Towards impact based monitoring of Estrogenic Endocrine Disrupting Chemicals (eEDC). eEDC sources and behaviour in the Zenne river, Brussels

There is an increasing awareness regarding the exposure to endocrine disrupting chemicals (EDC) in water resources. Evidence of the high biological activity of EDCs resulted in some EDCs with pharmaceutical use and of emerging concern to be included in the Watch List (2013/39/EU) of the European Water Framework Directive (WFD) where EU member states are urged to monitor these substanstances. Current deterministic water quality modelling methods are not sufficient to calculate the transport of estrogenic endocrine disrupting chemicals (eEDC) concentrations in a river. This is because eEDCs are present in very low concentrations and are very costly to analyse, its present and acts in a mixture of chemicals and little are understood regarding the interactions and transformation processes between eEDCs and its environment.

During this study, eEDC activity and its transport along the Zenne river in Brussels was investigated. The estrogenic equivalent concentrations (BEQ) were determined with Estrogen responsive elements - Chemical Activated Luciferase Gene Expression (ERE-CALUX) analysis at four samplings sites in the Zenne river. The samples were collected over a period of one year. Samples were also collected at a hospital wastewater outlet and at the inlet and outlets of the wastewater treatment plants which discharges into the Zenner river. A water mass budget and BEQ load budget was calculated by using the sampling sites as flux boxes boundaries in the study area of the Zenne River.

BEQ measured along the Zenne River were comparable to ranges measured in literature and were higher than EQS (environmental quality standard) standards for EE2 (17α-ethynylestradiol) and E2 (17β-estradiol). 4 Sampling events that met the eligibility criteria (<25% error in water fluxes due to uncertainty, spatial variation in rainfall, CSO events…) were selected for BEQ load calculations. Although the waste water treatment plants removed 93-98% of the BEQ received at the inlet, it was still identified as the major eEDC contributors to Zenne River. 9-57% of the total BEQ load could be attributed to the contribution of wastewater treatment works. A clear upstream (Z3) – downstream (Z11) gradient of the BEQ loads were visible.