For quite a while the impact of marijuana on one’s driving performance has been controversial subject, and it’s becoming more and more critical with states beginning to become more lenient with drug laws. In spite of drunk driving declining nationwide, driving under the influence of marijuana is becoming more common. In response, researchers from the National Institute on Drug Abuse have recently conducted a study on the effects of marijuana on one’s driving performance.
According to a recent national roadside survey from the National Highway Traffic Safety Administration on nighttime weekend drivers, 8.3 percent had alcohol in their system and 12.6 percent tested positive for THC in their system. The rates of THC rose 8.6 percent from 2007.
It is currently unlawful to drive under the influence of drugs or alcohol, however there is a .08 breath alcohol limit in place within many states. However, there are no limits for marijuana in any state. . . weird.
As a means to determine if there should be a set limit for marijuana, researchers conducted a study to see the effects of marijuana on one’s driving ability. The study selected 18 occasional marijuana smokers, 13 of which were men, whose ages ranged from 21 to 37. Participants took six 45-minute drives in a driving simulator. Each of the six driving sessions tested for varying combinations of high or low concentration THC, alcohol, and placebos. The placebos were created by giving participants fruit juice with alcohol swabbed around the rim, finished off with 1mL of alcohol, as a means to mimic the smell and taste of alcohol.
Researchers specifically focused on three parameters of the participant’s driving ability including weaving within the lane, how many times the car left the lane, and the speed of weaving. Alcohol was found to have an effect on the number of times the car left the lane and the speed of weaving, however marijuana only showed an increase in weaving. Data revealed that drivers with blood concentrations of 13.1 ug/L (which means micrograms per liter) of THC showed an increase in weaving, similar to drivers with a .08 breath alcohol concentration- which is the legal limit in many states.
The study also found that a combined use of marijuana and alcohol have more of an impact on one’s driving when used simultaneously. According to the study, smoking marijuana while drinking a little alcohol increases the absorption of THC, which enhances one’s high. THC also delays the peak of alcohol impairment, therefore it takes a person using marijuana and alcohol longer to feel drunk. In relation to the use of marijuana and alcohol together, Principal Investigator Dr. Mary Huestis says that cannabis is generally found with a low dose of alcohol. “Many young people have a couple beers and then cannabis,“ says Huestis, as quoted by Time.
Based on the data from this study, researchers believe that it is important to educate the public about the effects of marijuana before they begin driving. “I think this has added really good knowledge from a well-designed study to add to the current debate,” on marijuana’s effects on road safety, says Huestis.