Marijuana has become the leading drug found in fatally injured drivers, and its usage has spiked largely because nine states have legalized it for recreational use, according to a new report form Government Highway Safety Association.

In 2016, 43.6% of fatally injured drivers with known drug test results were drug-positive as compared with just 27.8% in 2006. Also, 41.1% of the drug-positive fatally injured drivers were positive for some form of marijuana.

While marijuana's effect on crash risk is not entirely clear, the best overall estimate in general is that it can increase crash risk by as much as 35%, according to the report.

The new report provides key facts and explores strategies to help states address impaired driving resulting from the use of marijuana and opioids — both of which are on the rise in the U.S.

Marijuana is now legal in nine states and the District of Columbia and medical marijuana is approved in 29 states and the District of Columbia.

At the same time, opioid use in the U.S. is an epidemic, with overdoses responsible for an estimated 115 deaths each day.

The authors of the report note that stakeholders want help. In a survey of State Highway Safety Officials, virtually all said drugged driving is a problem and the majority rated it equal to or more important than driving while impaired by alcohol.

Other noteworthy findings from the report:

• A review of 2016 FARS data on drug presence in fatally injured drivers finds that 50.5% of drug-positive drivers were positive for two of more drugs.

• In both 2015 and 2016, more drivers were drug-positive than alcohol-positive.

• In 2016, 1,064 fatally injured drivers, or 19.7% of the drug-positive drivers, were positive for some opioid, slightly less than half as many as were positive for marijuana.

• In NHTSA's 2013-14 roadside survey, 4.7% of drivers on weekend nights and 5.5% on weekday days tested positive for opioids, considerably fewer than tested positive for marijuana (12.7% and 8.7%, respectively).

• Estimating the effect on crash risk is even more difficult for opioids than for marijuana. The most supportable conclusion is that opioids can increase crash risk by a factor of no more than about 2.

Read the full report here.

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