WASHINGTON - More than half of drivers in fatal car crashes had drugs or alcohol in their system when the crash occurred, according to a study in the journal Addiction.
The study found that alcohol was the most common drug, followed by marijuana and stimulants like Adderall and amphetamines, Reuters reports.
From 2005 to 2009, 57 percent of 20,150 fatally injured drivers had at least one drug in their system after an accident, the study says.
The researchers used data from the National Highway Traffic Safety Administration and looked at road deaths in 14 states. Results showed that men and drivers at night were the most likely to have alcohol or drugs, including medication, in their system after the accident.
One in five drivers tested positive for multiple drugs. The data did not show the amount of drugs found in blood or urine samples of the drivers.
Robert Voas of the Pacific Institute for Research and Evaluation in Calverton, Md., says researchers are still working to determine at what point drugs weaken a person's ability to function.
"With alcohol, the amount of alcohol is more or less directly related to the level of behavior impairment," Voas, who was not part of the study, tells Reuters. "The relationship of a drug in the body to the behavior of the driver is less direct and clear."
Follow WTOP on Twitter.
(Copyright 2011 by WTOP. All Rights Reserved.)