Marijuana still is dangerous
The discussion regarding legalizing recreational marijuana in New Hampshire has, unfortunately, not included a full airing of the dangers of driving while under the influence of marijuana.
There is ample evidence that marijuana consumption affects driving skills. People smoke or ingest marijuana because the THC makes them “high;” that is, it relaxes them, increases appetite and increases their sense of well being to the point of euphoria. The flip side is alterations in thought formation, relaxed inhibitions, reduction in concentration, judgment and memory, and impairment of motor coordination and reaction time.
Epidemiologic data indicates that overall, the risk of being involved in a car crash roughly doubles after marijuana use. It increases greatly if alcohol is consumed simultaneously.
Law enforcement studies in Colorado (the Rocky Mountain High Intensity Drug Trafficking Area) show that after recreational marijuana was approved in 2013, marijuana related traffic deaths when a driver tested positive for marijuana more than doubled on a yearly basis from 2013 to 2016. Additionally, a survey by the Colorado Department of Transportation found that 69 percent of marijuana users have driven under the influence in the past year, and 27 percent admit to driving high almost daily.
The Highway Loss Data Institute, an automobile insurer organization, analyzed collision claim frequencies in Colorado, Washington and Oregon, three states that legalized recreational marijuana. It found an average six percent increase in collision claims (12.5 percent for Colorado, 9.7 percent for Washington, and statistically no change in Oregon, relative to nearby states.)
Simulator studies of subjects exposed to modest doses of THC show increased lane weaving, sleepiness during long drives and worse performance during complex, divided attention tasks. Practically, this means a slow and poor response to the proverbial child who dashes out onto the street in front of one’s car.
Even worse, an aircraft simulator study involving airline pilots who smoked one cigarette (four puffs) containing a moderate social dose of marijuana showed significant impairment up to 24 hours after smoking. Would Cpt. Sullenberger (“Sully”) have been able to land his plane in the Hudson River if he had smoked marijuana 24 hours before taking off?
A number of factors complicate an already complicated discussion around the dangers of driving under the influence of marijuana. The first of which is that alcohol can lead to further impairment, and many people are using both alcohol and marijuana together. A blood alcohol level of 0.04 may double the impairment after smoking marijuana.
Despite active research and development, we don’t yet have a reliable breathalyzer test for THC. Blood levels of THC rapidly decline after one stops smoking, and can be zero two and a half hours later. Once an accident occurs, or a police officer stops a driver for erratic driving, it can take one to four hours to bring a driver to a hospital to obtain an authorized blood sample.
Further, testing urine for breakdown products is unfair to drivers, as it’s THC in the brain, reflected by THC in the blood not the urine, that impairs driving. A chronic user who stops THC may have breakdown products in the urine for weeks.
There are specially trained law enforcement officers, called Drug Recognition Experts who can recognize and document impairment from marijuana, as opposed to alcohol or other drugs. However, we don’t have enough of them, especially in rural areas of our State.
To add to the complexity, CBD (cannabidiol) preparations are now widely available over the counter, as long as they are derived from hemp (which has a very low concentration of THC.) A recent study of nine CBD products showed the presence in four of a dangerous synthetic designer drug associated with toxic reactions and death, showing the dangers of lack of quality control in an unregulated industry.
So, what are we as a community and a state to do?
Our options include doing nothing now, and relying on education, law enforcement and existing laws relative to DUI to protect our citizens. We would then await development and validation of a comparable breathalyzer device for THC, or a different quick roadside test such as of saliva.
Or, we could focus our efforts more on alcohol, given that drivers intoxicated with alcohol tend to drive faster and to overestimate their skills compared to normal; drivers under the influence of THC tend to drive slower to compensate. Remember the Cheech and Chong movie in which they were arrested on the freeway for going 20 mph?
Do we mimic Colorado, which has set a 5 nanogram/milliliter limit? Impairment starts at 1-2 ng/ml. Do we mimic Rhode Island, Delaware, Utah, Arizona, Indiana, Georgia and Oklahoma, which have a zero tolerance law for THC and its metabolites? How about Pennsylvania at 1 nanogram, Nevada at 2 nanograms or West Virginia at 3?
Law enforcement, our Legislature and governor, scientists and the public need to get together to come up with a solution, because those children do dash out into the street unexpectedly, and the clock is ticking.
My vote is a blood level of 2 nanograms/milliliter.
Dr. Andelman is a retired anesthesiologist from Portsmouth Regional Hospital.