuO2 after exposure to beryllium oxide. The incidences of lung tumors following combined exposures were 15% at initial alveolar depositions of 7.6 nCi 239Pu and 14 .mu.g Be, 38% at 76 nCi 239Pu and 14 .mu.g Be, 12% at 3.8 nCi 239Pu and 91 .mu.g Be and 58% at 59 nCi 239Pu and 91 .mu.g Be. Previous exposure to beryllium oxide did not significantly change the incidence of lung tumors following a subsequent exposure to 239PuO2 despite the effects of Be on the alveolar clearance of 239Pu.

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