A study from one of the largest drug testing laboratories in the US found that marijuana use is on the rise among US workers

• Marijuana use is on the rise among US workers, a study from Quest Diagnostics found, increasing by 16% since 2014.
• Overall drug use among workers also hit a 14 year high.
• But there is a silver lining: the rate of US workers testing positive for opiates decreased by 21% between 2017 and 2018 and has decreased by 37% since the peak in 2015.

Marijuana use is increasing among US workers as more states legalize the drug for recreational and medical consumption, a new study from Quest Diagnostics found.

The rate of US workers and job applicants who tested positive for all drugs - including opiates, cocaine, heroin, and marijuana - hit a fourteen year high last year, the study found based on an analysis of nearly 9 million urine tests.

Since 2014, marijuana use among the US workforce increased by 16% to 2.8% of workers. Perhaps most worryingly, marijuana use has increased over 24% since 2014 to 0.88% in safety-sensitive jobs such as airline pilots and train operators.

Marijuana is legal for adults over the age of 21 in ten states, and for medicinal use in 33 states. More states, including New Jersey, New York, and Illinois are weighing measures to legalize the drug this year.

"Our in-depth analysis shows that marijuana is not only present in our workforce, but use continues to increase," said Barry Sample, Quest Diagnostics' senior director of science and technology. "As marijuana policy changes, and employers consider strategies to protect their employees, customers and general public, employers should weigh the risks that drug use, including marijuana, poses to their business."

There is a silver lining, however.

The rate of US workers testing positive for opiates decreased by 21% between 2017 and 2018 and has decreased by 37% since the peak in 2015, according to the study. There is some evidence to show that legalized marijuana can decrease the likelihood of relapse for those suffering from opioid addiction.

One of the drawbacks of the study is that the active compound in the marijuana plant - THC, or tetrahydrocannabinol - is fat soluble and can be stored in the body for months, so it's not clear whether urine tests can detect whether someone is intoxicated by marijuana, or simply had consumed at some point in the weeks prior to the test.

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