Polycyclic aromatic hydrocarbons (PAHs) are compounds formed by two or more aromatic rings that derive mainly from the incomplete combustion of organic matter such as coal, petroleum derivatives, oil or biomass.
The generic term ‘dioxins’ indicates a group of 210 polychlorinated aromatic chemical compounds, divided into two families: PCDD (polychlorinated dibenzodioxin) and PCDF (Polychlorinated dibenzofurans).
Dioxins are not produced intentionally but are undesirable by-products originated from different chemical and/or combustion processes, especially during waste combustion.
They are particularly stable and persistent compounds in the environment, toxic to humans, animals and to environment itself. Dioxins and furans are in fact 2 of the 12 classes of persistent organic pollutants internationally recognized by the UNEP (United Nations Environment Program).
There are 75 dioxins congeners and 135 furans congeners, which differ in the number and position of chlorine atoms on benzene rings. Among these, only 17 (7 PCDD and 10 PCDF) have particular concern from a toxicological point of view.