Multiple states in the US currently allow recreational marijuana or medicinal use of cannabis and multiple more states may be following suit in upcoming elections.
Even those who support the legalization have concerns over driver safety and how to determine if one is impaired.
Breathalyzers are currently being developed and tested but are not ready for roadway spot checks. Moreover, breathalyzers may have difficulty accurately detecting both inhaled and ingested marijuana.
California law enforcement officers are piloting road-side saliva tests but objective data is still lacking regarding the accuracy of oral fluid tests.
Currently when law enforcement tests an impaired driver for marijuana use, a urine test can be performed which only looks for a metabolite called THC-COOH. Despite its abbreviation it is a non-psychoactive component of marijuana, as opposed to delta-9-tetrahydrocannabinol (delta-9-THC), which does cause euphoria. Hence the shortcoming to this testing method are two-fold, as the non active THC-COOH isn’t even the correct metabolite to measure intoxication and it can linger in the body for weeks, hence not allowing an adequate quantitative measure to determining one’s impairment.
Two medical students, however, figured out what needs to be tested and how. Graham Lambert and Charles Cullison, both entering their third year at Touro University Nevada, performed research for an American College of Legal Medicine (ACLM) poster contest.
One of the lead researchers and osteopathic medical student Graham Lambert said, “This is an issue because it’s non-psychoactive. It stays in the body for long periods of time, long after any psychoactive effects.” Their research lead them to conclude that testing should instead look for an alternate THC metabolite, 11-OH-THC.
Why? Let’s break this down. Now both delta-9-THC and 11-OH-THC are psychoactive compounds that can be tested in the blood. However law enforcement has to determine whether euphoria was present and a factor in one’s unlawful driving. Both delta-9-THC and 11-OH-THC crosses the blood brain barrier, a semipermeable endothelial cell barrier that helps decide what substances can enter and leave the brain. But 11-OH-THC’s is more readily active and can bind to the brain’s cannabinoid receptors tighter, lasting longer and causing more of a psychoactive effect.
Additionally, 11-OH-THC is a metabolite also seen in high quantities after ingesting marijuana edibles.
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In 2012, Sharma et al found the 11-OH-THC to last twice as long in the blood than delta-9-THC, which would make sense due its strong binding properties. Yet the psychoactive 11-OH-THC will rapidly be metabolized to an inactive form hence its presence on a test will signify activity rather than just “hanging around”.
Once Lambert and Cullison determined this, they went to Assemblyman Steve Yeager, D-Las Vegas, who is Chair of the Assembly Judiciary Committee. Yeager helped sponsor a bill, AB135 that would convert marijuana testing for drivers from the inaccurate urine test to a blood test that would look for specifically 11-OH-THC.
Also lead researcher and osteopathic medical student, Charles Cullison said, “Blood alone accurately shows the levels of hydroxy (11-OH-THC) and marijuana.”
In regards to getting the bipartisan law passed through the State Senate with a “Veto-less” majority, Cullison stated, “We couldn’t have done this without the help of many people.”
After Nevada lawmakers passed AB 135, Governor Brian Sandoval signed it into law. The antiquated urine testing will not be used to test drivers pulled over for possible DUI but a blood test instead.
Clockwise: Assemblyman Steve Yeager, DO student Graham Lambert, DO Student Charles Cullison, Governor Brian Sandoval
The legal limit of marijuana that is measured in nanograms per milliliter ng/ml would be 2 ng/ml for delta-9-THC and 5 ng/ml for 11 Hydroxy-THC. This does not change with passage of AB135, nor do the circumstances surrounding when to test, as current protocols are in place once a person fails his sobriety test.
Daliah Wachs, MD, FAAFP is a nationally syndicated radio personality on GCN Network, iHeart Radio and Board Certified Family Physician