Environmental justice issues in drinking water contaminant exposure in a European context

Previous studies have documented ethnic and sociodemographic disparities in exposure to drinking water (DW) contaminants. A majority were conducted in the U.S., with fewer studies conducted in other regions. This research aims to assess available evidence regarding environmental justice (EJ) issues in Europe, identify contaminants and potential drivers. A Scoping Review was conducted, exploring the existing European studies from 1990 to 2022. The review encompasses types of DW contaminants studied in relation to EJ, research designs, and potential drivers contributing to inequalities in exposure to specific contaminants. In addition, a case study was conducted in Ille-et-Vilaine, France, focusing on contaminants identified in the review and using a national monitoring database. Inequalities in contaminants' exposure were assessed using a composite deprivation index, FDep, at the census tract level (IRIS) applied in multilevel models and geographically weighted regression models, accounting for the rural-urban heterogeneity. Results show a limited number of primary studies focusing on EJ and DW contaminants exposure in Europe (n = 16). Various chemical contaminants such as nitrates, trihalomethanes (THMs), heavy metals, fluoride and pesticides have been assessed. Case study findings suggest some association between FDep and contaminants, with a different level of correlation depending on the contaminant. THMs show a negative correlation with deprivation, while lead displays a positive correlation related to the FDep. Disparities in exposure were also found according to the spatial scale of analysis. In rural areas, higher deprivation levels were associated with higher levels of nitrate (OR: 1.47; 95%CI: 1.02, 2.15) and lower level of fluoride (OR: 0.16; 95%CI: 0.07, 0.30) or THMs (OR: 0.73; 95%CI: 0.55, 0.98) in tap water. This study emphasizes the need for comprehensive research on EJ and DW contaminants exposure on a larger scale. Understanding complex interactions between contaminant distribution, socioeconomic factors, and exposure is essential for addressing EJ in drinking water.