By Eric R. Pedersen / RAND Corporation

As marijuana outlets open after the drug is legalized, the density of those recreational retailers is associated with more use and a greater intensity of use among young adults, according to a new RAND Corporation study.

The study is among the first to examine associations between the density of marijuana outlets and marijuana use over time, and is the first to include unlicensed dispensaries in such an analysis.

Studying young adults in Los Angeles County the year before and the year after marijuana was available for recreational purchase in retail shops in California, the study found that the density of licensed marijuana outlets was associated with young adults' marijuana use, heavy use and intentions to use. The density of unlicensed outlets was associated with young adults' heavy marijuana use and symptoms of cannabis use disorder.

The findings are published by The American Journal on Addictions.