Neurotoxic chemicals damage our brains and nervous systems, often through chronic, low-level exposure. Effects can take years — or even decades — before they start to show, but can lead to everything from memory loss and cognitive decline to behavioural issues and developmental delays in children. In severe cases, long-term exposure has been linked to neurodegenerative diseases such as Alzheimer’s and ALS.

The risk is especially high during pregnancy and early childhood, when the brain is still developing. Even minimal exposures during this period can lead to permanent harm. Like many other harmful chemicals there is simply no clear safe level when it comes to neurotoxicants.

Why aren’t neurotoxicants regulated?

The EU Chemicals Strategy for Sustainability recognises neurotoxicity as one of the “most harmful” types of chemical hazards and calls for such substances to be phased out.

But despite this acknowledgement, there is still no clear path to regulate them. Policymakers have so far struggled to identify neurotoxic substances, a crucial step that should prompt regulatory action. 

As a result, it is still possible to use many of these brain-damaging chemicals in everything from cleaning agents and paints to heat stabilisers and biocides.

Lack of test data is behind the problem

Part of the problem is that standard chemical testing doesn’t adequately detect all neurotoxic effects. The commonly used tests focus on more short-term toxicity — for example, extensive organ damage — and often miss the subtle but severe neurological effects that develop slowly over time.

This results in major data gaps. And without comprehensive neurotoxicity data, regulators currently can’t identify or prioritise these chemicals for regulatory action under REACH, the EU’s flagship chemicals regulation.

In other words, the absence of data does not mean the absence of danger — it simply means the system isn’t looking for the right things.

Many neurotoxicants do meet the SVHC criteria

REACH states that chemicals that cause chronic, severe harm to human health or the environment can be classified as SVHCs. Neurotoxicants can clearly fit this definition when their effects are irreversible, long-term, and occur at very low exposure levels. Yet, so far, very few have been formally proposed under this category. One example is n-hexane, a solvent recently proposed as an SVHC because of its neurotoxic effects.

That chemical has been on ChemSec’s SIN List since 2008 (alongside many other substances that have later been officially recognised by the EU). This shows that the potential for regulating these brain-damaging chemicals is already strong enough. What’s missing is the political will to act on it.

With the recent addition of three neurotoxic chemicals to the SIN List, we demonstrate that there are neurotoxicants that should be treated as “equivalent level of concern” to other highly hazardous substances, and thereby qualify for inclusion on the EU Candidate List.

With this update, the SIN List does what it has always done. It looks into the future and paves the way for future regulation. If history tells us anything, it’s that when a chemical is added to the SIN List, regulation eventually follows.