Japan Finalizes PFHxS‑Related Substances Under CSCL

By Yuko Howell, Regulatory Affairs Lead, Supply Chain Team, UL Solutions

On April 17, 2026, Japan published a ministerial ordinance specifying chemical substances subject to regulation as Perfluoro(hexane‑1‑sulfonic acid) (PFHxS)‑related substances under the Chemical Substances Control Law (CSCL). The ordinance will take effect on June 17, 2026.

The ordinance was issued jointly by the Ministry of Health, Labour and Welfare (MHLW), the Ministry of Economy, Trade and Industry (METI), and the Ministry of the Environment (MOE), pursuant to Article 1, Paragraph 1, Item 37 of the CSCL Enforcement Order. It establishes the specific chemical substances that fall within the scope of PFHxS related substances defined at the cabinet order level.

Background and international context

PFHxS and its related substances were added to the list of elimination substances under the Stockholm Convention on Persistent Organic Pollutants (POPs) at the Convention’s Tenth Conference of the Parties in June 2022. In response, Japan initiated domestic procedures to align its chemical control framework with the treaty decision.

Following deliberations by the Pharmaceutical Affairs and Food Sanitation Council, the Chemical Substances Council, and the Central Environment Council, Japan amended the CSCL Enforcement Order in December 2025 to designate PFHxS related substances as Class I Specified Chemical Substances. The newly published ministerial ordinance completes this regulatory framework by identifying the individual substances subject to control.

Scope of the ordinance

The ordinance specifies 117 individual substances as PFHxS related substances. These include individual chemicals, salts, derivatives, reaction products, and certain polymers that meet the regulatory definition set out in the CSCL Enforcement Order.

PFHxS related substances are defined as compounds that:

• Contain either a (tridecafluoroalkyl) sulfonyl group with six carbon atoms, or a [(tridecafluoroalkyl) sulfinyl] oxy group with six carbon atoms; and
• May, through chemical transformation by natural processes, generate perfluoro(hexane 1 sulfonic acid) or certain perfluoroalkane sulfonic acids.

The detailed listing in the ordinance reflects Japan’s intent to capture PFHxS precursors that could contribute to environmental formation of PFHxS, rather than regulating only the acid itself.

Regulatory implications

Under CSCL Article 2, Paragraph 2, Class I Specified Chemical Substances are substances designated by cabinet order due to their persistence, bioaccumulation, and potential for long term toxicity to humans or higher trophic animals. Once a substance is classified as Class I, CSCL imposes stringent controls.

As of June 17, 2026, the manufacture, import, and use of the 117 listed PFHxS related substances will be prohibited in principle. In addition, products containing these substances will be subject to related restrictions under CSCL, including import prohibitions for specified articles.

Considerations for companies

The ordinance has significant implications for companies operating in Japan or supplying products to the Japanese market. Because the list includes reaction products and certain polymers, businesses will need to evaluate not only intentionally added substances but also intermediates and by products that may fall within the scope of the designation.

Companies that previously transitioned from PFOS to alternative fluorinated chemistries may be particularly affected, as some PFOS substitutes fall within the PFHxS related substance definition. Supply chain communication, formulation reviews, and substance inventories should be updated ahead of the June 17 effective date to ensure compliance.

Next steps

With the publication of the ordinance, Japan’s regulatory treatment of PFHxS related substances is now fully established. Attention is expected to shift toward implementation, enforcement, and updates to public chemical inventories, including NITE CHRIP and related regulatory databases.

Companies are advised to closely review the list of 117 substances and assess potential impacts on existing products, raw materials, and ongoing R&D activities.

Reference

Official Gazette of Japan, April 17, 2026 (MHLW/METI/MOE Ordinance No. 3) (Japanese only)