carbon, chlorine, hydrogen, and oxygen. However, the word dioxin is most commonly
used to refer to only one of these chemicals, the compound 2, 3, 7, 8-tetrachlorodibenzo-
p-dioxin (TCDD). Some scientists consider TCDD to be the most toxic synthetically
TCDD is a useless by-product of the manufacture of certain weedkillers and several other
industrial processes. Disposal of the chemical is difficult because it does not readily
degrade (break down) in soil or water. One of the most effective methods of disposing of
dioxin is burning it at high temperatures. Soil and water in parts of Canada, Europe, and
the United States, however, have become contaminated with dioxin because of improper
disposal of industrial wastes.
The health effects of TCDD are not completely understood. The chemical is extremely
deadly to certain animals, but no human deaths have been directly linked to it. However,
some people have developed such health problems as headaches, stomachaches, and a
severe skin rash called chloracne as a result of exposure to dioxin. Some researchers
also believe the chemical may cause birth defects and cancer.
TCDD was first identified as a contaminant in 1957. It was present in Agent Orange, a
weedkiller used by U.S. armed forces in the 1960's and early 1970's, during the Vietnam
War. Dioxin was not recognized as a major public health hazard until the mid-1970's.
Gary F. Bennett, Ph.D., Prof. of Biochemical Engineering, Univ. of Toledo.
See also AGENT ORANGE; MISSOURI (Recent developments).
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