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. It's potentially possible that people could have detectable levels in their hair without ever using the drug. 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. A false positive reading could have drastic effects on a child's life.
False positives occur more frequently among minorities than among whites.