Sacramento, CA: The Office of Environmental Health Hazard Assessment (OEHHA) and the California Environmental Protection Agency have added marijuana smoke to the state’s list of official carcinogens, pursuant to Title27, California Code of Regulations, section 25305(a)(1).

Under state law, the Governor’s office is required to publish an annual list of chemicals that possess potential carcinogenic properties and/or are associated with reproductive toxicity, such as arsenic, lead, and tobacco smoke. Products containing such chemicals are required to carry warning labels. Business establishments with ten employees or more are also are mandated to post signs indicating whether there is a likelihood that an individual may be exposed to such chemicals while on the premises.

State environmental regulators determined that there is “limited” evidence “suggestive” that marijuana smoke exposure may be associated with an increased cancer risk in humans. Their review added, “[T]he similarities in chemical composition and in toxicological activity between marijuana smoke and tobacco smoke, and the presence of numerous carcinogens in marijuana (and tobacco) smoke, provide additional evidence of carcinogenicity.”

Presently, over 300 separate chemicals – including aspirin and alcoholic beverages – are designated as carcinogens under California law.

Labeling requirements for marijuana smoke will not take effect until June 2010. Neither marijuana nor edible products containing marijuana will be designated as carcinogens under state law.

Regulators made no official determination regarding the status of cannabis vapor, which does not contain combustion gases and has been determined to be a “safe and effective vehicle” for cannabis delivery in clinical trials.

Authors of the review did note that the largest population case-control study ever to assess the use of marijuana and lung cancer risk did not find a positive association between long-term cannabis smoking and cancer.

California NORML Coordinator Dale Geiringer said that the ruling did not come as a surprise because it has been well known for years that cannabis smoke contains known carcinogenic chemicals. However, he noted that the intake of these noxious chemicals “can be completely eliminated by vaporization or by consuming marijuana orally.”

NORML Deputy Director Paul Armentano said that it remains unclear what effect, if any, these new regulations will have on the dispensing of medical marijuana in California. “Since it is marijuana smoke, not marijuana per se, that is at issue here, it is not clear that legally operating medicinal cannabis dispensaries will have to alter their actions to comply with Prop. 65,” he said – noting that few such facilities allow patients to smoke cannabis on the premises. “Liquor stores are not required to post warnings on the premises just because they dispense alcohol, so why would medical cannabis dispensaries be treated any differently?”