Positive Workplace Drug Tests for Marijuana, Cocaine Sharply Dropped Since 1988

Positive workplace tests for marijuana and cocaine have dropped sharply since 1988, while tests revealing prescription drug abuse are increasing, according to a study by the medical-testing company Quest Diagnostics Inc.

The findings come from a review of more than 125 million urine drug tests conducted from 1988 through 2012. Last year, 3.5 percent of samples were positive, down from 13.6 percent in 1988. About three-quarters of tests were conducted for pre-employment screening.

Between 2002 and 2012, positive tests for amphetamines, including prescription drugs such as Adderall, more than doubled. From 2005 to 2012, positive tests for Vicodin increased 172 percent, while those positive for OxyContin increased 71 percent. Workers tested after they have been involved in an accident on the job show higher levels of painkiller use.

“Even when used under prescription, these drugs can have an impact on workplace safety,” Barry Sample, director of drug-testing technology for Quest, told The Wall Street Journal.

The decrease in positive marijuana tests may be due in part to workers becoming better at passing drug tests, according to the article. Labs are trying to reduce the number of people who use other people’s urine to pass drug tests, by experimenting with oral swabs and hair tests.

The study found positive tests for methamphetamine decreased after 2005, but have begun to increase again, particularly in safety-sensitive industries including railroads and trucking.

Last year, a report from Amtrak found a growing number of their employees have been testing positive for drugs and alcohol, increasing the risk of a serious railroad accident. The report found drug and alcohol use by conductors, mechanics and engineers who operate the trains greatly exceeds the national average for the railroad industry. Amtrak’s signal operators and mechanics tested positive for drugs four times as frequently as those working for other railroads. Cocaine and marijuana are the most frequently used drugs.