Seveso disaster
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The Seveso disaster was an industrial accident that occurred in Seveso, Italy on July 10, 1976 in a small chemical manufacturing plant of ICMESA.
During the production of 2,4,5-trichlorophenol, a herbicide, fungicide, and chemical intermediate, an uncontrolled reaction occurred bursting the security disk of the tank and releasing a jet of chemical steam into the atmosphere. Probably several kilograms of the dioxin TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) were released into the atmosphere and the chemical was spread throughout a large section of the Lombard Plain between Milan and Lake Como. The occurrence of the reaction was particularly interesting as it occurred around 12:30pm on a Saturday, when the plant was actually closed for the weekend and hence no manufacturing processes were running. Somehow the mixture of chemicals which had been left in the boiler mid production cycle, managed to spontaneously react producing enough heat and energy to eventually cause a full run away reaction. It is uncertain exactly how this managed to occur, but there have been questions as to why the plant was left with a production mid cycle. 3,000 pets and farm animals died and 70,000 animals were slaughtered later to prevent dioxin from entering the food chain. 193 people in the affected areas suffered from chloracne and other symptoms.
Due to the fact that dioxin is highly toxic, many were concerned about the long-term outlook for the residents of Seveso. Fortunately, in the long run human symptoms were not grave. Cancer rates were increased only slightly, if at all, and other problems relating to reproduction and mental illness were far less than many had worried at the time of the accident. Scientists still have not been able to prove that dioxin was the cause of these illnesses.
Treatment of the soil in the affected areas was so complete that it now has a dioxin level below what would normally be found. The disaster lead to the Seveso Directive, which was issued by the European Community and imposed much harsher industrial regulations. The Seveso Directive was updated in 1999, ammended again in 2005 and is currently referred to as the Seveso II Directive (or COMAH Regulations in the United Kingdom).