"There is anecdotal evidence that medical marijuana is finding its way into the hands of teenagers, but there's no statistical evidence that legalization increases the probability of use," said Daniel I. Rees, a professor of economics at the University of Colorado Denver, reports Science Codex.
|D. Mark Anderson, Ph.D.|
|D. Mark Anderson, assistant professor of economics, Montana State University|
Rees coauthored the study with Benjamin Hansen, assistant professor of economics at the University of Oregon, and D. Mark Anderson, assistant professor of economics at Montana State University.
They looked at the relationship between the legalization of cannabis for medicinal uses and marijuana consumption, using nationally representative data on high school students from the Youth Risky Behavior Survey (YRBS) for 1993-2009, a period during which 13 states, including Alaska, California, Colorado, Hawaii, Maine, Nevada, Oregon and Washington, legalized medical marijuana.
Seventeen states and the District of Columbia have now legalized medicinal cannabis, with legislation pending in seven more.
"This result is important given that the federal government has recently intensified its efforts to close medical marijuana dispensaries," said Hansen, who studies risky behaviors in adolescents and adults. "In fact, the data often showed a negative relationship between legalization and marijuana use."
Director Gil Kerlikowske of the Office of National Drug Control Policy (ONDCP) and other federal officials claim the legalization of medical marijuana has led to an increase in marijuana use among teens in the United States, and have targeted dispensaries operating within 1,000 feet of schools, parks and playgrounds.
|University of Colorado|
|Daniel I. Rees, University of Colorado Denver: "There is anecdotal evidence that medical marijuana is finding its way into the hands of teenagers, but there's no statistical evidence that legalization increases the probability of use"|
Marijuana use by 10th and 12th graders has risen in the past three years, according to the 2011 report "Monitoring the Future: National Results on Adolescent Drug Use," prepared each year by the Michigan Institute for Social Research. About one in 15 high school seniors smoke marijuana or near-daily, according to the report, which surveyed 46,700 students in the eighth, 10th and 12th grades, in 400 secondary schools.
The new study, "Medical Marijuana and Teen Marijuana Use," is currently a non-peer-reviewed, working paper made available by the Institute for the Study of Labor (IZA), a private, nonprofit independent research institute based in Bonn, Germany. IZA conducts internationally oriented labor market research.
The paper is available online at http://www.iza.org/en/webcontent/publications/papers/viewAbstract?dp_id=6592.
Researchers examined the relationship between medical marijuana legalization and a variety of outcomes including marijuana use at school, whether the respondent was offered drugs on school property, alcohol use, and cocaine use.
|University of Oregon|
|Benjamin Hansen, University of Oregon: "In fact, the data often showed a negative relationship between legalization and marijuana use"|
Their results provided no evidence that legalization led to increases in the use of marijuana at school, the likelihood of being offered drugs on school property, or the use of other substances.
In addition to using the national Youth Risk Behavior Survey, the researchers drew on YRBS data for the period 1993 through 20098 and data from the National Longitudinal Survey of Youth 1997 (NLSY97). None of these sources provided evidence that teenage marijuana use increases with the legalization of medical marijuana.
The YRBS and NLSY97 contain information on self-reported marijuana use. The researchers also analyzed the Treatment Episode Data Set (TEDS), containing information on whether patients at federally funded drug treatment facilities tested positive for marijuana upon admission. The results suggested that legalization of medical marijuana was unrelated to the likelihood the patients ages 15 to 20 tested positive for cannabis.
"We are confident that marijuana use by teenagers does not increase when a state legalizes medical marijuana," said Montana State's Anderson, who studies health economics, risky behavior and crime.