New research suggests that cannabis smokers are at less risk of developing cancer than cigarette smokers. Although the chemical structures of marijuana and tobacco are strikingly similar, tobacco has the added nemesis of nicotine in it while cannabis contains tetrahydrocannabinol (THC, the active ingredient in pot).
It is theorized that THC may actually inhibit the carcinogenic properties of some other chemicals. This report is detailed in today's edition of the medical journal Harm Reduction. The study reviews and analyzes some other studies that have already
pointed out this startling fact. Marijuana contains about four times the amount of tar found in cigarettes and this means that the lung cancer risk must quadruple. But this is not an established fact, says Robert Melamede, chairman of the department of biology at the University of Colorado at Colorado Springs. "Current knowledge does not suggest that cannabis smoke will have a carcinogenic potential comparable to that resulting from exposure to tobacco smoke," he said adding that the same was true of breast, colon and rectal cancer; all of which have strong causative links to smoking. "While both tobacco and cannabis smoke have similar properties chemically, their pharmacological activities differ greatly," Melamede said. He added that in laboratory rats the THC in pot actually "exerts a protective effect", while nicotine accentuates the carcinogenic properties of tobacco. The smoke from tobacco contains 4,000 known chemicals among which at least a dozen are implicated as carcinogens.