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Americans have decided weed isn't dangerous so they’re smoking more

Advocates for legalization say the public is right about pot being relatively harmless, but the authors of a new study say more research is needed.
Foto di Tracie Van Auken/EPA

Millions more Americans have started smoking weed more often in the last decade — including many who get high on a daily basis — because they don't think it's dangerous.

That's the conclusion of a new study published in the British medical journal Lancet Psychology, which found that the percentage of Americans who said they smoked weed at least once in the previous year climbed nearly 3 percent in a decade, a nationwide increase of about 10 million people.


The researchers say the findings "suggest the need for education regarding the risk of smoking marijuana," but advocates for legalization say the public is right about pot being relatively harmless.

Related: Is the DEA's plan to let scientists grow their own pot just smoke and mirrors?

As evidence, the pro-legalization camp is pointing to data from the same study that shows the percentage of people with "marijuana use disorders" — the medical term for people who smoke so much that it becomes a problem — has not increased over time.

The findings are drawn from federal surveys of 596,500 adults in the US conducted from 2002 to 2012. Over that decade, the percentage of Americans who said they smoked weed at least once in the previous year climbed from 10.4 to 13.3 percent.

At the same time, the number of people who reported smoking marijuana on a "daily or near daily" basis jumped from 1.9 to 3.5 percent. The increase means the number of heavy users skyrocketed from 3.9 million in 2002 to 8.4 million in 2012.

The reason so many people started getting high, the researchers found, is that they stopped worrying it was bad for them. The surveys found that "the prevalence of perceiving great risk of harm from smoking marijuana once or twice a week" fell from 50.4 percent of respondents in 2002 to just 33.3. percent in 2012. This shift in perception "generally began in 2006–07," the researchers noted.


"I still don't know why 2007," lead author Dr. Wilson Compton told the Guardian. "I can't think of any sentinel event that happened in that year; the best we've come up with is the laws started changing enough to see public attitudes change enough."

Related: Feds can't prosecute medical marijuana users who follow state law, court rules

Compton, a researcher at the National Institute on Drug Abuse, and his co-authors noted that more states are set to vote on marijuana legalization in November, including proposals to allow recreational use in Arizona, California, Maine, Massachusetts and Nevada. They also said more research is "urgently needed" on "the effect of marijuana use on future risk of psychiatric disorders, and deleterious effects of marijuana exposure."

But their findings suggest that even while the percentage of heavy weed smokers more than doubled and the number of casual users increased dramatically, there was no change in the percentage of users who reported symptoms of "marijuana use disorders," such as memory problems, trouble sleeping, and depression. That number remained steady at 1.5 percent.

"It really highlights what a lot of people already know to be true," Mason Tvert, spokesperson for the Marijuana Policy Project, told the Guardian. "Countless adults consume marijuana responsibly and should not be treated as if they are drug abusers."

Follow Keegan Hamilton on Twitter: @keegan_hamilton