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Hair Testing Criticized As Unreliable, Biased


Summer 1999

Some high schools in the U.S. are adopting hair testing to detect illicit drug use. Hair testing can reveal drug use within a larger time frame than urine testing because urine is excreted relatively quickly from the body. Hair grows at the rate of about a half-inch per month. Hair testing usually uses a sample of many hairs gathered together that total about the diameter of a shoe lace. The sample is cut at the scalp and the newest one-and-a-half inch are used to detect drug use within the last 90 days. The federal government, which has set standards for urine testing, has not set standards for hair testing (Christopher Wren, "Hair Testing by Schools Intensifies Drug Debate," New York Times, June 14, 1999, p. A14).

Psychemedics Corporation, the largest hair testing company in the U.S., sponsors pilot programs in private schools. According to Raymond C. Kubacki Jr., president of Psychemedics, 80 schools in 26 states are using his company's services to test their students for drugs.

Psychemedics recently sponsored free hair testing for a year to two private schools in New Orleans De la Salle High School and St. Augustine High School. At De la Salle, only 28 of the 870 students tested positive with three months' notice of the test. Test results were released to parents, and students who tested positive were referred to drug counseling. When the students who tested positive were retested, only three tested positive. The purported success of the two programs prompted the principals of two public schools in New Orleans to call for the use of hair testing on their students. The Orleans parish school board is considering whether to permit such testing.

Scientists at the National Institute on Drug Abuse (NIDA) and the Society of Forensic Toxicologists (SFT) say hair testing is not sufficiently reliable for widespread use. Hair testing "is not ready for use yet, where people's lives are at stake," said Edward Cone, a former NIDA researcher on hair tests and now a researcher with Conechen Research. In a 1990 report SFT said, "The use of hair analysis for employees and pre-employment drug testing is premature and cannot be supported by the current information on hair analysis for [drug abuse]" (Leslie Kean, "Hair Tests Raise Doubts," Baltimore Sun, May 30, 1999).

Drug molecules may bind more readily to "coarser" black hair than to lighter hair, creating disparities in test results, and passive exposure to marijuana smoke may produce greater rates of false positives. "It's potentially possible that people could have detectable levels in their hair without ever using the drug. I think it's going to take more research before these problems are resolved," said Michael J. Welch, a research chemist for the National Institute of Standards and Technology. "Dark hair, blond hair and dyed hair react differently, thus creating questions of equity among ethnic groups and genders," said Dr. Bruce Burlington, director of the FDA's Center for Devices and Radiological Health. A U.S. Navy study released by NIDA in 1995 shows that dark, coarse hair is more likely to retain external contamination, and thus more likely to give a false positive.

In an editorial, the New York Times wrote: "[T]he reliability of hair tests has yet to be firmly established, and until it is, such tests should not be used. A false positive reading could have drastic effects on a child's life." Scientists have questioned whether hair tests "have a racial bias. False positives occur more frequently among minorities than among whites." The newspaper concluded: "The Orleans [Parish] school board would be better advised to emulate school districts in Florida, New Jersey and Washington, which have chosen instead to build comprehensive drug education programs and trust between school administrators and students" (Editorial, "A Threat to Student Privacy," New York Times, July 4, 1999).

Psychemedics Corp. - 1280 Massachusetts Ave., Cambridge, MA 02138, Tel: (617) 868-7455 or Toll Free: (800) 628-8073, Web: <>.

Dr. Edward Cone - Conechen Research, 441 Fairtree Drive, Severna Park, MD 21146, Tel: (410) 315-8643.

Society of Forensic Toxicology - P.O. Box 5543, Mesa, AZ 85211-5543, Tel/Fax: (602) 839-9106, Web: <>.

Orleans Parish School Board - 3510 General De Gaulle Dr., New Orleans, LA 70114, Tel: (504) 365-8800.