ZDHC MRSL 4.0 Adds 16 Substances and Sets PFAS Limits

ZDHC has published version 4.0 of its Manufacturing Restricted Substances List (the MRSL — the industry's benchmark for chemicals banned from use in production), adding 16 new restricted substances and setting hard numeric limits on PFAS contamination at 25 µg/kg for individual compounds.

The update lands squarely on Tier 2 and Tier 3 suppliers — mills, dyehouses, tanneries and chemical formulators — across textile, apparel, leather and footwear production. If your facility runs ZDHC-conformant chemistry, or your buyer contract references the MRSL, your chemical inventory review starts now.

What's new in version 4.0?

The 16 additions include bisphenols, formaldehyde, polychlorinated biphenyls (PCBs) and certain UV absorbers, targeting chemical risks such as endocrine disruption, carcinogenicity and aquatic toxicity. ZDHC said the update reflects new scientific developments and evolving industry needs.

Existing restrictions also tightened. Limits drop for:

• alkylphenol ethoxylates (APEOs — surfactants used in scouring and wet processing)
• chlorinated paraffins
• certain organic solvents

Housekeeping changes run alongside: three substances join the MRSL Candidate List for continued monitoring, two move to the Archive List, and titanium dioxide comes off the MRSL entirely after changes to its regulatory classification. Version 4.0 also updates formulation limits, analytical methods and material-specific guidance covering textiles, leather, rubber, foams and adhesives, with tailored sections for suppliers, formulators and testing labs.

"With version 4.0, we have added some significant harmful chemicals and, against a backdrop of increasing legislative complexity, we have improved the clarity of the listings to keep its practical application at the forefront," said Phil Patterson, chair of the ZDHC MRSL Council. "Our goal is to help the industry make better-informed chemical choices and drive meaningful progress towards safer manufacturing."

How does the MRSL treat PFAS now?

This is the part with real procurement consequences. Version 4.0 confirms that intentionally adding PFAS is not permitted in compliant chemical formulations — full stop. For unintentional contamination, ZDHC set three thresholds: 25 µg/kg for individual PFAS, 250 µg/kg for the sum of PFAS, and 50 mg/kg for total fluorine content.

A concurrent PFAS position paper and practical interpretations document reinforces ZDHC's stance against intentional use across the textile, apparel, leather and footwear supply chain. The paper is unambiguous on one point buyers should note: even where a specific end use is legally or contractually required to hit performance targets traditionally delivered by PFAS — military equipment, technical textiles, protective clothing — using the substances still counts as non-compliant. Trace-level unintentional contamination is treated differently.

ZDHC was candid about the analytical ceiling. "No chemical management system, testing method or regulation, including the ZDHC MRSL, can guarantee the absence of detectable trace PFAS from every possible source across a global supply chain today. That is a limitation of current analytical science, shared across the industry, not a gap specific to ZDHC," the organization said in the position paper. "We aim to close that gap as responsibly, transparently, and quickly as science and industry capabilities allow, through the ZDHC MRSL V4.0 and closer collaboration with chemical formulators, certifiers, and testing laboratories."

What does this force sourcing and compliance teams to do?

Three moves follow directly from the text. First, chemical inventory screening: the 16 new substances and lowered APEO, chlorinated paraffin and solvent limits mean formulations that passed yesterday may fail tomorrow — formulator declarations need rechecking against version 4.0. Second, PFAS contract language: brands specifying performance requirements in military, technical or protective applications must reconcile those specs with the no-intentional-use rule, because ZDHC offers no exemption lane. Third, testing protocols: updated analytical methods and the 25/250 µg/kg and 50 mg/kg thresholds give labs concrete pass-fail lines for unintentional traces.

ZDHC said it will keep working with brands, suppliers, formulators, certifiers and testing organizations to provide consistent guidance as scientific, regulatory and analytical capabilities evolve. The decision the update forces is simple to state: requalify your chemistry against MRSL 4.0 before your buyer does it for you.