Alcohol Impairs Driving More Than Marijuana

New Scientist ^

[RCW2001]

Alcohol impairs driving more than marijuana

19:00 20 March 02

Arran Frood

A single glass of wine will impair your driving more than smoking a joint. And under certain test conditions, the complex way alcohol and cannabis combine to affect driving behaviour suggests that someone who has taken both may drive less recklessly than a person who is simply drunk.

These are the findings of a major new study by British transport researchers. The unpublished research, seen exclusively by New Scientist, stops well short of condoning driving under the influence of even small amounts of cannabis. But in a week which has seen renewed debate in Britain surrounding the criminalisation of cannabis, it throws an uncomfortable spotlight on a problem confronting governments everywhere - how to deter the growing numbers of cannabis users from "dope driving".

Photo: Getty Images

At present there is no accurate test that can reveal whether a driver has taken cannabis before driving, and developing one will not be easy. But even when this problem is cracked, another will remain - where to set the safety threshold for smoking cannabis.

Advocates of zero tolerance say there should be penalties for drivers caught with any amount of recently smoked cannabis in their body. The new research suggests that would only be credible if governments also adopted zero tolerance on drink driving.

Middle of the road

The new study was undertaken by the Transport Research Laboratory in Crowthorne, Berkshire, and confirms the results of a preliminary study more than a year ago. Researchers at the TRL, led by Barry Sexton, gave 15 volunteers doses of cannabis or alcohol, or a combination of both, before letting them loose on an array of psychomotor tests and a sophisticated driving simulator.

The volunteers were given either enough alcohol to raise alcohol levels in the blood to 50 milligrams per 100 millilitres - about 60 per cent of Britain's legal limit of 80 mg/100 ml - or a specially prepared marijuana joint designed to deliver the same high typically experienced by smokers.

In the study, cannabis significantly affected only one criterion, known as tracking ability. Volunteers found it more difficult to hold a constant speed and follow the middle of the road accurately while driving around a figure-of-eight loop. The TRL researchers point out in their draft report that this test requires drivers to hold their concentration for a short time, a task which is particularly badly affected by the intoxicating effects of cannabis.

Cautious driving

However, volunteers drinking the equivalent of a glass of wine fared worse than those who had smoked a joint. Those who were given both alcohol and cannabis performed worse still, reinforcing the idea that alcohol has a cumulative effect when taken with other drugs.

But the study also found that drivers on cannabis tended to be aware of their intoxicated state, and drove more cautiously to compensate. Indeed, doped-up volunteers often rated themselves as being more impaired than police surgeons brought in to evaluate their sobriety.

Surprisingly, drinking alcohol didn't offset this cautious behaviour, opening up the unproven possibility that a driver who is moderately drunk might be better off under some conditions if they had also smoked.

This cautious behaviour is in line with findings by other researchers. "Whereas alcohol promotes risk taking like fast speeds and close following, cannabis promotes conservative driving, but may cause attention problems and misperceptions of time," says Nicholas Ward, technical adviser to the Immortal project - a three-year European Union trial designed to quantify the crash risk drivers face after taking various drugs and medicines.

19:00 20 March 02

[SamAdams76]

Hola amigos! Guess I'm gonna have to lay off the Bud and smoke more weed. Party on!

[WhyisaTexasgirlinPA]

Of course there are all those pesky "cannabis" related accidents in the drive thru of Wendy's..... lol

[Atlas Sneezed]

They could have saved the money and asked anyone who went to high school in the 1970s for this information.

[SeeRushToldU_So]

In the 70's pot used make me stop four hundred yards from a stop light and admire the colors.

Beer I might just drive through the light.

Thankfully I lived and quit doing that sorta stuff.

[Free the USA]

Check the Bump List folders for articles related to and descriptions of the above topic(s) or for other topics of interest.

[Liberal Classic]

I dunno. It's pretty easy to get "impaired" on either one.

[ThinkLikeWaterAndReeds]

And a .50 cal sniper rifle will kill you faster than a S&W 45, but not by much

[Vladiator]

Sooooo, how do I sign up to be a test subject?

[bpjam]

I can't wait to see this article posted on DOPESMOKERS.COM as 'proof' that there are no negative effects of smoking pot.

[Cicero]

These days, with a loaded subject like this, you can't believe what you hear. Scientists all have agendas, too. Five years from now, they'll run the tests again and it will come out the other way--because the research was sponsored by French vineyards. This one sounds like it was sponsored by dope smokers.

[WhyisaTexasgirlinPA]

There used to be a show on Tv called "Thirtysomething"... in one episode they tell the story of when a couple was dating and they got pulled over by a highway patrolman while they were high....

Patrolman: Do you know how fast you were driving?

Elliot: Uh, 65 miles per hour?

P: No

E: 70?

P: No

E: 80?

P: No, 15... you were going 15 miles per hour on the highway.... lol.....

[RCW2001]

LOL...ahhh yes. Thank you 'cruise control'...

[SeeRushToldU_So]

LOL...ahhh yes. Thank you 'cruise control'...

Cruise control is a drunks best friend!

[Principled]

Alcohol impairs driving more than marijuana

Can't be true. Alcohol is legal...pot isn't.

[kinghorse]

Hey brahs, Jim Anchow knows his bud(s). I think Bud should build a bud plantation in Belize or something. Hari hari.

[Sir Gawain]

-

[Texaggie79]

I hated driving stoned. I thought every car behind me was an undercover cop.

[Jonathon Spectre]

We should still keep locking people up for possessing a naturally-occurring lifeform.

For the children, of course. Where are our government boot-licks?!

[LadyDoc]

The liver will metabolize one ounce of whiskey or one glass of wine in one hour. So if you drink a glass of wine with supper, by the time you drive home it's out of the system. And it takes two glasses of wine to be "legally drunk" (-0.1 blood alcohol level)

Marijuana has a long half life. One joint may not impair immediately afterward as much as one glass of wine. But pot smokers don't just smoke one joint. They smoke several a week, or more commonly, several each day.

But three joints a day will accumulate and lead to measurable cognitive changes. In other words, three joints a day would be like having a constant blood alcohol level of 0.1mg-- which a normal person could establish by drinking one or two shots of whiskey every hour all day and night. We have a name for such people: Alcoholics.

In other words, like many of the early "pot is harmless" arguments, such comparisons are meaningless.