Major Constituents of the Vapor Phase of the Mainstream Smoke of Non - Filter Cigarettes

In 1953, the first successful induction of cancer in a laboratory animal with a tobacco product was reported with the application of cigarette tara to mouse skin (Wynder et al., 1953). The particulate matter of cigarette smoke generated by an automatic smoking machine was suspended in acetone (1:1) and painted onto the shaven backs of mice three times weekly for up to 24 months. A clear dose response was observed between the amount of tar applied to the skin of the mice and the percentage of skin papilloma­ and carcinoma-bearing animals in the test group (Wynder et al., 1957). Since then, mouse skin has been widely used as the primary bioassay method for estimating the carcinogenic potency of tobacco tar and its frac­ tions, as well as of particulate matters of other combustion products (Wynder and Hoffmann, 1962, 1967; NCI, 1977a, 1977b, 1977c, 1980; Hoffmann and Wynder, 1977; IARC, 1986a). Intratracheal instillation in rats of the PAH-containing neutral subfraction of cigarette tar led to squa­ mous cell carcinoma of the trachea and lung (Davis et al., 1975). A ciga­ rette tar suspension in acetone painted onto the inner ear of rabbits led to carcinoma with metastasis in thoracic organs (Graham et al., 1957).