As legal marijuana expands in the U.S., a record share of workers is testing positive for the substance in workplace drug screening. Overall drug use among workers tested by employers generally held steady last year, found an annual tally from Quest Diagnostics, one of the largest drug-testing laboratories. In drug tests given to workers after accidents on the job, marijuana positives rose sharply last year, hitting the highest level in a quarter-century, the Wall Street Journal reports. Of the more than six million general workforce tests that Quest screened for marijuana in 2022, 4.3% came back positive, up from 3.9% the prior year. That is the largest marijuana positivity rate since 1997. Positivity rates last year for certain classes of opioids and barbiturates declined. While marijuana was the main driver of the rise in positive drug tests, more tests also came back positive for amphetamines. Positive tests for amphetamines rose to 1.5% in 2022, up from 1.3% in 2021, according to Quest, which doesn’t differentiate between prescribed medications and illicit drug use.
More than two-thirds of U.S. states have legalized recreational or medicinal use of marijuana. That push has some employers questioning whether to keep testing for the drug, as they weigh safety risks and legal liabilities. The patchwork of rules makes employer oversight a minefield, said Scott Pollins, an employee-rights lawyer in Philadelphia. Workers might live in areas where marijuana is allowed and still be subject to federal testing requirements, or they may work for a company with a policy that subjects employees to testing. The percentage of employees testing positive for marijuana after an on-the-job accident rose to 7.3% in 2022, an increase of 9% compared with the prior year. From 2012 to 2022, post-accident marijuana positive test rates tripled, tracking with widening legalization. Because some drug screens can detect drug use that goes back days, if not weeks, a positive marijuana test may not indicate on-the-job use, said Katie Mueller of the National Safety Council, which provides employers with safety training and education. This makes it hard for employers to tell if their workers are impaired on the job.