Chewing tobacco not “safe” alternative to smoking

People who use chewing tobacco expose themselves to even higher levels of a particular cancer-causing compound than tobacco smokers do, according to a new study.

Researchers found that compared with cigarette smokers, adults who used chewing tobacco appeared to have greater exposure to a substance called NNK, one of the prime carcinogens in tobacco. In laboratory animals, NNK has been found to cause cancer of the lung, pancreas, liver and nasal mucosa.

The researchers say these findings reinforce the message that smokeless tobacco is not a “healthier” alternative to smoking.

“Smokeless tobacco products have been proposed by some as safer alternatives to cigarettes, but they are not safe,” lead study author Dr. Stephen S. Hecht, a professor of cancer prevention at the University of Minnesota Cancer Center, Minneapolis, said in a statement.

“The only likely safe alternative to smoking is the long-term use of nicotine replacement therapy as a means to reduce dependence,” he added.

Hecht and his colleagues report their findings in the journal Cancer Epidemiology, Biomarkers & Prevention.

Their study involved 420 cigarette smokers and 182 tobacco chewers who did not smoke. All of the subjects were part of various studies testing ways to help them quit.

Hecht’s team looked specifically at the study participants’ urine levels of NNAL, a byproduct of NNK used to estimate a person’s exposure to the cancer-causing agent. They found that on average, smokeless-tobacco users had even higher levels of NNAL than smokers did.

The findings do not mean cigarettes are the safer form of tobacco, however. Cigarette smoke contains a number of carcinogens that are not present in chewing tobacco, the researchers point out.

But the results do suggest that when it comes to NNK, chewing tobacco may be a “more efficient means” of delivering this substance to the bloodstream, according to Hecht.

There are some brands of smokeless tobacco marketed as being “low-nitrosamine” that do seem to have lower levels of NNK, Hecht and his colleagues note. However, they stress, people who use such products still show “substantial” amounts of NNAL in their urine.

SOURCE: Cancer Epidemiology, Biomarkers & Prevention, August 2007.

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