Carcinogens in tobacco smoke: benzo[a]pyrene from Canadian cigarettes and cigarette tobacco.

We evaluated the benzo[a]pyrene (BaP) content in the smoke from 35 brands of Canadian cigarettes and 5 brands of Canadian tobaccos for roll-your-own cigarettes. For the cigarettes, mean values of BaP ranged from 3.36 ng to 28.39 ng per cigarette, roughly in proportion with declared tar values. The relationship between declared tar and yields of BaP, however, does not allow accurate prediction of one from the other. For the tobaccos, mean BaP values ranged from 22.92 ng to 26.27 ng (average, 24.7 ng) per cigarette. The implications of these findings are discussed with respect to overall exposure.