Respiratory tract tumours in hamsters exposed to acetaldehyde vapour alone or simultaneously to benzo(a)pyrene or diethylnitrosamine.

Syrian golden hamsters were exposed to 0 or 2500-1650 ppm acetaldehyde vapour, 7 hr/day, 5 days/week for a period of 52 weeks. A proportion of the animals was given, simultaneously, either intratracheal instillations of benzo(a)pyrene (BP) or subcutaneous injections of diethylnitrosamine (DENA). All treatments were stopped after 52 weeks. The study was terminated after 81 weeks. Major effects attributed to acetaldehyde exposure included growth retardation, rhinitis, hyperplasia and metaplasia of the nasal, laryngeal and tracheal epithelium, nasal and laryngeal carcinomas, and a markedly increased incidence of BP-initiated tracheobronchial carcinomas. There was no evidence of acetaldehyde enhancing the development of DENA-initiated tumours of the respiratory tract. It was concluded that acetaldehyde is an irritant, as well as a carcinogen, for the respiratory tract of Syrian golden hamsters. Possible mechanisms of the carcinogenicity of this aldehyde are briefly discussed.