The US Environmental Protection Agency (EPA) has again delayed parts of its ban on trichloroethylene (TCE), a toxic solvent that remains important in several industrial applications including the manufacture of battery separators for lead-acid batteries.
The latest postponement pushes the effective date for certain exemption conditions to May 18, 2026, while litigation over the agency’s 2024 TCE rule continues through the US courts.
TCE has long been used as a degreasing solvent and processing aid across a range of sectors. The agency concluded in 2014 that the chemical poses serious health risks including cancer, neurological damage, developmental toxicity and liver toxicity.
Under the EPA’s December 2024 rule, most commercial and consumer uses of TCE are being phased out. However, a limited number of industrial uses were granted temporary exemptions under Section 6(g) of the Toxic Substances Control Act (TSCA), including its use in “specialty polymeric microporous sheet material manufacturing” – the process used to produce microporous battery separators.
Microporous separators are a critical component in lead-acid batteries. Typically made from polyethylene filled with silica and processing oils, they physically isolate the positive and negative plates while allowing ionic conductivity through the electrolyte. During production, TCE has historically been used as a processing solvent to extract oils and create the controlled porous structure needed for separator performance.
The chemical has been particularly associated with the manufacture of polyethylene separators used in automotive starter batteries, industrial flooded cells and valve-regulated lead-acid (VRLA) batteries. Manufacturers have argued that replacing TCE is technically difficult because separator porosity, mechanical strength and electrical resistance are tightly linked to the extraction process.
Separator manufacturers granted an extended compliance period for TCE
Agency documents indicate that the separator sector received an extended compliance period because the process occurs in highly industrialised facilities capable of implementing stricter worker protections while alternatives are developed.
The ongoing court challenge has centred partly on these exemptions. Industry groups including the Alliance for a Strong US Battery Sector and separator producer Microporous have petitioned against aspects of the rule. Agency filings show that concerns were raised over the feasibility of its Workplace Chemical Protection Program requirements for exempted applications.
Although the exemptions remain in place temporarily, the agency has repeatedly stated that all TCE uses are ultimately intended to be prohibited.
The issue has particular relevance for the lead-acid battery supply chain because separator production is a specialised and highly concentrated industry. Any disruption to separator manufacturing could have knock-on effects for automotive, motive power and stationary storage battery production.
EPA said the latest delay is intended to “preserve the status quo” while litigation proceeds.
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