Propylene Glycol Ethers: Widespread Use and Missing Neurotoxicity Testing

Organic solvents are known to affect the nervous system, but neurotoxicity testing is not routinely required for industrial chemicals under current European regulations. Glycol ethers are widely used in consumer and industrial products. They can cross skin and lung barriers, distribute systemically, and penetrate the blood-brain barrier due to their physicochemical properties, while their neurotoxic potential remains poorly characterized. P-series glycol ethers now dominate the European market, making exposure assessment critical for public health. We compiled and integrated data from five authoritative sources to build an inventory of glycol ethers currently used in Europe and performed a structured descriptive analysis of high-volume propylene glycol ether compounds. Six high-volume compounds (≥1000 t/year) were selected for analysis. Production volumes, Swiss product registrations, occupational exposure limits, and product categories were compiled. Propylene glycol methyl ether (PGME) showed the highest tonnage (100,000-1,000,000 t/year) and was present in 9497 registered products, followed by propylene glycol ethyl ether (PGEE) (10,000-100,000 t/year; 1333 products). Paints/coatings and cleaning agents were the most frequent product categories, while additional presence in personal care and indoor-use products was observed. These products may lead to exposure depending on use conditions, such as spraying or inadequate ventilation, which can increase inhalation and skin contact. Their presence in diverse products suggests potential for both occupational and chronic low-level exposures. By providing an integrated overview of market presence, use patterns, and available neurotoxicity evidence for propylene glycol ethers, our findings highlight a critical gap in chemical risk assessment: the absence of neurotoxicity testing despite high production volumes and widespread use. Integrating neurotoxicity endpoints and new approach methodologies into regulatory frameworks is essential to strengthen public health protection.