First of its Kind Study Shows Cannabis Has Little to No Significant Effect on Driving
Friday 30 Oct 2015
Researchers at the
University of Iowa’s (UI’s) National Advanced Driving Simulator (NADS)
published a new study that examined how inhaling cannabis affects
driving. The results may help shape the rules of how law enforcement
handles drivers under the influence of cannabis.
“Alcohol is the most common drug present in the system in roadside
stops by police; cannabis is the next most common, and cannabis is often
paired with alcohol below the legal limits.
We know alcohol is an issue, but is cannabis an issue or is cannabis
an issue when paired with alcohol? We tried to find out.” ~ Tim Brown,
associate research scientist at NADS and co-author of the study.
The new study, conducted by Gary Gaffney, Tim Brown and Gary Milavetz,
put 18 participants through a 35 to 45 minute simulated driving test,
with one group having consumed alcohol, another having vaporized
cannabis, and a third group under the influence of both alcohol and
cannabis. The effort was sponsored by the National Highway Traffic
Safety Administration, National Institute of Drug Abuse, and the Office
of National Drug Control Policy.
Four important findings were reported:
Drivers under the influence of only cannabis showed little driving
impairment when compared to drivers under the influence of alcohol or
Drivers with blood concentrations of 13.1 ug/L THC
(delta-9-tetrahydrocannabinol, which is the active ingredient in
cannabis) showed similar impairment to drivers with a .08 breath alcohol
concentration, the legal limit in most states. The current legal limit
for THC in Washington and Colorado is 5 ug/L.
Drivers who use alcohol and cannabis together weave more on a
virtual roadway than ones that used either substance independently,
although consuming both does not double the impairment.
Analyzing a driver’s oral fluids can detect recent use of cannabis
although it should not be considered a reliable measure of impairment.
For the study, researchers selected 13 men and five women between the
ages of 21 and 37 who reported drinking alcohol and using marijuana no
more than three times a week. After spending the night at the UI’s
facilities to ensure sobriety, participants were taken to NADS for
“dosing” followed by a simulated drive in a 1996 Malibu sedan mounted in
a 24-feet diameter dome.
Before the simulation test, each participant had 10 minutes to drink an
alcoholic beverage, or a juice with flavoring that mimicked alcohol, and
then another 10 minutes to inhale a placebo or vaporized cannabis. The
goal was to have some participants’ blood alcohol level at about 0.065
percent, and some participants’ blood concentrations at about 13.1 ug/L
THC, and some under the influence of both.
Once in the simulator, drivers were assessed on: weaving within the
lane; how often the car left the lane; and the speed of weaving. The
researchers reported that drivers with only alcohol in their systems
showed impairment in all three areas. They reported that participants
only under the influence of cannabis showed impairment only with weaving
within the lane.
Andrew Spurgin, a postdoctoral research fellow with the UI College of
Pharmacy, shared another important fact as part of the study:
“Everyone wants a Breathalyzer which works for alcohol because
alcohol is metabolized in the lungs. But for cannabis this isn’t as
simple due to THC’s metabolic and chemical properties.”
The study’s finding are not likely to have any immediate effect on the
current legal limits for THC, but hopefully it will slow the attempts to
deploy devices for instant roadside THC testing before further research
can be conducted.
About the Author
Anna Hunt is a staff writer for WakingTimes.com and an entrepreneur with
over a decade of experience in research and editorial writing. She and
her husband run a preparedness e-store outlet at www.offgridoutpost.com,
offering GMO-free storable food and emergency kits. Anna is also a
certified Hatha yoga instructor. She enjoys raising her children and
being a voice for optimal human health and wellness. Read more of her
excellent articles here. Visit her essential oils store here.
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No Significant Effect on Driving) was originally created and published
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