Micropollutants in European rivers: A mode of action survey to support the development of effect‐based tools for water monitoring

Abstract

Environmental quality monitoring of water resources is challenged with providing the basis for safeguarding the environment against adverse biological effects from exposure to anthropogenic chemicals originating from diffuse and point sources. Although current regulatory efforts focus on monitoring and assessing a few legacy chemicals, many more anthropogenic chemicals are and will become detected in aquatic resources as a result of progress in analytical techniques. Assessing this type of exposure information based on available standard approaches from prospective risk assessment for single chemicals inevitably leads to indication of risk in most surface water bodies. As an alternative to generic assessment approaches, effect-based monitoring approaches are suggested. This offers the advantage of reducing uncertainties of effect extrapolation and additionally accounts for mixture effects. To become a credible complement to chemical monitoring information, however, a better understanding of the capabilities and gaps of available effect-based tools is needed. The authors therefore undertook to 1) compile organic contaminants detected in freshwater monitoring studies, 2) provide a synopsis of the mode of action knowledge available for the detected compounds, 3) perform a hazard ranking to identify priority mixtures, and 4) reflect on the challenges to make bioassays fit for effect-based monitoring. The present Focus article shows that chemical occurrence in European freshwaters seems to be highly variable in composition and relative abundancies. Further, although the present mode of action knowledge remains limited, the authors already see the need for batteries of effect-based tools if a more comprehensive coverage of prevailing effect qualities for mixtures is to be targeted. Finally, they suggest a list of organic compounds that could serve as a reference list for effect-based tool validation studies. Environ Toxicol Chem 2016;35:1887-1899. © 2016 SETAC.

Risk‐based approach in the revised European Union drinking water legislation: Opportunities for bioanalytical tools

“…A wide range of mode‐of‐action categories has been observed for water‐relevant chemicals (Busch et al ). Responses of water concentrates (extracts) in bioassays can be used as indicators for the presence of particular (groups of) chemicals that may cause adverse health effects.…”

“…It may be possible to establish a standard protocol to determine the sensitivity of individual in vitro bioassays to detect effects of (relevant) regulated chemicals at their respective guideline values. Including a list of reference chemicals (e.g., based on the list included in the report by Busch et al []) and their expected mode of action can aid in the comparison between in vitro bioassays.…”

An expanded conceptual framework for solution-focused management of chemical pollution in European waters

“…In contrast to current chemical monitoring, effect-based tools provide measures for the load of an environmental compartment with all chemicals exhibiting an effect on a toxicological endpoint and thus reduce the risk that major contributors to risk are overlooked. However, a careful analysis and prioritisation of MoAs is required and has been made by Busch et al [5] for about 1000 chemicals that are frequently detected in European water bodies. More than 50 effect-based tools addressing prominent MoAs are under evaluation with individual chemicals, defined mixtures and environmental mixtures.…”

“…A key component for the identification of hazard drivers in complex mixture exposure is the EDA approach, where combinations of non-target/target screening [31] with bioanalytical tools can be applied in different tiers to identify drivers of toxicity or in combination with toxicity information or hazardous properties of encountered substances [35, 42]. Stepwise approaches for the use of bioanalytical tools, which details the developing methodologies for innovative monitoring also including mixtures, have been presented [5, 22, 43]. …”

“…Challenges remain to causally link the occurrence of specific polluting chemicals and chemical mixtures to the quality status of waters, to identify major chemical stressors, to identify emission and transport pathways, and finally to define solutions for the abatement of pollution-related risks and impacts. Complex mixtures of priority pollutants and emerging substances [5], transformation products [6] and natural compounds occur in aquatic systems, and the possibility to assess their combined effects is still limited [7–9]. Recently, the introduction of appropriate mixture assessment approaches was forwarded as a regulatory need, with a proposal to use a default model for assessing aggregated responses for a set of chemicals when more specific approaches still lack implementation [10].…”