Box 18B Examples of accidents ­ industrial installations

Flixborough incident, UK, 1974

The Flixborough Works of Nypro (UK) Limited were virtually demolished by a huge explosion in 1974. Of those working on the site at the time, 28 were killed and 36 others suffered injuries. Outside the works, injuries and damage were widespread but no one was killed. There were 53 people recorded as casualties, while hundreds more suffered relatively minor injuries. Property damage extended over a wide area. The cause of the accident was the rupture of a piece of temporary pipework which allowed cyclohexane to be released. The cyclohexane formed a cloud of vapour (mixed with air) which then exploded.

Accidental release of tetrachlorodibenzo-p-dioxin (TCDD), Seveso, Italy, 1976

On 10 July 1976 a chemical reactor safety valve lifted at the ICMESA plant at Seveso, due to the development of an uncontrollable exothermic reaction within a process vessel during the production of trichlorophenol. The fluid mixture burst through the valve orifice and was dispersed over a wide area by wind. Following this, vapours escaped from the plant and approximately 1800 ha of densely populated land was contaminated. Plants and animals were severely affected, and people who had been exposed to the toxic cloud developed dermal lesions (chloracne). Contamination of the soil with dioxin was found up to ten years later.

Explosion leading to release of arsenic, Manfredonia, Italy, 1976

Ten tonnes of arsenic trioxide, 18 tonnes of potassium oxide and 60 tonnes of water were released from an ammonia cooling column at a petrochemical factory. Following the incident, 1000 people were evacuated from an area of 2 km2 around the plant. A number of sheep were poisoned by arsenic and tests on sea water and fish showed abnormally high levels of arsenic. An area of 15 km2, consisting mainly of olive and almond plantations, was contaminated. Arsenic levels in the soil ranged from 200 mg/m2 at the edge of the factory area to more than 2000 mg/m2 in the factory area.

Fire at the Sandoz agrochemical warehouse, Schweizerhalle, Switzerland, 1986

A fire broke out on 1 November 1986 at an agrochemical warehouse at Sandoz's Schweizerhalle works, near Basle in Switzerland. Extensive pollution of the river Rhine resulted when 30 tonnes of substances, including the fluorescent dye Rhodamine B, two organophosphorus pesticides (disulfoton and thiometon), 150 kg of mercury and a fungicide (ethoxyethylmercuryhydroxide) were washed into the river during fire-fighting operations. The city of Basle was also affected by a cloud of mercaptans associated with the warehouse fire. The accident resulted in massive fish kills in the river downstream of Basle. An estimated 500 000 fish were killed, including 150 000 eels (Anguilla anguilla). Benthic organisms were virtually eliminated over a 400 km stretch of the Rhine. The wider and longer-term impacts of the accident were not as great as originally predicted. The suspended solids of the river water appear to have reduced the effects of the contaminated runoff by adsorbing a large quantity of the pesticides, thus limiting their effective concentrations.

Fire at chemical plant, Auzouer-en-Touraine, France, 1988

A fire started after an explosion at a chemical plant which was producing a variety of different chemicals. Runoff water from the fire-fighting operation flowed into the river Brenne carrying with it a mixture of highly toxic chemicals, including phenols, arsenic and cyanides; 19 km of the river Brenne and up to 50 km of the Loire were polluted and more than 200 000 residents in the surrounding towns and villages had their water supplies cut off for a number of days.