Opponents to cannabis legalization often argue that allowing regulated sales of the substance will be bad for youth. Not only would legalization make cannabis more accessible, they argue, but it would also teach young people that marijuana is safe and OK to use.
But that doesn't seem to be the case, according to a new survey of research gathered by the US Centers for Disease Control (CDC).
After analyzing data collected from 1.4 million high school students by the CDC between 1993 and 2017, researchers found that teen cannabis use has actually decreased in legal states. In jurisdictions that allow recreational cannabis use, the number of high school students that reported consuming cannabis in the past 30 days dropped by eight percent over those 24 years. The amount of high school students who reported consuming cannabis at least ten times in the past 30 days also decreased by nine percent.
However, the reduction in teen cannabis use was only noticed after states legalized recreational cannabis. Allowing medical marijuana was not associated with any decrease in adolescent cannabis consumption.
"Because our study is based on more policy variation than prior work, we view our estimates as the most credible to date in the literature," Mark Anderson - an associate professor at Montana State University and the study's lead author - told CNN.
While researchers said it isn't clear why fewer teens are consuming cannabis in legal states, they did offer one possible explanation: "It is more difficult for teenagers to obtain marijuana as drug dealers are replaced by licensed dispensaries that require proof of age."
But since some of the states included in the study had legalized recreational cannabis very recently, the research team thinks it would be worthwhile to re-evaluate the data at a later date.
"Because many recreational marijuana laws have been passed so recently, we do observe limited post-treatment data for some of these states," Anderson said. "In a few years, it would make sense to update our estimates as more data become available."
But for the time being, it looks pretty likely that cannabis legalization doesn't encourage more teens to smoke weed.