WHAT CONSTITUTES A POSITIVE RESULT IN HAIR ANALYSIS - PROPOSAL FOR THE ESTABLISHMENT OF CUTOFF VALUES

Hair is still a seldom used specimen in most laboratories but its anal ysis has the potential of making a valuable contribution. Despite the many worthwhile reports, the scientific community at large still has r eservations about the validity of hair analysis. Some of this is due t o a lack of consensus among the active investigators on how to interpr et the results from an analysis of hair. In USA, passive exposure seem s to be a major problem, which can only be eliminated with difficulty. On the other hand, in Europe, scientists are performing standard deco ntamination procedures. It would be very helpful if a group of active researchers on hair analysis, representative of academic, government a nd private laboratories could define what are the areas of agreement a nd what are the issues that require further efforts to get a consensus . We propose the following guidelines: (1) a complete decontamination procedure, including the analysis of the wash solution; (2) two distin ct analytical methods (immunoassay and GC/MS, or two different GC/MS m ethods); (3) the establishment of cut-off values (using 30-mg hair sam ples), 0.5 ng/mg of 6-MAM in the case of heroin abuse, and 1 ng/mg of cocaine in the case of cocaine abuse, which can be decreased to 0.5 ng /mg when use is supported by other evidence of drug intake.