Japan Issues New Handling Rules for Class I Specified Chemical Substances Present as Impurities under the CSCL, Based on the BAT Principle 
On March 31, 2026, Japan’s Ministry of Health, Labour and Welfare (MHLW), Ministry of Economy, Trade and Industry (METI), and Ministry of the Environment (MOE) jointly issued a new “Notice concerning the Handling of Chemical Substances Containing Class I Specified Chemical Substances as Impurities” under the Act on the Evaluation of Chemical Substances and Regulation of Their Manufacture, etc. (Chemical Substances Control Law, CSCL). Under the CSCL, Class I Specified Chemical Substances—whose manufacture, import, and use are, in principle, prohibited—are subject to rules governing cases in which they are unintentionally generated during manufacture (i.e., present as impurities). In connection with the amendment of the administrative notification “On the Operation of the Act on the Evaluation of Chemical Substances and Regulation of Their Manufacture, etc.” effective April 1, 2026, the three ministries issued this new Notice regarding the handling of such impurities.
Under the CSCL, when a Class I Specified Chemical Substance is unintentionally generated as an impurity during the manufacture of another chemical substance, the principle of “Best Available Technology/Techniques (BAT)” is applied. If the concentration is reduced—using industrially and economically feasible techniques—to a level at which no risk of adverse health effects through environmental contamination is recognized, the impurity is not treated as a Class I Specified Chemical Substance. Furthermore, when a business operator discovers that a chemical substance it manufactures or imports contains a small amount of a Class I Specified Chemical Substance as an impurity, the operator must establish a BAT‑based “voluntary management upper limit” and reduction measures, and must submit these in writing in advance to the three ministries, explaining their appropriateness. After submission, the operator must continually confirm that the concentration does not exceed the upper limit, make ongoing efforts to reduce the concentration, and report its management status upon request from the ministries. However, for certain specified substances, concrete threshold values have been established. If the operator submits, in the prescribed format, that it will manage the substance in accordance with BAT within those threshold values, periodic reporting thereafter is not required.
In addition, the Notice clarifies provisions for plastic recyclates manufactured using post‑consumer plastic as part of the raw material. For Class I Specified Chemical Substances that may be present in trace amounts in such recyclates and for which international management values have been established, operators must submit, in advance and using the prescribed format, documentation to the three ministries showing that they will manage the substance in accordance with BAT.
Chemical substances for which BAT‑based reporting has been submitted are no longer treated as Class I Specified Chemical Substances under the CSCL. However, to prevent environmental contamination, business operators remain responsible for strict management and for ensuring appropriate communication of relevant information.
Procedures and Management Obligations toward the Three Ministries
When a business operator discovers that a chemical substance it manufactures or imports contains a small amount of a Class I Specified Chemical Substance as an impurity, the operator must take the following measures:
- Setting a “voluntary management upper limit”:
Establish a BAT‑based voluntary management upper limit and submit it in writing in advance to the three ministries, together with reduction measures and other relevant information, explaining its appropriateness. - Continuous reduction efforts:
After submission, continually confirm that the concentration does not exceed the voluntary management upper limit and make efforts to reduce the concentration. The operator must also report its management status upon request from the ministries and revise the upper limit or other measures as necessary.
Establishment of Threshold Values for Specified Substances and Exemption from Periodic Reporting
For certain specified substances listed in the table below, concrete threshold values have been established. When management is conducted in accordance with BAT within these threshold values, submitting documentation in advance to the three ministries eliminates the need for periodic reporting. When appropriately managed within these threshold values, the substances are regarded as not being treated as Class I Specified Chemical Substances.
| Class I Specified Chemical Substance | Conditions / Scope | Threshold Value |
|---|---|---|
| Hexachlorobenzene (HCB) | Tetrachlorophthalic anhydride (TCPA) | 200 ppm or less |
| Pigments, dyes, etc. manufactured using TCPA as a raw material | 10 ppm or less | |
| Polychlorinated biphenyls (PCB) | Concentrations considered unsuitable for international circulation | 50 ppm or less |
| Short‑chain chlorinated paraffins (SCCP) | Concentrations based on decisions under the Stockholm Convention | Less than 1 wt% (10,000 ppm) |
Handling of Plastic Recyclates
In response to the circular economy, provisions have been clarified for cases in which “plastic recyclates”—materials manufactured using post‑consumer plastic as part of the raw material—are newly manufactured or imported. For Class I Specified Chemical Substances that may be present in trace amounts in such recyclates and for which international management values exist, operators must submit documentation in advance to the three ministries, using the prescribed format, showing that they will manage the substance in accordance with BAT.
Related Links
- Notice on the Handling of Chemical Substances Containing Class I Specified Chemical Substances as Impurities (March 31, 2026)
https://www.meti.go.jp/policy/chemical_management/kasinhou/about/260331bat_oshirase.pdf - “Procedures When Class I Specified Chemical Substances Are Present as Impurities” (METI)
https://www.meti.go.jp/policy/chemical_management/kasinhou/about/class1specified_history.html#history9 - “On the Operation of the Act on the Evaluation of Chemical Substances and Regulation of Their Manufacture, etc.” (latest amendment: April 1, 2026) (METI)
https://www.meti.go.jp/policy/chemical_management/kasinhou/files/about/laws/laws_t_r080401_51_0.pdf - Chemical Substances Control Law (CSCL) – e‑Gov Law Search
https://laws.e-gov.go.jp/law/348AC0000000117?occasion_date=20250601
