Hair analysis--perspectives and limits of a proposed forensic method of proof: a review

In the last few decades, a significant trend has been the self-administration of drugs to 'get high' or to achieve other desired pleasurable effects. This trend has produced major efforts to combat drug misuse or abuse. One such effort has been to utilize analytical toxicology to identify individuals who abuse drugs. Recognizing that individuals who abuse drugs might report for work in an impaired condition and create risk for themselves, for co-workers, or for others around them, many employers have established programs to deter drug use by their employees. These programs often include collection of a urine specimen and analysis of that specimen for drugs of abuse. Recently, some investigators have proposed that hair samples should be used in place of, or in addition to, urine samples for this purpose. Among the subjects which are relevant to utilizing hair as a specimen for detection of drugs of abuse and which will be covered in this review are the following: hair morphology and growth; which analyte--parent or metabolite(s); specimen collection and preparation; external contamination; comparison/standard specimens; segmental vs. whole hair analysis; and interpretation of results.