More than 81 percent of U.S. companies use hair tests to screen employees for drug use, according to the American Management Association. Hair tests---along with urinalysis, blood tests, sweat tests and saliva tests---can be used to detect chemicals in the body. Hair testing is unfamiliar to many people, who may want more information on hair testing and how it works.
Purpose
Hair testing is used for several different purposes. Some companies use hair tests to screen employees for drug use. Health professionals may use hair tests to determine whether a person has been exposed to a chemical or environmental contaminant. Hair tests may also be used in the course of criminal investigations.
Function
When substances enter the body through inhalation or ingestion, they make their way to the bloodstream, where they circulate with blood as it provides nourishment to the body's cells, including the hair follicles. Trace amounts of the contaminant remain in the hair shaft and can be detected with a radioimmunoassay screen.
Benefits
According to a study published in a 1997 issue of Security Management, hair testing is a safe and effective way to detect chemical exposure. In the case of corporate drug testing, hair testing has the added benefit of being difficult for employees to subvert. Hair testing also shows chemical exposure over a longer period of time than other forms of testing, such as blood or urine tests. According to the Agency for Toxic Substances and Disease Registry (ATSDR), 5 inches of hair can show about a year's worth of chemical exposure.
Considerations
According to ATSDR, differing lab standards for collection and analysis may lead to inconsistent results. When a test shows that hair is contaminated, there's usually no way to tell whether it became contaminated through environmental exposure, voluntary or involuntary ingestion or through another factor, such as your diet. For that reason, hair analysis alone isn't considered sufficient to diagnose environmental exposure. Hair testing may also not indicate very recent drug use or exposure since it takes time for the substance to circulate through the body and become part of the hair follicles.
Warning
According to the University of Arizona Center for Methamphetamine and Other Illicit Drug Education, dark hair is more likely to show drug use or environmental exposure than fair hair because chemicals bind more firmly to the melanin in dark hair.
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