Study: Youth Marijuana Use has Declined in King County, Washington Since Marijuana Legalization

According to a new study published by the US Centers for Disease Control and Prevention, the use of marijuana among youth has declined since Washington State legalized marijuana for recreational purposes.

For the study, titled Trends and Characteristics in Marijuana Use Among Public School Students — King County, Washington, 2004–2016, researchers examined biennial trends in adolescents’ reported use of marijuana following the passage of Initiative 502 in 2012, which legalized marijuana for everyone 21 and older. The researchers, who were from the Public Health Department for Seattle and King County Washington, gathered the data via students’ responses to the Washington State Healthy Youth Survey. The study found that legalization was associated with immediate declines in monthly cannabis use among youth.

“Despite the legalization of the retail sale of marijuana to adults in Washington in 2012, evidence from the biennial Washington State Healthy Youth Survey indicates that the prevalence of past 30-day marijuana use among students in grades 10 and 12 began to decline that year”, states the study. “The decline continued in 2016 among grade 10 students and did not change significantly among grade 12 students. This decline or absence of change in youth marijuana use after the legalization of retail sales to adults is consistent with trends reported in Colorado and Oregon, states that legalized adult retail sales of marijuana in 2013 and 2014, respectively.”

Below is the full abstract of the study:

What is already known about this topic?

Youth marijuana use can have adverse health outcomes. However, reports from Colorado, Oregon, and Washington indicate no statewide increase in youth marijuana use following retail legalization for adults.

What is added by this report?

Following 2012 legalization of retail marijuana sale to adults in Washington, past 30–day marijuana use decreased or remained stable through 2016 among King County students in grades 6, 8, 10, and 12. Among grade 10 students, the decline in use occurred among males while the rate among females remained steady. Use of alcohol or other substances was four times as frequent among marijuana users as among nonusers.

What are the implications for public health practice?

Understanding the reasons for youth marijuana use, particularly among females, might help inform policy, strategies, and educational campaigns.


You can find more information on this study by clicking here.

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