Hair drug testing as an epidemiological tool to investigate patterns of drug use: a multi-country study

Prevalence and patterns of drug use among the general population is one of the key epidemiological indicators used by the EMCDDA to assess the drug situation in Europe. This indicator is helpful to understand various aspects of illicit drug use among the general population including patterns of use, risk perceptions, social and health correlates, as well as the consequences of the use of illicit drugs. The indicator makes use of several tools, including drug surveys of the general and school populations, innovative new approaches such as wastewater-based drug epidemiology and targeted surveys including web surveys.

One innovative new approach being trialled by the EMCDDA is hair drug testing, which can detect illicit drugs and their breakdown products (metabolites) in hair. The method involves collecting hair samples from volunteers and analysing them for traces of substances which may have recently been consumed. In a pilot project involving partners in France, Italy and Portugal, the EMCDDA is testing this method alongside a web-based drug use survey modelled on the European Web Survey on Drugs.

The project involves recruiting volunteers in drug-checking services, drug-consumption rooms, music festivals and raves in the three countries concerned and collecting hair samples from them for drug use screening. After providing a few strands of their hair, participants are asked to fill in an online questionnaire on their drug use behaviour. The hair sample is sent for analysis, stored anonymously and destroyed after the study. The first sampling will be carried out at events in Spring and Summer 2022 and results will be available in September. The purpose is to compare what participants think they consumed against the evidence revealed through the chemical analysis of the hair samples. While not representative of the general population, complementary drug monitoring methods, such as these, can provide valuable additional information about variations in use among different groups of people who use drugs. Although this method cannot assess levels of consumption, it can provide important insights into substances used.

This innovative method will allow: 1) the identification of the substances that have actually been used, with additional relevance for the use of new psychoactive substances as these are difficult to assess in traditional methods (e.g. surveys); 2) validate the self-reported information reported in the web-based survey (as opposed to the chemical analysis of the hair); 3) understand which substances are present on the market and 4) the results of the chemical analysis will be reported back to the participants, together will information about the substances found and the possibility of a harm reduction intervention in case the participant wishes. It will therefore combine an innovative monitoring tool and an innovative harm reduction intervention.