Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) constitute a group of highly toxic organic compounds formed unintentionally, mainly in waste combustion processes or as by-products of industrial manufacturing of certain chemicals, such as chlorinated pesticides. PCDD/Fs can enter the food chains where they persist and bioaccumulate. Human exposure to dioxins occurs mostly from ingesting contaminated food. PCDD/Fs have been characterized by the US Environmental Protection Agency as likely to