Our recent studies on tobacco
smoke carcinogen and toxicant
biomarkers and
cancer risk among male smokers in the Shanghai Cohort Study showed that exposure to tobacco-specific
nitrosamines (TSNA) and
polycyclic aromatic hydrocarbons (PAH) is prospectively associated with the risk of
cancer. These findings support the hypothesis that the smokers'
cancer risk is a function of the dose of select tobacco
carcinogens and highlight the importance of understanding the factors that affect the intake of these
carcinogens by smokers. Given that tobacco constituent exposures are driven, at least in part, by the levels of these constituents in cigarette
smoke, we measured mainstream
smoke TSNA and PAH levels in 43 Chinese cigarette brands that participants of the Shanghai Cohort Study reported to
smoke. In all brands analyzed here, mainstream
smoke levels of NNN and NNK, the two carcinogenic TSNA, were generally relatively low, averaging (±SD) 16.8(±25.1) and 14.2(±9.5) ng/cigarette, respectively. The levels of PAH were comparable to those found in U.S. cigarettes, averaging 15(±9) ng/cigarette for
benzo[a]pyrene, 119(±66) ng/cigarette for
phenanthrene and 37(±19) ng/cigarette for
pyrene. Our findings indicate that the generally low levels of NNN and NNK are most likely responsible for the relatively low levels of the corresponding
biomarkers in the urine of the Shanghai Cohort Study participants as compared to those found in the U.S. smokers, supporting the role of the levels of these constituents in cigarette
smoke in smokers' exposures. Our findings also suggest that, in addition to smoking, other sources contribute to Chinese smokers' exposure to PAH.