For example, the frequency of marijuana use for men decreased 7.5 percent. (sciencedaily.com)
But because federal regulations make it difficult to study the medical effects of marijuana, it's difficult for anyone to say how long - term recreational marijuana use affects your health. (policygenius.com)
By contrast, the number of drivers who tested positive for marijuana use jumped 145 percent — from 47 in 2013 to 115 in 2016. (sbnation.com)