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Environmental Impact of Waste-to-Energy
Published in Efstratios N. Kalogirou, Waste-to-Energy Technologies and Global Applications, 2017
The toxicity-weighted mass of a mixture of congeners is expressed in toxic equivalent concentration (TEQ). To this end, toxic equivalency factors (TEFs), values that express the toxicity of a given PCDD/F (congener) in terms of the most toxic congener 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), ared used. See Figure 8.3, to which a TEF = 1.00 is given. TEF values are given for 17 PCDD/Fs (called the “dirty 17”), ranking from 0.0001 to 0.5, as shown in Table 8.2, which outlines the TEF values from the World Health Organization (WHO) (Bundesministerium fur Umwelt, 2013; Umwelt Bundesamt, 2017), and which are most frequently used but differ for some congeners. To calculate the TEQ concentration in ng/m3, the concentration of each congener in the list is multiplied by the TEF, and the results are added.
Persistent Pulp Mill Pollutants in Wildlife
Published in Mark R. Servos, Kelly R. Munkittrick, John H. Carey, Glen J. Van Der Kraak, and PAPER MILL EFFLUENTS, 2020
J.E. Elliott, P.E. Whitehead, P.A. Martin, G.D. Bellward, R.J. Norstrom
Laboratory studies have shown that dioxins cause a wide variety of teratogenic, immunologic, reproductive, carcinogenic and developmental toxic effects in birds and mammals (Peterson et al. 1993). 2,3,7,8-TCDD is considered to be the most toxic congener and is used as the standard to which the toxicity of all other halogenated aromatic hydrocarbons are compared using a system of toxic equivalency factors (TEFs; Safe 1990) which combine to give an overall toxic equivalency (TEQ). Avian embryos appear to be more sensitive to exposure than are adult birds, although considerable interspecies variability in sensitivity is evident in both forms. Acute oral LD50 doses range from 15 to >810 μg kg−1 body weight for the northern bobwhite (Colinus virginianus) and the ringed turtle-dove (Streptopelia risoria), respectively (Hudson et al. 1984); those for avian embryos range from 250 ng kg−1 injected into the air cell for the domestic chicken embryo, 1,100 ng kg−1 for ring-necked pheasant (Phasianus colchicus) embryos and between 1,000 and 10,000 ng kg−1 for eastern bluebird (Sialia sialis) embryos when injected into the albumin (Allred and Strange 1977; Martin et al. 1989; Nosek et al. 1992). Adult hen ring-necked pheasants injected at 1.0 μg kg−1 wk−1 over a 10-wk period suffered severe weight loss, resulting in 57% mortality and almost complete reproductive failure. However, dietary levels of 0.3 and 3.0 ng kg−1 TCDD fed for 18 wk caused no impacts on the productivity or survivability of embryos in bobwhites (Kenaga and Norris 1983).
Industrial and Hazardous Waste Incineration
Published in Gaetano Joseph Celenza, Specialized Treatment Systems, 2020
Dioxin is the name given to the family of polychlorinated dibenzo-para-dioxins (PCDD), whose primary derivative is the basic structure shown in Figure 1.18 and which can be chlorinated in multipositions resulting in 75 possible compounds. Similarly, furans are derivatives of polychlorinated dibenzofurans (PCDF) with the structure shown in Figure 1.19, which can also be chlorinated in multipositions resulting in 135 possible compounds. Most data has concentrated on what is considered the most toxic of the possible compounds, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), equating related compounds to TCDD equivalence (TEQ), using toxic equivalent factors (TEF) [1].
Signature tracing of PCBs congeners in breastmilk of mothers living in selected urban centers of Pakistan
Published in Human and Ecological Risk Assessment: An International Journal, 2023
Shagufta Tahir, Abdul Qadir, Mehvish Mumtaz, Nadia Jamil, Mujtaba Baqar, Asad Ullah Saeed, Naeem Khan, Richard Halbrook
PCB congeners could be classified based on their degree of chlorination, tendency for substitution, and affinity for binding to receptors. PCBs that bind strongly to the aryl hydrocarbon receptor (AhR) are called DL-PCBs (Van den Berg et al. 2006). The 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most dangerous of all dioxins, is used to compare congeners to determine their toxic equivalency factor (TEF). As a result, a toxic potency 1 (TEF 1), or toxic equivalent factor, is assigned (Chirollo et al. 2018). Toxic equivalents (TEQ) were calculated for selected DL-PCB congeners PCB-77, PCB-169, PCB-118, PCB-156, and PCB-189. The concentration of each congener was multiplied by its TEF value, and the resulting TCDD equivalents are toxic equivalents validated by WHO (Van den Berg et al. 2006) explained in Eq. (1).
Bioremediation Performance of Two Telluric Saprotrophic Fungi, Penicillium Brasilianum and Fusarium Solani, in Aged Dioxin-contaminated Soil Microcosms
Published in Soil and Sediment Contamination: An International Journal, 2021
Isabelle Delsarte, Etienne Veignie, Yann Landkocz, Catherine Rafin
After two months of incubation, soils were air-dried (20 ± 1°C) for one week, homogenized, and passed through a 2-mm sieve. The residual levels of PCDD/Fs were analyzed in 20 g soil samples by the INRA soil analysis laboratory (Arras, France) according to EPA method 8290. PCDD/F levels were determined via gas chromatography and a high-resolution mass spectrometry detector (GC/HRMS). The presence of 17 PCDD/F congeners was assessed in each sample. TEQ values were calculated using the measured PCDD/F concentrations and toxic equivalency factors (TEFs, WHO-05).