Nicotine patches, gum not risk-free, study says
Although using nicotine patches and gum is far better than smoking, they may not be totally safe, researchers at the University of Minnesota have found.
Tests at the university's Cancer Center show, for the first time, that nicotine absorbed from smoking cessation aids has the potential to be converted into NNK, a carcinogen that causes lung cancer.
``It raises a red flag,'' especially for long-term nicotine replacement therapy, said Stephen Hecht, the Wallin professor of cancer prevention at the university and the study's lead author.
Hecht cautions that people should not stop using nicotine replacement therapies because of the study's findings.
``It clearly is better to be on the patch or gum than smoke,'' Hecht said. ``We don't want people to stop using these products and go back to smoking. That would be terrible. Smoke is filled with horrible stuff.''
Jack Henningfield, a researcher at Johns Hopkins University in Baltimore who also does consulting work for the tobacco-dependency treatment industry, agrees.
``Smoke from tobacco products is known to have 40 or more known carcinogens,'' he said. Henningfield said he wouldn't trade the potential risk in cessation aids for someone slipping back to smoking.
Hecht's research is important, Henningfield said, but needs to be proven outside the lab. Until then, ``it's not research that should cause people to think for one second about the safety of their patch,'' he said.
However, Hecht said tobacco cessation devices may not be completely without potential side effects. ``We don't have the data to say not to use them for long-term therapy,'' he said.
In the study, Hecht and his colleagues found that nicotine absorbed from the patch and gum is converted into pseudooxynicotine, a direct precursor of NNK. This is the first time researchers were able to show this conversion occurs in mammals, Hecht said.
But Hecht said more research is needed to establish whether the pseudooxynicotine is then converted into NNK, the deadly carcinogen.
``We don't know if it happens in humans, but it readily happens in the test tube, so it's possible, even likely, that it happens in humans,'' Hecht said.
To complete the conversion, pseudooxynicotine must be exposed to nitrite. Hecht said this can occur in humans under the right conditions, such as during an inflammation or in the stomach, which has the acid makeup ideal for such a conversion.
Hecht is not sure whether he will attempt to determine whether the last link in the conversion chain exists because it would require a series of experiments, a considerable amount of work and some additional funding.
``It's difficult to demonstrate, but we may give it a shot,'' he said.