Via NBC News:
Alcohol remains, by far, the most common mind-altering substance detected in dead drivers, observed in the blood of nearly 40 percent of those who perished across six states during 2010, the Columbia study notes. (That rate remained stable between 1999 and 2010.)
Cannabinol, a remnant of marijuana, was found in 12.2 percent of those deceased drivers during 2010, (up from 4.2 percent in 1999). Pot was the most common non-alcoholic drug detected by those toxicology screenings.
“The increased availability of marijuana and increased acceptance of marijuana use” are fueling the higher rate of cannabinol found in dead drivers, Li told NBC News.