A demonstrable need to follow scientific evidence in the derivation of environmental quality standards: a case study of European surface waters.

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Bibliographic Details
Title:	A demonstrable need to follow scientific evidence in the derivation of environmental quality standards: a case study of European surface waters.
Authors:	Wilson, Iain¹ (AUTHOR) iain.wilson@wca-consulting.com, Merrington, Graham¹ (AUTHOR), Peters, Adam¹ (AUTHOR), Middleton, Elizabeth² (AUTHOR), Garman, Emily³ (AUTHOR), Schlekat, Christian³ (AUTHOR)
Source:	Integrated Environmental Assessment & Management. May2025, Vol. 21 Issue 3, p480-484. 5p.
Subject Terms:	Nickel, Acute toxicity testing, Freshwater ecology, Bioavailability, Environmental standards, Water management, Risk assessment
Company/Entity:	European Commission
Abstract:	Environmental quality standards (EQS) derived under the European Water Framework Directive are legally binding and enshrined in individual European Member State Country national legislation. These EQS are derived following well-established guidance documents. In 2013, EQS for nickel were derived for freshwaters to be protective against long- and short-term exposures, at 4 and 34 µg L−1, respectively. The value for long-term exposures uses chronic ecotoxicity data and accounts for bioavailability, whereas the short-term value uses acute data and does not account for bioavailability. In 2022, the European Commission revised these values as part of the ongoing legislative process. Despite an increase in available data for both chronic and acute ecotoxicity endpoints, the update and development of chronic and acute biotic ligand models (BLMs) published in peer-reviewed literature, and the accessibility of vastly more monitoring data (used in the European EQS derivation), the values for the nickel EQS were reduced by increasing the assessment factors to account for increases in apparent uncertainties. The Commission's 2022 derivation failed to consider additional chronic data for more than 20 species as well as the updated and new acute and chronic BLMs. As a result, the derived nickel EQS is limited in its applicability and relevance to European freshwater ecosystems, as illustrated in practice by the observation that monitoring sites can comply with the chronic EQS but fail the acute EQS. Here, we provide an explanation as to why this has occurred and detail what it means for the risk assessment of nickel in European Member State freshwaters. Finally, we outline a path forward that should be relevant for any risk-based and evidence-driven regulatory framework and acknowledging that political decisions are part of the process, but that these should be separate and after scientific aspects are undertaken. Key points For a derived environmental quality standard (EQS) to be considered protective, it must be relevant to the specific exposure scenarios and ecosystems it is intended to protect; Haber's Rule indicates that an EQS for continuous exposures should be lower than one derived to be protective of short, transient, exposures. The acute EQS (maximum allowable concentration, MAC) for nickel has not been derived using the scientifically recognized standard of bioavailability-based concepts nor using the most updated and relevant information, the appropriate guidance has not been followed, and implementation of the EQS has not been considered. Water chemistry conditions that are relatively insensitive to Ni exposures (e.g., low pH, high dissolved organic carbon and medium hardness) that meet the bioavailable annual average (AA) EQS, because they present low potential risks, may find themselves showing an exceedance when assessed against the MAC. [ABSTRACT FROM AUTHOR]
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Description
Abstract:	Environmental quality standards (EQS) derived under the European Water Framework Directive are legally binding and enshrined in individual European Member State Country national legislation. These EQS are derived following well-established guidance documents. In 2013, EQS for nickel were derived for freshwaters to be protective against long- and short-term exposures, at 4 and 34 µg L−1, respectively. The value for long-term exposures uses chronic ecotoxicity data and accounts for bioavailability, whereas the short-term value uses acute data and does not account for bioavailability. In 2022, the European Commission revised these values as part of the ongoing legislative process. Despite an increase in available data for both chronic and acute ecotoxicity endpoints, the update and development of chronic and acute biotic ligand models (BLMs) published in peer-reviewed literature, and the accessibility of vastly more monitoring data (used in the European EQS derivation), the values for the nickel EQS were reduced by increasing the assessment factors to account for increases in apparent uncertainties. The Commission's 2022 derivation failed to consider additional chronic data for more than 20 species as well as the updated and new acute and chronic BLMs. As a result, the derived nickel EQS is limited in its applicability and relevance to European freshwater ecosystems, as illustrated in practice by the observation that monitoring sites can comply with the chronic EQS but fail the acute EQS. Here, we provide an explanation as to why this has occurred and detail what it means for the risk assessment of nickel in European Member State freshwaters. Finally, we outline a path forward that should be relevant for any risk-based and evidence-driven regulatory framework and acknowledging that political decisions are part of the process, but that these should be separate and after scientific aspects are undertaken. Key points For a derived environmental quality standard (EQS) to be considered protective, it must be relevant to the specific exposure scenarios and ecosystems it is intended to protect; Haber's Rule indicates that an EQS for continuous exposures should be lower than one derived to be protective of short, transient, exposures. The acute EQS (maximum allowable concentration, MAC) for nickel has not been derived using the scientifically recognized standard of bioavailability-based concepts nor using the most updated and relevant information, the appropriate guidance has not been followed, and implementation of the EQS has not been considered. Water chemistry conditions that are relatively insensitive to Ni exposures (e.g., low pH, high dissolved organic carbon and medium hardness) that meet the bioavailable annual average (AA) EQS, because they present low potential risks, may find themselves showing an exceedance when assessed against the MAC. [ABSTRACT FROM AUTHOR]
ISSN:	15513777
DOI:	10.1093/inteam/vjaf014