About 35 percent of American companies screen applicants for drugs before they are hired. Traditionally, a urine sample is taken, but the test only detects drugs which have been taken in the past few days.
A hair test can detect drugs which have been taken in the past few months, but some critics say the results are unreliable.
"It's become the newest rage as the new type of testing," says Bob Pippin, the owner of Alcohol and Drug Testing Incorporated in Raleigh. He says companies like it because it tells you a lot more than a urine test.
"They like the hair testing for the simple reason that it does go back far enough to give them an idea if they're having a chronic problem in the past," Pippin said.
The hair test is two to three times more expensive than the urine test, and can take weeks to get the results. But the accuracy of the test is the biggest concern. The fear is that false positives will keep people from getting jobs.
For example, tests show that dark hair retains more drugs for a longer period of time.
"A person with blonde hair may not be accused, but a person with black hair may be accused of drug use," says research scientist Dr. Douglas Rollins. "As long as that possibility exists, I don't think the test should be used until we've solved and resolved some of these issues."
For now, most companies are sticking with urine tests. But Pippin says the danger with the urine test is that a new hire could literally do crack cocaine on Friday and test negative on Monday.
"We drug test him by urine, he comes back clean, and we just hired a crack cocaine head," Pippin said. "They don't know it and we don't know it until we see symptoms or problems."
Many companies in the Triangle do pre-employment drug screening. Pippin says for the most part, companies are still using the urine test for these screenings, but tend to use the hair test after a person is employed if they think that individual may have a drug problem.
He says the fastest growing group of people asking for the hair test is parents.