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.
