Since 2012, 11 states have legalized marijuana use for adults as Arizona voters are considering on their ballots this year. Researchers are just beginning to understand the effects of those laws.

Colorado and Washington were the first states to legalize the drug, and California, the most populous state in the nation, followed them.

Among the most pointed concerns with legalization — and key arguments against the campaign in Arizona — are whether it has caused more young people to use the drug and whether more people are dying in auto crashes caused by impaired drivers.

Data show little change in either area.

Surveys of young people in Colorado, for example, show a slight decline in the percentage of middle and high school students using the drug. In Washington, the rates have remained the same. California hasn’t released a full study of such trends since retail sales there began in 2018.

Opponents of Proposition207 say the risk is too great if young people are given the impression that marijuana is not harmful, or if drivers become lax about getting behind the wheel when they are high. [Read more at azcentral.]