Cal NORML Testifies at Hearings on Carcinogenicity of Marijuana Smoke

   SACRAMENTO, Nov 19, 2007.    The Cal. Office of Environmental Health Hazard Assessment (OEHHA) has decided to investigate the carcinogenicity of marijuana smoke.   The decision came following hearings before an expert panel in Sacramento, where California NORML testified that existing scientific evidence has failed to show that marijuana smoke is carcinogenic.   The purpose of the hearings was to determine whether  OEHHA should investigate marijuana smoke for possible inclusion on the official state list of carcinogens under Prop. 65.

            The expert panel agreed that the best epidemiological studies have failed to show a connection between marijuana smoking and lung cancer in humans.  In particular, they cited a large, well-controlled study by Dr. Hashibe and Tashkin at UCLA, which found no increase risk of respiratory cancer in marijuana-only smokers.    However,  the panel expressed concern   that marijuana smoke is known to contain many (though by no means all) of the carcinogens found in tobacco smoke.   They also noted that a couple of smaller studies had suggested a possible link between prenatal exposure to marijuana and two  rare childhood cancers.  

            California NORML coordinator Dale Gieringer pointed out that  recent studies have shown that THC and other cannabinoids in marijuana smoke may actually suppress cancers, including lung cancer.  Coincidentally, on the same day as the hearings, a new study was released showing that CBD, the second most common cannabinoid in marijuana, inhibits growth of breast cancer.  
            Cal NORML emphasized that marijuana smoke is not a well defined substance since marijuana comes in many varieties and kinds of preparations.  Most of the lab studies of marijuana smoke have used marijuana supplied by the government's  NIDA farm, which supplies low-grade leaf resembling cigarette tobacco in consistency.  In contrast,  because DEA regulations prevent use of non-NIDA marijuana, there have been virtually no studies on smoke from higher-grade sinsemilla bud, which has now become the most popular form of marijuana,  particularly in medical use. 

            The panel agreed that this was an excellent point and asked for help in identifying the kind of marijuana used in studies to date.   It went on to vote 4-2 for an official OEHHA investigation of marijuana smoke, on the grounds that existing data were inconclusive.

            Should the OEHHA decide to classify marijuana smoke as a carcinogen,  then warning signs would be required on all premises where public exposure is likely the most likely candidate being cannabis clubs.   If the OEHHA rules the other way, it should help deflate wrong-headed claims by pot opponents that marijuana is more dangerous than cigarettes.

            California NORML's testimony on carcinogenicity of marijuana smoke can be found at

CA NORML 2261 Market St. #278A San Francisco CA 94114