Effects of Lead Oxide on the Induction of Lung Tumors in Syrian Hamsters 2

In 10 weekly intratracheal injections, 4 groups of Syrian golden hamsters were given a suspension (in isotonic saline plus 0.5% carboxymethylcellulose solution) of lead oxide (PbO), benzo[a]pyrene (BP) mixed with PbO, BP, or control vehicle, respectively. Another group was kept as an untreated control. Atypical epithelial proliferations, adenomas, and an adenocarcinoma were observed in the lungs of hamsters given BP mixed with PbO, whereas no tumorous changes were found in the other groups. These neoplastic changes originated mostly in the bronchiolo-alveolar area. PbO alone induced hyperplastic and squamous metaplastic foci of the alveolar area. These results suggested a cocarcinogenic effect of PbO.