"A drug’s metabolite is the compound produced when the body processes a particular drug. Identifying these compounds is the focus of workplace drug testing analysis. Marijuana possesses the greatest total number of detectable metabolites at 31 but fewer major components. For amphetamines, no metabolites are identified because these substances normally pass through the body essentially unchanged in chemical structure."
"Marijuana continues to be the most commonly detected illicit drug, according to the DTI analysis of urine drug tests. Marijuana positivity in the combined U.S. workforce increased 6.2 percent, to 1.7 percent in 2013 compared to 1.6 percent in 2012. In the safety-sensitive workforce, marijuana positivity increased 5.6 percent (0.67% vs. 0.63%). In the general U.S. workforce, the positivity rate increased 5 percent, to 2.1 percent in 2013 compared to 2.0 percent in the prior year.
Drug Positivity Rates Of US Employees Subjected to Urine Drug Tests, by Worker Category