Investigations on the carcinogenic burden by air pollution in man. XII. Early pathological alterations of the bronchial epithelium in syrian golden hamsters after intratracheal instillation of benzo(a)pyrene.

The ultrastructural alterations occurring in the bronchial epithelium of Syrian golden hamsters treated once weekly for life with 0.63 mg BP were examined during the first 20 weeks of treatment. It was demonstrated that epithelial cells penetrated the basement membrane thus finally forming small bronchogenic tumours (adenomata) composed of ciliated, nonciliated and a few basal cells. No squamous metaplasis occurred.