As Californians prepare to vote in the November election on whether to legalize marijuana for recreational use, one pressing public health question is whether legalization will contribute to greater use of cannabis by teenagers.
Based on the emerging evidence from other states that have legalized marijuana for medical or recreational usage, the answer seems to be no.
However, legalization aside, public health experts stress the importance of effective public health campaigns that educate teens about the health effects of marijuana use in general.
Since California became the first state to legalize marijuana for medical use in 1996, 24 other states have followed suit. Proposition 64 on the November ballot will make it legal for recreational use among adults 21 and older. Among other provisions, it would make it legal for those adults to possess 1 ounce of marijuana and cultivate six plants.
See description of Proposition 64 here.
The impact on teens has been a perennial issue in debates over legalization. At a spring hearing on Capitol Hill, Sen. Dianne Feinstein, D-Calif., said that marijuana use among 12-to-17-year-olds has “escalated dramatically in the states that have legalized marijuana.”
San Diego County District Attorney Bonnie Dumanis also sounded alarm bells about legalization’s impact on teens.
“If marijuana is legal for those 21 and older, it becomes ‘normalized’ and sends the wrong message to our teens,” a position paper put out by her office stated. “If the adults around them are using and growing marijuana, and eating marijuana products like gummy bears and lollipops, they may conclude that marijuana must be okay and safe.”
“Concerns that increased adolescent marijuana use is an unintended effect of state medical marijuana laws seem unfounded,” according to a 2015 study published in Lancet Psychiatry.
So far, only four states (Alaska, Oregon, Washington and Colorado) and the District of Columbia have legalized marijuana for recreational use among adults.
The evidence from Colorado and Washington, both of which legalized marijuana in 2012 for recreational use, suggests that the change has not increased marijuana usage among teens or increased their access to it.
The most definitive findings are in a report issued in June by the Colorado Department of Public Health and Environment. It found that “four out of five Colorado high school students had not used marijuana in the previous 30 days, a rate that remains relatively unchanged since 2013.”
In fact, the percentage of youth using marijuana in Colorado is slightly lower compared to the national percentage (21.2 percent in Colorado vs. 21.7 nationally).
What’s more, teen marijuana use is considerably lower than it was in 2009 — three years before marijuana was legalized in the state.
Check out this infographic on teen marijuana use in Colorado.
“These statistics clearly debunk the theory that making marijuana legal for adults will result in more teen use,” said the Marijuana Policy Project‘s Mason Tvert, who co-directed the 2012 legalization campaign. “Elected officials and voters in states that are considering similar proposals should be wary of claims that it will hurt teens. ”
A study published this spring in the American Academy of Pediatrics about Washington State, which legalized recreational use of marijuana for adults over 25, undercuts the notion that legalization will make it easier for teenagers to get hold of the drug. According to the study, teenagers in Washington reported that they did not have any greater access to marijuana after legalization than before.
At the same time, the study found that teens could get hold of marijuana far more easily than cigarettes or alcohol — and that they reported that it had become more difficult to get cigarettes, alcohol or illicit drugs like cocaine, while access to marijuana remained unchanged.
That raised some red flags among researchers, who said that states that legalize marijuana need to work more aggressively to reduce marijuana use among teens “given the detrimental health effects associated with adolescent marijuana use.”
“States should specifically implement measures that make it more difficult for teens to access marijuana in the first place,” principal investigator Natalie Colaneri said.
Data from the 25 states that have legalized medical marijuana use also suggests that easier access to marijuana does not lead to greater usage among teenagers.
An in-depth 2015 study published in Lancet Psychiatry concluded that there is “no evidence for an increase in adolescent marijuana use after passage of state laws permitting use of marijuana for medical purposes.”
The study analyzed an annual survey of 8th-, 10th- and 12th-grade students administered in 400 schools nationwide.
“Concerns that increased adolescent marijuana use is an unintended effect of state medical marijuana laws seem unfounded,” the researchers noted. “Our study findings suggest that the debate over the role of medical marijuana laws in adolescent marijuana use should cease, and that resources should be applied to identifying the factors that do affect risk,” the researchers concluded.
After a long period of decline, marijuana use among 12-to-17-year-olds nationally has ticked up in recent years.
But in general, the increase has not come in states where marijuana has been legalized for medical uses. A study in the American Journal of Public Health showed that “passing medical marijuana laws does not seem to directly affect the views of young people in medical marijuana states.”
But researchers caution that there are still many unknowns about what the long-term impact of legalization might be. While there may not be any immediate impact on marijuana use among teenagers, it is possible that legalization could contribute to increased usage during adulthood. And regardless of its legal status, there are clear health dangers from overuse — and teenagers are at greater risk, according to a recent National Academy of Sciences report.
The report pointed to the impact of “persistent cannabis use” on cognitive functioning, and said it was associated with a decline in scores on IQ tests. Researchers said these findings point to marijuana having “a neurotoxic effect on the adolescent brain,” underscoring the importance “of prevention and policy efforts targeting adolescents.”