As states try to restrict sales of over-the-counter cold and allergy medicine to keep it from being cooked into methamphetamine, there is evidence meth is becoming the workplace's latest drug headache.

Meth use by workers and job applicants soared 68 percent last year, according to data that will be released today by Quest Diagnostics from the 7.1 million drug tests it administered for employers in 2003. If use continues to rise at this pace, meth will surpass cocaine this year as the illegal stimulant of choice.

No end is in sight. Meth labs are migrating east and churning out increasingly pure and addictive drugs.

In the past, meth recipes were passed by word of mouth between drug lab operators, said Ed Childress, special agent with the Drug Enforcement Administration. But the Internet has put meth recipes within anyone's reach.

The number of DEA meth lab seizures has risen from fewer than 8,000 in 1999 to 10,000 last year. "It's pushed its way like a firestorm across the United States," Childress said.

The trend is ominous in light of fresh research by UCLA brain mapping expert Paul Thompson. He found that regular meth users lose about 1 percent of their brain cells each year, a loss comparable to that associated with Alzheimer's.

Workers use meth because it halts fatigue and offers a feeling of self-confidence without an obnoxious high. But increasingly large doses are needed to produce the same high, which leads to addiction.

About 70 percent of Quest's drug tests are given to job applicants in pre-employment screening.

Overall, marijuana remains by far the most popular drug, accounting for more than half of positive tests and about 3 positive tests per 100 given. In comparison, 3.2 in 1,000 tested positive for meth in 2003, up 68 percent from 1.9 in 2002.

Barry Sample, Quest's science and technology director, said methamphetamine use is what drove the 17 percent jump in amphetamine use from 2001 to 2002.

That increase was considered shocking but is dwarfed by last year's rise. The past six years, workplace amphetamine use has surged 145 percent.