Cannabis doubles car crash risk

Friday February 10th, 2012

Cannabis users who drive within three hours of taking the drug are at double the risk of crashing than those who are not under the influence of alcohol or drugs, researchers said today.

In the first review of its kind, researchers from Dalhousie University, Canada, examined nine studies with 49,411 people to establish if cannabis use alone increased the risk of a motor vehicle collision.

Writing in the British Medical Journal, the authors reveal that if cannabis is consumed before driving a motor vehicle, the risk of collision is nearly doubled. Previous results have also found that there is also a substantially higher chance of collision if the driver is aged 35 or younger.

Cannabis is the most widely used illicit substance globally and recent statistics have indicated a global increase in usage and rates of driving under influence.

A roadside survey carried out in Scotland in 2007 showed that out of 537 drivers tested, 15 per cent who were aged 17-39 admitted to having used cannabis within the previous 12 hours.

All motor vehicle collisions involved in the study took place on a public road and involved one or more moving vehicles such as cars, vans, sports utility vehicles, trucks, buses and motorcycles. Results were taken through blood samples or direct self-report.

The authors concluded that cannabis use impaired safe driving and increased the chance of collisions.

An accompanying editorial, from Wayne Hall at the University of Queensland Centre for Clinical Research, Australia, said further evidence was required so that countries already carrying out drug testing could help to inform those countries that have yet to introduce it.

British Medical Journal February 10 2012

Tags: A&E | Drug and Alcohol Abuse | North America

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