The Society of Environmental Toxicology and Chemistry (SETAC) Europe held its 33^rd Annual Meeting in Dublin, Ireland. Smithers experts presented various topics, along with other conference participants, around the theme of “Data-Driven Environmental Decision-Making.”
 
Dr. Kalumbu Malekani, Chief Scientific Officer, Smithers Environmental Risk Sciences Division, shares highlights below from research presented during ecotoxicology sessions focusing on endocrine disruption.
 
Generating Relevant Datasets for Regulatory Assessment of Endocrine Disruption
 
This session included “Refining in vivo fish tests by the inclusion of thyroid hormone system-sensitive endpoints to improve regulatory relevant data,” a collaborative research project (EU Horizon 2020 project EndocRine Guideline Optimisation, ERGO) aimed to include thyroid hormone system (THS) sensitive endpoints into the OECD fish test guidelines (TGs).
 
The presenter discussed nine current OECD guidelines with their respective modalities: estrogen, androgen, steroidogenesis, and thyroid. None of the six OECD fish test guidelines covers the thyroid modality. Using zebrafish as a model, they presented results on thyroid hormone system disruption (THSD). Four THSD-sensitive endpoints were selected for evaluation. These included: 

• Eye development (eye size and retinal layer structure)
• Swim bladder inflation
• Thyroid histopathology
• Thyroid hormone (T3, T4) levels

 
OECD TG 210 (fish ELS) is used as a model for in vivo testing, while the OECD TG 236 (Fish Embryo Acute Toxicity) will be used for non-animal testing.
 
The four endpoints will be validated with chemicals representing identified key molecular initiating events for THSD and negative control chemicals. Protocols are being developed for OECD validation beginning in 2023/2024. The partners encourage research with more OECD-validated species, such as Japanese medaka and fathead minnow.
 
In “Amphibian Studies to Investigate the Endocrine Disruption Properties through the Thyroid Modality: A Comparison of their Statistical Power,” an EFSA representative discussed the results of testing a hypothesis that the statistical power for key diagnostic responses on the T-modality differs across the three available amphibian study designs (i.e., AMA, LAGDA, and EAMA). The response variables across the study types that were reported included: 

• Total length
• Wet weight
• Hind limb length (HLL)
• Normalized hind limb length (nHLL)
• Snout-vent length (SVL) 

Other responses like developmental stage and time to reach NF stage 62 are still under investigation.
 
The results presented are still in the preliminary phase of analysis, and differences in the variability and sensitivity of the time to event parameters, i.e., developmental stage, are expected. However, preliminary conclusions indicated no differences between study designs on most morphometric parameters. Observed differences included HLL between the AMA and EAMA and the LAGDA results for SVL. During the discussion, there was a tacit consensus in the audience that there was no need to perform a LAGDA test when the results of an AMA at level 3 were positive, as it would not provide any new information.

Other topics at the conference covered a wide range of research and regulatory themes, including hot topics such as New Approach Methods for bioaccumulation assessment, the impacts of microplastics, pollinator risk assessment, life cycle assessment, biodegradation and persistence of chemicals, and climate change and its effects on environmental micropollutants.

We look forward to the SETAC North America 44^th Annual Meeting in Louisville, KY, in November, and the SETAC Europe 34^th Annual Meeting in Seville, Spain, in 2024.

To discuss these themes and other research presented at the SETAC Europe meeting, reach out to Dr. Malekani, or contact our experts to learn more about the research Smithers is conducting in endocrine activity research.

Watch Dr. Malekani’s interview with Joseph Marini, Senior Research Biologist, about his poster and platform presentations at the SETAC Europe Meeting in Dublin: