For many years, the demonizing claims being made against cannabis have been crumbling as research slowly dispels them. Fifty years ago people earnestly believed that the consumption of cannabis was directly linked to the development of an array of mental illnesses, and violent and hypersexual behavior.
Medical opinion must be guided by research
But these prejudices are still hanging on. Today, an individual who responsibly informs their doctor of their marijuana use, because, as with any medicine, chemical interactions may change the resulting chemical behavior, are most frequently urged to cut back. Various reasons are given for a physicians concern. Some, who appear to have fallen behind on the research, still express concern about "brain cell damage" a remnant from the Reagan era's Just Say No campaign.
The main objection, that even the most well-informed physicians feel justified in making, is that even if cannabis itself is not particularly harmful, its most common method of ingestion, smoking, is bad for the lung tissue, regardless of the harmlessness of the substance being smoked. The belief piggybacked its way in on the back of growing opposition to tobacco, and the understanding that tobacco obstructs pulmonary flow and shortens breath.
When a chemical defined by its action doesn't act
Because some of the same chemicals, which have identifiable carcinogenic impact in cigarettes, are also found in cannabis smoke, many believe that the cancer-causing potential of cannabis is proportionate to the amount of these chemicals. The fact that cannabis contains four times more tar (or oil) than cigarettes sparked the 1990s claim that smoking a joint was as bad for the lungs as smoking four cigarettes. This extrapolation makes perfect sense at face value, but doesn't hold up when compared to actual cancer rates.
Rewriting the medical records
The results of a new government-run research program are now forcing medical authorities to overturn these beliefs. The study has been ongoing for the past twenty years, following the smoking habits of over 5000 people. Researchers found that, contrary to popular belief, smoking cannabis, does not interfere with lung function or capacity. This holds true for ongoing regular -even including daily- and long term consumption. Curiously, as a general rule, cannabis smokers had better lung function than nonsmokers, which researchers attribute to the smoking action itself, rather than the cannabis. Pot smokers inhale deeply and hold those breaths to make the most of their supply, expanding the lung's capacity.
Dr. Tashkin found that, in almost all instances, cannabis consumers had rates of cancer that were no different from those who didn't smoke cannabis. The one exception to this rule was between cannabis smokers and individuals who didn't smoke anything (including tobacco), in which marijuana smokers actually had lower levels of lung cancer.