Don't be a dope: cannabis and driving

DON'T BE A DOPE

Pubdate: 16 December, 2000

Source: New Scientist (UK)

Contact: letters@newscientist.com

Author: Arran Frood

DON'T BE A DOPE

If you're going to smoke a joint, don't drive home

IT'S official: smoking dope makes you a worse driver. But cannabis has less effect on driving ability than alcohol, according to a study by the Transport Research Laboratory (TRL) in Crowthorne, Berkshire.

The Department of Environment, Transport and the Regions asked the TRL Safety Department to investigate the effect of cannabis intoxication on driving ability. Cannabis is by far the most common illegal drug found in the bloodstream of road accident victims, and THC-the active ingredient in cannabis-can remain in the body for more than a month.

Barry Sexton and his colleagues at the TRL recruited 15 volunteers to complete driving tests while under the influence of low or high doses of cannabis, or no drug at all. The volunteers either smoked ready-rolled cannabis joints or rolled their own with resin supplied under government licence. They were then put through their paces on a sophisticated driving

simulator.

The researchers measured their accuracy at steering the car, known as "tracking ability", and other psychomotor responses, such as hazard perception and braking responses. They took blood and saliva samples at regular intervals and also tested the subjects' coordination, balance and timing.

The first thing the researchers noticed was that the subjects drove more slowly under the influence of dope, compensating for their intoxication by driving more cautiously. Tracking ability was the only test criterion that was adversely affected: the volunteers found it very difficult to follow a figure-of-eight loop of road when given a high dose. Reaction times to motorway hazards and performance on cognitive tests in the lab were not significantly affected.

Trials previously completed under similar test conditions at the TRL have shown that alcohol and tiredness have a more adverse effect on driving ability, affecting higher cognitive processes. The results of the cannabis and driving study agree with similar research carried out in Australia, the US and Holland.

The Technical Officer of the Legalise Cannabis Alliance, which is a British political party, comments that "any person who is not in full control of their body should not drive, be it through tiredness, alcohol, cannabis or drugs ... but everything must be seen in proportion. We need to legalise and regulate cannabis in a similar way to alcohol to be able to see the size of the problem."

Jane Eason of the Royal Society for the Prevention of Accidents favours the roadside tests to spot cannabis intoxication now being tried by British police. "We would welcome any measure that might make the roads of Britain safer."

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see also Cannabis and driving