Marijuana use and driving in Washington State: Risk perceptions and behaviors before and after implementation of retail sales

3/1/19–Washington is among the first states to legalize recreational use of marijuana. This study examined marijuana use and risk perceptions before and after retail sales of recreational marijuana began in July 2014, the relationship between risk perceptions and marijuana use, and the relationship between self-reported marijuana use and drug test results. The study concluded that the prevalence of daytime THC-positive drivers increased substantially a few months after retail sales of marijuana were legal. Read