As illicit drug use takes an increasingly greater toll in the workplace, more and more private companies and government agencies will begin instituting mandatory drug testing programs.

Already, more than half of the Fortune 500 companies require job applicants and, in some cases, current employees to submit to drug tests. Five years ago, only 3 percent required drug testing.While drug testing may seem a quick solution to an epidemic problem, there are serious difficulties with such tests. One involves the reliability of the labs involved.

Unfortunately, there are no national certification standards for drug testing laboratories. In addition, most states have not enacted guidelines or regulations that apply specifically to labs that test for illicit drugs.

That has prompted widespread concern that the increasing number of drug testing labs many of them "Mom and Pop" labs with questionable credentials are not qualified to conduct the tests and may not meet rigid quality control tests.

The National Institute on Drug Abuse conducted an informal sampling of 50 such labs and discovered "a tremendous variability" in the test results. Little wonder the federal government and various employee unions are expressing concern over the proficiency standards within the drug testing industry.

And it's a valid concern. When a person's entire future, not to mention his employment, is riding upon the results of such testing, the possibility of "variable" results has to be disconcerting.

For example, it certainly has to be disconcerting to the hundreds of U.S. soldiers who have been discharged because of positive drug tests (a "number" of those soldiers were reinstated when "false positives" were discovered in the tests).

Two steps ought to be taken. First, when a drug test comes back "positive," there ought to be additional examinations to make sure that the reading was not a mistake.

Second, with the future of so many Americans riding on the results of drug tests, Congress should act quickly to ensure that companies conducting the tests are qualified and that they meet minimum proficiency standards.

Bills to establish professional standards for drug testing labs are before both the House and the Senate and need quick action. Let's make sure the drug tests are accurate and the people performing them are competent.