, 2007). The importance of TSNA content www.selleckchem.com/products/Sorafenib-Tosylate.html is based on the existing strong evidence supporting their role in causation of cancers of the lung, pancreas, oral cavity, and esophagus in smokers and oral cavity and pancreas in smokeless tobacco users (Bartsch & Spiegelhalder, 1996; Hecht, 1998; Hecht & Hoffmann, 1988; Magee, 1996; Preston-Martin & Correa, 1989) and the relationship between amount of exposure to TSNAs and cancer risk (Church et al., 2009; Yuan et al., 2009). Thus, completely switching to the use of lower-TSNA smokeless products instead of smoking is seen by some public health researchers as a potential strategy to reduce harm in those smokers who are unable or unwilling to quit tobacco use (Bates et al., 2003; Levy et al., 2004).

Whereas the actual public health impact of oral products like Camel Snus and Marlboro Snus is yet unknown, the initial analyses revealed that single pouches of these products contain relatively low amounts of TSNA and nicotine, as compared with traditional smokeless products (Stepanov, Jensen, Hatsukami, & Hecht, 2008). However, since their first introduction to the market, there have been a number of changes in the design of both Camel Snus and Marlboro Snus, including modifications in packaging, flavors, and pouch sizes. It is unknown whether these changes were accompanied by changes in the processing and/or type of tobacco used for the manufacturing of these products. Furthermore, it is unknown how changes in pouch size affected the dose of constituents to which consumers are exposed from the use of a single pouch.

To determine whether these alterations were accompanied by any changes in TSNA and nicotine content, we examined the available data on 60 samples of Camel Snus and 87 samples of Marlboro Snus that were either purchased by our group or received from other researchers in the period 2006�C2010. Analyses of these products were conducted for different purposes and at different times; however, the standard methods routinely used in our laboratory, as well as the inclusion of positive and negative controls for quality control purposes, ensure comparability of these results. We examined the levels of total nicotine, unprotonated nicotine, and the sum of N��-nitrosonornicotine Carfilzomib (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), the only TSNA classified as carcinogenic to humans (International Agency for Research on Cancer, 2007). Materials and Methods Snus Samples Snus samples were either purchased in Minneapolis and St. Paul, Minnesota area or received from other researchers in different parts of the United States, as a part of various projects.