October 15, 2020 by Graham Merrington

GrahamAdam and Dean have just published the paper “Perspectives on Relevancy Assessment for Non Standard Ecotoxicity Data in Environment Quality Standard derivation: Examples for Diclofenac” in Bulletin of Environmental Contamination and Toxicology.

The paper focuses upon relevancy assessment of complex and non-standard ecotoxicity data for use in EQS derivation, which can be particularly challenging. These types of data are becoming more common in environmental assessments of pharmaceuticals, and often require specialist knowledge to ensure consistent and rigorous relevancy evaluation. In this work we applied broadly accepted relevancy criteria to a series of non-standard ecotoxicity studies on diclofenac, focusing on aspects that should be accounted for in studies used in EQS derivation. The key recommendations from the work are that:

  • Reliability can usually be assessed independently of the potential use of the data, and the outcomes of a reliability assessment will generally be applicable regardless of the chemical risk assessment regime in which it is used. However, study relevance relates specifically to the purpose for which the results of a study are to be used, and this eventual purpose should clearly inform and underpin all aspects of the relevancy assessment.
  • Some elements of a study (e.g. measurements, endpoints or responses at specific exposure concentrations) may be relevant for EQS setting, while others are not (but may be relevant for another purpose). This means that relevancy assessments should be sufficiently detailed and rigorous to ensure that all critical elements are considered on an individual basis. Unlike the assessment of reliability—whereby failure to satisfy all of the reliability criteria may not render the entire study unreliable—specific data is either relevant for a specific regulatory purpose or it is not.
  • The relevancy of specific measured responses in tissues or organs of individual organisms to the long-term sustainability of populations should be directly demonstrated in a straight-forward manner by including traditional growth, development, or reproduction endpoints in studies of behavioural or histopathological effects.
  • If studies, or specific elements of studies, are identified as not reliable and/or not relevant then they should not be considered to add any significant ‘weight’ to a weight-of-evidence approach. The evidence used in such an approach should still be required to be credible, scientifically robust, and relevant to the purpose of the assessment even it is perhaps somewhat peripheral to the technical aims of, for example, EQS derivation. If a study has been reviewed and has been concluded to be either not reliable and/or not relevant, it is reasonable to suggest that it can contribute little towards a robust weight-of-evidence assessment other than perhaps to highlight a potential source of uncertainty.
  • For transparency, technical regulatory documents should detail all the studies that were considered for inclusion but were rejected on grounds of either reliability or relevance. In addition, details of search terms applied in identifying potentially useful published studies should be included to confirm that searches were sufficiently wide to cover all potentially relevant species and endpoints. These inclusions would assist in providing a clear auditable decision trail for others to follow.

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