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Editor's Note: The revised Categories and Management of Handling for Concerned Chemical Substances was published on May 13, 2025 to introduce the final updates for cybutryne. There are no significant changes compared with the draft, except for the provisions on exemptions and grace periods. Details can be accessed here.
Taiwan EPA is consulting on designating cybutryne as a “chemical substance of concern” under the Toxic and Concerned Chemical Substances Control Act (TCCSCA). The 30-day consultation period will end on December 26, 2024.
Cybutryne is the common name for N'-tert-butyl-N-cyclopropyl-6-(methylthio)-1,3,5-triazine-2,4-diamine (CAS number 28159-98-0). It has been found by several scientific studies to be toxic and persistent, with a significant half-life in the marine/aquatic environment and potential to impact unacceptably non-target organisms and the base of food chains leading to seafood production and other ecosystem services.
In response to this concern, in July 2021, at the 76th session of the Marine Environment Protection Committee (MEPC 76), the International Maritime Organization (IMO) adopted an amendment to the International Convention on the Control of Harmful Anti-fouling Systems on Ships (AFS Convention) to control cybutryne. More specifically, it prohibits usage of cybutryne in anti-fouling systems for new applications as well as for ships those already have applied with an anti-fouling system which contain cybutryne from 1 January 2023.
To align with international trends and enhance regulatory oversight, Taiwan is to control it by amending the Categories and Management of Handling for Concerned Chemical Substances. The key points of this amendment are as follows:
1. Designate cybutryne as a Concerned Chemical Substance, with the following details
Chemical name | CAS No. | Control concentration standard % | As being hazardous | Specified handling | Graded handling quantity | Regular reporting frequency | Exemption | Containers and packaging rules | Record |
N'-tert-butyl-N-cyclopropyl-6-(methylthio)-1,3,5-triazine-2,4-diamine (cybutryne) | 28159-98-0 | All (no low concentration exemption) | — | Manufacture, import, sale, use, and storage | — | Monthly | Used by academic and inspection institutions for testing, research, education purposes | — | Record down one by one |
2. Prohibit the use of cybutryne in the production of antifouling paints, antifouling systems, and biocides.
3. Detail compliance requirements by the stipulated deadlines:
By September 1, 2026, stakeholders must ensure that all containers, packaging, operational sites, and facilities are properly labeled and accompanied by safety data sheets.
By September 1, 2026, activities related to the manufacture, import, sale, use, and storage of cybutryne must obtain approval documents.
From September 1, 2026, it will be mandatory to maintain operational records and report monthly.
