ON COSMETICALLY TREATED HAIR - ASPECTS AND PITFALLS OF INTERPRETATION

Popular hair cosmetic treatments like bleaching or permanent waving we re found to affect the stability of incorporated drugs and to cause al terations of the fibers at an ultrastructural level. This may result i n a partial or complete loss of drug substances, depending on the part icular drug molecule and on its concentration prior to the cosmetic tr eatment. Moreover, from literature, there is some evidence that drug m olecules are not only incorporated into the growing fiber by passive d iffusion from blood into the matrix cells and melanocytes, but that th e substances enter the hair also via perspiration such as sweat and se bum. Since penned and bleached hair shows an enhanced sorption capacit y, the risk of false positives or an unusually high drug concentration in cosmetically treated hair was under investigation. Virgin, permed, mildly as well as severely bleached tresses were exposed to artificia l sweat or sebum containing cocaine, benzoylecgonine, 6-acetylmorphine , morphine and codeine (500 ng/g). Except codeine, the concentrations measured by GC/MS were very small and quite close to the detection lim it indicating a minor importance of drug uptake into hair fiber from t he endogenous-exogenous shunt via sebum or sweat. From the results it is concluded that an increased risk of false positive results in hair analysis on bleached and permanent waved hair fibers does exist, but i s not particularly severe. (C) 1997 Elsevier Science Ireland Ltd.