| OCR Text |
Show 3 the reported inconsistencies of dose-concentration relationships for drugs in hair, there is a preference for the incorporation of drugs such as codeine, cocaine and PCP into pigmented hair over nonpigmented hair (62,64,65,69, 74, 86). This observation has the potential for creating a bias in the interpretation of drug concentration data in hair. In order for hair to be a legally defensible forensic sample, the mechanism(s) underlying this potential bias must be understood to accurately interpret drug concentrations in hair from persons with different hair colors. Another potential use for the analysis of drugs in hair is in the area of compliance or recidivism monitoring. Some investigators have suggested that hair can act as an historical record of drug exposures (4, 6-9). Knowing the rate of hair growth in an individual and the location of the drug along the long axis of the hair shaft, it may be possible to determine the approximate time of drug use. The location of the drug may be found by identifying the proximal and distal ends of the hair and segmenting the hair into sections of any desired length. If drug is incorporated into the hair as the hair is being formed, it should be localized in a particular segment(s) that correlates with the time of drug administration. Noncompliance in a drug treatment program would be determined by gaps in the detection of the treatment drug in hair segments that were predicted to correspond to when the drug was ingested. Recidivism in a drug treatment program would be detected by fmding an abused drug in a hair segment that corresponds to an abstinence period. The limitations of the determination of drug incorporation into hair segments include inconsistent rate of hair growth and the assignment of a "time zero" from which subsequent drug exposure will be monitored. It may be possible to overcome these limitations by administering a "marker" substance which would theoretically "tag" the hair at the onset of a treatment program, providing a more precise point of reference from which to establish the ensuing time frame. As the treatment program proceeds, segmental analysis could be performed on collected hair samples and the position of the "marker" drug localized. This technique has been utilized by Uematsu |
