Study of cocaine incorporation in hair damaged by cosmetic treatments

The present study investigated the alleged relationship occurring between possible hair damage resulting from repeated cosmetic treatments and the uptake of cocaine from a soaking solution into the hair matrix, simulating external contamination. Different types of drug-free hair were submitted to either bleaching, dyeing, or straightening. Untreated and treated hair were then soaked in a cocaine solution for 60 min. The analytical procedure included a common washing and decontamination step, followed by GC–MS detection. Morphological changes of hair submitted to cosmetic treatments were assessed by scanning electron microscopy (SEM). Minor damage was observed at the surface of thermally straightened hair, whereas substantial morphological changes of the hair structure was observed after bleaching and dyeing. Accordingly, untreated and straightened hair did not exhibit any significant uptake of cocaine upon 60 min soaking, whereas bleached and dyed hair exhibited considerable cocaine uptake, yielding final concentrations above the 0.5 ng/mg cut-off value.