Drug use by American workers increased each year between 2015 and 2017, and drug abuse by transportation and warehousing workers skyrocketed by 21% during that period, placing it first among all job categories.

These conclusions were reached as the result of the first-ever analysis of industry-specific data from more than 10 million urine drug test results that were performed by Quest Diagnostics.

The other top five job sectors experiencing year-over-year double-digit increases in positivity rates were Other Services (Except Public Administration), 15.4%; Finance and Insurance, 13%; Retail Trade 12.8%; and Wholesale Trade 11.8%. “Other Services” is a catch-all category ranging from auto and machinery repair to organizing religious and public policy advocacy.

Eight industry sectors experienced year-over-year increases with at least 20% increases in marijuana positivity rates between 2015 and 2017, according to the Quest Diagnostics report.

The shocking rise in Transportation and Warehousing drug use was largely due to major increases in both cocaine and marijuana positivity.

Year-over-year cocaine positivity increased more than 22% between 2015 and 2017 (0.22% in 2015, 0.25% in 2016, and 0.27% in 2017). Marijuana positivity increased by more than 33% over the same timeframe.

"Our analysis suggests that employers can't assume that workforce drug use isn't an issue in their industry,” said Dr. Barry Sample, senior director, science and technology, for Quest Diagnostics Employer Solutions. “In fact, drug test positivity in the majority of industry sectors analyzed is growing."

In a 2017 survey by the National Safety Council, 71% of employers reported being directly impacted by prescription drug misuse in their workforce, including absenteeism, decreased productivity, and on-the-job near miss or injury.