It's about that time of year when yachtsmen's thoughts turn to antifouling. And in these environmentally conscious times, many will wonder about the ethics of what they are doing. We go sailing to enjoy the marine environment, and we don't want to damage it. TBT did untold harm to sea life before it was banned. And any antifouling is by definition toxic to marine creatures at least to some extent. So is it really safer to use copper than to use TBT as the active ingredient?
According to the Copper Antifouling Environmental Programme (CAEP), which gave a major presentation at METS recently, independent research findings support the use of copper in antifouling.
Duncan Norman, chairman of CAEP, said that without antifouling, all immersed surfaces would grow both hard fouling - barnacles etc - and soft fouling - weed and slime.
“Fouled boats are hard to control and dangerous,” he said. “Fouling reduces speed, increases the power needed, and so energy consumption, pollution and all the rest.”
But perhaps an even more persuasive argument is that: “Fouled hulls transfer invasive species across habitats.” In other words, a properly antifouled boat is actually less of an environmental threat than a fouled boat.
“Copper has always been number one in the paint formulator's armoury,” he said, recalling the traditional practice of copper sheathing the hulls of sailing ships. “There is no other biocide that does not carry a health or environmental risk.” But co-biocides could assist copper in doing the job, and also reduce the amount of copper needed, he added.
The EU-based CAEP is sponsored by five companies that represent the leading copper suppliers and representatives from paint suppliers. It funds independent research and publishes scientific data relating to the use of copper in antifouling paint and its impact on the wider environment.
It recently presented a dossier to the EU, giving evidence for the Biocidal Products Directive, which is expected to publish its recommendations late next year. CAEP is currently presenting evidence in the US and Japan, for similar legislation and controls there. But its members are confident that the case for copper continuing to be used for the foreseeable future is unarguable.
Mr Norman pointed out that copper was ubiquitous in the world's oceans. “It is the eighth most common element in seawater, and apparently compatible with all forms of marine life, as well as being effective as an antifouling.”
However, CAEP had called on CEFAS, the Centre for Environment, Fisheries and Aquaculture Science, an agency of Defra, which was much involved in the TBT work in the 1980s, to investigate the scientific case for using copper. Mike Waldock, science director at CEFAS, presented a summary of his findings.
He said that laboratory studies had shown copper could be harmful in heavy concentration, but his study had been looking at the toxic values of concentrations of copper “in the real world.”
Antifouling paints are formulated to release copper at a controlled rate, which ensures that organisms are inhibited from attaching to the protected surface and that the copper will be deactivated as it moves away from the surface, ensuring no environmental toxicity, according to CAEP.
Dr Waldock explained that there was a difference between labile copper, which was toxic, and non-labile copper, in other words copper bound to organic compounds, which was non-toxic. Copper released into the marine environment from antifouling came into this category, he said.
The study had involved exposing mussel larvae and oyster larvae to seawater samples taken from sites around the coast, including marinas, where there were high concentrations of copper from antifoulings.
This “very sensitive testing” showed the same marine organisms studied in the laboratory living happily in areas of shipping and boating activity. Of 342 samples tested, only one “broke the rules,” he said.
“There is little risk to marine species at current concentrations in harbours, marinas and estuaries.”
But he stressed that there was still a need to use antifoul sensibly and to control waste paint. One area where yachtsmen can improve matters, CAEP members agreed, was what they do when they remove antifoul from their boats when laid up ashore.
“We must provide people with the right information. They should put down tarpaulins and collect it all up. They should use copper safely, both in application and removal. Make sure everything is done properly. By cleaning up you can reduce the inputs quite a lot.”
For more information visit www.copperantifouling.com
