Ten year’s worth of data from a survey of American college students with 1.1 million participants shows that of-age students are less likely to binge drink where recreational cannabis is legal. That’s according to a new study just published in Addictive Behaviors, one of the first to investigate how university students’ substance consumption changes after states legalize recreational marijuana. Researchers have already detected trends of increased cannabis consumption among college students after legalization. But this new study suggests that students are substituting cannabis for alcohol and binge drinking less often as a result.

Recreational Marijuana Legalization Decreased Binge Drinking Among Of-Age College Students

In a newly published study, researchers examine trends in college students’ alcohol, nicotine, prescription opioid and other drug use after recreational marijuana legalization. Using data from surveys of American university students from 2008 to 2018, researchers wanted to see how recreational marijuana legalization (RML) impacts other substance use trends.

The study highlights how RML was linked to decreased binge drinking prevalence among university students old enough to legally consume alcohol. After states legalize recreational weed, researchers observed a decrease in college binge drinking by an average of 6 percent.

Oregon State University Ph.D student Zoe Alley, one of the study’s authors, said the decrease could be accounted for by the wider availability of cannabis after legalization. “When you reach the legal drinking age, suddenly a lot of people transition to using more alcohol because now it’s more available and marijuana is not,” said Alley. Legalizing marijuana, by contrast, may prevent students who turn 21 from substituting alcohol for cannabis based on availability.

The data supports Alley’s hypothesis. In Oregon, for example, where cannabis and alcohol are about equally available, fewer people are turning to alcohol. As a result, there appears to be less alcohol misuse and abuse.

Researchers Expect Legalization to Change Substance Use Trends in U.S. and Canada

The phenomenon of expanding or substituting substances based on availability and convenience is one researchers are only beginning to understand. But experts expect RML to alter substance use trends in both the U.S. and Canada. In Canada, the legal age for alcohol and cannabis are in many provinces lower than they are in the U.S. But a dearth of retail stores and product shortages in Canada have made cannabis less available than alcohol, at least so far.

Still, expanding the availability of legal cannabis could reduce binge drinking in Canada, too, as it has in the United States. And that could be a big win for public health.

Many experts acknowledge that the harms and risks of alcohol outweigh the risks of cannabis consumption. From cancer to liver disease, to sexual assault, drunk driving, and fatal alcohol poisoning (problems that plague college campuses), alcohol is the greater health and public safety risk.

But the exact relationship between RML and other substance use is still up for debate. Some studies have shown RML increases alcohol consumption in some populations, while others show a decrease or no relationship at all between legalization and alcohol use. This new study specifically examines how legalization changes alcohol use trends among college students who are 21 and over. “The biggest takeaway from our paper is that problem binge drinking in college students who are 21 and over changes after the implementation of recreational marijuana use,” said Alley.