The Seveso disaster was an industrial accident that occurred in Seveso, Italy on July 10, 1976.
It occurred when a chemical plant released large amounts of the dioxin TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) into the atmosphere and the chemicals spread throughout a large section of the lombard plain between Milan and Lake Como. The release killed off large amounts of vegetation and about 3300 animals were killed by the dioxin, while a further 70,000 were slaughtered to prevent dioxin from entering the food chain. Several people in the affected areas suffered from skin leasions and other symptoms. 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 outbreak. Treatment of the soil in the effected 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.