Priorisation des biocides émis par les matériaux de construction en vue de leur surveillance dans le milieu aquatique

In recent years, because of the large number of compounds and their diversity, the concept of prioritization of substances for which monitoring in the aquatic environment is needed emerged. Indeed, 100,000 substances are registered in Europe. However, contexts are very different from a study to another, many selection criteria are possible and water monitoring could be limited by insufficient analytical tools, which make the prioritization of micropollutants difficult. Biocidal substances are very toxic to aquatic organisms and their uses are numerous (more than 800 substance/product type couples are registered under the Biocidal Product Regulation), in particular in urban areas where they are used as disinfectants, pesticides, preservatives in cosmetics or building materials, etc. However, they are still poorly monitored in waters. Among the urban transports of micropollutants into natural receiving waters, this work focused on urban discharges during wet weather (stormwater and combined sewer overflows), which are contaminated by runoff on urban surfaces, such as buildings. Indeed, biocides are often added to building materials (paints, renders, etc.) in order to protect them from the growth of microorganisms on their surfaces. In order to select substances of interest, prioritization was conducted on 25 biocides, which are commonly used in building materials. They were prioritized according to several criteria related to their emissions in the environment, to the exposition of aquatic populations and to their ecotoxicity. For each criterion, a risk-based score between 1 and 10 was assigned. Twenty biocides were finally selected as relevant to monitor in the aquatic environment.