New Tool Assesses Complex Water Pollution Pressures

Researchers have developed and applied a new characterization tool designed to assess the complex mixture of pollutants in surface and drinking water. The Key Factor Toxicity, or KFTox, tool integrates two complementary approaches for chemical water quality assessment to better capture the combined effects of polluting substances. This development addresses a significant limitation in traditional monitoring, which often fails to adequately characterize ecological and human health risks from complex chemical mixtures. The study was published in Environmental Sciences Europe and provides a practice-oriented approach for water quality authorities.

The European Water Framework Directive aims to ensure water quality sufficient to sustain ecosystems and support drinking water production. However, water quality is affected by complex mixtures of polluting substances whose combined effects are poorly captured by traditional single-compound monitoring. This gap limits the ability to characterize risks and hampers effective water quality management. The KFTox tool was developed to align with the objectives of the Water Framework Directive and its latest amendment, which encourages the development of quantitative methods for chemical pollution assessment.

The KFTox tool integrates a Chemistry Track and a Bioassay Track to provide a comprehensive view of water quality. The Chemistry Track calculates mixture toxic pressures using Species Sensitivity Distributions and mixture modelling. Both tracks utilize colour-coded impact-related pollution classes to support interpretation by water quality authorities, making the complex data more accessible for management decisions.

The Bioassay Track measures biological activities in water samples using a comprehensive panel of bioassays. These bioassays are benchmarked against effect-based trigger values relevant to both ecological and human health. The panel includes assays measuring general toxicity, endocrine disruption, reactive modes of action such as the induction of oxidative stress response and genotoxicity, and xenobiotic metabolism. This biological approach provides information that is complementary to the chemical analysis, helping to detect unmonitored compounds and mixture effects that might be missed by chemical monitoring alone.

A nine-month case study applied the KFTox tool to samples from surface water abstraction points, process water, and produced drinking water. The Chemistry Track indicated low toxic pressure from over 500 monitored substances, while the Bioassay Track revealed multiple activities exceeding trigger values, highlighting potential risks. The selected bioassays proved relevant for water quality assessment and provided critical information complementary to the Chemistry Track.

The differences between the two tracks illustrated the importance of combining chemical and biological approaches in water quality assessment. This highlights the value of an integrated approach for assessing chemical water quality and prioritizing mitigation measures.

Subject of Research: Development and application of the Key Factor Toxicity tool for assessing chemical water quality in surface and drinking water.

Article Title: The Key Factor Toxicity: development and application of a toxic pressure characterization tool for surface and drinking water

Article References: Houtman, C. J., de Baat, M. L., Brekelmans, S., van Oorschot, Y. G. M., Osté, L., Pronk, T. E., Al Saify, I., & Posthuma, L. (2026). The Key Factor Toxicity: development and application of a toxic pressure characterization tool for surface and drinking water. Environmental Sciences Europe. https://doi.org/10.1186/s12302-026-01511-8

Image Credits: AI Generated

DOI: 10.1186/s12302-026-01511-8

Keywords: water quality, toxic pressure, KFTox, drinking water, surface water, pollution assessment, bioassays, European Water Framework Directive, chemical mixtures, environmental health, Factor, Toxicity