Companies use drug tests to avoid employing drug users, yet 74 percent of drug users are employed, and one out of six employees has a drug problem, according to corporatedrugtesting.com.

“Employers want to reduce the risk associated with drug and alcohol users,” said Tom Aderhold, director of corporate services at Drug & Alcohol testing in Tampa.

Aderhold said drug tests also serve for individuals on probation, parents who are concerned about their children or law firms that represent clients with a child custody case where drug use is an issue.

The most common and least expensive way to perform a drug test is by urinalysis. That test, however, only detects drug use for the previous two or three days before the body naturally flushes it out.

Also, some people may feel nervous giving a urine sample and spend hours drinking water in the testing facility’s lobby before they’re ready.

According to its Web site, Quest Diagnostics performs more than 10 million substance abuse tests annually. And 95 percent of test results come negative back within 24 hours. The other 5 percent of the results, which include all the positives and some negatives, come within 72 hours.

A hair test, though about four times as expensive as a urinalysis, is more effective because it can detect drug use for the previous three months, Aderhold said.

Aderhold also said that there are only a few laboratories in the country that are effective in testing hair, and results are usually delayed.

The two processes that are considered the “gold standard” in drug testing are immunoassay and gas chromatography/mass spectrometry.

Immunoassay is performed much like a pregnancy test, he said. An absorbent tip with amino acids is dipped into the sample, and animal antibodies that are cultured react to specific drugs which turns the tip a different color.

Gas chromatography/ mass spectrometry is another way to test for drugs. In this process, the sample is analyzed for constitutes and elements. The test then measures the concentration of the elements to see if the sample is positive for cocaine, marijuana, amphetamines, opium or phencyclidine (PCP), said Aderhold.

There are many security measures that are utilized to ensure samples aren’t tampered with. For example, Quest Diagnostics immediately seals and labels the urine sample and then deposits it into a bag.

Then, the person who provided the sample has to read and complete a checklist certifying that the technician who took the sample followed the procedure.

A survey conducted by the Gallup Institute of Princeton, commissioned by the Institute for a Drug-Free America, revealed that about 71 percent of employers now use pre-employment drug tests.

Many companies that perform drug tests also utilize methods such as random testing or reasonable suspicion testing. This helps for a more accurate picture of employees’ drug use, since the original urine test could be passed by abstaining from drugs for a few days.

Aderhold also cleared up the belief that eating poppy seeds can cause someone to fail a drug test.

“It’s not a myth; in fact it’s very real,” he said. “I’ve seen opium show in a drug test for that reason, but it may not exceed the legal limit.”