PFHxS-related compounds, which are potentially hazardous substances because of their non-biodegradability, high degree of bioaccumulation potential, and chronic toxicity, were designated as Class I Specified Chemical Substances under the Order for Enforcement of the Act on the Regulation of Their Manufacture and Evaluation of Chemical Substances from 17 June 2026, in order to prevent environmental pollution. This revision is based on the decision at the 10th Conference of the Parties to the Stockholm Convention on Persistent Organic Pollutants in 2022. In addition, products in which PFHxS-related compounds are used were prohibited from being imported from 17 June 2026.