Dr. Phillip Drum on Cannabis, Impaired Driving, Legislation & More
- Breathe Free USA
- Jan 1
- 4 min read
Updated: Jan 4
Dr. Phillip Drum, a Doctor of Pharmacy, discusses a variety of topics related to cannabis - impaired driving and testing, failure of our legislators to legislate, concerning effects of CBD, and historical and current marijuana potency. Dr. Drum notes that there is an accurate way to test for marijuana impaired driving, contrary to popular belief. More details below:
CBD
CBD was approved by the FDA as the drug Epidiolex for very rare seizure symptoms. In a study of 500 children, the drug had a 25% efficacy rate, when accounting for placebo effect.
CBD is not a benign substance. The insert for Epidiolex recommends checking liver function prior to starting Epidiolex then checking it later to see if it’s damaging the liver. It also warns about sedation and not driving under the influence.
THC Blood Tests
THC is a fat soluble molecule. It peaks early in the bloodstream, then it quickly dissipates into fatty tissue.
There is a 90% decrease of THC in the bloodstream within 80 minutes.
To detect THC in the blood, the test needs to be conducted right away.
The biggest fatty organ in the body is the brain; this is where THC is residing.
Impaired Driving & Impairment Testing
Dr. Drum was involved in a study approved by the National Institute of Health that looked at driving fatalities or injuries by an impaired driver. The average time to draw blood was 2.3 hours.
A study tested the impairment level of THC with a simulated driver. The driver smoked marijuana. When he was weaving drastically across the road, his blood THC level tested at 13.1 ng/mL (nanograms per milliliter). This same amount of weaving was seen at a blood alcohol level of 0.08. 2.3 hours later (the average time it would take to test such a driver involved in a fatality or injury) this same marijuana impaired driver had a blood test with a THC level of 2, illustrating the ineffectiveness of blood testing to determine impairment.
When marijuana was legalized in Washington state, the state approved a per se THC level (legal impairment level) of 5 ng/mL if blood was drawn within 2 hours - much too high given how quickly this level drops.
Blood testing: in conclusion
In conclusion, blood is not useful in determining THC levels. A brain test would be more effective but unlikely to be approved.
Myth: Police officers can’t determine impairment from marijuana
In 2016 study, Drug Recognition Experts (DREs) - officers with 2 additional weeks of training to recognize different types of drug impairment - were able to identify THC impairment with a 96.7% accuracy using standard field sobriety tests. Specifically, marijuana impairment could be determined if the subjects failed two or more field sobriety tests, including:
3 or more failures of the finger to nose test
Eyelid tremors during modified Romberg balance test
2 or more 1 legged stand clues
2 or more failures in the walk and turn test
These are tests used for drunk driving and work for marijuana also.
Note that the subjects impaired with THC had a level of 1 ng/ML or higher, considerably lower than the legal levels.
There was no correlation between the standard field sobriety test and blood THC levels, again illustrating the inefficacy of blood tests for THC detection.
Legislation & Enforcement Barriers
Dr. Drum gives several examples of legislation and enforcement issues, including barriers to charging and prosecuting the marijuana impaired driver that caused his sister's death, resistance of legislators to pass effective legislation regarding marijuana impaired driving, and resistance to using effective tests and testing procedures.
In 2020 there was a bill in California that was overwhelmingly supported by the California Assembly and Senate that would require coroners to test for drugs in driving fatalities. At the time of this podcast they did not test for drugs. The Governor vetoed the bill. When Dr. Drum asked why they would not override the veto - which they had the had the support to do - the bill’s author replied that they never override a governor’s veto in the state of California.
In Italy, they look at the carboxy metabolite, which is non-psychoactive. They determined that if it is found in the urine, the chance of being in a car crash increases 10 times. Currently this testing is used by the Department of Transportation and is required for school but drivers, interstate truckers, ship operators, and pilots. It is not, however, used by law enforcement for impaired driver testing.
Potency Increase
In the 70s marijuana was 0.5 - 2% THC. Now it averages closer to 20%, while the vape and dab products can be 90% THC.
Edibles:
The maximum FDA approved dose Dronabinal (Delta 9 THC) is 10mg of THC. Now edibles can have hundreds of mg of THC in a single edible. In CA they allow 2000 mg of THC to be in a “medical product”.
Interviewer: Dennis Berry
