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National Institutes of Health
Scientists ID Cancer-Causing Agent in Smokeless Tobacco
Study rats received equivalent of daily half-tin of ingredient over 30 years
Wednesday, August 22, 2012
The culprit, found in such products as chewing tobacco and snuff, is a nitrosamine compound called (S)-NNN. Nitrosamines in tobacco are considered to be cancer-causing, according to the U.S. National Cancer Institute.
Authors of the new study acknowledge that such compounds are found in many foods, including beer and bacon. But they say that levels are much higher in smokeless tobacco products, leading them to suggest that the U.S. government should therefore ban or regulate (S)-NNN.
The researchers are scheduled to present their findings Wednesday at the American Chemical Society annual meeting, in Philadelphia.
"This is the first example of a strong oral-cavity carcinogen that's in smokeless tobacco," study author Stephen Hecht, from the University of Minnesota, said in a society news release. "Our results are very important in regard to the growing use of smokeless tobacco in the world, especially among younger people who think it is a safer form of tobacco than cigarettes. We now have the identity of the only known strong oral carcinogen in these products."
Roughly 9 million Americans use smokeless tobacco products, according to the release. This has raised alarm about the potentially elevated risk users may face for the mouth, esophageal and pancreatic cancer.
In the study, laboratory rats were given two types of low-dose NNN for 17 months. That timeframe was equated to human consuming a half-tin of smokeless tobacco on a daily basis for 30 years.
One type of NNN known as (S)-NNN was found to prompt the onset of oral and esophageal tumors.
In theory, (S)-NNN can be removed from smokeless tobacco products, with some particular products already featuring reduced levels of the compound, according to the release.
"The most popular brands of smokeless tobacco that are sold in the U.S. have unacceptably high levels of this particular carcinogen," Hecht said. "And smokeless tobacco is a known cause of oral cancer. Obviously, we need to decrease the levels of this material in all smokeless tobacco products or eliminate it altogether."
Scientists note that research with animals often fails to provide similar results in humans. Because this study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.
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