What is Hair Drug Screening?

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  • Written By: Kerrie Main
  • Edited By: A. Joseph
  • Last Modified Date: 19 November 2018
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Many employers conduct drug screenings as part of their hiring processes. There are several types of tests that can detect drugs in a person’s system, and hair drug screening is one of the most expensive and thorough tests. Hair drug screening uses a small sample of a person’s hair to test the follicles for any traces of current or previous drug use.

Employee drug testing became legal in the United States when President Ronald Reagan signed Executive Order 12564, which laid the ground for the Drug-Free Workplace Act of 1988. Since then, both private and government-run organizations in the U.S. can legally drug test current and prospective employees. Employers conduct these tests because they believe that drug-addicted employees put the company at risk for accidents, thefts and attendance issues.

The hair drug screening process typically occurs at a drug screening facility. Approximately 40 to 50 strands of hair from the scalp are cut and then tested. If the person has a shaved head, other types of body hair can be used, such as underarm hair or arm hair. Most testing facilities utilize enzyme immunoassay antibodies (EIA) to detect illegal substance in the hair follicles.


Average human hair grows 0.5 inches (1.27 cm) per month, and the majority of testing centers conduct testing on only 1.5 inches (3.81 cm). This indicates that most hair drug screening tests look only for drug use within the previous 90 days. The most common types of illegal drugs tested for in this type of screening are marijuana, amphetamines, cocaine, opiates and phencyclidine.

Companies and businesses that have high security protocols, such as banks and law enforcement agencies, typically utilize hair drug screening rather than other methods. In some cases, if a prospective employee disputes a failed urine test, he or she will have to take a hair test to prove the absence of illegal substances. Hair tests usually are more expensive than other types of drug screenings, such as those that test urine, sweat or saliva.

There are many misconceptions and myths about hair drug screening tests. Hair coloring techniques, such as bleaching or dyeing, does not affect the testing results, because coloring covers only the exterior hair follicles. Hair shampoos, conditioners, gels and sprays also do not affect the test. Some people believe that being around secondhand illegal drug smoke, including crack cocaine or marijuana, might cause a person to fail the test. This also is not accurate, because the test looks at the hair's metabolites, which are produced by the body after drug consumption.



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Post 3

@irontoenail - To some extent I agree with you, but I think there are certain professions where drug testing should be mandatory and expected. Pilots, for example, should not be doing drugs and I don't care if they are only having a joint on the weekend or not. The same goes for anyone who is going to be operating machinery. If they don't like it, they can find a different profession.

I think doctors, nurses, policemen and possibly teachers should be included in that as well. When you are trusted with the lives of other people I don't think doing drugs is a good look.

Post 2

@Mor - It also doesn't make financial sense. I've seen studies which show that most workplaces that start drug screening with a hair test or other methods, spend thousands of dollars on the effort and hardly ever catch anyone.

I don't understand how this is good for business. It annoys your employees and wastes money in order to catch, at most, a handful of people who are probably only using drugs in their leisure time.

And that's not even bringing up the legality of firing people because they happened to smoke a single joint three months ago. Most workplaces claim they are only testing in order to get people into addiction services, but that doesn't seem likely to me.

Post 1

I have to say that I just don't trust these kinds of tests. I've heard that drug testing in general tends to get a large percentage of false positives and that really frightens me. I don't have anything to hide, but it's possible that one day I could lose my job just because I didn't pass a hair or urine drug screening.

And for what reason? I mean, if someone isn't working properly, then fire that person. I don't understand why the average office has to ensure that its workers never touch drugs.

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