Dioxin sources and industrial emissions control — a review

Abstract

Dioxin, the collective term for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, are generated during various chemical and high temperature processes. They have been shown to be toxic to humans and animals with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exhibiting the greatest toxicity. Dioxin has been shown to exhibit immunotoxicity, reproductive and developmental toxicity in several animals. Epidemiological studies on groups of humans with prolonged or elevated exposure to dioxin have indicated increased cancer rates above threshold levels of exposure. Conversely, other studies have concluded that dioxin is a net anticarcinogen. There has been much study aimed at quantifying the relative contributions of the identified dioxin sources to the environmental load. Although some data suggests that burning of vegetation produces measurable amounts of dioxin it is rather industrial process waste streams which emit the greatest amounts. Processes implicated include organic chemical synthesis, metal processing, paper pulp bleaching and incineration of organic materials. Dioxin emission reduction strategies for high temperature processes have focussed upon the minimisation of the conditions at which dioxin forms in exhaust streams. Additionally, screening of process materials has been practised as have substitution of process chemicals in the pulp and paper bleaching industry.

2-Hydroxy-4-(3′-oxo-3′H-benzofuran-2′-yliden)but-2-enoic acid biosynthesis from dibenzofuran using lateral dioxygenation in a Pseudomonas putida strain B6-2 (DSM 28064)

“…Dioxins, which are typically formed as undesired byproducts of industrial and municipal activities (Jaiswal et al 2011), are toxic, carcinogenic, mutagenic, and persistent environmental pollutants (Hiraishi 2003;Ritchie 2000). Their removal from the environment is very challenging.…”

Degradation of dibenzofuran via multiple dioxygenation by a newly isolated Agrobacterium sp. PH-08

“…Dioxins (polychlorinated dibenzo‐ p ‐dioxins (PCDDs) and dibenzofurans (PCDFs)) are a class of two‐ring aromatic compounds and the most persistent pollutants in the environment, reaching environmental matrices mainly through industrial activities (Ritchie ). Dioxins have been ubiquitously found in sediment, soil and atmospheric samples (Hites ).…”