Marijuana Use Ups Crash Risk
February 10, 2012

Marijuana Use Ups Crash Risk

A Canadian study in this week´s issue of the British Medical Journal highlights the dangers of driving under the influence of pot, which nearly doubles the risk of a serious or fatal car crash, writes Sharon Kirkey for the Vancouver Sun.

Using cannabis within three hours of driving causes accidents at nearly twice the rate as those who are not under the influence of drugs or alcohol claims the paper´s authors, from Dalhousie University.

Lead author Mark Asbridge, an associate professor in the department of community health and epidemiology at Dalhousie told Kirkey: “Surveys of young drivers have also shown rates of driving under the influence of cannabis have surpassed rates of drinking and driving in some jurisdictions.”

“Not only is cannabis relatively easy to obtain, many young people really don´t believe cannabis impairs.”

Previous studies into cannabis and automobile accidents have had mixed results. Some showed an increased risk of an automobile collision after using marijuana, others have found either no association whatsoever, or even a lower risk.

For this study, researchers reviewed nine studies with a total sample of 49,411 subjects from Australia, New Zealand, the US, France and the Netherlands to determine the driving risks.

The studies tested for tetrahydrocannabinol (THC), the active chemical in cannabis, by analyzing blood samples or using direct reports of cannabis use from those involved. Most studies used any amount greater than zero as the cut-off for a positive test result.

Duncan Vernon, a road safety manager at the Royal Society for the Prevention of Accidents (RoSPA), told BBC News that previous studies in controlled lab conditions had shown that cannabis does impair a driver´s ability drive safely and responsibly.

“This new research strengthens the evidence that driving under the influence of cannabis increases the likelihood of being seriously injured or killed in a collision,” Vernon explained.

“This adds to the argument that a system needs to be put in place to monitor the number of serious and fatal accidents where impairment from illegal drugs was a contributory factor, so that appropriate action can be taken to prevent them.”

The study concluded with the suggestion that the consumption of cannabis indeed impairs safe motoring ability and increases the chance of collisions.


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