A review of persistent organic pollutants: dioxins, furans, and their associated nitrogenated analogues

Abstract

Dioxins and furans are no doubt the most notorious class of organochlorine toxicants in the environmental system whose adverse effects are detrimental to public health with extreme negative economic impacts. Polychlorinated dibenzop-dioxin and dibenzofurans and dioxin-like compounds such as the polychlorinated biphenyls, carbazoles are in the class of persistent organic pollutants-prioritized under the Stockholm convention as the "dirty dozens", besides being listed as group 1 human carcinogens by the International Agency for Research on Cancer. Because of their recalcitrant nature in the environment, bioaccumulation in lipids of cells of animals and their general toxicities, this family of compounds has received increased scientific interest in pollution and toxicology research. Accumulation of these toxicants in lipids of animals, and human exposure has been traced to animal products such as meat, eggs, milk and fish. Combustion events, industrial and municipal waste incineration practices, open fires and some industrial activities especially those dealing with metallurgy are well-established sources of these environmental contaminants. The critical aspects of dioxins, furans and their analogues; notably their sources their mechanistic formation by precursor initiation, de novo pathways, how they manifest their toxicity by activation of aryl hydrocarbon receptor, detoxification of these chemicals from the environment and the analytical methods used to quantify and detect from environmental sample matrices has been explored in this work. This review also provides an in-depth examination of the toxic characteristic behaviour of dioxins and furans, polycyclic aromatic hydrocarbons as well as the emerging nitrogenated analogues of dioxins such as polychlorinated carbazole, and carbazole itself.

Thermal catalytic mineralization of ortho-dichlorobenzene at low temperature: an in situ FT-IR and XPS mechanistic investigation

“…Presently, 17 congeners are highly toxic and are considered A1 carcinogens, with 2,3,7,8-tetra chloro-dibenzo-para-dioxin (2,3,7, [TEF = 1 (LD 50 = 0.04 mg kg À1 )] being identified as one of the most toxic compound. 1 However, it should be noted that D&Fs do not occur naturally and are mainly products of different incineration processes having a chlorine source together with combustion, industrial, and reservoir sources. [2][3][4] PCDDs and PCDFs are A1 carcinogens and owing to their high toxicity, high biological half-life, high environmental persistence, bioaccumulation, and carcinogenicity, should not be present in the atmosphere, and hence they need to be either completely degraded or mineralized to CO 2 .…”

“…Presently, 17 congeners are highly toxic and are considered A1 carcinogens, with 2,3,7,8-tetra chloro-dibenzo- para -dioxin (2,3,7,8-TCDD) [TEF = 1 (LD 50 = 0.04 mg kg −1 )] being identified as one of the most toxic compound. 1 However, it should be noted that D&Fs do not occur naturally and are mainly products of different incineration processes having a chlorine source together with combustion, industrial, and reservoir sources. 2–4…”

Effects of Soil Quality on the Microbial Community Structure of Poorly Evolved Mediterranean Soils

“…On the other hand, forest fires can alter soil properties and the structure of microbial communities [9]. For instance, it has recently been reported that the combined effect of fire and the presence of chromium affects soil microbial communities [10], whereas toxics compounds such as dioxines or furanes are released into the environment by forest fires [11,12]. These substances can also alter the metabolism of soil microbiota [13].…”

A Theoretical Study of the Interactions between Persistent Organic Pollutants and Graphene Oxide

“…In detail, they can accumulate in the fatty tissue of living organisms including humans, and are found at higher concentrations at higher levels in the food chain [ 4 , 5 ]. They are also toxic to humans and wildlife, and are widely associated with adverse effects on growth, development, reproduction, and survival [ 6 ]. For example, polycyclic aromatic hydrocarbon (PAH), which is a kind of common POPs, is classified as possible or probable human carcinogens [ 7 ].…”