What if every day was 4/20 in Minnesota?

Minnesota is among several states considering legislation to join 10 others in legalizing recreational marijuana use. Research indicates about half of adults have used marijuana at some time in their lives — typically in their teens and 20s.

The University of Minnesota's recent survey on its Twin Cities campus found 22 percent of students have used marijuana within the past month.

"I always found marijuana to be something that helped me relax," said one of those students in an interview with MPR News. He asked to remain anonymous for fear of hurting his job prospects.

When he was 16, he was getting high every two weeks or so, he said. But by his senior year of high school, he was using weed pretty much daily. He said he was struggling with some mental health issues.

"That probably led to a bit of irresponsible use at the time," he said. "Right now, I would say it's more again back to kind of a weekend thing. I don't want it to interrupt my school work or anything."

Now he describes himself as a moderate recreational user like most of his peers.

"Millions of people are already using cannabis and that way. They're using it recreationally with some restraint," said Kevin Hill, an assistant professor of psychiatry at Harvard Medical School and author of "Marijuana: The Unbiased Truth about the World's Most Popular Weed." He said for most, marijuana use is not much different from alcohol use.

"I actually like the comparison between alcohol and cannabis," He said. "I think that [with] both substances you have to recognize that the overwhelming majority of users do it in a 'responsible way.'"

Polls have shown that 6 in 10 Americans favor the legalization of marijuana.

But as with alcohol, some users slip into dependency. Hill said about a tenth of adults and a fifth of youth who use pot develop an addiction. He said while most people know the risks of drinking, there's much less awareness of the problems marijuana can cause for some people: depression, anxiety and impotence, for instance. Hill said people need to be educated about pot.

"You have to know what the risks are, what you're getting into," he said.

But Hill said many health professionals feel ill-prepared to discuss pot with patients — because there just isn't enough known about marijuana's health effects.

"Many health care professionals feel grossly inadequately prepared in terms of being ready to talk to patients about their recreational use and the possible adverse effects of it," he said. "I think they are looking for more guidance about what is a responsible amount of cannabis use. Is there such a thing? If a patient has other medications that they're taking, what are the interactions between regular cannabis use or some amount of cannabis use and those other medications?"

Dr. Tyler Osetrele, a Mayo Clinic addiction expert, said pot is a lot more powerful than it used to be.

"The THC content, which is the active ingredient in marijuana, that was around 1 percent back in the 70s. Now, they have strains that are around 30 percent. "

Osetrele said even if we don't know how safe marijuana is for most people, one thing is clear: "Depression and anxiety is difficult to treat when individuals smoke marijuana regularly."

And he said steady, heavy use is associated with less success in life.

"As individuals get older, marijuana use is associated generally with less academic, less career success, higher dropouts in college and high school, more absences from work," he said.

To avoid some of the physical effects of smoking, such as coughing or chest tightness, some people are vaping marijuana's active ingredients — or eating them in candies and other treats.

Edibles may spare the lungs, but dosing is much harder to gauge.

"Unfortunately, what happens with edibles is people take one and don't feel the effects in an hour," said Mike Van Dyke, a marijuana-focused epidemiologist with the Department of Public Health and Environment in Colorado, which legalized recreational use in 2014. "They take another one and then, when they finally feel the effects, it's the cumulative effect of everything they've taken. They've way over consumed."

And that can lead to misery. The Centers for Disease Control and Prevention's list of effects from consuming too much marijuana includes "extreme confusion, anxiety, paranoia, panic, fast heart rate, delusions or hallucinations, increased blood pressure and severe nausea or vomiting."

Colorado tries to educate the public about responsible use.

Since legalization in 2014, there hasn't been a substantial change in use among Colorado high school students. Use among adults has increased steadily but slowly, though. Nearly 16 percent of Colorado adults report they got high on pot in the past month.

The state health department issues regular reports on marijuana and health. It has also produced TV ads to promote responsible use. In one a fictitious "budtender" named Meg says, "Double dipping, by taking another edible too soon, can really ruin your day — like paranoia and hallucinations ruin your day."

Van Dyke said medical professionals should talk about cannabis with patients — because of the absence of comprehensive health information.

"They should be saying there's a huge amount that we don't know. There is a decent risk of becoming addicted to marijuana just like alcohol or tobacco. And I think there are known negative health consequences, particularly around the higher risk of mental health effects," he said.

We might start seeing health warning ads in Minnesota if the state legalizes recreational use. Proposed legislation would channel a large share of marijuana tax revenue to efforts to monitor, research and address physical and mental health issues related to the drug, said the bill's chief sponsor, Rep. Mike Freiberg, DFL-Golden Valley, who is also a public health attorney.

"The best approach is to make sure that there are significant public health protections in place."