Driving While High

Driving While High

Driving While High – Is It OK To Drive Under The Influence Of Marijuana?

Men were more likely to do so than women. Driving high can lead to trouble The overall acceptance of driving while high isn’t that surprising considering that marijuana is now legal Estimated Reading Time: 3 mins.

San Pedro Driving Range

Getting High and Driving

About 70 percent of people polled said that people who drive while impaired by marijuana are "not much of a problem" or only a "somewhat serious problem," whereas just 29 percent said it was a very serious problem. By contrast, 79 percent of Americans think drivers who are impaired by alcohol are a very serious problem. Those in the 79 percent group are right about the dangers of alcohol: In , nearly a third of all fatal accidents were caused by alcohol impairment , according to the Centers for Disease Control and Prevention.

But is it really safe to drive while high on marijuana? A review of 60 studies presented in at the International Conference on Alcohol, Drugs and Traffic Safety found that marijuana impairs all the cognitive abilities needed for safe driving, including tracking, motor coordination , visual function and divided attention.

Still, driving while high may not be nearly as dangerous as driving while drunk. The cognitive impairments caused by marijuana are correlated with only modest reductions in driving performance in driving simulations, according to a study in the American Journal of Addictions. Drunk drivers, by contrast, were likely to do all three. Increased accidents? The tie between marijuana and traffic accidents is even shakier.

For example, although a study in the journal Public Health Reports found that 11 percent of drivers killed in accidents had taken at least one drug, the link to marijuana is unclear. Those drivers were not necessarily using marijuana, and even if they had the drug in their systems, that doesn’t mean they were high at the time of the accident, Hansen said.

In traffic-fatality studies, any amount of THC in the blood, no matter how tiny, counts as a positive drug test. So at least some of the people whose deaths are counted in such studies may not have been high at the time of the accident, Hansen said. People who are drunk "are physically impaired, and they don’t really think they’re physically impaired," Hansen told Live Science "They’ll drive faster, they’ll follow cars at closer distances, they’ll make rash, last-minute decisions.

For instance, people who have smoked just a third of a joint will say they are impaired, even when driving tests show no such effects, according to a study by the National Highway Traffic Safety Administration. And in a study in the Journal of Law and Economics , Hansen and his colleagues found that in the year after medical marijuana laws were passed, traffic fatalities fell. The sharpest reductions were found in evening accidents and drunk-driving or alcohol-related accidents.

However, it’s tricky to untangle the relationship, as traffic fatalities have been falling nationwide for several years, according to the Insurance institute for Highway Safety. Improved car safety, lower drunk-driving rates overall or other unknown factors could play a role in that decline, according to the National Highway Traffic Safety Administration.

Current state guidelines may not be setting legal marijuana blood limits appropriately, he said. In the Drug and Alcohol Dependence study, within-lane weaving began to occur once the person’s blood levels reached about 13 micrograms of THC per liter of blood. In fact, people with that level of THC had the same level of impairment as people with a blood alcohol content of 0. But the legal limit for THC in Washington and Colorado is 5 micrograms per liter — less than half the amount found to be impairing in that study.

Smoking a joint typically raises a person’s THC levels to about 20 micrograms per liter, Hansen said. The study also found that marijuana and alcohol had an additive effect on impairment, and people frequently consume the two together, so legal drug limits should account for these additive effects, the study found. Her work has appeared in Scientific American, Wired.

She holds a master’s degree in bioengineering from the University of Washington, a graduate certificate in science writing from UC Santa Cruz and a bachelor’s degree in mechanical engineering from the University of Texas at Austin. Tia was part of a team at the Milwaukee Journal Sentinel that published the Empty Cradles series on preterm births, which won multiple awards, including the Casey Medal for Meritorious Journalism. Live Science newsletter Stay up to date on the latest science news by signing up for our Essentials newsletter.

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