A panel of three people
Dr. Julia Dilley, left; Dr. Ashley Brooks-Russell, center; and Dr. Adam Darnell, right, took part in a panel discussion cannabis legalization outcomes. (Photo by Cori Medeiros)

By Addy Hatch

The number of retail cannabis shops in a location is associated with higher marijuana use among young people there.

That’s just one of the public health-related findings presented Friday morning at the Inland Northwest Research Symposium on the campus of Washington State University Spokane. Panelists shared some of the research and outcomes from Washington, Oregon and Colorado, where marijuana is legal for recreational use.

Nicholas Lovrich, PhD, WSU Regents Professor Emeritus and chair of the WSU Committee on Cannabis Research and Outreach, introduced the panel by noting that marijuana purchases in the three states rival alcohol sales, so tracking, monitoring and documenting public health consequences is “no trivial matter.” 

In Washington, for example, retail sales are $1.3 billion so far this fiscal year, which ends June 30, according to Adam Darnell, PhD, of the Washington State Institute for Public Policy. That institute is required under Washington’s recreational marijuana law to undertake a cost-benefits analysis of its effects; the next study will be published on Sept. 1.

The Oregon Department of Human Services Division of Public Health looked at local policies and their effect on marijuana use to try to identify best practices for public health. Cities and counties can restrict sales in a variety of ways, including outright bans, moratoriums, requiring limited hours or imposing zoning rules for business locations, said Julia Dilley, PhD, of the Oregon Department of Human Services Division of Public Health. Oregon cities and counties can even impose local taxes on marijuana businesses.

Dilley said most cities and counties in Washington have enacted policies specific to marijuana businesses, with zoning restrictions being the most common. A third of the population of Washington lived in places where sales of recreational marijuana were banned as of 2016, two years after retail sales launched, she said.

Retail bans appear to affect youth marijuana use, she noted. In Oregon, the percentage of 11th graders who had used marijuana within the past 30 days was 22.1 percent in communities without bans, and 19.6 percent in communities with bans. The percentage of 8th graders who reported current marijuana use was about even in both kinds of communities, however. Still, said Dilley, “there are associations between use and policy.”

Also in Oregon, where there’s no cap on the number of retail licenses granted by locale, higher density of retail marijuana shops correlates to higher use of marijuana by young people. For 11th graders, 16 percent reported recent marijuana use in less-dense areas, while 24.3 percent reported recent use in the areas with the highest retail density.

In Washington, Oregon and Colorado, however, the percentage of young people statewide using marijuana hasn’t changed much following legalization.

Researchers in Colorado used a scientific literature review to monitor the public health effects of legalized marijuana, said Ashley Brooks-Russell, PhD, MPH and an assistant professor at the Colorado School of Public Health at the University of Colorado. Among their most controversial findings was moderate evidence that longtime, daily or near-daily use of marijuana is associated with cases of cyclic vomiting, called cannabinoid hyperemesis syndrome.

“This triggered people – it gave them the sense of ‘reefer madness’ all over again,” Brooks-Russell said.

Also controversial was the finding that there’s substantial evidence marijuana is addictive, she said.

Among the report’s findings:

  • There’s substantial evidence that second-hand exposure to marijuana would not show up in a urine screening;
  • There’s substantial evidence that marijuana use increases the risk of a motor vehicle crash;
  • And there’s moderate evidence that using marijuana during pregnancy is associated with reduced cognitive function in children months or years after they’re born.

Watch a recording of the panel discussion: https://www.youtube.com/watch?v=mmSRVVOTm3Y

Started in 2005, the Inland Northwest Research Symposium highlights current research and innovations in the health sciences at Spokane. All faculty and student researchers are invited to submit abstracts and posters, and the panel discussion was followed by poster presentations and oral presentations. Friday’s panel was presented by Cindy Corbett, PhD, MSN, BSN, associate dean for research at the WSU College of Nursing, and interim vice chancellor at WSU Spokane.