Neurotoxic chemicals

Neurotoxicity is the effect of toxic substances on the nervous system. Exposure to neurotoxic substances can impair brain function, damage neurons and disrupt communication between nerve cells. Neurotoxicity is an important cause of neurodegenerative diseases such as Alzheimer’s and Amyotrophic Lateral Sclerosis (ALS), which are characterised by a gradual and permanent loss of neurons in the central nervous system. Other typical consequences of neurotoxic substances include brain lesions and the irreversible degeneration of nerves and muscles, causing serious adverse effects in affected people and animals.

The nervous system is particularly vulnerable during early development. Even low-level exposure during pregnancy or childhood can lead to long-term deficits in learning ability, memory, and behaviour (Grandjean & Landrigan, 2014). These effects are irreversible and carry a heavy societal cost. For instance, the economic burden of lead exposure in children in the EU has been estimated at tens of billions of euros annually (Trasande et al., 2016).

In recognition of these severe and lasting impacts, neurotoxic chemicals were included in the EU Chemicals Strategy for Sustainability (CSS) among the group of “Most Harmful Substances” – a category of chemicals for which there is an explicit policy aim to phase them out, in particular from consumer products. Importantly, the most harmful substances, such as those giving rise to chronic neurotoxic effects, require broad risk management measures such as the Generic Risk Approach (GRA).

The most harmful substances, as defined in the EU CSS, represent a broader set of chronic hazards than currently covered by Substances of Very High Concern (SVHC) in REACH. For some chemicals, however, the effects are so severe that they already meet the SVHC criteria under REACH via the Equivalent Level of Concern (ELoC) route.

An illustrative example is n-hexane, already on the SIN List (since 2008), which has now been proposed by ECHA as an SVHC specifically due to its neurotoxic properties. Such cases demonstrate that those neurotoxic chemicals that meet SVHC criteria must be prioritised for phase-out, just like CMR or PBT substances.

While there are standardised test protocols to capture neurotoxic effects available, these are seldom applied to industry chemicals in the testing that is obligatory under REACH. In addition, many of the most concerning neurotoxic effects, such as ALS or Alzheimer's disease, cannot be captured in relatively short-term testing. To enable both effective risk reduction and phase-out, more targeted testing and assessment methods are urgently needed to systematically identify neurotoxic chemicals. Without this, many substances with potentially severe neurotoxic properties risk slipping through current regulatory frameworks.

ChemSec is therefore pushing for all the most harmful substances from the CSS, including neurotoxic substances, to be captured by an extended GRA in the revised REACH Regulation, ensuring a faster and more effective regulatory process. By including neurotoxicants meeting the SVHC ELoC criteria on the SIN List, we aim to send a clear signal that the regulatory framework must address these hazards. This mirrors our earlier efforts with endocrine-disrupting substances, which were added to the SIN List long before the EU eventually decided to regulate them.

The three substances included on the SIN List due to their neurotoxicity are:

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