Dioxins are a group of structurally and chemically related polyhalogenated aromatic hydrocarbons which includes polychlorinated dibenzo-p-dioxins (PCDDs or dioxins), dibenzofurans (PCDFs or furans) and dioxin-like polychlorinated biphenyls (dl-PCBs). They constitute a class of persistent environmental compounds, usually found as a mixture of congeners. This book provides new research on the sources and impacts of dioxins.