Legal pot may induce more teens to smoke it, UC Davis study suggests

Does legalizing recreational marijuana cause more teens to smoke it? That’s highly possible, according to a new UC Davis study, which found teens in Washington state were “significantly” less aware of its potential harm and more likely to have smoked pot after it became legal.

“Adolescents are particularly important to look at since some will go on to chronic use. This is something we need to look at further ... to prevent any unintended consequences down the road,” said Magdalena Cerdá, associate professor in emergency medicine and associate director of the UC Davis Violence Prevention Research Program.

In Washington state, where recreational marijuana became legal in 2012, the study found a 14 percent and 16 percent decrease in perceptions of marijuana’s harmfulness among eighth- and 10th-graders, respectively, and a 2 percent and 4 percent increase in their past-month usage. Those attitudes and usage rates were significantly higher compared with same-age students in states where marijuana was not yet legalized.

The study, by Cerdá and epidemiology professor Deborah Hasin of Columbia University’s Mailman School of Public Health, was published Tuesday in the JAMA Pediatrics publication.

There was no similar change among Colorado teens after recreational pot was legalized, which Cerdá suggested may be due to the state’s “more robust” network of dispensaries and advertising prior to legalization.

Recreational marijuana is legal only for adults 21 and over in Washington and Colorado.

The researchers relied on University of Michigan data that annually surveys about 254,000 students in the eighth, 10th and 12th grades in 47 states. Researchers compared the self-reported answers of Colorado and Washington students before recreational pot legalization (2010-2012) and post-legalization (2013-2015).

Among states without legalized marijuana use, the study found that perceived harmfulness decreased by 5 percent among eighth-graders and 7 percent among 10th-graders, while usage decreased by 1.3 percent and 0.9 percent.

Colorado and Washington legalized recreational marijuana in 2012. Voters in California, Maine, Nevada and Massachusetts approved it last month.

Based on the study results, Cerdá said states such as California with legalization laws should consider investing in substance abuse treatment efforts for adolescents.

She and her co-author also want to study how legalizing recreational pot affects teens’ use of alcohol, prescription drugs and tobacco.

This story was originally published December 27, 2016 at 8:20 AM with the headline "Legal pot may induce more teens to smoke it, UC Davis study suggests."