In the months after Washington voters approved legalized marijuana in 2012, Clayton Mosher, a sociology professor at Washington State University Vancouver, noticed what he believed to be unnecessary safety concerns.

Years after sales began, Mosher believes the apprehension has been proven to be unwarranted.

“We’re only four years out, but I don’t think you’re going to see a lot of negative outcomes,” Mosher said. “We’ve done a really good job in our state, I think.”

Mosher, who has studied marijuana policy for roughly 30 years, recently released his new book “In the Weeds,” which he co-wrote with Scott Akins, an associate sociology professor at Oregon State University. The book traces the evolution of society’s views on the drug and how it has affected policy.

The book tackles the effects, medical applications and possible harms of marijuana. While legalization across the U.S. won’t happen in the foreseeable future, and the rollout of some states’s new marijuana laws have been clunky, the benefits have considerably outweighed the risks in Washington, Mosher said.

One of the chief concerns following the 2012 vote was that easier access to the drug would lead to more motor vehicle crashes. In 2016, 110 Washington drivers died while under the influence of the drug, according to a 2018 report from the state Traffic Safety Commission. By comparison, 132 people died while under the influence of alcohol, 152 from speeding and 154 from distracted driving.

“The idea that it was going to lead to this carnage on the roads is really not manifesting,” Mosher said.

Another concern was that youth use would rise sharply. In 2016, 26 percent of 12th graders reported using marijuana in the previous 30 days, according to the most recent Washington State Healthy Youth Survey. Rates were lower for younger students.

Mosher said the state has established a system of robust checks on marijuana dispensaries that has limited the number of teens accessing the drug.

Some studies have linked marijuana to psychosis, schizophrenia and other mental illnesses. Mosher questioned how those studies quantified their results and characterized many of the conclusions as correlational.

“We really don’t know what’s going on there,” Mosher said. “It’s by no means a proven relationship.”

Mosher also recognized some issues with marijuana.

On the business side, he pointed to a lack of proper licensing restrictions — especially in Oregon — as a major reason the drug has been overproduced, dramatically lowering prices. Also, while risks to teens are not as pronounced as many thought a few years ago, some attitudes toward marijuana are problematic, he said.

“A lot of people think, especially young white males, that ‘I drive better when I’m smoking pot,’” Mosher said.

But the few negative outcomes don’t harsh legal marijuana’s high, Mosher said.

Mosher specifically pointed to safety benefits — a better ability to test marijuana for pesticides and mold — and revenue — hundreds of millions of tax dollars collected by the state each year. He added that the revenue could be directed toward education about how to safely consume the drug, including campaigns against driving under the influence.

A major takeaway from “In the Weeds” is that marijuana has been used for many centuries and has not caused the issues that many have theorized, Mosher said.

“If the sky was going to fall, it probably would’ve fallen by now,” Mosher said, “Legalization didn’t create marijuana, and we’ve seen some positive effects of this.”