BUILDING TRUST. SHAPING SAFETY
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Technical Notices

Prohibition of Cybutryne in Anti-Fouling Coating Systems

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The International Convention on the Control of Harmful Anti-Fouling Systems on Ships (AFS Convention) currently prohibits the use of harmful Organotins in anti-fouling paints used on ships.

The IMO has published amendments to the AFS Convention, given in Resolution MEPC.331(76), which come into force on 1 January 2023, as can be found attached.

These amendments introduce new requirements that ban the future installation of anti-fouling systems which contain a toxic substance called cybutryne (CAS No. 28159-98-0). The amendments also include requirements for ships that already have installed an anti-fouling system containing cybutryne.

The key amendments include the following requirements:

  • All ships shall not apply or re-apply anti-fouling systems containing cybutryne on or after 1 January 2023.
  • All ships bearing an anti-fouling system that contains cybutryne in the external coating layer of their hulls or external parts or surfaces on 1 January 2023 shall either:
  1. Remove the anti-fouling system; or
  1. Apply a coating that forms a barrier to this substance leaching from the underlying non-compliant antifouling system.


The above actions must be implemented 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.

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