Dietary selenium- and benzo[a]pyrene-induced respiratory tract tumours in hamsters

The modifying effect of selenium as sodium selenite on chemicallyinduced respiratory tract tumours was tested in Syrian goldenhamsters. Groups of 40 hamsters per sex (controls 60 per sex)were fed the following semisynthetic diets: control diet (0.1p.p.m. Se, low fat); high-Se diet (5 p.p.m.); high-fat diet(20% sunflower oil); or high-Se + high-fat diet. After an adaptationperiod of 30 days on the diets, respiratory tract tumours wereinduced by intratracheal instillation of benzo[a]pyrene attachedto ferric oxide. The experimental period was 429 days for malesand 374 days for females. Respiratory tract tumours includedmainly epidermoid papillomas, epidermoid carcinomas and combinedepidermoid and adenocarcinomas. Selenium included either ina low-fat or high-fat diet did not influence the tumour responsein the respiratory tract or in other organs. Neither was therea correlation between the serum or liver Se levels in the presenceof respiratory tract tumours. The tumour response in the respiratorytract and also in other organs was slightly enhanced by dietaryfat.