Environmental Risk Assessment for Contaminants of Emerging Concern in the Belgian Part of the North Sea.

Belgian coastal waters are influenced by densely populated cities, industrial activities, and marine shipping, and they are therefore subject to chemical contamination. In the NewSTHEPS project (2012-2019), more than 150 contaminants of emerging concern (CECs) were detected in the Belgian Part of the North Sea, including hormones, personal care products (PCPs), pesticides, non-hormone pharmaceuticals, phenols, and phthalates. In this study, we developed and used an automated algorithm to calculate the marine screening level predicted no-effect concentration (PNECscreen) of substances, and to identify the organisms and organism groups most sensitive to these chemicals, based on ecotoxicological data from the ECOTOX Knowledgebase. By combining these PNECscreen values, existing Environmental Quality Standards (EQS) from the European Union (EU) Water Framework Directive (WFD), as well as predicted no-effect concentrations (PNECs) from other sources, with environmental concentrations of substances measured in the NewSTHEPS project, we assessed the risk of different classes of CECs at four sampling stations. The distribution of risks was comparable between open sea and harbor sampling locations, and also between samples collected with grab sampling and passive sampling. In total, 33 substances, including 11 hormones (natural and synthetic ones), two personal care products (PCPs), four pesticides, eight non-hormone pharmaceuticals, two phenols, and six phthalates, were found to be associated with potential environmental risks (median risk quotient > 1), with fish most frequently being the most sensitive organisms. The majority (23/33, ie > 80%) of these substances, particularly hormones and phthalates, have not been included in the EU WFD EQS directive's Priority List or associated Watch Lists. While the risks associated with pharmaceuticals were primarily driven by individual substances, hormones, phthalates, and pesticides with endocrine disrupting and/or neurotoxic potentials, were estimated to contribute to a 'something from nothing' effect, where mixture risk arises even when all individual components are present at concentrations below their effect thresholds.