Recent studies
Safety of cannabis

Various strains of medical marijuana in front of a vaporizer

Cannabis smoke contains thousands of organic and inorganic chemical compounds. This tar is chemically similar to that found in cigarette smoke and includes many of the same carcinogens.[53]

A statement from a source in the US Department of Justice in 1988 said, "Nearly all medicines have toxic, potentially lethal effects. But cannabis is not such a substance. There is no record in the extensive medical literature describing a proven, documented cannabis-induced fatality. In practical terms, cannabis cannot induce a lethal response as a result of drug-related toxicity."[54][dubious – discuss]

From January 1997 to June 2005, the U.S. Food and Drug Administration (FDA) reported zero deaths caused by the primary use of cannabis. In contrast, common FDA-approved drugs which are often prescribed in lieu of cannabis (such as anti-emetics and anti-psychotics), were the primary cause of 10,008 deaths.[55] The cannabinoid THC has an extremely low toxicity and the amount that can enter the body through the consumption of cannabis plants poses no threat of death.[56]

Cannabis smoke contains substances that can damage DNA and increase the risk of cancer just like tobacco smoke, though no definitive link between cannabis and cancer has been found.[57] Cancer causing chemicals in cannabis smoke have been found in amounts 50% higher than those found in tobacco smoke. According to the British Lung Foundation, smoking three to four joints (cannabis cigarettes) a day has been found to be associated with the same degree of damage to tissue in the airways of the lung as 20 or more tobacco cigarettes a day.[58]

The Journal of the American Medical Association released findings from a 20-year study that bolstered evidence that cannabis doesn't do the kind of damage tobacco does. Analysis of over 5,000 smokers showed that cannabis did not appear to harm lung function, although cigarettes did. Cigarette smokers' scores worsened steadily over the course of the study. Participants who smoked up to 1 joint daily for 7 years, or 1 joint weekly for 20 years, were not linked with worse scores. Dr Donald Tashkin suggested the reason for this might be that cannabis helps fight inflammation and may counteract the effects of irritating chemicals in the drug.[57] The study concluded: "Occasional and low cumulative marijuana use was not associated with adverse effects on pulmonary function".[59]

Cannabis usage has been shown to negatively affect the ability......