"The Drug Treatment Outcomes Research Study (DTORS) was one example of European research with encouraging results regarding employment (Jones et al., 2009). This study investigated drug use, health and psychosocial outcomes in 1 796 English drug users attending a range of different types of treatment service. Follow-up interviews were conducted between 3 and 13 months after baseline (soon after initial treatment entry).

"Marijuana positivity continued its upward climb in both the federally-mandated, safety-sensitive and general U.S. workforces. In oral fluid testing, which detects recent drug use, marijuana positivity increased nearly 75 percent, from 5.1 percent in 2013 to 8.9 percent in 2016 in the general U.S. workforce. Marijuana positivity also increased in both urine testing (2.4% in 2015 versus 2.5% in 2016) and hair testing (7.0% in 2015 versus 7.3% in 2016) in the same population.