Ralph Crane//Time Life Pictures/Getty Images
RALPH CRANE//TIME LIFE PICTURES/GETTY IMAGES

A new study finds that among 44,000 U.S. drivers involved in fatal
single-vehicle car crashes between 1998 and 2009, 25% tested
positive for drug use. The most common drugs were marijuana,
cocaine and amphetamines.
It's not clear whether drugs caused the accidents.
The connection might make sense intuitively, but there isn't much
data on the impact of drug use on traffic deaths, according to the
new study in the Journal of Studies on Alcohol and Drugs,
which sought to clarify the link./.../