Feb. 22 (UPI) -- A university study has debunked the belief that legalizing medical marijuana increases recreational use of pot among U.S. adolescents.
Researchers at Columbia University's Mailman School of Public Health analyzed 11 separate studies dating to 1991, publishing their findings Thursday in the journal Addiction.
"For now, there appears to be no basis for the argument that legalizing medical marijuana has increased teens' use of the drug," Dr. Deborah Hasin, a professor of epidemiology at Columbia's Mailman School and senior author of the study, said in a press release.
In examining 2,999 papers from 17 literature sources, researchers found no significant changes, increases or decreases in adolescent recreational use after medical marijuana laws were enacted.
Medical marijuana is legal in 29 states, with California legalizing it first in 1996, according to the National Conference of State Legislatures. Recreational marijuana among adults is legal in eight states and the District of Columbia.
"Although we found no significant effect on adolescent marijuana use, we may find that the situation changes as commercialized markets for medical marijuana develop and expand, and as states legalize recreational marijuana use," Hasin said in release by the Society for the Study of Addiction. "However, for now, there appears to be no basis for the argument that legalizing medical marijuana increases teens' use of the drug."
And even fewer studies have examined the effects of medical marijuana laws among adults.
"Although we found no significant effect on adolescent marijuana use, existing evidence suggests that adult recreational use may increase after medical marijuana laws are passed," Hasin said. "The $8 billion cannabis industry anticipates tripling by 2025. Obtaining a solid evidence base about harmful as well as beneficial effects of medical and recreational marijuana laws on adults is crucial given the intense economic pressures to expand cannabis markets."