Polychlorinated Dibenzodioxins - Historical Perspective

Historical Perspective

Low concentrations of dioxins existed in nature prior to industrialization as a result of natural combustion and geological processes. Dioxins were first unintentionally produced as by-products from 1848 onwards as Leblanc process plants started operating in Germany. The first intentional synthesis of chlorinated dibenzodioxin was in 1872. Today, concentrations of dioxins are found in all humans, with higher levels commonly found in persons living in more industrialized countries. The most toxic dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), became well known as a contaminant of Agent Orange, a herbicide used in the Vietnam War. To speed up chemical reactions, the U.S. manufacturers (mainly Monsanto) had increased the temperature in the process of preparation. This increased the concentration of TCDD many times more than other types of pesticides that were being used by U.S. farmers. Later, dioxins were found in Times Beach, Missouri and Love Canal, New York and Seveso, Italy. More recently, dioxins have been in the news with the poisoning of President Viktor Yushchenko of Ukraine in 2004, the Naples Mozzarella Crisis the Irish pork crisis of 2008, and the German feed incident of 2010.