Comparative study of the carcinogenic activities of nas and some chemical carcinogens when introduced into the buccal pouch of the Syrian hamster.

Studies were carried out on the carcinogenic effects of nas, 7,12-dimethylbenz-[a]anthracene (DMBA), DMBA+nas, dimethylnitrosamine (DMNA), diethylnitrosamine (DENA), and N-methyl-N-nitrosourea (MNU) when introduced into the buccal pouch of the Syrian hamster. Nas alone induced no tumours in the buccal pouch but tumours at other sites occurred in 18.8% of the treated animals, compared with 4.4% of the controls. Three of 11 hamsters treated with DMBA alone developed tumours. No tumours appeared in the buccal pouch following treatment with DMBA + nas but they developed at other sites in 6 of the 11 hamsters treated. DMNA and DENA induced no macroscopic changes in the mucous membrane of the buccal pouch. Following DMNA administration, tumours developed only in the liver; no tumours developed following the application of DENA. Tumours developed at various sites, including the buccal pouch, in 20 of the 25 hamsters treated with MNU.