Pubdate: Tue, 02 Sep 2014
Source: Day, The (New London,CT)
Copyright: 2014 Associated Press
Author: Joan Lowy, Associated Press
Page: A1
Bookmark: (Cannabis and Driving)


Studies Inconclusive on 'Speed and Weed'

Washington (AP) - As states liberalize their marijuana laws, public 
officials and safety advocates worry that more drivers high on pot 
will lead to a big increase in traffic deaths. Researchers, though, 
are divided on the question.

Studies of marijuana's effects show that the drug can slow decision- 
making, decrease peripheral vision and impede multitasking, all of 
which are critical driving skills. But unlike with alcohol, drivers 
high on pot tend to be aware that they are impaired and try to 
compensate by driving slowly, avoiding risky actions such as passing 
other cars, and allowing extra room between vehicles.

On the other hand, combining marijuana with alcohol appears to 
eliminate the pot smoker's exaggerated caution and seems to increase 
driving impairment beyond the effects of either substance alone.

"We see the legalization of marijuana in Colorado and Washington as a 
wake-up call for all of us in highway safety," said Jonathan Adkins, 
executive director of Governors Highway Safety Association, which 
represents state highway safety offices.

"We don't know enough about the scope of marijuana-impaired driving 
to call it a big or small problem. But anytime a driver has their 
ability impaired, it is a problem."

Colorado and Washington are the only states that allow retail sales 
of marijuana for recreational use. Efforts to legalize recreational 
marijuana are underway in Alaska, Massachusetts, New York, Oregon and 
the District of Columbia. Twenty-three states and the nation's 
capital permit marijuana use for medical purposes.

It is illegal in all states to drive while impaired by marijuana.

Colorado, Washington and Montana have set an intoxication threshold 
of 5 parts per billion of THC, the psychoactive ingredient in pot, in 
the blood. A few other states have set intoxication thresholds, but 
most have not set a specific level. In Washington, there was a jump 
of nearly 25 percent in drivers testing positive for marijuana in 
2013 - the first full year after legalization - but no corresponding 
increase in car accidents or fatalities.

What worries highway safety experts are cases like that of New York 
teenager Joseph Beer, who in October 2012 smoked marijuana, climbed 
into a Subaru Impreza with four friends and drove more than 100 mph 
before losing control. The car crashed into trees with such force 
that the vehicle split in half, killing his friends.

Beer pleaded guilty to aggravated vehicular homicide and was 
sentenced last week to 5 years to 15 years in prison.

A prosecutor blamed the crash on "speed and weed," but a Yale 
University Medical School expert on drug abuse who testified at the 
trial said studies of marijuana and crash risk are "highly 
inconclusive." Some studies show a two-or three-fold increase, while 
others show none, said Dr. Mehmet Sofuoglu. Some studies even showed 
less risk if someone was marijuana positive, he testified.

Teenage boys and young men are the most likely drivers to smoke pot 
and the most likely drivers to have an accident regardless of whether 
they're high, he said.

"Being a teenager, a male teenager, and being involved in reckless 
behavior could explain both at the same time - not necessarily 
marijuana causing getting into accidents, but a general reckless 
behavior leading to both conditions at the same time," he told jurors.

In 2012, just over 10 percent of high school seniors said they had 
smoked pot before driving at least once in the prior two weeks, 
according to Monitoring the Future, an annual University of Michigan 
survey of 50,000 middle and high school students. Nearly twice as 
many male students as female students said they had smoked marijuana 
before driving.

A roadside survey by the National Highway Traffic Safety 
Administration in 2007 found 8.6 percent of drivers tested positive 
for THC, but it's not possible to say how many were high at the time 
because drivers were tested only for the presence of drugs, not the amount.

A marijuana high generally peaks within a half hour and dissipates 
within three hours, but THC can linger for days in the bodies of 
habitual smokers.

Inexperienced pot smokers are likely to be more impaired than 
habitual smokers, who develop a tolerance. Some studies show 
virtually no driving impairment in habitual smokers.

Two recent studies that used similar data to assess crash risk came 
to opposite conclusions.

Columbia University researchers compared drivers who tested positive 
for marijuana in the roadside survey with state drug and alcohol 
tests of drivers killed in crashes. They found that marijuana alone 
increased the likelihood of being involved in a fatal crash by 80 percent.

But because the study included states where not all drivers are 
tested for alcohol and drugs, a majority of drivers in fatal crashes 
were excluded, possibly skewing the results. Also, the use of urine 
tests rather than blood tests in some cases may overestimate 
marijuana use and impairment.

A Pacific Institute for Research and Evaluation study used the 
roadside survey and data from nine states that test morethan 80 
percent of drivers killed in crashes. When adjusted for alcohol and 
driver demographics, the study found that otherwise sober drivers who 
tested positive for marijuana were slightly less likely to have been 
involved in a crash than drivers who tested negative for all drugs.

"We were expecting a huge impact," said Eduardo Romano, lead author 
of the study, "and when we looked at the data from crashes we're not 
seeing that much." But Romano said his study may slightly 
underestimate the risk and that marijuana may lead to accidents 
caused by distraction.

Many states do not test drivers involved in a fatal crash for drugs 
unless there is reason to suspect impairment. Even if impairment is 
suspected, if the driver tests positive for alcohol, there may be no 
further testing because alcohol alone may be enough to bring criminal 
charges. Testing procedures also vary from state to state.

"If states legalize marijuana, they must set clear limits for 
impairment behind the wheel and require mandatory drug testing 
following a crash," said Deborah Hersman, former chairman of the 
National Transportation Safety Board. "Right now we have a patchwork 
system across the nation regarding mandatory drug testing following 
highway crashes."
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MAP posted-by: Jay Bergstrom