The Associated Press:
Chicago - Smoking a joint once a week or a bit more apparently doesn't
harm the lungs, suggests a 20-year study that bolsters evidence that
marijuana doesn't do the kind of damage tobacco does.
The study by researchers at the University of California, San
Francisco, and the University of Alabama at Birmingham was released
Tuesday by the Journal of the American Medical Association.
The findings echo results in some smaller studies that showed while
marijuana contains some of the same toxic chemicals as tobacco, it does
not carry the same risks for lung disease.
It's not clear why that is so, but it's possible that the main active
ingredient in marijuana, a chemical known as THC, makes the difference.
THC causes the "high" that users feel. It also helps fight inflammation
and may counteract the effects of more irritating chemicals in the
drug, said Dr. Donald Tashkin, a marijuana researcher and an emeritus
professor of medicine at the University of California, Los Angeles.
Tashkin was not involved in the new study.
Study co-author Dr. Stefan Kertesz said there are other aspects of marijuana that may help explain the results.
The analyses showed pot didn't appear to harm lung function, but
cigarettes did. Cigarette smokers' test scores worsened steadily during
the study. Smoking marijuana as often as one joint daily for seven
years, or one joint weekly for 20 years was not linked with worse
scores. Very few study participants smoked more often than that.
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