Findings so far show that the regular use of marijuana or THC may play a role in cancer and problems in the respiratory, and immune systems.
CancerIt is hard to find out whether marijuana alone causes cancer because many people who smoke marijuana also smoke cigarettes and use other drugs. Marijuana smoke contains some of the same cancer-causing compounds as tobacco, sometimes in higher concentrations. Studies show that someone who smokes five joints per day may be taking in as many cancer-causing chemicals as someone who smokes a full pack of cigarettes every day.
Tobacco smoke and marijuana smoke may work together to change the tissues lining the respiratory tract. Marijuana smoking could contribute to early development of head and neck cancer in some people. Smoking marijuana has also been link to testicular cancer.
Immune SystemOur immune system protects the body from many agents that cause disease. It is not certain whether marijuana damages the immune system of people. But both animal and human studies have shown that marijuana impairs the ability of T-cells in the lungs' immune defense system to fight off some infections.
Lungs and AirwaysPeople who smoke marijuana regularly may develop many of the same breathing problems that tobacco smokers have, such as daily cough and phlegm production, more frequent chest colds, a heightened risk of lung infections, and a greater tendency toward obstructed airways. Cancer of the respiratory tract and lungs may also be promoted by marijuana smoke, since it contains irritants and carcinogens.
Marijuana smokers usually inhale more deeply and hold their breath longer, which increases the lungs' exposure to carcinogenic smoke. Thus, puff for puff, smoking marijuana may increase the risk of cancer more than smoking tobacco does.
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