The number of adult cannabis users in the United States increased by ten million from 2002 to 2014, said a study Thursday that called for better education on the potential pitfalls. The increase coincided with a general rise in the potency of the popular recreational drug and a growing belief that it is not harmful, researchers wrote in The Lancet Psychiatry.

The findings, the US-based team wrote, “suggest a potential benefit of education and prevention messages” even as many US states are relaxing cannabis policies. Based on a survey of over 500,000 US adults between 2002 and 2014, the study found that marijuana use rose from 10.4 percent of the population in 2002 to 13.3 percent in 2014—from 21.9 million to 31.9 million. READ MORE