Thursday, March 5, 2009

One Will Get You Twenty

The Legend:  Smoking just one marijuana cigarette, or joint, does the same amount of damage to the respiratory system as smoking an entire pack of cigarettes.

Status:  False

  • The number of cigarettes equal to one joint has been reported from 4 to 20.

This is a widespread piece of misinformation. You might have even heard it in health class when you were in school. Marijuana critics have been known, on occasion, to exaggerate or misuse statistics to support their "evil weed" agenda. That is the case with this rumor.

In 1980, Dr. Donald Tashkin of UCLA, one of the leading experts on the health effects of marijuana, published an article that described large airway damage in marijuana smokers greater than that seen in persons smoking 16 cigarettes a day, (Tashkin, 1980). You can see how this rumor started.

Dr. Tashkin's point was that marijuana smoke was more damaging to large airways while tobacco smoke was more damaging to smaller airways. Largely ignored the same study was information that suggested 1) marijuana smokers had overall better lung health than cigarette smokers, 2) that unlike tobacco, pot does not appear to cause emphysema, and, 3) that hand-rolled joints can have significant variation in size and weight when compared to standard sized tobacco cigarettes.

Additional research has observed that marijuana smokers tend to smoke their product differently, inhaling deeper and holding smoke in their lungs longer. They also smoke less on a daily basis, (Tashkin, 2005; Wu et. al., 1988). All of this additional, and conveniently overlooked, information makes comparing joints to cigarettes difficult.

Dr Tashkin, whose research is always sited to support this one-to-sixteen ratio rumor has rejected the idea that smoking one joint is equal to smoking 16 cigarettes.