Could legal weed lead to fewer opioid deaths? New study offers tantalizing evidence

By Andrew Sheeler

The Sacramento Bee

SACRAMENTO, Calif. — Counties with greater numbers of cannabis dispensaries saw fewer opioid-related deaths, according to a study recently published by the University of California, Davis.

Study co-author Greta Hsu, a UC Davis professor of management, was careful to point out that correlation was not causality, and that further study of the subject is needed.

“We’re trying to get as precise as we can, but with this kind of data you don’t see causality,” she said.

The study is the first of its kind to look at medical and recreational cannabis dispensary operations compared to opioid-related deaths, all at the county level.

It suggests a potential relationship between greater prevalence of dispensaries and fewer recorded opioid fatalities.

“Given the alarming rise in the U.S.’s fentanyl-based market and in deaths involving fentanyl and its analogs in recent years, the question of how legal cannabis availability relates to opioid-related deaths can be regarded as a particularly pressing one,” researchers said in a statement released by UC Davis.

California residents voted in 2016 to legalize cannabis for recreational consumption, following in the footsteps of states like Colorado, Washington and Alaska. The study accounted for 812 counties across the country that allow recreational or medical marijuana dispensaries.

“According to this estimate, an increase from one to two storefront dispensaries in a county is associated with an estimated 17% reduction in all opioid related mortality rates,” an excerpt from the study reads.

Hsu said that she wanted to look at the county level, rather than the statewide level, because cannabis availability is not uniform even in states where it is legal for consumption.

With state and federal cannabis data at the county level in sparse supply, Hsu and study co-author Balazs Kovacs of Yale University used an unorthodox, if comprehensive, source for their data.

“We grabbed data from, which I guess you could refer to as the Yelp of cannabis,” Hsu said.

Weedmaps is an Irvine-based prolific website where people can locate cannabis dispensaries in their area.

Hsu said that both cannabis and opioids such as fentanyl are “potential pain management kinds of drugs,” and the availability of the former could have an impact on people’s choice to seek out the latter.

Hsu and Kovacs have been studying Weedmaps data since 2014, she said. Originally, they were looking at how the cannabis industry was evolving.

“We were really interested in this as a new industry that’s in the gray so it’s kind of interesting how that affects how the industry grows,” Hsu said.

But as their research progressed, they saw a public health question that they might be able to answer, she said.

Hsu said that more research is needed on the subject; their study didn’t look at individual users and the decisions they made, which would provide more specific information on whether allowing more cannabis dispensaries would be an effective tactic for curbing opioid abuse.

“This is not causal. So we don’t want to say for sure that having cannabis dispensaries is good,” Hsu said. “We’re seeing some initial evidence for it.”