Experimental respiratory carcinogenesis: interaction between alpha radiation and benzo(a)pyrene in the hamster

We have previously shown that a high incidence of lung cancer can be induced in hamsters by multiple intratracheal instillations of either benzo(a)pyrene (BaP) or polonium-210 (210Po). The present experiments have used low doses of these 2 carcinogens, singly and together, in simultaneous and sequential designs. In terms of unequivocal lung tumors, 15 weekly instillations of 210Po (total 0.05 μCi) and BaP (total 4.5 mg) given simultaneously on the same carrier particles induced twice the prevalence of lung tumors expected from the additive effect of either carcinogen alone. In a separate experiment, a single instillation of 0.04 μCi 210Po led to only 1 tumor in 139 animals (0.7 percent) in contrast to 23 tumors among 135 animals (17 percent) when it was followed 18 weeks later by 7 weekly instillations of BaP (total 2.1 mg). These results suggest synergistic action between alpha radiation and BaP in the induction of lung cancer