Every US state that has legalized marijuana has made the minimum age 21, in line with the drinking age. New research out of Canada suggests it may be OK to go a little lower. In a study published in the journal BMC Public Health, researchers say they determined "19 is the optimal minimum legal age for non-medical cannabis use" based on four factors: general health, mental health, educational attainment, and cigarette smoking. They say mental health outcomes were better among those who started smoking pot at ages 19 or 20 than those who started at 18 or younger, and note fewer people in the older age group developed a tobacco habit as well as a cannabis habit. Levels of completed education were higher among those who first used cannabis at age 21 and up.
As for general health, it was "significantly better" among users who started at age 18 versus younger than 18, but there was no no significant difference between first use at 18 and older ages. "Assuming equal weight for these individual outcomes, the 'overall' MLA for cannabis use was estimated to be 19 years," the researchers write. That's "contrary to the Canadian federal government's recommendation of 18 and the medical community's support for 21 or 25," says the study's lead author, Dr. Hai Nguyen of Newfoundland's Memorial University, in a press release. "Keeping the legal age below 21 may strike a balance between potential increases in underground markets and illegal use, and avoiding the adverse outcomes associated with starting to use cannabis at an earlier age," he adds. (Read more cannabis stories.)