January 29, 2025 by Iain Wilson


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With colleagues at NiPERA, Iain, Adam and Graham have published a Brief Communication on the current situation with the short and long-term Environmental Quality Standard (EQS) (called the Maximum Allowable Concentration (MAC) and Annual Average (AA), respectively) for nickel under the European Water Framework Directive. In 2022, The European Commission revised the existing nickel MAC and AA EQS, and these are set to be included in European Union legislation in 2025. Unfortunately, the revisions produced on behalf of the Commission did not use all the new reliable and relevant acute and chronic nickel data produced since the previous derivation in 2013. They also did not utilse the revised chronic biotic ligand model, or the new acute biotic ligand model that were available. The biggest change in the revised EQSs however, was to increase the assessment factors, resulting in a 50% decrease in the AA and 75% decrease in the MAC.

This brief communication outlines the practical environmental outcomes of this revision, which result in freshwaters in Europe, especially those not sensitive to nickel exposures, passing the AA nickel EQS, but failing the MAC EQS, a clear breach of Haber’s Law. The outcome of not utilising all the available data, knowledge and understanding about a substance or following well-developed guidance or general good practice in risk assessment are made clear. The Ni EQSs are legally binding standards, and yet these revisions are of limited ecological or practical environmental relevance.