Pubdate: Sun, 15 Feb 2015
Source: Herald, The (Everett, WA)
Copyright: 2015 The Daily Herald Co.
Note: The Washington Post


WASHINGTON - A new study from the National Highway Traffic Safety 
Administration finds that drivers who use marijuana are at a 
significantly lower risk for a crash than drivers who use alcohol.

And after adjusting for age, gender, race and alcohol use, drivers 
who tested positive for marijuana were no more likely to crash than 
who had not used any drugs or alcohol prior to driving.

For marijuana, and for a number of other legal and illegal drugs 
including antidepressants, painkillers, stimulants and the like, 
there is no statistically significant change in the risk of a crash 
associated with using that drug prior to driving. But overall alcohol 
use, measured at a blood alcohol concentration threshold of 0.05 or 
above, increases your odds of a wreck nearly seven-fold.

The study finds that the measurable presence of THC (marijuana's 
primary active ingredient) in a person's system doesn't correlate 
with impairment in the same way that blood alcohol concentration does.

The NHTSA doesn't mince words: "At the current time, specific drug 
concentration levels cannot be reliably equated with a specific 
degree of driver impairment."

In heavy marijuana users, measurable amounts of THC can be detectable 
in the body days or even weeks after the last use, and long after any 
psychoactive effects remain.

Several states have passed laws attempting to define 
"marijuana-impaired driving" similarly to drunk driving. Colorado, 
for instance, sets a blood THC threshold of 0.5 nanograms per 
milliliter. But that number tells us next to nothing about whether a 
person is impaired or fit to drive. The implication is that these 
states are locking up people who are perfectly sober.

A companion study released by the NHTSA identified a sharp jump in 
the number of weekend night-time drivers testing positive for THC 
between 2007 and 2013/2014, from 8.6 percent to 12.6 percent.

Numbers like these are alarming at first glance. They generate plenty 
of thoughtless media coverage. They're used by marijuana legalization 
opponents to conjure up the bogeyman of legions of stoned drivers 
menacing the nation's roads.

But all these numbers really tell us is that more people are using 
marijuana at some point in the days or weeks before they drive. With 
legalization fully underway in several states, there's nothing 
surprising about this.

"The change in use may reflect the emergence of a new trend in the 
country that warrants monitoring," the NHTSA study concludes.

So, should we all assume that we're safe to blaze one and go for a 
joyride whenever the whimsy strikes us? Absolutely not.

There's plenty of evidence showing that marijuana use impairs key 
driving skills. If you get really stoned and then get behind the 
wheel, you're asking for trouble.

What we do need, however, are better roadside mechanisms for 
detecting marijuana-related impairment. Several companies are 
developing pot breathalyzers for this purpose.

We also need a lot more research into the effects of marijuana use on 
driving ability, particularly to get a better sense of how pot's 
effect on driving diminishes in the hours after using. But this kind 
of research remains incredibly difficult to do, primarily because the 
federal government still classifies weed as a Schedule 1 substance, 
as dangerous as heroin.
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MAP posted-by: Jay Bergstrom