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Your Hair Can Tell

THE standard method of checking for drug use is by analyzing a urine sample. But recently the National Institute of Justice, a research arm of the U.S. Justice Department, financed a study of the potential use of hair analysis to determine whether a person is a drug user. Although scientists generally believe that more research needs to be done before they are willing to rely on the analysis of a sample of hair to determine drug use, the method clearly has advantages.

Drugs such as cocaine and heroin, for example, will not be found in the urine even a few days after use. Yet these drugs will show up in a hair analysis months later. This is because drug residues remain embedded in the hair as it grows. Bernard Gropper of the National Institute of Justice observes: “Hair has the advantage of long-term memory. It’s a permanent record, like tree rings.” A three-inch [8 cm] strand of hair will give a six-month history, since head hair grows at a rate of about a half inch [1 cm] a month.

Another advantage is that people cannot elude the detection of drugs in a hair analysis as easily as they can in a urinalysis. Drinking a lot of water before giving a sample of urine, for example, may distort the drug test. But a hair analysis is different. In fact, examination of a few strands of hair said to have come from the head of the 19th-century British poet John Keats revealed that he used increasing amounts of opium toward the end of his life. It is suggested that the drug was used for medicinal purposes, since Keats was dying of tuberculosis.