“Marijuana is taken by … musicians. And I’m not speaking about good musicians, but the jazz type…”
Harry J. Anslinger (Commissioner of the US Bureau of Narcotics, 1930-1962)
Marijuana is the most widely used illicit drug in the United States. According to the National Survey on Drug Use and Health, 95 million Americans age 12 and older have tried marijuana at least once. Not surprisingly, experimental science involving cannabis has been largely restricted due to its illegality. Thus, while some health consequences of cannabis are known, the long term health effects of cannabis smoking remain unclear.
So… What are the FACTS?
- Marijuana smoke contains a 50-70 percent higher concentration of carcinogens than tobacco smoke contains (carcinogens are substances that cause cancer).
- Marijuana smokers inhale deeper and hold their breath longer than tobacco smokers do. This further increases the lungs’ exposure to carcinogenic smoke
- Regular marijuana smokers show deregulated growth of epithelial cells in their lung tissue- such pathological changes precede the development of lung cancer in tobacco smokers.
- Regular cannabis smokers have a higher prevalence of chronic bronchitis symptoms (wheezing, sputum production, chronic cough) and a higher incidence of acute bronchitis than non-smokers.
- Regular cannabis consumption is associated with airway injury, lung inflammation and impaired pulmonary defense against infection.
Despite these facts, epidemiological studies have been repeatedly and perhaps unexpectedly unsuccessful in linking marijuana use to respiratory cancers.
In 2006, the largest case-control study of its kind, funded by the National Institute of Health’s National Institute on Drug Abuse at UCLA, found no association between marijuana smoking and cancer. Researcher Donald Tashkin, MD, of the study explained “We know that there are as many or more carcinogens and co-carcinogens in marijuana smoke as in cigarettes, but we did not find any evidence for an increase in cancer risk for even heavy marijuana smoking.” While two-pack-a-day or more cigarette smokers were found to have a 20-fold increase in lung cancer, no elevation in risk was seen for even the heaviest marijuana smokers (the heaviest marijuana users in the study had smoked more than 22,0000 joints).
So… Why doesn’t smoking marijuana cause cancer if smoking cigarettes does?
The answer is not clear, but Dr. Tashkin and his team of researchers say it might have something to do with tetrahydrocannabinol, or THC, which is a chemical found in marijuana smoke. Cellular studies and even some studies in animal models suggest that THC has antitumor properties, either by encouraging the death of genetically damaged cells that can become cancerous or by restricting the development of the blood supply that feeds tumors. While the nicotine in tobacco has been show to inhibit the destruction of cancer-causing cells, THC appears to do the opposite seemingly lessening the tumor-promoting properties of marijuana smoke.
Marijuana is Not a Demon Weed or a Benign Substance…
In other words, just because cannabis has not been confirmed as a cause of respiratory cancers this does not make it healthy. While not cancer-causing, prolonged exposure to marijuana smoke will leave your lungs open to injury and infection. Recently, studies have shown that vaporizing cannabis exposes the user to lower levels of harmful substances than smoking cannabis. Vaporizers are a safer cannabinoid delivery system; however, they still do not eliminate respiratory irritation completely.
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