TBT anti-fouling paints came into use in the 1960s, replacing less effective coatings based on copper. But in the mid-1980s, scientists discovered that TBT leached from ships' hulls was causing deformities in oysters and dog whelks.
Use of TBT coatings on vessels of less than 25 metres in length was banned in the UK in 1987, and similar measures were taken in most EC countries, the USA and Japan. However, efforts to prohibit their use on larger vessels have been frustrated by the difficulty of securing a global agreement amid claims by TBT coating producers and shipping interests that alternative anti-fouling paints were less effective and liable to increase costs.
Pressure for a ban on TBT has increased following recent studies which showed that the chemical is bioaccumulating in marine food chains, with particularly high levels being detected in whales, dolphins and seals off the US and Japanese coasts (ENDS Report 277, p 13 ).
At the same time, chemical manufacturers such as Rohm & Haas and Courtaulds have developed anti-fouling paints containing less persistent biocides. Other alternatives include silicon-based coatings which prevent the adhesion of organisms to ships' hulls, and novel cleaning systems to remove organisms from hulls.
In November, a working group convened under the auspices of the International Maritime Organization (IMO) adopted a resolution on TBT which will be forwarded for adoption by the IMO Assembly next November. The resolution calls for a global instrument to ban the application of all organotin anti-fouling compounds by 1 January 2003, as well as a ban on the presence of such coatings on ships from 1 January 2008. Lobbying from some shipping interests for a deferral of the former ban to 2006 was resisted.
The instrument is also expected to introduce controls on anti-fouling systems in general. IMO member countries are being encouraged to develop procedures for evaluating the environmental and commercial impacts of anti-fouling systems.
Meanwhile, several environmental initiatives were agreed by the IMO's Marine Environment Protection Committee at its annual meeting in November. They included:
The Convention, which entered into force in 1995, requires parties to have national oil spill contingency plans and clean-up equipment, and to co-operate with neighbouring countries in the event of a spill. Ships and ports must also have emergency plans, and report spills to the authorities.
The new protocol is to be formally adopted in 2000. It will extend the Convention's requirements to chemical spills.
The main purpose of the new study will be to assess the feasibility of reducing greenhouse gas emissions through a variety of technical, operational and market-based approaches.