jeudi 10 octobre 2019

Dioxins: who is lying?

https://www.tandfonline.com/doi/full/10.1080/10962247.2015.1058869

The main source of dioxin and dioxin-like products formation is anthropogenic. There is also evidence of formation in nature, but the dominant sources proceed from human interaction, especially combustion-related processes. PCDD/Fs formation is driven by reactions at high temperature between organic compounds and chlorine. Therefore, activities such as waste incineration, metal smelting, forest fires, and diesel fuel combustion are the perfect breeding environment for the formation of the different dioxin-like congeners, since chlorine and volatile organic compounds are unavoidable from the feed materials of these processes (Kulkarni et al., 2008Kulkarni, P.S.J.G. Crespo, and C.A. Afonso2008Dioxins sources and current remediation technologies a reviewEnviron. Int. 34(1):13953. doi:10.1016/j.envint.2007.07.009[Crossref][PubMed][Web of Science ®] [Google Scholar]).
The principal mechanism in the formation of PCDD/Fs is known as “de novo synthesis.” Basically, de novo synthesis reaction is the oxidative breakdown and transformation of macromolecular carbon structures to aromatic compounds (Addink and Olie, 1995Addink, R., and K. Olie1995Role of oxygen in formation of polychlorinated dibenzo-p-dioxins/dibenzofurans from carbon on fly ashEnviron. Sci. Technol. 29(6):158690. doi:10.1021/es00006a023[Crossref][PubMed][Web of Science ®] [Google Scholar]; Buekens et al., 2001Buekens, A.L. StieglitzK. HellH. Huang, and P. Segers2001Dioxins from thermal and metallurgical processes: Recent studies for the iron and steel industryChemosphere 42(5):72935. doi:10.1016/S0045-6535(00)00247-2[Crossref][PubMed][Web of Science ®] [Google Scholar]). One part of these PCDD/Fs from de novo synthesis will remain in the solid phase and the other part will desorb to the gas phase and be carried by off-gas flow (Buekens et al., 2001Buekens, A.L. StieglitzK. HellH. Huang, and P. Segers2001Dioxins from thermal and metallurgical processes: Recent studies for the iron and steel industryChemosphere 42(5):72935. doi:10.1016/S0045-6535(00)00247-2[Crossref][PubMed][Web of Science ®] [Google Scholar]).

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