One in Seven U.S. Adults Used Marijuana Last Year, Study Finds

With legal marijuana expanding to 30 states, researchers set out to determine the prevalence of marijuana use among American adults.

One in seven adults in the United States used marijuana in 2017, according to a new study published in Annals of Internal Medicine.

With more states legalizing marijuana in some capacity, researchers from the Northern California Institute for Research and Education and San Francisco VA Medical Center sought to determine the rate of marijuana use by surveying about 9,000 U.S. adults aged 18 years and older throughout the U.S. They also asked participants about their preferred forms of cannabis.

“Despite legalization of recreational marijuana in some states and the development of a multibillion dollar cannabis industry, national data on the prevalence of use of other forms of marijuana are not available,” wrote researcher Stacey Steigerwald, MSSA.

Steigerwald and her colleagues found that 14.6 percent of respondents reported using marijuana in the past year, and 8.7 percent reported use in the past 30 days.

The prevalence of marijuana use was found to be higher in states with legalized marijuana. Among participants in recreational marijuana states, 20 percent said they had used marijuana in the past year. Of those in medical marijuana only states, 14.1 percent reported use. The prevalence of use was 12 percent in states without legal marijuana.

Researchers also found that younger adults were more likely to have used marijuana. The highest use was reported among adults between 18 and 34 years. That same trend was found earlier this year in a Gallup poll that showed one in four adults between the ages of 18-29 smokes marijuana “regularly” or “occasionally,” almost twice the rate of adults in other groups.

Smoking was found that the most prevalent method of marijuana use, at 55 percent. Of those surveyed who used multiple forms of cannabis, 53 percent said they smoke and consume edibles, while 31 percent reported smoking and vaping.

“Use of different forms of marijuana is common among U.S. adults and is more common among residents of states where recreational use is legal,” Steigerwald and colleagues said.

“Given trends in legalization, annual epidemiologic data on the different forms of use will be necessary to inform public policy. Studying the health effects of marijuana will also require exposure assessment tools that capture different forms of use.”

Full text of the new study, “Smoking, Vaping, and Use of Edibles and Other Forms of Marijuana Among U.S. Adults,” can be accessed through Annals of Internal Medicine.

marijuana joint

Where is Marijuana Legal?

While marijuana remains illegal under federal law, over the past 22 years a majority of U.S. states have passed their own laws permitting marijuana.

Thirty states have legalized medical marijuana, giving access to patients who have obtained a written recommendation of a licensed physician.

Nine of those 30 states have also legalized recreational marijuana, allowing adults 21 years and older to consume cannabis without doctor’s guidance. Many have established a regulated marketplace, allowing adults to buy marijuana products from licensed dispensaries.

While expanding legalization is likely contributing to increasing rates of use among adults nationwide, several studies reveal that looser cannabis laws have not increase rates of teen marijuana use.

How to Learn More

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