Influence of the Cosmetic Treatment of Hair on Drug Testing

The study investigated the impact of cosmetic hair treatments, such as bleaching and dyeing, on drug concentrations in hair samples. Hair samples from individuals who had undergone these treatments were analyzed for cocaine, opiates, cannabinoids, and nicotine. The results showed that drug content in treated hair decreased compared to untreated hair, with mean differences ranging from 30% to over 60%, depending on the drug and the extent of hair damage. Bleaching caused greater decreases than dyeing, and more damaged hair exhibited larger differences in drug concentration levels.