But very little is known about if or how recreational marijuana might replace, encourage or have any effect on alcohol or tobacco consumption.
“At this point you need to be very skeptical of anyone who claims that they know that cannabis legalization will be a net negative or a net positive for public health,” said Beau Kilmer, director of the Rand Drug Policy Research Center.
A team of researchers at the Rand drug policy center conducted a review of studies looking at how cannabis effects the use of alcohol, tobacco and other substances.
Kilmer said while most of the research done on marijuana looks at medical consumption, the group identified two peer reviewed studies that focused on drinking and recreational cannabis use among Oregon college students.
“Neither of these studies found a direct effect on alcohol,” he said, “but one of them found that cannabis use may have increased amongst those who reported binge drinking.”
These studies looked at just one population of people in one state, somewhat recently after it had legalized cannabis for recreational use. Kilmer cautioned that what can be gleaned from the research is limited.
As recreational cannabis expands to more states, Kilmer said he will be paying special attention to how various regulations might consumption trends.
So far, all states that allow retail sales require marijuana to be sold in stand-alone facilities. So you can't buy weed, beer and cigarettes all in the same place.
“One could image that if you could purchase cannabis in the same places as alcohol that could influence consumption patterns,” said Kilmer.
And while edibles are legal in many states, products that combine alcohol and tobacco are not permitted. If this were to change, it could promote complementary use.
“Outside of the United States it’s much more common for people to mix in tobacco when they’re rolling their joints,” Kilmer noted .
In Pennsylvania, conversations around recreational marijauna often focus on a hypothetical system with retail sales by for-profit venders. But there’s a range of legalization models.
For example, in Vermont and the District of Columbia, there are no dispensaries but people are allowed to cultivate marijuana for personal use. Dispensaries in several Canadian provinces are government-run, simliar to how alcohol is sold in Pennsylvania.
“There are a lot of middle ground options there. One could imagine that cautious jurisdictions may want to make changes incrementally,” said Kilmer. “Once you go all the way to the extreme, it’s a lot harder to put that genie back in the bottle.”
Find more stories in our series, The State of Cannabis.