With so much of the pushback around legalizing medical marijuana tied to its effects on teenagers, a new study reveals what most people already suspected: that legalization doesn't actually change how many teens smoke or don't smoke cannabis. 

The correlation between legalization and teen use has been hotly debated for years, but the study found that in states where the drug is legalized for medicinal purposes there was no increase in use among teenagers compared to usage levels before legalization, according to Live Science. Deborah Hasin, the senior author of the study and professor of epidemiology at Columbia's Mailman School of Public Health, said in a statement, "There appears to be no basis for the argument that legalizing medical marijuana has increased teens' use of the drug." 

The study pulled information from 11 other studies that tracked teen use between 1991 and 2014, then compared them to use of the drug within the past month to check for any difference. Researchers came to find that use among teens did not change after laws to legalize were passed in each respective state. The study was more focused on overall use, but further research may reveal changes in daily use, dependency, as well as the possible future effects and changes as more states begin to legalize recreational weed use as well.

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As much concern as there seems to be about marijuana use among young adults, Hasin says there are much fewer studies about how legalization affects them directly. "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," she explained. "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". 

1996 marked California becoming the country's first state to make medical marijuana legal and since then, 28 other states have followed suit.