THE Department of the Marine has defended advising fish farmers to use a chemical to control sea lice infestations which is not allowed for marine use in two of the world's largest fish farm producer countries.
The chemical, cypermethrin, is widely used in agriculture as an anti parasitic agent, particularly for sheepdipping. But regulatory authorities in Canada and Scotland confirm it is illegal for marine use because they believe its environmental impact has not been established.
There is also concern in Britain where an increasing number of freshwater pollution incidents have been linked to the agricultural use of pyrethroids, a group of chemicals including cypermethrin.
These are an attractive alternative to the older and hazardous organophosphate dips.
Pyrethroids are safer dips but the Scottish Environmental Protection Agency says they are "at least 100 times more toxic" when used in the aquatic environment.
The Department recommended cypermethrin use in April 1996, saying it had been effective in Scotland and Norway. But its use here is "of tremendous concern", according to Mr John Fouere, managing director of Cleggan Lobster Fisheries in Galway. "My understanding is that cypermethrin does not disperse easily in fresh water. It might break down all right, but not before binding quickly to sediment and crustaceans."
Mr Fouere and other shellfish producers have asked the Department if it had done adequate testing of the chemical in the marine environment.
"We were told that the technical decision had been taken by the appropriate authority to allow its use. They are more or less saying it's out of their hands. We do not accept this. Its use should be suspended until a full investigation of its marine effects is completed," he said.
Irish Lobster Association chairman Mr Donal Healy said his organisation had raised the issue with the Department repeatedly.
Areas surrounding fish cages were being damaged, he claimed. Shellfish were no longer living near the cages despite having been plentiful before. "The Department, we feel, is granting permission for cypermethrin use without full investigation of its impact on the food chain of other species."
In Canada, cypermethrin is a "banned substance", according to Mr George Long of Environment Canada, the federal agency responsible for the environment. "Like any other chemical use for any particular purpose, the scientific community has to look at its effects and impact. Our evaluation of cypermethrin is not complete, and will take some time."
He confirmed, nevertheless, that a Canadian fish farmer had been prosecuted for using it.
Lobstermen in New Brunswick, Canada, have brought a legal action against salmon farmers and the federal and provincial governments after 60,000 lobsters died in July 1996. Traces of cypermethrin were reportedly found in a number of them.
The case has yet to go to hearing, and how cypermethrin got into the lobsters has not been shown, nor has any connection with fish farming in the area been established.
In Scotland, "the current policy is not to authorise the use of cypermethrin because of a lack of field data on its fate and its effects on the environment", according to Mr Donny Morrison of the Scottish Environmental Protection Agency. He confirmed that the matter was under review by its fish farm working group.
Because of a switch to increased use of pyrethroids, inducing cypermethrin, in sheep farming, "there has been a significant increase in recorded incidences of `sheep dip pollution' over the past few months", Mr Morrison said.
Incidents during the past year matched the total for the previous 10 years. It represented a hidden form of pollution, as most people would not notice the disappearance of fresh water invertebrates. But their demise over large stretches of river can severely damage an ecosystem.
The Department of the Marine said cypermethrin's marine use in Ireland was under a trial licence granted by the Department of Agriculture, with its support. "The usage under this licence is strictly controlled by the competent authorities," a spokeswoman said.
The concentration of cypermethrin used in Ireland was much lower than that allegedly responsible for the Canadian lobster deaths. The Department considered it safe.
It cited several studies by the British company, Grampian Pharmaceuticals, and by independent bodies including the University of Maine, which showed "zero toxicity" to lobsters with a lice treatment called Excis (a brand containing cypermethrin produced by Grampian) immediately outside fish cages where the agent was applied.
Excis, used in Ireland, was not in use in New Brunswick last year, but was licensed for use in the US, and is used in Maine just across the water from where the lobster kill occurred.
Excis is designed for marine use, according to Mr Julian Braidwood, its development manager with Grampian. "This formulation (containing cypermethrin), if used properly will be safe."
He was confident the product would be cleared for use in Canada and Scotland but accepted that cypermethrin use was "an area of some sensitivity". As far as Excis was concerned, "it has been tested on two continents. It causes no form of sensitivity in shellfish, and it's very safe for consumers and operators of fish farms".
