How can we better protect our brains and hormone systems from chemical risks? PARC group of experts dedicated to Hazard Assessment recently shared preliminary results and key regulatory questions at ECHA Science Seminars, highlighting how chemical hazard assessment can better protect both the developing and adult brain, and help avoid regrettable substitutions that interfere with hormone systems – while reducing reliance on animal testing.

Organised by the European Chemicals Agency (ECHA) and publicly available via its YouTube channel, the seminars provide a platform where scientists and regulators openly discuss current challenges, evidence gaps, and how both established and new methodologies can strengthen chemical safety in Europe.

Protecting the developing and adult brain: why timing matters

One ECHA Science Seminar focused on new approach methodologies (NAMs) for adult and developmental neurotoxicity (ANT/DNT) – a critical area where conventional testing struggles to capture differences between life stages.

The seminar featured Ellen Fritsche and Jonathan Blum (Swiss Centre for Applied Human Toxicology, Basel), and Tamara Tal (Helmholtz Centre for Environmental Research - UFZ). They explored how NAMs can help distinguish effects on the developing versus the adult brain, emphasising that when exposure occurs can be just as important as what type of chemical it is.

The speakers introduced the developmental neurotoxicity in vitro battery (DNT IVB) and discussed how adverse outcome pathway (AOP) networks can integrate biological context into hazard assessment. Case studies including ethanol, retinoic acid, organophosphates, and PFAS illustrated how similar mechanisms can lead to different outcomes depending on life stage and potency.

The speakers highlighted:

Protecting the brain requires understanding developmental context. New methodologies allow us to ask more precise questions about when and how chemicals cause harm, while supporting the transition away from animal testing.

Several of the assays presented were developed within PARC, contributing directly to discussions on how NAM-based evidence could inform current and future CLP approaches to neurotoxicity.

Avoiding regrettable substitution: hormones matter

A second seminar addressed another urgent challenge: how to avoid replacing restricted chemicals with alternatives that may pose similar or new risks. Experts presented preliminary findings from PARC on the endocrine-disrupting activity of selected BPA alternatives, combining OECD test guidelines for endocrine disruption with new in vitro and in silico methodologies.

Sabrina Tait (Italian National Institute of Health) and Antonio De la Vieja (National Institute of Health, Spain) presented early results showing that some BPA alternatives can interact with hormone-related pathways, including effects on steroidogenesis and thyroid hormone transport.

Kiara Aiello Holden, coordinator of PARC Work Package dedicated to Hazard Assessment, introduced the project’s scope: a collaboration of 14 institutions across eight EU countries, prioritising BPA alternatives identified in ECHA’s Assessment of Regulatory Needs report – substances often not covered by industry due to low tonnage but likely to see wider future use. She emphasised:

Substitution alone does not guarantee safety. By systematically assessing how BPA alternatives interact with endocrine systems, we can help regulators avoid repeating past mistakes.

Why this matters

Brain development, neurological function, endocrine function and hormonal balance are central to human health. Current hazard assessment approaches do not always capture sensitive life stages or subtle biological interactions – yet these can have long-lasting consequences.

By combining standardised OECD methods with innovative NAMs, and by openly discussing limitations and uncertainties with regulators, PARC contributes to more protective, forward-looking chemical hazard assessment – while supporting the EU’s commitment to reduce, refine, and replace animal testing.

Stay engaged

Many PARC experts – alongside researchers beyond PARC – have already contributed to the ECHA Science Seminar series, with more presentations planned. Interested stakeholders are encouraged to explore ECHA’s Science Seminar YouTube channel to follow ongoing discussions on chemical safety, regulatory science, and how emerging evidence can better protect human health and the environment.

Link to seminars: https://www.youtube.com/watch?v=Ts55QFMnor4&list=PLOPGDACSd6qwL9t-vsr74mmcXdmc9qFes&index=6 ↗