The number of Hawaii workers testing positive for methamphetamine, cocaine, marijuana and opiates was flat year-over-year in the second quarter, according to Diagnostic Laboratory Services Inc.

Workplace drug testing results were the same as a year earlier for methamphetamine at 0.9 percent; cocaine at 0.4 percent; marijuana at 2.2 percent; and opiates at 0.2 percent.

“It is remarkably consistent,“ said Carl Linden, scientific director of toxicology at Diagnostic Laboratory. “This is the first time that we have seen this consistency.”

However, the number of people testing positive for synthetic urine doubled in the second quarter from the year-earlier period to 0.9 percent.

Positive results for synthetic urine, used to mask drug use, had been on the decline for a few years when people began warning each other online that laboratories were testing for it, Linden said.

Diagnostic Laboratory, which employs more than 500 workers, devised a detection method for synthetic urine in 2010, and use dropped off from 2.3 percent to 0.3 percent in 2013, but picked up again in the third quarter of 2014.

“It went down consistently for a few years. We thought it would pretty much disappear and go to zero, but it hasn’t,” Linden said. “It’s a significant presence out there. When you look on the Internet, synthetic urine manufacturers claim they’ve reformulated so labs can’t detect it, so maybe they feel it’s safe to try it again.”

Diagnostic Laboratory’s workforce quarterly sample size includes between 7,000 and 10,000 drug tests.