NEW YORK (Reuters Health) ¿ 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.