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Smokeless-Tobacco Products Have Higher Levels of Cancer-Causing Chemicals

Researchers find tobacco-specific nitrosamines

Higher levels of cancer-causing chemicals called tobacco-specific nitrosamines in smokeless tobacco products led to greater exposure to these carcinogens even after taking into account how much or how long the product was used, according to a study published in Cancer Prevention Research, a journal of the American Association for Cancer Research.

“Our results show that although the pattern of tobacco use — for example, amount of dip and number of dips — can influence the level of smokeless tobacco users’ exposure to tobacco-specific nitrosamines, the actual amount of these chemicals in the products also makes a significant difference,” said lead investigator Dorothy K. Hatsukami, PhD.

“The majority of smokeless tobacco users in the United States are not aware of the levels of cancer-causing chemicals in their smokeless tobacco products or of the tremendous variability in the levels of these chemicals across brands sold in this country,” Hatsukami added. “At a minimum, the FDA should provide smokeless-tobacco consumers information about the different levels of cancer-causing chemicals in different brands of smokeless tobacco and, ideally, require levels of tobacco-specific nitrosamines be substantially reduced, if not eliminated, in all products. Levels of these chemicals in smokeless tobacco products could be readily reduced by changing manufacturing practices.”

Levels of exposure to tobacco-specific nitrosamines are associated with disease risk, according to Hatsukami. Prior studies have shown that smokeless-tobacco users in the U.S. have about two to three times greater risks for oral cancer compared with those who do not use these products, she said. Pancreatic cancer has also been linked to smokeless-tobacco use.

“Now that the FDA has the authority to establish product standards — that is, mandate the reduction of harmful and potentially harmful constituents in tobacco products — there has been greater interest in understanding how levels of tobacco-specific nitrosamines in products relate to exposure,” Hatsukami said.

To study this, Hatsukami and her colleagues analyzed data from 391 adults in Minnesota, Oregon, and West Virginia who used smokeless-tobacco products daily. The smokeless-tobacco brands used by different participants varied in nicotine and tobacco-specific nitrosamine content. The study participants could not be current users of other tobacco or nicotine products.

At two assessment sessions, held approximately 1 week apart, demographic information, smokeless-tobacco–use history, and urine samples were collected from the participants. The urine samples were analyzed for biomarkers of exposure to nicotine and to the tobacco-specific nitrosamines N’-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK).

Analyses showed that levels of biomarkers of NNN and NNK in users’ urine samples were independently positively correlated with the number of years of daily smokeless-tobacco use, the number of tins of smokeless tobacco used each week, the mean daily dip duration, and the levels of NNN and NNK in the smokeless-tobacco products used.

The study was supported by the National Cancer Institute.

Source: AACR; December 18, 2014.

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