TSNA Exposure: Levels of NNAL Among Canadian Tobacco Users.

INTRODUCTION Tobacco smoke contains more than 7,000 chemicals, including known carcinogens, such as tobacco-specific nitrosamines (TSNAs). TSNA levels in cigarettes vary considerably within and across markets; however, the extent to which these different TSNA levels translate into differences in human exposure and risk remains unclear. The current study sought to examine TSNA exposure among Canadian tobacco users. METHODS Data from the 2007-2009 Canadian Health Measures Survey were used to measure levels of urinary NNAL [4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol], a metabolite of the TSNA NNK [4-(methylnitrosamino-1-(3-pyridyl)-1-butanone], among tobacco users (n = 507). Geometric mean concentrations of total urinary NNAL and creatinine-corrected total urinary NNAL were calculated. A linear regression model was used to examine predictors of urinary levels of NNAL. RESULTS The mean population level of total urinary NNAL and creatinine-corrected total urinary NNAL was 71.2 pg/ml and 82.0 pg/mg creatinine, respectively. NNAL levels were higher among older respondents (p = .02), among females (p = .04), and among those with greater daily cigarette consumption (p < .0001), greater levels of urinary free cotinine (p < .0001), and greater levels of urinary creatinine (p < .0001). Overall, the mean level of urinary total NNAL among Canadian tobacco users was approximately one fourth that of their U.S. counterparts. CONCLUSIONS The study findings provide the first nationally representative characterization of TSNA exposure among Canadian tobacco users. Although the findings indicate marked differences in TSNA exposure between Canadian and American populations of tobacco users, it is not known whether these differences in exposure translate into differences in risk.