Anti-fouling paints are used to coat the underwater surfaces of ships to prevent sealife such as algae and molluscs attaching themselves to the hull, thereby slowing down the ship and increasing fuel consumption.
In the early days of sailing ships, lime and later arsenic were used to coat ships' hulls, until the modern chemicals industry developed effective anti-fouling paints using metallic compounds.
These compounds slowly "leach" into the sea water, preventing barnacles and other marine life from attaching to the ship. But studies have shown that these compounds persist in the water, killing sealife, harming the environment and entering the food chain. One of the most effective biocides for use in anti-fouling paints, developed in the 1960s, was the organotin compound tributyltin (TBT), which has been proven to cause deformations in oysters and sex changes in whelks, as well as longer-term effects due to its persistence and bioaccumulation.
Chapter 17 of Agenda 21, developed by the 1992 Rio Conference on Environment and Development, called on States to take measures to reduce pollution caused by organotin compounds used in anti-fouling systems.
The harmful environmental effects of organotin compounds were recognized by IMO in 1989. In 1990 IMO’s Marine Environment Protection Committee (MEPC) adopted a resolution which recommended that Governments adopt measures to eliminate the use of anti-fouling paints containing TBT on non-aluminium hulled ships of less than 25 metres in length and eliminate the use of anti-fouling paints with a leaching rate of more than four micrograms of TBT per day.
In November 1999, IMO adopted an Assembly resolution that called on the MEPC to develop an instrument, legally binding throughout the world, to address the harmful effects of anti-fouling systems used on ships. The resolution called for a global prohibition on the application of organotin compounds which act as biocides in anti-fouling systems on ships by 1 January 2003, and a complete prohibition by 1 January 2008.
This instrument was later adopted as the International Convention on the Control of Harmful Anti-fouling Systems on Ships.
The International Convention on the Control of Harmful Anti-fouling Systems on Ships (AFS Convention), which was adopted on 5 October 2001, prohibits the use of harmful organotin compounds in anti-fouling paints used on ships and establishes a mechanism to prevent the potential future use of other harmful substances in anti-fouling systems. The Convention defines "anti-fouling systems" as "a coating, paint, surface treatment, surface or device that is used on a ship to control or prevent attachment of unwanted organisms".
The Convention entered into force on 17 September 2008.
Under the terms of the Convention, Parties to the Convention are required to prohibit and/or restrict the use of harmful anti-fouling systems on ships flying their flag, as well as ships not entitled to fly their flag but which operate under their authority and all ships that enter a port, shipyard or offshore terminal of a Party.
Anti-fouling systems to be prohibited or controlled are listed in Annex 1 to the Convention, which can be updated as and when necessary. Initially this included controls on organotin compounds which act as biocides in anti-fouling systems, which in the first instance all ships shall not apply or re-apply, and subsequently ships either shall not bear on their hulls or external parts or surfaces, or shall bear a coating that forms a barrier to such compounds leaching from the underlying non-compliant anti-fouling systems.
This applies to all ships (except fixed and floating platforms, floating storage units (FSUs), and floating production storage and off-loading units (FPSOs) that have been constructed prior to 1 January 2003 and that have not been in dry-dock on or after 1 January 2003).
Ships of 400 gross tonnage and above engaged in international voyages (excluding fixed or floating platforms, FSUs and FPSOs) are required to hold an International Anti-fouling System Certificate, for which they shall undergo an initial survey before the ship is put into service or before the International Anti-fouling System Certificate is issued for the first time, and further surveys when the anti-fouling systems are changed or replaced.
Ships of 24 metres or more in length but less than 400 gross tonnage engaged in international voyages (excluding fixed or floating platforms, FSUs and FPSOs) have to carry a Declaration on Anti-fouling Systems signed by the owner or authorized agent. The Declaration has to be accompanied by appropriate documentation to demonstrate that the anti‑fouling system used on the ship complies with the Convention.
Amendments to the Convention
Article 6 provides the mechanism for proposing amendments to Annex 1 of the AFS Convention (controls on anti-fouling systems) and sets out how the evaluation of a substance should be carried out. This mechanism provides for the establishment of a "technical group" to include people with relevant expertise to review proposals for other substances used in anti-fouling systems to be prohibited or restricted.
At its seventy-first session in July 2017, MEPC approved a new output to amend Annex 1 to the AFS Convention to include controls on cybutryne, as scientific data indicates that cybutryne causes significant adverse effects to the environment, especially to aquatic ecosystems. Work on this matter was carried out in the Sub-Committee on Pollution Prevention and Response (PPR) and it resulted in amendments to Annex 1 (Controls on anti-fouling systems) and appendix 1 to Annex 4 (Model form of International Anti-fouling System Certificate) of the AFS Convention, which were adopted by the MEPC at its seventy-sixth session in June 2021 and entered into force on 1 January 2023.
Similarly to the approach for organotin compounds, from this date ships shall not apply or re-apply anti‑fouling systems containing cybutryne, and subsequently ships either shall not bear this substance in the external coating layer of their hulls or external parts or surfaces, or shall bear a coating that forms a barrier to this substance leaching from the underlying non-compliant anti-fouling systems.
The latter requirement (removal or sealing) is effective 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, and is not applicable to: fixed and floating platforms, FSUs, and FPSOs that have been constructed prior to 1 January 2023 and that have not been in dry-dock on or after 1 January 2023; ships not engaged in international voyages; and ships of less than 400 gross tonnage engaged in international voyages, if accepted by the coastal State(s).
Resolutions and guidelines
The Diplomatic Conference adopted four resolutions:
Resolution 1 - Early and effective application of the Convention – This resolution requests Member States to prepare to be bound by the Convention and urges relevant industries to refrain from marketing, sale and application of the substances controlled by Annex 1 of the Convention.
Resolution 2 - Future work of the Organization pertaining to the Convention – The resolution invites IMO to develop guidelines for brief sampling of anti-fouling systems; guidelines for inspection of ships; and guidelines for surveys of ships. The guidelines are needed in order to ensure global and uniform application of the articles of the Convention which require sampling, inspection and surveys.
These guidelines were developed and adopted prior to the entry into force of the Convention, and subsequently revised. As a consequence of the introduction of controls on cybutryne, there was a need for the further revision of these guidelines. This was also carried out at the PPR Sub‑Committee, and revised guidelines were adopted by the MEPC at its seventy-eighth session in June 2022 as follows:
- resolution MEPC.356(78) on 2022 Guidelines for brief sampling of anti-fouling systems on ships;
- resolution MEPC.357(78) on 2022 Guidelines for inspection of anti-fouling systems on ships; and
- resolution MEPC.358(78) on 2022 Guidelines for survey and certification of anti-fouling systems on ships.
Another guidance document relevant for the implementation of the Convention is the Guidance on best management practices for removal of anti-fouling coatings from ships, including TBT hull paints (AFS.3-Circ.3-Rev.1), which is currently also being revised as a consequence of the introduction of controls on cybutryne.
Resolution 3 - Approval and Test Methodologies for Anti-Fouling Systems on Ships – This resolution invites States to approve, register or license anti-fouling systems applied in their territories. It also urges States to continue the work, in appropriate international fora, for the harmonization of test methods and performance standards for anti-fouling systems containing biocides.
Resolution 4 - Promotion of Technical Co-operation – The resolution requests IMO Member States, in co-operation with IMO, other interested States, competent international or regional organizations and industry programmes, to promote and provide directly, or through IMO, support to States, in particular developing States that request technical assistance for:
- (a) the assessment of the implications of ratifying, accepting, approving, or acceding to and complying with the Convention;
- (b) the development of national legislation to give effect to the Convention; and
- (c) the introduction of other measures, including the training of personnel, for the effective implementation and enforcement of the Convention.
It also requests Member States, in co-operation with IMO, other interested States, competent international and regional organisation and industry programmes, to promote co‑operation for scientific and technical research on the effects of anti-fouling systems as well as monitoring these effects.
Capacity-building workshops on anti‑fouling systems, conducted to support the Administrations of developing countries in the ratification and the uniform implementation and enforcement of the AFS Convention, are regularly held in various regions around the world under IMO's Integrated Technical Cooperation Programme.