The identification of a substance as an endocrine disrupter requires the weight of evidence evaluation of all available and relevant studies identified by a systematic review.

Most regulatory regimes have adopted the WHO definition of an endocrine disrupter or variations of this. The definitions share a common element in that they are based on two key requisite elements, i.e. that:

  • exogenous chemicals need to cause adverse effects in intact organisms, and;
  • that the adverse effects are linked to a plausible endocrine mode of action.

Adverse effects caused by endocrine disruption can be identified from standard (eco)toxicology studies. Evidence for mode of action is available from specific mechanistic studies.

wca offers an independent weight of evidence review of substances for potential endocrine disrupting effects in mammalian and wildlife species, which makes full use of existing internal company (eco)toxicity data and any relevant information in the published literature. The review evaluates data from agreed test guidelines for endocrine effects, as well as endpoints from standard toxicity tests that may be related to endocrine disruption. The weight of evidence evaluation is based on a framework that includes the following evaluation steps:

  • Systematic review – identification of all relevant studies in a transparent and robust manner
  • Study reliability – assessment of quality and reliability of studies
  • Study relevance – evaluation of endpoint relevance to the determination of mechanism and adverse effect
  • Balance of the weight of evidence – consistency of the evidence and biological plausibility of link between adverse effects and endocrine mode of action

The review concludes with advice on whether the available data would result in the determination of a substance as an endocrine disrupter, identifies data gaps (where these are present), and provides recommendations on what actions would be required.

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