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Reliable and high-quality test results regarding the chemical and ecological status of water bodies are crucial, as they serve as the basis for assessing the ecological and chemical status of waters and for developing effective water management plans.
At the EU level, Environmental Quality Standards (EQS) have been defined for 45 priority substances that determine the chemical status of waters. Furthermore, each EU Member State is required to establish additional EQS for specific pollutants released into water bodies.
However, the methodology for water status assessment does not take into account the effects of exposure to mixtures of different chemicals present in the environment nor their cumulative effects.
Given the vast number of legally defined EQS, it is important to note that over 100,000 chemical substances are commercially available in Europe, posing a significant challenge for analysts and legislators in their efforts to preserve aquatic ecosystems.
More specifically, a variety of chemical mixtures can be found in aquatic environments, including: antiseptics, surfactants, surfactant metabolites, flame retardants, biocides, personal care products, pharmaceuticals, hormones, UV blockers, industrial chemicals, nanoparticles, endocrine disruptors, illicit drugs, and others.
These environmental chemicals affect biological systems at multiple levels, from enzymatic systems to cells, organs, individual organisms, populations, and entire ecosystems.
Chemical mixtures can be toxic even when all their components are present at very low concentrations, as their combined action may result in harmful effects on aquatic organisms.
To evaluate water quality in relation to legally regulated and other compounds present in aquatic ecosystems, integrative methods, such as ecotoxicological testing, are considered necessary.
It is also crucial to monitor legally unregulated compounds, in order to promptly detect environmental changes, define specific pollutant profiles for river basins, and develop new approaches for characterising complex environmental mixtures of various chemicals. For this purpose, the Josip Juraj Strossmayer Water Institute has developed a non-targeted analytical screening method using high-performance liquid chromatography coupled with high-resolution mass spectrometry, which allows for the qualitative identification of a wide range of organic pollutants.
Identifying the pollutant stressors based on their potential ecotoxicological and toxicological effects, as well as their prevalence in the aquatic environment and impact on aquatic ecosystems, is the first step towards effective ecosystem management.
Systematic monitoring of unregulated substances in the aquatic environment, their prioritisation based on persistence, bioaccumulation, and toxicity, followed by subsequent ecotoxicological studies, represents an exceptionally complex multidisciplinary task, with the ultimate goal of defining new water quality standards for specific pollutants, thereby contributing to the regulation of their discharge into the environment.