The use of illegal drugs in the workplace has increased over the past year, according to Diagnostic Laboratory Services Inc.

Amphetamine use rose to 0.80% in the third quarter from 0.63% a year ago, while cocaine use climbed to 0.38% from 0.26%.

There were no significant changes in the use of marijuana at 2.76% compared with 2.72% in the third quarter of 2018, though fewer workers tested positive for opiates, which fell to 0.08% from 0.16%.

The use of synthetic urine — used to mask drugs — rose to 1.48% from 0.87%.

The company’s quarterly sample size typically includes between 7,000 and 10,000 drug tests.