As public awareness of the dangers associated with smoking grows, cigarette use declines in the United States. This, along with spreading bans on smoking in public places, is encouraging the U.S. cigarette industry to turn to another tobacco category, smokeless tobacco products. Currently, a number of new brands are being test marketed. Considering the addictive nature of smokeless tobacco, its health risks, and the potential of newly developed products to attract new consumers among young people and to be accepted as a substitute for smoking by some smokers, it is essential to carry out independent comprehensive chemical analysis of these products in order to provide consumers, researchers, and public health officials with this information. We report here the results of our study in which Taboka, Marlboro Snus, Camel Snus, and Skoal Dry were analyzed for TSNA, tobacco alkaloids, anions, PAH, and volatile aldehydes, and compared to the most popular traditional moist snuff brands.
Because of their abundance in some smokeless tobacco products and existing strong evidence supporting their role in causation of oral and pancreatic cancer in smokeless tobacco users, TSNA have become a reference group of carcinogens in these products, their levels to some extent defining the degree of risk. The possibility of limiting TSNA formation during tobacco processing, as demonstrated by the relatively low levels of these carcinogens in some tobacco products (Österdahl, Jansson, & Paccou, 2004
), has compelled some tobacco companies to make a serious effort to significantly reduce TSNA levels in their products (Stepanov, Jensen, Hatsukami, & Hecht, 2006
). Overall, the results of our study demonstrate the partial success of this effort, with the exception of the Skoal Dry brand, which has TSNA levels comparable to those in some traditional commercial brands. NNN and NNK levels are relatively low in Taboka, Marlboro Snus, and Camel Snus. When expressed per dry weight, NNN levels in these products are comparable to those in the Swedish snus General, while NNK was about 2 times lower (). The processing of Swedish snus involves pasteurization which leads to lower levels of TSNA. Taboka, Camel Snus, and probably Marlboro Snus, also contain pasteurized tobacco. The reduction in carcinogenic TSNA content in the new smokeless tobacco is encouraging. TSNA levels in traditional moist snuff analyzed in this study are similar to those reported earlier (Stepanov, Jensen, Hatsukami, & Hecht, 2006
). As known human carcinogens, NNN and NNK are not safe at any level, and even the lower amounts found in the new tobacco products are still 100 to 1000 times higher than nitrosamine levels in other products such as food and beer (Bartsch & Spiegelhalder, 1996
The consumer's acceptance of a smokeless tobacco product and addiction to it depends on the nicotine content and the pH – parameters defining the amount of biologically available unprotonated nicotine. Total nicotine levels expressed per dry weight of product are quite similar across the brands (). However, due to differences in pH values, there is a large variation in the levels of unprotonated nicotine. Taboka and Marlboro Snus have the lowest pH values and, consequently, the lowest levels of free nicotine. A positive aspect of the low free nicotine content is the lower addictive potential of these products. However, low unprotonated nicotine products could be more easily accepted by young people who initiate tobacco use. Moreover, the low-nicotine products may not provide a good substitute for cigarette smoking, potentially leading to dual use of the cigarettes and smokeless tobacco products (Hatsukami, Ebbert, Feuer, Stepanov, & Hecht, 2007
Camel Snus, slightly higher in total nicotine and pH than Taboka and Marlboro Snus, contains up to 9 mg unprotonated nicotine per gram dry weight – an amount similar to the most popular traditional brands. This high level of biologically available nicotine has the potential to satisfy those smokers who are looking for a substitute for smoking, and to keep them addicted to this product.
Levels of nornicotine were relatively high in Taboka, and generally elevated in new products as compared to the traditional brands (). There are some indications that nornicotine, which may accumulate in the brain (Crooks & Dwoskin, 1997
; Crooks, Li, & Dwoskin, 1995
), contributes to the addiction associated with tobacco use (Bardo, Green, Crooks, & Dwoskin, 1999
). Another potential risk is endogenous nitrosation of nornicotine in the stomach, which can lead to formation of NNN (Porubin, et al., 2007
). The potential health effects of the relatively high levels of anatabine observed in Taboka are unknown.
Nitrite and nitrate content in smokeless tobacco products are important for a number of reasons. Nitrate in saliva is converted to nitrite (Marletta, 1988
). The toxic properties of nitrite include methemoglobin formation (ALS, 1988
) and conversion to nitrosating agents, which can participate in endogenous synthesis of nitrosamines from tobacco alkaloids and dietary amines (Porubin, et al., 2007
; Shepard, Schlatter, & Lutz, 1987
). The relatively low levels of nitrite and nitrate in the new smokeless tobacco products probably reflect the manufacturer's effort to reduce toxicity of their products and to limit TSNA formation during tobacco processing. Among the other anions analyzed here, the relatively high levels of chloride in Camel Snus and in traditional moist snuff smokeless products are noteworthy. Sodium chloride is a known additive to smokeless tobacco, and is used as a flavor enhancer and antimicrobial agent. High doses of salt can damage the gastric epithelium, providing favorable conditions for the occurrence of mutations (Charnley & Tannenbaum, 1985
; Sugimura, 2000
). A positive correlation between daily salt intake and gastric cancer incidence has been reported (Hirayama, 1984
; Tsugane, 1991
). Local irritation from salt may increase the absorption of smokeless tobacco carcinogens in the oral cavity, and also may lead to chronic inflammation and tumor promotion.
The low levels of PAH in the new smokeless tobacco is a very positive sign (). Anthracene, BbF, BkF, and BaP are virtually undetectable in these products, while other PAH are present in trace amounts. However, PAH levels in the most popular brands currently used by millions of consumers are in some cases remarkably elevated. Even though human toxicity data for acenaphthylene, phenanthrene, anthracene, fluoranthene, and pyrene are not available, animal studies suggest a range of negative effects, including pulmonary, endocrine, and liver toxicity, as well as co-carcinogenicity (USDHHS, 2001
). BbF and BkF are IARC group 2B carcinogens (possibly carcinogenic to humans, IARC, 1983
), and to our knowledge, this is the first study to report their presence in smokeless tobacco. The sum of these carcinogens is comparable to the amounts of BaP detected in the same products, which, in turn, are similar to those reported in the literature (Hoffmann et al., 1987
; McNeill et al., 2006
). BaP has recently been classified by IARC as a group 1 carcinogen (carcinogenic to humans, IARC, 2007
Volatile aldehydes commonly occur in the human environment (IARC, 1995
; USDHHS, 2004
). Overall, their levels are relatively low in the products studied here, when compared to other sources of exposure such as the diet and alcoholic beverages (). A surprising finding was the relatively elevated levels of crotonaldehyde in Taboka and Marlboro Snus. The manufacturer should identify and eliminate the source of contamination of their products with this mutagen (Neudecker, Eder, Deininger, & Henschler, 1989
) and carcinogen (Chung, Tanaka, & Hecht, 1986
Expression of levels of toxic and carcinogenic constituents per dry weight of tobacco does not allow us to compare the actual exposure to these agents per single doses, or portions, of the products. In , we estimate the levels of the most important agents analyzed in this study per single portion of some new and traditional tobacco products. The moisture content of new smokeless tobacco products ranges from 10.1 to 31.2%, while that of traditional brands averages 54.1%. If portion sizes were similar for both groups of products, the toxicant and carcinogen intake from the new products would be somewhat similar to that from traditional ones. However, the differences in the portion size between the new and traditional smokeless tobacco products lead to even more drastic differences in toxicant and carcinogen amounts per dose. The mean weight of one pouch of a new smokeless tobacco product in our study was 0.287 g, while the weight of one pouch of General snus was 1.27 g, and the mean reported grams per dip of traditional moist snuff is about 1.5 (Hatsukami & Severson, 1999
). As a result, one pouch of a new smokeless tobacco product contains on average about 20 times lower amounts of the analyzed agents than an average portion of traditional products (). The levels of crotonaldehyde, even though relatively high in Taboka and Marlboro Snus when expressed per dry weight of product, become comparable to the levels of this carcinogen in an average portion of traditional moist snuff. It is not clear, however, whether users of these new products will use more pouches to compensate for the smaller amount of tobacco per pouch.
Average levels of nicotine, chloride, and some carcinogens per portion
In summary, we report here a large variation in the levels of important toxicants and carcinogens in a range of recently introduced smokeless tobacco products and some of the most popular traditional moist snuff brands. Some of the new smokeless tobacco products contain much lower levels of most of the carcinogens analyzed here, as compared to the traditional brands. More effort is required from the U.S. tobacco industry to further reduce levels of these important chemical agents in both new and conventional smokeless tobacco products.