The state's slumping economy may be having an effect on drug usage here, with the percentage of people testing positive for drugs falling between the third and fourth quarter, according to a workforce drug testing service.

Diagnostic Laboratory Services Inc. said drug use showed a decrease in the fourth quarter when compared with the prior three-month period.

"All drug classes in the fourth quarter of 2008 show a decrease from the previous quarter, which may be a reflection of people fearing job loss," said Carl Linden, Diagnostic Laboratory scientific director.

Diagnostic Laboratory gets its numbers from between 7,000 to 10,000 drug tests that are administered quarterly. Linden said there hasn't been enough historical data to show that drug use dips as the economy declines. But he said some people think drug use may fall because people are worried about losing their jobs or stop drug usage as they search for a job that requires testing.

"Some people theoretically think it would go up," he said. "And for the obvious reasons some people think it might go down."

The firm's data show cocaine use fell by half between the third and fourth quarter.

Opiate use was down slightly. That compared with a general two-year trend of more opiate-based drugs being prescribed for pain management, Linden said.

The firm also compared the fourth quarter of 2008 with the same period a year earlier. It found cocaine use down, opiate use up along with the use of marijuana.

Overall, 3.2 percent of all tests administered during the quarter were positive for drugs. The number of people who tested positive may be smaller because some test positive for more than one drug.