From The Washington Post By Ariana Eunjung Cha: Virtually everyone knows marijuana use in the United States has skyrocketed in recent years thanks to the loosening of state laws that had limited the drug to medicinal and related purposes. But by just how much has been anybody's guess.
A new survey of more than 500,000 adults now puts a number on the change — and it's big. From 2002 to 2014, the percentage of adults using marijuana jumped from 10.4 percent to 13.3 percent.
Those using it daily or close to that went from 1.9 percent to 3.5 percent. That means there could be 31.9 million adults using marijuana — with 8.4 million of them using it a lot.
The results, reported in Wednesday's The Lancet Psychiatry, also noted an important trend in how marijuana is regarded. Although the drug has "become increasingly potent over the past decade," the authors wrote, fewer people think it's harmful.
Wilson M. Compton, a researcher with the National Institute on Drug Abuse who worked on the study, described this shifting perception as a worrisome development and said it suggests a need for improved education on the risks.
“Understanding patterns of marijuana use and dependence and how these have changed over time is essential for policymakers who continue to consider whether and how to modify laws related to marijuana and for health-care practitioners who care for patients using marijuana," he explained.