What a dope: Cannabis use doubles the chances of a road traffic accident
Smoking cannabis within three hours of getting behind the wheel could almost double the risk of a serious crash, research suggests. Photo: PA
SMOKING cannabis within three hours of getting behind the wheel could almost double the risk of a serious crash, research suggests.
A review of nine studies found that drivers were more likely to be involved in a collision with another car after smoking the class B drug.
Today's research, published in the British Medical Journal (BMJ), found cannabis use resulted in a "near doubling of risk of a driver being involved in a collision resulting in serious injury or death".
The researchers, from Dalhousie University in Canada, said, however, that the impact of cannabis consumption "on the risk of minor crashes remains unclear".
Previous studies have suggested that cannabis impairs a person's mental abilities and the "motor tasks" needed for safe driving, increasing the risk of being a crash.
The experts added: "The results also accord with recent data for collisions that point to the increasing presence of drugs other than alcohol (especially cannabis and depressants of the central nervous system) in injured and fatally injured drivers."
The study is thought to be the first looking at crashes solely after taking cannabis. Others have not differentiated between the effects of alcohol and other substances.
The present review involved people who either tested positive for cannabis use through blood tests - or who said they had used cannabis - in the previous three hours.
More than 49,000 people were included in the nine studies.
The vehicles included cars, vans, sport utility vehicles, light or heavy trucks, buses, motorcycles or scooters, all terrain vehicles and snowmobiles.
In 2007, a roadside survey in Scotland found that out of 537 drivers tested, 15pc aged 17-39 admitted to having taken cannabis within 12 hours of driving.
Martin Barnes, chief executive of DrugScope, said: "This research paper confirms what the available evidence has suggested for some time: driving while under the influence of drugs such as cannabis can be dangerous.
- Jane Kirby
