Study: Marijuana Use Doubles Crash Risk

A recent study from the British Medical Journal highlights the dangers of driving under the influence of drugs. According to the research, people driving within three hours of smoking marijuana had almost twice the risk of being involved in a serious car accident as sober drivers.

Researchers at Canada’s Dalhousie University reviewed nine previously published papers documenting accidents of 49,000 people involved in accidents involving cars, trucks, buses and motorcycles.

The study focused on the accidents involving marijuana use. Marijuana use was confirmed by blood tests or was admitted by the driver after the accident had taken place.

In addition to finding that marijuana doubles the risk of collision, the study found that users of marijuana have a substantially higher risk of collision if the driver is under 35 years of age.

However, the study was unable to pinpoint a key issue-how much of marijuana’s active ingredient, tetrahydrocannabinol (THC) is needed to impair a driver to the point at which he or she is more likely to be involved in an accident.

The study also noted that in addition to serious accidents, marijuana use may also be a significant cause of minor accidents. However, this issue was not addressed by the study.

The number of people driving under the influence of drugs is not insignificant. In the United States alone, nearly 11 million people report having driven under the influence of a drug other than alcohol, with marijuana representing overwhelming majority.

However, researchers say that marijuana use behind the wheel is not as dangerous as drunk driving. The Canadian researchers found that drivers with a blood alcohol level of .08-the legal limit in most states-were almost three times more likely to be involved in a car accident.

Source: “Cannabis twice as likely to cause road smash,” Outcome Magazine, 2/11/12