Do cosmetic treatments increase the incorporation of amphetamines into hair?

Abstract

According to several studies, the concentration of drugs in hair may decrease by bleaching or dyeing; however, at the same time, treated hair could incorporate greater quantity of drugs from sweat or sebum than intact hair. The aim of this study is to assess the incorporation of amphetamine (AP), methamphetamine (MA) and 3,4-methylenedioxy-methamphetamine (MDMA) from sweat or sebum to virgin, dyed, and bleached hair. Drug-free head hair samples (from 20 volunteers) were divided into four locks, one of them was left untreated, another was subjected to dyeing treatment, and the last two were subjected to different degree of bleaching. Virgin, dyed, mildly as well as severely bleached locks of hair were exposed to artificial sweat or sebum containing AP, MA, and MDMA (500 ng/g), at 37 °C for a time period of 8 and 24 h, respectively. After the exposure, all the hair samples were tested by GC/MS in SIM mode, applying an already published method. Drug concentrations in hair ranged 0.41 to 2.20 ng/mg from artificial sweat, while only reached 0.27 ng/mg from artificial sebum. The differences of each drug concentration (AP, MA, MDMA) between different kind of hair were statistically compared: virgin hair vs. dyed hair, virgin hair vs mildly bleached hair, virgin hair vs. severely bleached hair. The differences between different drugs concentration within each kind of hair (virgin, dyed, mildly and severely bleached) were, as well, statistically compared: AP vs. MA, AP vs. MDMA, MA vs. MDMA. In all cases, differences were calculated between locks of hair from the same volunteer. The paired samples Student's t-test was applied in cases where the concentration differences followed the normal law. In these cases the extent of the difference was calculated with a confidence interval of 95%. The paired samples Wilcoxon's t -test was applied in cases where the concentration differences did not follow the normal law. Regarding the incorporation of AP, MA and MDMA from artificial sweat in vitro, the analysis provides evidence that the mean concentration for each drug in dyed or bleached hair is higher than the mean concentration in virgin hair, and that the differences between means are likely to be between 0.15 and 0.57 ng/mg, depending on the drug and the compared pairs. The incorporation of different drugs in the same kind of hair shows little differences in virgin and dyed hair, but the mean concentration of MDMA in bleached hair is higher than the mean concentration of AP; the differences between means are likely to be between 0.08 and 0.16 ng/mg. Regarding the incorporation of AP, MA and MDMA from artificial sebum in vitro, the differences between mean concentrations are lower for every compared pair, in relation to the incorporation from sweat. AP is not incorporated into hair from sweat or sebum to a greater extent than MDMA. Higher positivity rates for AP have been found in dyed or bleached hair in relation to virgin hair, detecting both significant [1] and non-significant [2] differences in the target populations. Based on these facts and the quantitative results of in vitro incorporation of amphetamine derivatives in hair, when interpreting the results from cosmetically treated hair, consideration should be given not only to the possibility that the treatment will lead to a decrease in drug concentration, but also to an increase. This consideration is particularly relevant if the detected levels are close to the cut-off.