Marijuana harms when it contributes to auto crashes or other incidents that injure or kill, a problem that is especially prevalent among young people. In a study reported by the National Highway Traffic Safety Administration, even a moderate dose of marijuana was shown to impair driving performance. The study measured reaction time and how often drivers checked the rearview mirror, side streets, and the relative speed of other vehicles.
Another study looked at data concerning shock-trauma patients who had been involved in traffic crashes. The researchers found that 15 percent of the trauma patients who were injured while driving a car or motorcycle had been smoking marijuana, and another 17 percent had both THC and alcohol in their blood. Statistics such as these are particularly troubling in light of recent survey results indicating that almost 36 million people age 12 or older drove under the influence of alcohol, marijuana, or another illicit drug in the past year.
