Cannabis Smoke Versus Tobacco SmokeCannabis smoke contains many of the same carcinogens as tobacco smoke, including greater concentrations of certain aromatic hydrocarbons such as benzopyrene, prompting fears that chronic marijuana inhalation may be a risk factor for tobacco-use related cancers. However, marijuana smoke also contains cannabinoids such as THC (delta-9-tetrahydrocannabinol) and CBD (cannabidiol), which are non-carcinogenic and demonstrate anti-cancer properties in vivo and in vitro. By contrast, nicotine promotes the development of cancer cells and their blood supply. In addition, cannabinoids stimulate other biological activities and responses that may mitigate the carcinogenic effects of smoke, such as down-regulating the inflammatory arm of the immune system that is responsible for producing potentially carcinogenic free radicals (unstable atoms that are believed to accelerate the progression of cancer).
Cannabis smoke — unlike tobacco smoke — has not been definitively linked to cancer in humans, including those cancers associated with tobacco use. However, certain cellular abnormalities in the lungs have been identified more frequently in long-term smokers of cannabis compared to non-smokers. Chronic exposure to cannabis smoke has also been associated with the development of pre-cancerous changes in bronchial and epithelium cells in similar rates to tobacco smokers. Cellular abnormalities were most present in individuals who smoked both tobacco and marijuana, implying that cannabis and tobacco smoke may have an additive adverse effect on airway tissue. The results suggest that long-term exposure to cannabis smoke, particularly when combined with tobacco smoking, is capable of damaging the bronchial system in ways that could one day lead to respiratory cancers. However, to date, no epidemiologic studies of cannabis-only smokers have yet to reveal such a finding. Larger, better-controlled studies are warranted.
Cannabis consumers who desire the rapid onset of action associated with inhalation but who are concerned about the potential harms of noxious smoke can dramatically cut down on their intake of carcinogenic compounds by engaging in vaporization rather than smoking. Cannabis vaporization limits respiratory toxins by heating cannabis to a temperature where cannabinoid vapors form (typically around 180-190 degrees Celsius), but below the point of combustion where noxious smoke and associated toxins (i.e., carcinogenic hydrocarbons) are produced (near 230 degrees Celsius). Because vaporization can deliver doses of cannabinoids while reducing the users intake of carcinogenic smoke, it is considered to be a preferred and likely safer method of cannabis administration than smoking marijuana cigarettes or inhaling from a water pipe. According to the findings of a recent clinical trial, use of the Volcano vaporizing device delivered set doses of THC to subjects in a reproducible manner while suppressing the intake of respiratory toxins.
"Our results show that with the Volcano, a safe and effective cannabinoid delivery system seems to be available to patients," investigators at Leiden University's Institute of Biology (the Netherlands) concluded.
"The final pulmonal uptake of THC is comparable to the smoking of cannabis, while avoiding the respiratory disadvantages of smoking."
(References: On the carcinogenicity of marijuana smoke. Recent Advances in Phytochemistry. 1975. **Author's Note: More recent studies on higher potency marijuana and/or sinsemilla have not been conducted and could potentially yield different results. | Cannabinoids and cancer: causation, remediation, and palliation. Lancet Oncology. 2005 | Cannabinoids: potential anticancer agents. Nature Reviews Cancer. 2003. | Nicotine exposure and bronchial epithelial cell nicotinic acetylcholine receptor expression in the pathogenesis of lung cancer. Journal of Clinical Investigation. 2003 | Cannabis and tobacco smoke are not equally carcinogenic. Harm Reduction Journal. 2005 | Ibid. | National Academy of Sciences, Institute of Medicine. Marijuana and Medicine: Assessing the Science Base. National Academy Press. 1999 | Tracheobronchial histopathology in habitual smokers of cocaine, marijuana and/or tobacco. Chest. 1997 | Histopathologic and molecular alterations in bronchial epithelium in habitual smokers of marijuana, cocaine and/or tobacco. Journal of the National Cancer Institute. 1998 | See footnotes 10 and 11 | Cannabis vaporizer combines efficient delivery of THC with effective suppression of pyrolytic compounds. Journal of Cannabis Therapeutics. 2004 | Hazekamp et al. 2006. Evaluation of a vaporizing device (Volcano) for pulmonary administration of tetrahydrocannabinol. Journal of Pharmaceutical Sciences 95: 1308-1317.) | Vaporization as a smokeless cannabis delivery system: a pilot study.
Clinical Pharmacology & Therapeutics. 2007.
Source: Cannabis Smoke and Cancer: Assessing the Risk - NORML