Dioxin-like compounds

Of great concern for air pollution problems resulting from the incident are dioxin-like compounds. In general, dioxin-like compounds can be generated when chlorine donor compounds are present. Depending on the source of the coal tar, chlorine content may range between 1 and 5000 ppm. 

U.S. ERA. An Inventory of Sources and Environmental Releases of Dioxin-Like Compounds in the United States for the Years 1987, 1995, and 2000 (EPA/600/P-03/002f, Final Report, November 2006). U.S. Enviroiunental Protection Agency, Washington, DC, EPA/600/P-03/002F. 

Wittich R-M (1998) Degradation of dioxin-like compounds by microorganisms. Appl Microbiol Biotechnol 49 489-499. 

In summary, improper e-waste recycling operations are the major contributors of dioxin and dioxin-like compounds to the terrestrial environment in China [7]. The lower concentrations of dioxin and dioxin-like compounds at reference sites than at e-waste recycling sites suggest the likelihood for these chemicals to transport atmospherically from where they are generated to distant areas. We can also infer that dioxin and dioxin-like compounds initially derived from burning of e-waste can enter ambient air and dust and finally deposit into soil. This notion is supported by the significant positive correlation between the levels of PCDD/Fs in dust and soil samples from Taizhou. 

US EPA (1994) Estimating exposure to dioxin-like compounds volume II Properties, sources, occurrence and background exposures, Washington, DC, EPA/600/6-88/005Cb... 

Dioxin-like activity during biodegradation processes of BP3, BP1 and 4-MBC by T. versicolor was below detection limits for all three compounds. These data indicate that metabolites produced by T. versicolor were in small amounts or rapidly metabolized in non-dioxin-like compounds. 

Persistent organic pollutants consist of a wide range of substances used in industrial applications, applied as pesticides, or generated inadvertently as byproducts of industrial processes. They are ubiquitous pollutants, distributed across the planet, even in regions where they have never been produced or used [32], Among others, the main groups of pollutants that have been studied in the Ebro river basin include PAHs, PPs, OCs and APs, considered as emerging compounds. Recently, the contamination by dioxin-like compounds has been considered. 

Dioxin-like compounds are known to be one of the most harmful persistent organic pollutants of the chlorine based compounds. Dioxins are repeatedly synthesized and decomposed by complicated mechanisms and temperature changes at different locations in municipal solid waste incineration processes and the final streams discharged are commonly exhaust gas and incineration ash. Dioxins in different discharge types and compositions of effluents could be affected by incineration conditions such as temperature, feeding and discharging methods and incinerator type [47]. 

A part from the general monitoring studies, other studies have been performed focusing the hotspots areas of the Ebro river basin, mainly the Ebro delta [30, 31] and the Vero-Cinca tributaries [98-100], and specific groups of compounds like semi-polar pesticides, DDTs and dioxin-like compounds. 

Eljarrat E, Martinez MA, Sanz P, Concejero MA, Pina B, Quiros L, Raldua D, Barcelo D (2008) Distribution and biological impact of dioxin-like compounds in risk zones along the Ebro river basin (Spain). Chemosphere 71 (6) 1156-1161... 

Enzymatic assays EROD Bg, Cc Liver Oxidative stress, dioxin-like compounds... 

Henshel, D.S. 1998. Developmental neurotoxic effects of dioxin and dioxin-like compounds on domestic and wild avian species. Environ. Toxicol. Chem. 17 88-98. 

Ryan, J.J., E. Dewailly, A. Gilman, C. Laliberte, P. Ayotte, and J. Rodrigue. 1997. Dioxin-like compounds in fishing people from the lower north shore of the St. Lawrence River, Quebec, Canada. Arch. Environ. Health. 52 309-316. 

Hazard of dioxin-like compounds is growing because they can be accumulated in living organisms when coming from the environment. 

Bunce, N. J., Petrulis, J. R. (1999). Dioxin-like compounds screening assays. In Meyers R. A. (Ed.). Encyclopedia of Environmental Pollution and Cleanup, Wiley, NY, pp 440-449... 

Organobrominated substances Polybrominated biphenyl ethers Bromophenols Dioxin-like compounds Tetrabromobisphenol A... 

Gale, R.W. Huckins, J.N. Petty, J.D. Peterman, P.H. Williams, L.L. Morse, D. Schwartz, T.R. Tillitt, D.E. 1997, Comparison of the uptake of dioxin-like compounds by caged channel catfish and semipermeable membrane devices in the Saginaw River, Michigan. Environ. Sci. Technol. 32 178-187. 

ESTIMATION OF EXPOSURE TO DIOXIN-LIKE COMPOUNDS USING SEDIMENTS, CAGED FISH, AND SPMDs... 

The dioxin toxic equivalency factor (TEF) approach is currently used worldwide for assessing and managing the risks posed by exposure to mixtures of certain dioxin-like compounds (DLCs). World Health Organization-TEF (WHO-TEE) values have been established for humans and mammals, birds, and (For new, refined values, see Ref. 12g.) It should be mentioned that 16 PCBs, the coplanar isomers with nonortho, monoortho, and diortho substitution by chlorine (overall, there are 209 isomers for this class of compounds) show dioxin-like toxic behavior. I-TE values are smaller, in the range of 0.0001-0.1. The most toxic isomers is 3,3, 4,4, 5-pentachlorodiphenyl with I-TE of 0.1. Polybrominated dibenzodioxins and furans with the 2,3,7,8 pattern also show dioxin-like toxicity, but their I-TE values are lower compared to PCDD/F. 

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