Drug use among Hawai'i workers and potential employees dipped in the first quarter of 2006, led by a decline in positive tests for crystal methamphetamine, according to figures from the state's two largest drug testing labs.

"It looks like the crackdown on these clandestine labs is making some impact on ice," said Clifford Wong, forensic toxicologist and lab director of Clinical Laboratories of Hawai'i.

Clinical Laboratories, which says it has most of the Neighbor Island market, saw the percentage of positive tests fall to 6.5 percent in the first quarter of 2006 from 7 percent in 2005. Diagnostic Laboratory Services Inc., which calls itself the largest drug testing company in the Islands, found that the percentage of positive workplace drug tests dropped to 4.1 percent in the first quarter of 2006 from 5.2 percent in 2005.

Diagnostic Laboratory Services tested 7,739 employees and potential employees between January and March. Clinical Laboratories tested 6,908 people for a wide variety of reasons.

Their results sometimes conflicted. But both companies saw drops in crystal meth use and increased use of cocaine.

Diagnostic Laboratory Services also saw marijuana use fall from 2.4 percent to 1.4 percent — while Clinical Laboratories reported no change in marijuana use.

"We saw a slight rise in most of the drugs at the end of 2005," said Carl Linden, scientific director of toxicology for Diagnostic Laboratory Services. "But in the first calendar quarter, we saw the most significant drop we've seen in a long time."

The drop in positive test results in the Islands follows 2005 declines reported on the Mainland by Quest Diagnostics Inc., which calls itself the country's leading provider of employer drug testing services.

Quest Diagnostics Inc. performed 7.3 million workplace drug tests in 2005 and saw employee drug use fall to 4.1 percent — the lowest level since the company began publishing its Drug Testing Index in 1988.

The decline was driven by a 12 percent fall in marijuana use between 2004 and 2005, Quest Diagnostics said. The percentage of positive amphetamine and methamphetamine results also fell from 8 percent to .48 percent.

"There is greater awareness and a lot of publicity on ice," said Wong of Clinical Laboratories of Hawai'i.

May Goya, employee relations manager for FCH Enterprises, parent company of Zippy's restaurants, Napoleon's Bakery plant, Catered Experience, Osaka Okazuya and the Food Solutions International plant in Waipi'o, has been overseeing the company's pre-employment and random drug testing program for all of its 2 1/2 years and refuses to get excited about the drop in crystal meth test results.

"We've seen this cycle before where there's a drop from a lot of enforcement activity," Goya said. "It's too soon to say the problem is gone. You can't say it's over."

Goya has seen declines in the use of some drugs that only lead to "spikes in other drugs."

And while crystal meth use fell, both Clinical Laboratories of Hawai'i and Diagnostic Laboratory Services found increased cocaine use.

The cocaine "cartels have been dropping their prices for cocaine in order to compete with ice," Wong said. "All of a sudden, cocaine is starting to pop up. This is a business and these guys have competition so they're going to lower their prices to compete with methamphetamine."

Reach Dan Nakaso at dnakaso@honoluluadvertiser.com.