
EPA Flags Unreasonable Risk from D4 in Industrial and Environmental Use
EPA draft risk evaluation finds octamethylcyclotetrasiloxane (D4) poses significant risks to workers and aquatic life, signalling regulatory change for industry.


The US Environmental Protection Agency (EPA) has proposed Significant New Use Rules (SNURs) for 37 chemical substances under the Toxic Substances Control Act (TSCA), published on 4 April 2025 in the Federal Register. These SNURs, if enacted, will require manufacturers and processors to notify the EPA 90 days before engaging in any significant new use. This regulatory shift directly affects US-based manufacturers and global supply chain actors importing or using the listed chemicals in consumer or industrial applications.
The SNUR proposal, listed under docket EPA-HQ-OPPT-2024-0332, targets substances with potential health and environmental risks. The EPA's action ensures pre-emptive oversight on chemical uses deviating from approved conditions, particularly where substances are used in adhesives, surfactants, UV-cured resins, perfumes, and catalysts. Industries involved in coatings, polymers, detergents, and advanced manufacturing must assess compliance readiness.
Under TSCA section 5, the EPA is authorised to evaluate chemical risks before they enter commerce. The new rules affect entities in chemical manufacturing (NAICS 325) and petroleum refining (NAICS 324110). Importers are also required to certify compliance with TSCA regulations and adhere to Section 12(b) export notification duties.
The chemicals subject to these SNURs include substances with known or predicted hazards such as skin sensitisation, respiratory effects, and aquatic toxicity. For example, the substance CAS 185953-94-8, used in epoxy coatings, may cause skin irritation and must not be processed without suitable PPE or hazard communication programmes. Surface water discharge limits also apply to certain chemicals.
The proposed rule outlines economic impacts, with SNUN (Significant New Use Notification) costs estimated at $45,000 for large businesses and $14,500 for small enterprises. Export notification costs are estimated at $106 per chemical-country combination. These figures underline the importance of early compliance planning to avoid operational delays or regulatory breaches.
Public comments are invited until 6 May 2025. Manufacturers, importers, and downstream users should review the full list of affected substances and identify any that overlap with current or planned operations. Failure to comply with the new rules post-finalisation could result in enforcement actions under TSCA.
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