Marijuana and Alcohol and Driving, Oh My!

(Fall 2015) A recent study using a driving simulator to mimic real-world situations found that marijuana users’ abilities behind the wheel decrease. Individuals operating a vehicle with blood concentrations of 13.1 µg/L THC (the active ingredient in marijuana) tended to weave within the lane, much like those with a .08% BAC (blood alcohol content), the legal limit in most states. Even if participants’ THC and alcohol concentrations were below these impairment levels, drivers with both substances in their systems were unsteady in their lane. Alcohol alone, however, was responsible for a greater rate of lane departure and a higher weaving speed.

A different study focusing on the combination of these two drugs highlights another issue when it comes to driving. Its results found that using the two substances in tandem creates a marked increase in blood concentrations of THC as compared to marijuana used by itself. This synergistic effect raises the odds of an auto accident above those of either marijuana or alcohol use alone. The findings of this research will no doubt be taken into account in future discussions on drugged driving laws.

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