Variation of Benzo[ a ]pyrene, NNN, and NNK Levels in 16 Commercial Smokeless Tobacco Products.

This study examined the variation of benzo[ a ]pyrene (B[ a ]P), N '-nitrosonornicotine (NNN), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) levels in 16 smokeless tobacco products from several different product subcategories obtained at two different locations and at two different procurement times. B[ a ]P quantities range from 0.6 to 160 ng/g on a wet-weight basis, whereas NNN and NNK quantities range from 276 to 10473 ng/g and 79 to 28882 ng/g, respectively. The B[ a ]P, NNN, and NNK quantities vary widely among various smokeless tobacco product categories and among various brands within each product subcategory. Dry snuff products contain the highest B[ a ]P, NNN, and NNK quantities, whereas loose and portioned snus products contain the lowest B[ a ]P, NNN, and NNK levels. In general, variation of B[ a ]P, NNN, and NNK levels across four sets of each product brand purchased six months apart and at two different locations show statistically significant differences ( p < 0.05), although with a much narrower product set-to-set variability.