The leak of a ton and a quarter of the toxic liquid chlorobutadiene came from the Du Pont chemical plant at Maydown near Londonderry on Tuesday. The environmental authorities were not told until yesterday because, a spokesman for the firm said last night, 'we did not appreciate the size of the spill until today'.
An urgent investigation into the potential impact of the leak, described by the Department of the Environment as 'extremely worrying', was immediately launched by the Northern Ireland departments concerned with health, agriculture and the environment. The Irish Republic has also been informed, since Lough Foyle, linking the river Foyle to the sea, forms part of the border.
Du Pont said the spill was the result of a 'process upset'. A detector in the system had picked up the leak, a spokesman added, and a full investigation was launched.
Chlorobutadiene is a colourless smelly liquid which is highly flammable and floats like an oily scum on the top of water. It is more commonly known as chloroprene and is the starting point for the manufacture of neoprene - synthetic rubber.
It is toxic by inhalation or ingestion, and can be absorbed through the skin. Health concerns would focus on the possibility that it might be carcinogenic. The long- term exposure limit for inhaling the vapour in air is 10 parts per million.
It is thought to be regularly discharged from the plant, though in highly diluted form.
Animal tests have shown that its chemical relative butadiene is a mutagen and can cause cancer. Firemen who had to deal with spillage of butadiene after a road accident would be advised to wear full protective clothing and not to allow the material to leak away into watercourses or down drains.
The Ulster environment department said there had been no reports of fish killed and no visible effects had been observed. But as a precaution people were advised not to eat fish from the lough.Reuse content