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Polychlorinated dibenzo-p-dioxins

Chlordane Polychlorinated dibenzopdioxins (PCDDs) are a family of 75 different compounds commonly referred to as polychlorinated dioxins or just dioxins. With general chemical formula of C12H8XClXO2, these compounds have varying harmful effects. The PCDD family is divided into eight groups of chemicals based on the number of chlorine atoms in the compound:

  • mono-chlorinated dioxin
  • di-chlorinated dioxin (DCDD)
  • tri-chlorinated dioxin (TrCDD)
  • tetra-chlorinated dioxin (TCDD)
  • penta-chlorinated dioxin (PeCDD)
  • hexa-chlorinated dioxin (HxCDD)
  • hepta-chlorinated dioxin (HpCDD)
  • octa-chlorinated dioxin (OCDD)

The chlorine atoms can be attached to the dioxin molecule at any one of eight positions. The name of each dioxin indicates both the number and the positions of the chlorine atoms. For example, the dioxin with four chlorine atoms at positions 2, 3, 7, and 8 on the dioxin molecule is called 2,3,7,8tetrachlorodibenzopdioxin or 2,3,7,8TCDD. 2,3,7,8TCDD is one of the most toxic to mammals of all PCDDs and has received the most attention and it serves as a prototype for the PCDDs. Dioxins with toxic properties similar to 2,3,7,8TCDD are called dioxinlike compounds.
PCDDs (mainly 2,3,7,8TCDD) may be formed during the chlorine bleaching process used by pulp and paper mills. PCDDs occur as a contaminant in the manufacturing process of certain chlorinated organic chemicals, such as chlorinated phenols. 2,3,7,8TCDD is a byproduct formed during the manufacture of 2,4,5trichlorophenol (2,4,5TCP). 2,4,5TCP was used to produce hexachlorophene and the herbicide, 2,4,5trichlorophenoxyacetic acid (2,4,5T). In most industrialized countries the use of products contaminated with PCDDs has been greatly reduced.
Chlorinated chemicals, like pentachlorophenol (PCP), used to preserve wood, do contain some of the more highly chlorinated PCDDs. The use of PCP has been restricted to certain manufacturing applications.
PCDDs can enter your body when you breathe contaminated air, eat contaminated food, or have skin contact with contaminated soil or other materials. The most common way PCDDs can enter your body is by eating food contaminated with PCDDs

 


Structure formula of 2,3,7,8-Tetrachlorodibenzo-p-dioxin


3D structure of 2,3,7,8-Tetrachlorodibenzo-p-dioxin