Exposure to Dioxin and Dioxin-Like Compounds1
Dioxin and dioxin-like compounds (DLC) are a family of natural and human-made chemicals that are ubiquitous and biologically persistent. They are associated with a broad spectrum of adverse biological effects, both cancer and non-cancer. Dioxin entered the public lexicon as a result of a number of high-profile news stories over the past several decades. Although never intentionally produced, dioxins were later found to be significant chemical by-products in the synthesis of a range of chemical products. For example, dioxin was a common contaminant in products produced from chlorophenol, including Agent Orange, a chemical defoliant used in Vietnam, and a bactericide used for disinfection. Inappropriate disposal of waste from the manufacture of hexachlorophene led to significant exposure of residents of Times Beach, MO, to dioxin. The area was subsequently cleaned up by the U.S. Environmental Protection Agency (USEPA) under Superfund legislation. However, the major source of environmental dioxin release today is as a by-product of almost every combustion process. Dioxins then move through the environment where they bioconcentrate in animals and fish, which become a source of low-level exposure to the population. There are a number of PBTs, or persistent, bioaccumulative and toxic compounds, that are receiving international attention. The focus of this chapter is the occurrence and fate of dioxin in the environment, dioxin toxicity and current exposure to the population, and strategies to manage the general population risks associated with dioxin.