Detox shampoos for EtG and FAEE in hair – Results from in vitro experiments

Abstract

In this study, we investigated if “detox” shampoos, which are sold online can have an impact on EtG or FAEE concentrations in hair. Recently, we showed, that prolonged washing with water can lead to significant washout of EtG in hair [1] . According to customer reviews, positive drug testing results could be avoided after long-term incubation with shampoo under a swimming cap. To evaluate the potential of four detox shampoos, we incubated distal hair samples from three subjects, obtained during a standard haircut, for 2.5, 5, 7.5 and 10 h. For EtG, three shampoos performed similar to deionized water. The fourth shampoo showed additional heavy washout effects with a decrease of up to 86% after 2.5 h. For the apolar FAEE, no washout was observed. Incubation with two shampoos resulted in increases in FAEE concentrations due to FAEE being present as shampoo ingredients. Further investigation of EtG washout in proximal forensic hair samples ( n = 9) with the most potent shampoo showed a mean decrease in deionized water of 23% ± 25%, and a decrease by the use of detox shampoo of 73% ± 12%, compared to non-incubated hair after 8 h. Detox shampoos proved to have the potential to alter EtG and FAEE concentrations in hair during in vitro experiments. Further in vivo studies need to be performed. Since several possibilities of manipulation (e.g., by heat, chemical treatment, washing-out) are known for hair – and dilution or adulteration are known for urine – but not for blood, further investigations of alcohol markers for abstinence monitoring should include phosphatidyl ethanol (PEth) in blood [2] , [3] . Especially for abstinence monitoring, one should not only rely on one marker in hair – as pointed out in the consensus: “A concentration < 7 pg/mg does not contradict self-reported abstinence of a person during the corresponding time period before sampling.” This statement implies that it is not a proof of abstinence. However, in practice of traffic medicine, the result (EtG < 7 pg/mg) is very often interpreted as a proof of abstinence.