NEW YORK — Marijuana use is becoming more accepted among U.S. adults as states loosen pot laws, new national survey data shows.

More are using marijuana, using it more often and far fewer think it’s risky, the government survey found.

That’s understandable, experts say, as dozens of states now allow medical marijuana and four states have recently legalized pot for recreational use.

More than a half million U.S. adults participated in the survey over a dozen years, and the responses show a shift in attitude. Only a third of adults in 2014 said they thought weekly marijuana use was dangerous, down from half of adults in 2002.

That runs counter to scientific research about pot, said Dr. Wilson Compton, lead author of the study published online Wednesday by the journal Lancet Psychiatry.

“If anything, science has shown an increasing risk that we weren’t as aware of years ago,” said Compton, deputy director of the National Institute on Drug Abuse.

Other research has increasingly linked marijuana use to mental impairment, and early, heavy use by people with certain genes to increased risk of developing psychosis, he noted.

Some highlights of the report, which compared 2002 to 2014:

n About 1 in 8 adults said they used marijuana in the past year, up from 1 in 10. The number of marijuana users grew to about 32 million.

n Daily use doubled, to 3.5 percent or about 8.4 million U.S. adults

n Changes in marijuana use and perception began to really climb in 2006-07.

n No increase was seen in reported marijuana use disorders, like impaired memory, difficulty thinking and withdrawal symptoms like cravings, sleeplessness and depression.

That’s surprising since law enforcement officials say marijuana is more potent than in the past, wrote Australian researcher Wayne Hall in an editorial in the journal.

More use should mean more reports of marijuana-related disorders. Another U.S. survey did find such an increase in recent years, Hall noted.

“I agree that this is a puzzle,” and needs to be researched further, Compton said.

Marijuana use remains illegal under federal law.