Introduction
In 2002 the British Lung Foundation issued a major report entitled "The Smoking Gun" which contained some worrying claims about the health effects of smoking cannabis. The press picked up on it and reported it in some detail, usually presenting the claims made in the report as hard fact. In the years following The Smoking Gun further research has been undertaken, not least of all by Donald Tashkin of the University of California, Los Angeles (Times-tribune report, May 2009):
"UCLA's Dr. Donald Tashkin studied heavy marijuana smokers to determine whether the use led to increased risk of lung cancer and chronic obstructive pulmonary disease, or COPD. He had hypothesized that there would be a definitive link between cancer and marijuana smoking, yet the results proved otherwise. "What we found instead was no association and even a suggestion of some protective effect," says Dr. Tashkin, whose research was the largest case-control study ever. The study was funded by the National Institutes of Health.
Tobacco smokers in the study had as much as a 21-fold increase in lung cancer risk. Cigarette smokers, too, developed COPD more often in the study, and researchers found that marijuana did not impair lung function. Dr. Tashkin, supported by other research, concluded that the active ingredient tetrahydrocannabinol, or THC, has an "anti-tumoral effect" in which "cells die earlier before they age enough to develop mutations that might lead to lung cancer."
However, the smoke from marijuana did swell the airways and lead to a greater risk of chronic bronchitis."
UKCIA
