Synthetic Amorphous Silica (SAS) in tyre manufacturing: Essentiality, safety, performance and sustainability

Synthetic Amorphous Silica (SAS) is an essential functional material for the tyre industry, enabling the production of high-performing and sustainable tyres. SAS has a long-established history of safe use in tyres and supports sustainability efforts through the entire tyre lifespan.

Its unique reinforcing properties enhance tyre durability, reduce rolling resistance, and improve wet grip, contributing to improved fuel efficiency, extended electric vehicle range, and reduced greenhouse gas emissions. These benefits are consistent with the objectives of the European Green Deal and the EU ambition to reduce transport-related greenhouse gas emissions by 90% by 2050.

Impact of recent EU regulatory developments

Hazard-based classifications can trigger downstream consequences in product legislation that go beyond workplace risk-management considerations.For the tyre industry, the Ecodesign for Sustainable Products Regulation (ESPR) will introduce product requirements, including specific provisions on ‘Substances of Concern’ (SoC). Currently, SAS is proposed for a harmonised classification as Specific Target Organ Toxicity - Repeated Exposure, Category 1, with the respiratory tract as target organ (STOT RE 1). As such, if the proposal moves forward, SAS will automatically be designated as SoC under the ESPR. Downstream impacts will include information disclosure obligations and possible implications for product design. In this context, a potential classification of SAS would have significance extending well beyond occupational handling scenarios.
While the classification would not constitute a restriction on use, this will increase the pressure to phase out SAS at the design stage, not merely to manage exposure.

For the tyre industry, the principal regulatory risk would not arise from demonstrated exposure during use, but from the way in which hazard classification can influence design acceptability and product-policy screening criteria. The classification could create disproportionate pressure to replace a technically important material even in the absence of a functionally equivalent alternative capable of delivering the same balance of performance, safety, and sustainability outcomes.

Any regulatory measure affecting SAS should therefore be grounded in a robust evaluation and consideration of its properties, an assessment of exposure conditions within longstanding industrial uses, and an evaluation of socio-economic implications for downstream industries. Regulatory action that does not adequately account for these dimensions could generate unintended consequences for the resilience of the European industrial value chain, including for the tyre industry.

For further detail, see the joint position paper by ASASP and Tyres Europe.