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Fewer alcohol-impaired drivers on the road; drugged drivers up: NHTSA

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Washington – Although the number of alcohol-impaired drivers on U.S. highways has decreased, more drivers are now using marijuana and prescription drugs, according to two recent studies from the National Highway Traffic Safety Administration.

In one study, the latest version of the National Roadside Survey, drivers across the country participated at anonymous and completely voluntary roadside testing locations, where researchers collected breath test results, an oral fluid sample and a blood sample.

Results showed that the number of drivers with alcohol in their system had decreased by nearly one-third since 2007 – and more than three-quarters since 1973.

However, nearly 1 in 4 drivers tested positive for at least one drug that could affect driving safety. Nearly 13 percent tested positive for marijuana, an increase of 48 percent.

NHTSA researchers noted that a positive test for drugs does not necessarily imply impairment, since traces of some drugs can show up in blood samples after impairment has passed.

In another NHTSA study, researchers found that marijuana users are more likely to be involved in crashes, but noted that other factors might contribute to the higher risk. For example, marijuana users are more likely to be young men, who are at a higher risk for crashes.