INFLUENCE OF THE COSMETIC TREATMENT OF HAIR ON DRUG-TESTING

An important issue of concern for drug analysis in hair is the change in the drug concentration induced by the cosmetic treatment of hair. T he products used for this treatment are strong bases and they are expe cted to cause hair damage. As a result drugs may be lost from the hair matrix or, under conditions of environmental contamination, be more e asily incorporated into the hair matrix. We investigated the effects o f cosmetic treatment in vivo by analysing hair samples selected from p eople who had treated their hair by bleaching or dyeing before sample collection. All of the subjects admitted a similar drug consumption du ring the time period for which the strands were analysed. Samples were Viewed under a microscope to establish the degree of hair damage. Tre ated and untreated portions from each lock of hair were then selected, separated and analysed by standard detection procedures for cocaine, opiates, cannabinoids and nicotine. In all cases the drug content in h air that had undergone cosmetic treatment decreased in comparison to u ntreated hair. The majority of the mean differences were in the range of 40%-60% (cocaine, benzoylecgonine, codeine, 6-acetylmorphine and TH C-COOH). Far morphine the mean difference was higher than 60%, and two cases (THC and nicotine) differed by approx. 30%. These differences d epended not only on the type of cosmetic treatment, as bleaching produ ced higher decreases than dyeing, but also on the degree of hair damag e i.e. the more damaged the hair, the larger the differences in the co ncentration levels of drugs.