James Lynch: The secret risk that could haunt the cannabis industry

He smoked marijuana as a teen but just got his learner’s permit, so at age 20 my son knows more about cannabis than about driving.

But he does know the two don’t mix.

It sounds obvious – it’s dangerous to drive while high on marijuana – but Americans are of two minds. Most understand you shouldn’t drive while high, but the public seems far too tolerant of the practice.

That disconnect in people’s minds promises to cause more auto crashes and inevitably more deaths and higher auto insurance costs. That last is where I come in – I’m chief actuary at the Insurance Information Institute; we help increase public understanding of insurance – what it does and how it works.

The legal marijuana industry is booming. Though it remains illegal at the federal level, 46 states and the District of Columbia have legalized marijuana as a medicine or for recreation. Recreational sales began in Colorado and Washington in 2014; Oregon began a year later. In the past year, California and Nevada started. Massachusetts launches later this year.

The North American market will quintuple in the next decade, with sales passing $47 billion. Compare: Wine sales in the United States were about $60 billion in 2016, according to the Wine Institute.

There is a social cost. Tetrahydrocannabinol (THC) delivers a pleasant high but hinders driving skills.

Reaction time slows. Attention drifts. Reasoning skills ebb. That is why driving while high is illegal in every state. As researchers said almost a decade ago, cannabis use causes “impairment in every performance area that can reasonably be connected with safe driving.”

Or as my son put it, on weed “you are WAY too messed up to drive.”

Most Americans understand that. A Harris poll conducted for an insurance trade group last year found that 91 percent of Americans thought driving while high was dangerous; 87 percent believe high drivers are a hazard to others.

The bulk of the research shows that Americans are right. The National Academy of Sciences, Engineering and Medicine looked at all of the research and concluded there is substantial evidence that cannabis use increases the risk of motor vehicle crashes.

But there is a disconnect – people are far more tolerant of high drivers than they should be. An Insurance Information Institute poll found that 27 percent of Americans said they would ride with a driver who is high. Only 3 percent said they would ride alongside a drunk driver.

People may be thinking of something my son pointed out – if he were high, he believes he would compensate by driving slower. It’s a common belief, and there is some experimental research that shows that with lower levels of THC in the bloodstream, people try to compensate (though people become more brazen as their high intensifies).

Other research indicates combining alcohol and cannabis compounds the problem. Alcohol use inhibits a different set of driving behaviors than cannabis, and it makes drivers overly bold – canceling out whatever caution cannabis may instill.

Regardless, cannabis use appears to make the driving environment less safe. The first three states with recreational sales saw crash rates significantly higher than they would have been, according to research published last year by the Highway Loss Data Institute.

In Colorado, crash rates were 14 percent higher than comparable (non-recreational) states. In Washington crash rates were 6.2 percent higher. In Oregon, 4.5 percent.

It makes perfect sense, as one researcher laid out to me. When a person is driving, they are either in an emergency or a non-emergency. The non-emergencies (what drivers experience most of the time, of course) are generally easy to handle, and a high driver might get by.

During an emergency, the driver needs complete control over their faculties. A high driver has ceded that. They’re gonna crash.

It’s important to understand the dangers and remember the following before getting behind the wheel:

Wait four to six hours after smoking before driving – longer if you’ve ingested edibles.

Don’t mix – combining alcohol and cannabis can amplify the danger.

Even if you’re not high, do not get in a car with a driver who is.

If there are enough crashes, insurance rates will rise, and that could trigger a political backlash that could nip this nascent industry in the bud.