Hawaii workers’ use of methamphetamine dropped slightly in the first quarter, but the use of synthetic urine rose.

Workforce drug tests by Honolulu-based Diagnostic Laboratory Services Inc. showed that synthetic urine — used to mask drug use — climbed to 1.2 percent of tested workers, up from 0.9 percent in the year-earlier period, the lab said Wednesday. The use of crystal meth, also known as ice, was 0.6 percent, down from 0.8 percent in the first quarter of 2016.

“This could be that our shrinking job pool is drawing out more synthetic urine users or that more crystal meth users are turning to synthetic urine,” said Carl Linden, DLS’ scientific director of toxicology. “Last year they were almost even, and now synthetic urine is double the crystal meth level.”

Diagnostic Laboratory Services said synthetic urine use initially dropped in 2010 after a detection method was identified.

Meanwhile, workers’ use of cocaine, marijuana and opiate remained steady year over year at approximately 0.2 percent, 2.5 percent and 0.4 percent, respectively.

DLS’ sample size typically uses between 7,000 and 10,000 drug tests.