May 24, 2022 by Grace Panter

Last week I attended the session on “Investigating endocrine-disrupting properties of chemicals: developments and challenges towards new approach methodologies (NAMs)”, at SETAC-Copenhagen. It was great to be at a conference, in person, listening to presentations and catching up on the science. The presentations were held in one of the main auditoriums, signifying just how popular and active this area is.

From the posters and presentations, a couple of themes stood out:

• Inclusion of thyroid hormone system disruption biomarkers in fish test guidelines. Several presentations and posters were from the EndocRine Guideline Optimisation (ERGO) project, investigating the effects of thyroid disruption on swim bladder development and eye morphology (including subsequent visually mediated behaviour). A lot of work is on-going in this area, but it remains unclear if the effects on these endpoints are specific to thyroid disruption, or how sensitive the endpoints are. It is therefore still not possible to know whether inclusion of such biomarkers in fish test guidelines could eventually replace testing on amphibians.
• Expansion of adverse outcome pathways (AOPs) into networks. Many of the AOPs that have been developed focus on one taxon, but is there the potential for cross-species AOPs? For some AOPs this is not possible, for example swim bladder inflation is specific to fish, but for other AOPs key events could be applicable to several taxa, so is there the potential to create AOP networks. One example is the on-going development of an AOP network for thyroid hormone system disruption across vertebrate taxa.
• The challenges of linking changes observed in the laboratory (i.e., in organ histopathology or behaviour) to effects on the population. More work is still required to understand the population relevance of an apical change and how the magnitude of an effect would relate to the population. For example, would a three-day delay in metamorphosis result in an effect on the population? There is a need to validate more population models.
• The Annex to the European Food Safety Authority/European Chemicals Agency (EFSA/ECHA) endocrine disrupter guidance on how to consider the Xenopus eleuthereombroynic thyroid assay (XETA) was recently published.

wca provide a study monitoring service for endocrine studies and can prepare weight of evidence risk assessments (ecotoxicology and toxicology). If you would like more information on our services in this area, please contact Grace Panter, Becky Brown or Owen Green.