Quest Diagnostics, a provider of employer-related drug testing, has found that drug use among American workers has hit its lowest level since 1988.

Quest Diagnostics, which handled more than 9 million drug tests last year, found positive tests for marijuana were down 6.3 percent among the U.S. general workforce compared to 2005.

Of all urine workplace drug tests performed by Quest Diagnostics during 2006, 3.8 percent had positive results, down from 4.1 percent in 2005 and 13.6 percent in 1988.

"We believe this continued decline in workforce drug positivity may be driven by two factors: increased employer vigilance about the impact of workplace drug abuse on liability and the cost of decreased productivity, and the possibility that those who abuse drugs may tend to avoid employment at companies that actively conduct drug testing," said Barry Sample, Ph.D., Director of Science and Technology for Quest Diagnostics' Employer Solutions division.

Data from the 2005 National Survey on Drug Use and Health (NSDUH) presented by the Department of Health and Human Services supports the idea that drug testing is a deterrent to employee drug use, according to the company. The survey found that individuals whose employers do not have a drug testing program reported a nearly 50 percent higher incidence of illicit drug use, in the previous 30 days, compared to those with drug testing programs - 7.1 percent compared to 10.5 percent.

Source: Quest Diagnostics