Ashok K. Rathoure
Jul 6, 2018
Citations
0
Influential Citations
8
Citations
Journal
Biodiversity International Journal
Abstract
The term dioxin refers to a group of chemical compounds sharing certain similar structures and biological characteristics.1 Dioxin is the common name for 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD) but is also used for the structurally and chemically related polychlorinated dibenzo-para-dioxins (PCDD), dibenzofurans (PCDF) and the coplanar polychlorinated biphenyls (PCB). There are 75 PCDD congeners, 135 PCDF and 209 PCB. Seven PCDD and 10 PCDF with substitutions at the 2,3,7 and 8 positions are considered toxic and 11 PCB have dioxin-like toxicity. Dioxin compounds are not created intentionally, but are formed inadvertently by a number of human and natural activities. These activities include combustion and incineration, forest fires, chlorine bleaching of pulp and paper, certain types of chemical manufacturing and processing and other industrial processes.2 Many forms of dioxin exist. One form, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) is considered the most toxic form. It is also the most studied form. Toxic equivalents (TEQs) are used to describe the toxicity of 16 other forms relative to 2,3,7,8TCDD. Persistent, bioaccumulative and toxic chemicals (PBTs) are substances that can build up to levels that can be harmful to human and ecological health. These contaminants may travel long distances in the atmosphere and can move readily from land to air and water. Bioaccumulation is the accumulation of chemicals in organisms from the surrounding environment through absorption, ingestion and inhalation.3 Dioxins dissolve more easily or are more attracted to oily or fatty compounds than water. Because of this, they are more prevalent in animals with body fat, soils and sediments than they are in water. The same goes for other wildlife. Dioxin works its way to the top of the food chain. Dioxin was the primary toxic component of Agent Orange, was found at Love Canal in Niagara Falls, NY and was the basis for evacuations at Times Beach, MO and Seveso, Italy (Table 1).