Pubdate: Wed, 18 May 2016
Source: National Post (Canada)
Copyright: 2016 Canwest Publishing Inc.
Author: Sharonn Kirkey
Page: A1


Canada is about to legalize POT, yet how we'll detect high DRIVERS is
more than a little HAZY

About half of pot-smoking Canadians who get behind the wheel while
high believe the drug doesn't impair their ability to drive safely -
and 20 per cent say nothing would make them stop driving while stoned.

That's the conclusion of a new survey, suggesting considerable
nonchalance about marijuana and driving. It comes as the federal
government is studying the idea of setting legal limits for driving
under the influence of weed, similar to those for alcohol.

A scientific advisory committee is reviewing the international
literature to determine if there is a consensus on appropriate
blood-level limits for THC, the major psychoactive component of
marijuana, Justice Canada told the National Post Tuesday.

In the U.S., states that have legalized recreational pot, as the
Trudeau government has vowed to do next spring, have set THC limits
for driving ranging from one nanogram of THC per millilitre of blood,
to five. Other states forbid the presence of any levels of THC.

"What a lot of people want is a number for Canada," said Doug
Beirness, vice-chairman of the Canadian Society of Forensic Science
committee advising Ottawa on drugs and driving.

"It's a legal shortcut. It means that the prosecutor does not have to
prove that the person's ability to operate a vehicle is impaired. It's
a given - if you're over this number, it's a given you're impaired."

The trouble is, "the science doesn't necessarily support that." In
fact, new research suggests a blood-cannabis concentration is not a
reliable predictor of how impaired the person really is. The cannabis
levels of people who get arrested or are involved in crashes seem to
make no significant difference.

Sponsored by the American Automobile Association, the study compared
drivers who tested positive for THC to drug-free "controls."
Researchers looked at how well THC concentrations correlated - or
didn't - with scores on roadside sobriety tests and other examinations
by specially trained drug recognition experts.

The weed-positive drivers, unsurprisingly, were more likely to exhibit
physical signs of being high.

They also performed worse on "walk-and-turn" tests and one-leg stand
tests, and had more misses on the finger-to-nose test.

However, "neither the walk-and-turn, nor one-leg stand tests showed
increasing rates of error as a function of THC concentrations," the
authors report. The only difference was the finger-to-nose test:
drivers with higher THC loads had a harder time finding their noses.

In a State Farm survey of 3,000 Canadians of driving age across Canada
in March, almost nine out of 10 respondents said they have never
driven under the influence of marijuana. However, 44 per cent of those
who do drive high think they can drive safely.

Jake Nelson, AAA's director of traffic safety advocacy and research,
says other research has shown that not only do many motorists believe
marijuana "isn't that unsafe," some believe it makes people better

Beirness worries setting a legal THC limit could send a message to
users that it's safe, within limits, to drive high. While the effects
of booze are "profoundly physical" - slurred speech, lost balanced,
warped motor co-ordination - the effects of cannabis are cognitively
based. "They're in your head," he said.

"You can see effects on things like concentration. When you're driving
you have to concentrate on a million different things at once, but you
can't switch your attention as easily" when on pot.

When governments introduced the 0.08 blood limit for alcohol, "we
probably made a mistake," added Beirness, a senior research associate
for the Canadian Centre on Substance Abuse.

"What we did essentially was tell people it was OK to drive after
drinking" as long as they didn't exceed the limit.

Decades later, "we're pondering the same question, and whether we set
a limit, any limit, whatever it might be, for cannabis, we're still
saying to people, 'It's still OK to go out and smoke cannabis and
drive. Just don't get over that limit.'

"What we need to do is create a culture where driving after smoking
cannabis is just not OK."
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