The Governors Highway Safety Association and the Foundation for Advancing Alcohol Responsibility, national nonprofit safety groups, reported that 43 percent of fatally injured drivers with known test results tested positive for drugs, while 38 percent tested positive for alcohol. The figures are from National Highway Traffic Safety Administration data for 2015, the most recent year available.
This is the first time occurrences of drugged driving have surpassed those of drunken driving as shown by tests on dead drivers, according to Jim Hedlund, a former NHTSA official who wrote the report. The report also found that the biggest risk comes from driving under the influence of both alcohol and drugs.
The drugged driving report, which summarizes findings from multiple studies, said law enforcement officers often have a hard time recognizing drivers under the influence of drugs, who are more difficult to assess than those driving drunk.
“Officers need to know more than they do for alcohol how to suspect drug impairment, and know that it can exhibit itself in different ways,” Hedlund said in an interview. “Drug impairment has different signs and symptoms — think of the difference between uppers and downers.”
On the operators’ side, many drivers are ignorant about how drugs can impair their driving, and some may think they drive better while using marijuana, which is not true. Marijuana can increase crash risk by 22 to 36 percent, according to studies cited in the report. The report recommends that states develop education campaigns, which can include discussing drugged driving in driver education classes, and informing physicians and pharmacists about risks from driving on prescription drugs.
Hedlund said testing for alcohol is pretty straightforward — an officer looks for signs of drinking and can confirm the presence of alcohol with a breath test. But it’s more difficult to detect drug impairment roadside, the report said.
The report acknowledges some of the difficulties with doing blood tests for marijuana. Marijuana is not metabolized in the system in the same way as alcohol, so while a person with a blood-alcohol level of 0.08 or higher is considered too drunk to drive, it is not possible to say the same thing absent other evidence about a person testing positive for tetrahydrocannabinol, or THC, the main psychoactive component in marijuana.
Delays in drawing blood for a test can allow drugs to metabolize in the system and not provide an accurate measure, while some drugs can remain in the body for days or weeks, long after impairment has ended, the report noted.
Fortunately, there are additional ways to evaluate impairment, the report said. For example, the national Drug Evaluation and Classification Program trains law enforcement officers to identify drug impairment through a 90-minute, 12-step evaluation. Roadside screenings for drugs that use saliva are being tested, and tests that use breath are being developed, Hedlund said. One problem is that data on drug-impaired driving are not very good, because not all drivers in fatal crashes are tested, Hedlund noted. The report recommends that states test for drugs all fatally injured drivers and people arrested for driving under the influence to get better information on how big the problem is.