Comparative carcinogenicity of cigarette mainstream and sidestream smoke condensates on the mouse skin

Abstract

The direct carcinogenic effects of sidestream (SS) and mainstream (MS) smoke condensates of a filtered commercial brand of blond cigarettes were compared using a lifetime mouse skin tumorigenicity assay on female NMRI mice. Each cigarette was smoked by a smoking machine under the standard conditions, and the separately collected SS and MS smoke condensates were extracted with acetone/methanol as described elsewhere. These were tested for carcinogenicity on an area of 1-1.5 cm shaved skin of mice on the lower back. The mice were treated with half of each dose (5, 10 or 15 mg) twice a week, for only 3 months. No substance was used as promoter or as an additional initiator of carcinogenicity. No statistically significant difference was found when the life spans of MS-treated and untreated animals were compared. In contrast, the life spans of SS-treated mice were significantly (P less than 0.01) shorter than those of MS-treated animals or those of all three negative control groups together. The observed carcinogenic effects were based on tumours and lesions found only on the site of application of the test material. Of 210 mice (effective number, 129) serving as the negative controls, 3 developed skin lesions but no tumours. Of 210 MS-treated mice (effective number, 177), 7 developed tumours (4 malignant and 3 benign) and 35 had a uniform type of precancerous skin lesions. The numbers of tumours or lesions were not increased dose-dependently. Of 210 SS-treated animals (effective number, 182), 30 developed tumours (16 malignant and 14 benign) and 56 had a uniform type of precancerous skin lesion. The initiation of these latter lesions was found to be dose-dependent (P less than 0.001). The SS-treated animals developed two to six times more skin tumours than the MS-treated mice. Comparing the negative controls with the MS- or SS-treated animals, the overall carcinogenic effect observed was statistically significant. Comparing the MS- with SS-treated animals, the overall carcinogenic effect of SS was much higher than that of MS (P less than 0.001).

Passive Smoking and Cervical Cancer Risk: A Meta-analysis Based on 3,230 Cases and 2,982 Controls

“…Evidences show that at least 17 carcinogenic chemicals contained in * tobacco smoke are emitted at higher levels in sidestream smoke than mainstream smoke (Mohtashamipur et al, 1990). And benzo (a) pyrene diol epoxide, one of the metabolites of tobacco smoke is found in both mainstream and sidestream smoke, that shows a direct aetiological association with lung cancer (Denissenko et al, 1996).…”

Differential sensitivity of male germ cells to mainstream and sidestream tobacco smoke in the mouse

“…SS smoke is a mixture of over 4000 chemicals, including more than 50 carcinogens and 200 toxicants (U.S. Department of Health and Human Services, 2006). Although there are few qualitative differences between MS and SS smoke (Fowles and Dybing, 2003), some toxicants, including carcinogens, are significantly elevated in SS smoke (Mohtashamipur et al, 1990;Fowles and Dybing, 2003;California Environmental Protection Agency, 2005). This suggests that passive smoking may produce effects that differ from those induced by active smoking.…”

Passive smoking and lung cancer: a cumulative meta‐analysis

“…1,2 At least 17 of these compounds are emitted at higher levels in sidestream smoke than in mainstream smoke, and animal bioassays indicate that sidestream tobacco tar is more carcinogenic per unit weight than mainstream tar. [3][4][5] Recent evidence indicates that one of the metabolites of tobacco smoke (benzo(a)pyrene diol epoxide), found in both mainstream and sidestream smoke, shows a direct aetiological association with lung cancer. 6 Given present knowledge about the carcinogenic activity of tobacco smoke, the existence of an association between passive smoking and lung cancer is biologically plausible.…”