(From The Province: October 19, 2005)

The key difference between cannabis and tobacco smoke is that cigarettes contain nicotine, the cancer-causing chemical of tobacco.  Cannabis, on the other hand, contains tetrahydrocannabinol (THC, active ingredient in pot), that has been shown to reduce the carcinogenic properties of some chemicals.

Robert Melamede, chairman of the department of biology at the University of Colorado, said there is no evidence that cannabis smoking increases the risk of lung cancer or other cancers related to tobacco smoking such as breast, colon and rectal cancer.

Both tobacco and cannabis smoke have similar chemical properties, it is their pharmacological activities that differ greatly.