(CNN) The National Transportation Safety Board said Tuesday that the probable cause of a crash that killed 12 people on a church bus near Concan, Texas, in March 2017 was that the 20-year-old man whose truck hit the bus was under the influence of marijuana and a sedative.

In its report, the board says that there has been an increase in the number of drug-impaired drivers across the country and that something must be done about it.

That call to action seems to match up with a report released Thursday from the Insurance Institute for Highway Safety's Highway Loss Data Institute.

The second study looked at the number of police-reported accidents before and after the legalization of recreational use of weed. The findings were similar: a 5.2% increase in crash rates after legalization than before weed was legal in those states.

Other research has found that in a small sample of drivers who used weed before driving, they had slower thinking and perceptual skills. Drivers under the influence of weed tended to weave more when tested in simulators, studies show , although scientists say more research needs to be done to better understand the correlation between blood or oral fluid concentrations and psychoactive effects of tetrahydrocannabinol or THC, the main psychoactive ingredient in cannabis.

Driving while impaired by any substance, including marijuana, is illegal in all states.

come up with a system of best practices and model specifications for oral fluid drug screening devices that police can use when they pull someone over. The National Transportation Safety Board said in its report on the fatal accident in Texas -- where recreational use is illegal -- that police across the country need better training and better tools to detect whether a driver is under the influence of drugs. It also encouraged the National Highway Traffic Safety Administration tocome up with a system of best practices and model specifications for oral fluid drug screening devices that police can use when they pull someone over.

There are no national standards or standardized tests for weed-impaired drivers like there are for alcohol. The tests designed to determine whether someone is driving drunk are only moderately successful in determining that someone is impaired from using weed, studies have shown

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more drivers on the road under the influence. About 6 in 10 Americans support marijuana legalization, an October poll found , and thus more states will probably legalize recreational use -- meaning there will probably bemore drivers on the road under the influence.