Currently, one of nine drivers involved in fatal crashes would test positive for marijuana,” Dr. Guohua Li, director of the Center for Injury Epidemiology and Prevention at Columbia, and co-author of the study told HealthDay News. The researchers found that drugs played an increasing role in fatal traffic accidents. Drugged driving accounted for more than 28 percent of traffic deaths in 2010, which is 16 percent more than it was in 1999. The researchers also found that marijuana was the main drug involved in the increase. It contributed to 12 percent of fatal crashes, compared to only 4 percent in...