At wca we derive and apply Predicted No Effect Concentrations (PNECs) and environmental quality standards (EQS) within national and international regulatory regimes. We have helped government and commercial clients to derive and implement defensible EQS for metals, industrial chemicals, pesticides, biocides, medicines, endocrine active substances and nanoparticles.

We have used assessment factor, species sensitivity distribution, time-to-event and fully probabilistic statistical approaches to derive EQS for substances in surface waters (freshwater, saltwater and drinking water), sediments, soils and wastes. This includes providing advice to the European Commission on how EQS can be developed for biota and how non-testing approaches such as Quantitative Structure-Activity Relationships can be used in a robust EQS derivation framework.

We have expertise in the derivation of PNECs and quality standards for both data rich and data poor substances within the technical guidance for the Water Framework Directive and other regulations. This work has included the derivation of limit values using biological field data and weight of evidence approaches.

We also have practical experience of providing implementation frameworks for the use and interpretation of environmental standards and PNECs. This includes assisting clients in contextualising and mitigating risks and also using guideline values to assist in defining when a waste material is no longer classified as a waste.

The implementation and final ‘use’ of limits values and PNECs is often overlooked in the desire to derive a value by which to assess potential chemical risks. However, this step is often the difference between having a metric that is biologically relevant or something that is unusable and irrelevant.

New tools and techniques for setting and implementing limit values are continuing to be developed and wca has had practical experience of successfully deriving and using (bio)availability-based tools for trace elements in regulatory frameworks for soils and waters in the UK and internationally.

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