Chewing tobacco is more harmful than smoking

People who use chewing tobacco expose themselves to higher levels of cancer-causing compounds than tobacco smokers.

Researchers from the University of Minnesota Cancer Center, Minneapolis, studied 420 cigarette smokers and 182 tobacco chewers who did not smoke. All the people were part of various studies testing ways to help them quit. It was found that compared with cigarette smokers, adults who chewed tobacco appeared to have greater exposure to a substance called NNK (a nitrosamine), 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 urine levels of NNAL, a by-product of NNK used to estimate a person's exposure to the cancer-causing agent were studied. It was found that on average, tobacco chewers had higher levels of NNAL than smokers.

The findings reinforce that smokeless tobacco is not a "healthier" alternative to smoking. Though some have proposed smokeless tobacco products as safer alternatives to cigarettes, they are not safe. The only supposedly safe alternative to smoking is the long-term use of nicotine replacement therapy as a means to reduce dependence.

However, the findings do not suggest that cigarettes are a safer form of tobacco. Cigarette smoke contains a number of carcinogens that are not present in chewing tobacco. 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. There are some brands of smokeless tobacco marketed as being "low-nitrosamine" that do seem to have lower levels of NNK. However, people who use such products still show "substantial" amounts of NNAL in their urine.