Ban on use of Anti-Fouling Systems that contains Cybutryne

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The IMO has adopted amendments to the Anti-Fouling Systems Convention (AFS convention) vide Resolution MEPC 331 (76), which restricts the use of Cybutryne and also includes an operative passage with respect to the issuance of the new AFS certificate. 

These amendments will enter into force on Jan 2023. 

Classification society IRS has shared the below helpful circular for Members who might be interested to learn more of the amendments. 


  1. IMO adopted amendments to the AFS Convention vide Resolution MEPC 331 (76) to include controls on Cybutryne and an operative paragraph with respect to issuance of the new International Anti-fouling System Certificate. The amendments will enter into force on 1 January 2023.
  2. The amendments prohibits application or re-application of anti-fouling systems containing Cybutryne (CAS No. 28159-98-0) on all ships from 1 January 2023.
  3. Following rows have been added to the table in Annex 1 to the 2001 AFS Convention: 

    Anti-fouling system Control measures   Application  Effective date
     Cybutryne CAS No. 28159-98-0  Ships shall not apply or re-apply antifouling systems containing  All ships 1 January 2023
     Cybutryne CAS No. 28159-98-0  Ships bearing an anti-fouling system that contains this substance in the external coating layer of their hulls or external parts or surfaces on 1 January 2023 shall either:
    (1) remove the antifouling system; or
    (2) apply a coating that forms a barrier to this substance leaching from the underlying noncompliant anti-fouling system.
     All ships except:
    (1) fixed and floating platforms, FSUs, and FPSOs that have been constructed prior to 1 January 2023 and that have not been in drydock on or after 1 January 2023;
    (2) ships not engaged in international voyages; and
    (3) ships of less than 400 gross tonnage engaged in international voyages, if accepted by the Coastal State(s).
     At the next scheduled renewal of the anti-fouling system after 1 January 2023, but no later than 60 months following the last application to the ship of an anti-fouling system containing Cybutryne

  4. Further, the amended Annex 4 of the AFS Convention provides a revised model form of the International Antifouling System (IAFS) Certificate. Based on verification of compliance to amended requirements, an updated IAFS Certificate will be issued reflecting the compliance options for controlled anti-fouling systems on the ship.
  5. Ship owners/ managers and masters are advised to take note of above requirements and accordingly ensure that necessary planning is done while procuring anti-fouling paints so that it does not contain Cybutryne. In case of ships where anti-fouling system already contains Cybutryne (CAS No. 28159-98-0) as on 1 January 2023, planning will be required for either the removal of such anti-fouling paint or for application of a sealing coating in consultation with the paint manufacturer in order to comply with the amended requirements.



Captain Anuj Velankar

Regional Loss Prevention Director (Singapore)