Dioxins were only identified in the 1970s but are among the most toxic substances produced by modern industry. Although there are 210 different types, only about 17 are toxic. They are produced mainly through incineration and by chemical and pharmaceutical industries.

They can be absorbed through the skin or consumed in food. Once in the system, they can accumulate over 30 years and can cause damage to cells and increase the risk of cancer.

Although the Belgian crisis is one of the biggest cases of dioxin contamination in Europe, dioxin scares are not that rare. On July 10th, 1976, a valve blew in one of the silos of the Icmesa chemical plant near Milan owned by the Swiss firm Roche. It pumped dioxins into the air above a community of some 36,000, particularly in the town of Seveso.

Some 600 domesticated animals died and nearly 1,300 people suffered from chest and skin injuries, many lasting years, while 193, mainly children, suffered from chloracne, a blotching of the skin that takes years to disappear. Several thousand still retain dioxin traces but there have been no reports of abnormal birth clusters.