Illicit drugs are metabolized or eliminated unchanged in the urine and/or feces then join the sewer system. The quantification of these products in wastewater disposal has two advantages: firstly, to assess the contamination of the environment and also contribute to the estimation of illicit drug consumption in a catchment. Analytical methods adapted to the complex organic load of wastewater have been developed and validated to assess the levels of contamination of influents and effluents from 26 sewage treatment plants in France for seventeen compounds (illicit drugs and metabolites). The results of the analysis were used to evaluate the elimination of these compounds depending on the treatment technologies used in wastewater treatment plants. Concentrations in the influent were used to estimate the illicit drug consumption by back calculation and showed qualitative and quantitative differences of drug use among urban areas in metropolitan France and overseas. In the last part, toxicology studies on a bacterial model and behavioural studies with an animal model have been conducted with concentration levels close to the levels found in surface water and no significant effect was observed.
