A study of the dose response of mouse skin to cigarette smoke condensate

Smoke condensate from two types of cigarette, dissolved in two solvents, has been applied regularly to the backs of mice at each of seven different dose levels. Treatment was continued 3 times weekly for up to 110 weeks, by which time 509 of the 1428 treated mice had developed skin tumours. The dependence of tumour incidence on age was adequately described by the Weibull distribution. The relation - ship between dose of smoke condensate and tumour incidence rate was, however, erratic. It was less regular than the simple relationship which has in previous work been found to obtain when the pure carcinogen benzo(a)pyrene is applied to mouse skin.