For the first time in more than 10 years, the percentage of positive drug tests among American workers has increased, according to a company that conducts the tests.
The increase is fueled by a rise in use of marijuana and amphetamines, Quest Diagnostics found.
The findings come from an analysis of 8.5 million drug test results. The positive drug test result rate increased to 3.7 percent in 2013, compared with 3.5 percent in 2012. It is the first time the positive rate for national workplace urine drug tests has increased since 2003, the company reported.
In Colorado, marijuana was detected in 20 percent more employment-related drug tests performed by Quest during the first year recreational use of the drug was legal, The Coloradoan reports.
"While it's interesting, and it could be a harbinger for things to come, I think it's a little too early to draw conclusions at this point," Dr. Barry Sample, Director of Science and Technology at Quest Diagnostics Employer Solutions, told the newspaper. Sample said he did not see evidence that employers are changing their drug-screening patterns to reflect Colorado's legalization law.
In Washington state, where recreational use of marijuana has also been legalized, Quest found a 23 percent increase in drug tests that were positive for marijuana. In contrast, the company found an increase of 6.2 percent nationally.
Employers in Colorado are getting mixed messages about how to deal with employees who use marijuana. While recreational use of marijuana is legal for adults in the state, it remains illegal under federal law. Under Colorado state law, employers can ban use of marijuana at work.
Another state law prohibits employers from dismissing workers for engaging in lawful activities off the premises of the business during nonworking hours.