2,3,7,8-Tetrachlorodibenzo-£-dioxin concentrations

Three isomeric tetrachlorodibenzo-p-dioxins were studied. All were insoluble in TFMS acid. To dissolve these compounds and form cation radicals, UV irradiation was necessary. The 1,2,3,4-tetrachloro compound was particularly sensitive to UV irradiation, and as a solid, even turned pink when exposed to ordinary fluorescent light. When subjected to constant UV irradiation, radical ions were induced rapidly. The change in the cation radical concentration was monitored by the ESR signal as illustrated in Figure 10. To determine whether the tetrachloro isomer had been converted to lower chlorinated derivatives after UV irradiation, the dissolved dioxin was then poured into ice water and recovered. The GLC retention time of the recovered dioxin was unchanged in addition, no new GLC peaks were observed. Moreover, the ESR spectrum see Figure 11) for the recovered material was not altered between widely... 

TAetection of the highly potent impurity, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), necessitated an environmental assessment of the impact of this contaminate. Information was rapidly needed on movement, persistence, and plant uptake to determine whether low concentrations reaching plants, soils, and water posed any threat to man and his environment. Because of the extreme toxicity of TCDD, utmost precautions were taken to reduce or minimize the risk of exposure to laboratory personnel. Synthesis of uniformly labeled C-TCDD by Muelder and Shadoff (I) greatly facilitated TCDD detection in soil and plant experiments. For unlabeled experiments it seemed wise to use only small quantities of diluted solutions in situations where decontamination was feasible and to rely on the sensitivity afforded by electron capture gas chromatography... 

Tetrachlorodibenzo-p-dioxin (TCDD) is a contaminant in 2,4,5- trichlorophenoxyacetic acid (2,4,5-T) which may occur in the manufacturing process. Before 1971 some samples of 2,4,5-T contained from 2-50 ppm TCDD (i) in the technical acid. Highest concentrations of TCDD occurred before 1968. 

The half-life of the 2,3,7,8-tetrachlorodibenzo-p-dioxin in isooctane was estimated to be 40 min for the 0.5 meter exposure and 3 hours for the one meter exposure. The half-life in 1-octanol was essentially the same. The 24-hour photolysis products of the 2,3,7,8-tetrachlorodibenzo-p-dioxin were examined by gas chromatography. The smallest concentration of 2,3,7,8-tetrachlorodibenzo-p-dioxin that could be detected by the instrument was 0.5 ppm. When an injection of the 24-hour photolysis product was made, no tetra was detected. An additional confirmation of the disappearance of the 2,3,7,8-tetrachlorodibenzo-p-dioxin in the 24-hour photolysis products was obtained when thej yiaterial was submitted to the Chemical-Biology Research Laboratory for rabbit testing. No chloracnegenic activity was indicated. ... 

In mammals, phenobarbital and phenytoin increase serum ceruloplasmin concentrations (Aaseth and Norseth 1986). Chronic copper poisoning in sheep is exacerbated when diets contain heliotrope plants (Heliotropium sp., Echium spp., Senecio sp.). Aggravated effects of the heliotrope plants include reduced survival and a twofold to threefold increase in liver and kidney copper concentrations when compared to control animals fed copper without heliotropes (Howell et al. 1991). Rats given acutely toxic doses of 2,3,7,8-tetrachlorodibenzo-para-dioxin had elevated concentrations of copper in liver and kidney because of impaired biliary excretion of copper (Elsenhans et al. 1991). Morphine increases copper concentrations in the central nervous system of rats, and dithiocarbam-ates inhibit biliary excretion (Aaseth and Norseth 1986). In human patients, urinary excretion of copper is increased after treatment with D-penicillamine, calcium disodium EDTA, or calcium trisodium diethylenetriamine penta acetic acid (Flora 1991). 

Ellenberger, S.A., PC. Baumann, and T.W. May. 1994. Evaluation of effects caused by high copper concentrations in Torch Lake, Michigan, on reproduction of yellow perch. Jour. Great Lakes Res. 20 531-536. Elsenhans, B., W. Forth, and E. Richter. 1991. Increased copper concentrations in rat tissues after acute intoxication with 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin. Arch. Toxicol. 65 429-432. 

Whyte, J.J., M.R. van den Heuvel, J.H. Clemons, S.Y. Huestis, M.R. Servos, D.G. Dixon, and N.C. Bols. 1998. Mammalian and teleost cell line bioassay and chemically derived 2,3,7,8-tetrachlorodibenzo-jo-dioxin equivalent concentrations in lake trout (Salvelinus namaycush) from Lake Superior and Lake Ontario, North America. Environ. Toxicol. Chem. 17 2214-2226. 

Brunstrom, B. and J. Lund. 1988. Differences between chick and turkey embryos in sensitivity to 3,3, 4,4 -tetrachlorobiphenyl and in concentration/affinity of the hepatic receptor for 2,3,7,8-tetrachlorodibenzo-p-dioxin. Comp. Biochem. Physiol. 91C 507-512. 

Williams, L.L. and J.P. Giesy. 1992. Relationships among concentrations of individual polychlorinated biphenyl (PCB) congeners, 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQ), and rearing mortality of chinook salmon (Oncorhynchus tshawytscha) eggs from Lake Michigan. Jour. Great Lakes Res. 18 108-124. 

According to the vendor, Cement-Lock technology has successfully removed polycyclic aromatic hydrocarbons (PAHs), PCBs, and tetrachlorodibenzo-1,4-dioxin (TCDD)/2,3,7,8-tetra-chlorodibenzofuran (TCDF) from soils and sediments in bench-scale tests. Metal concentrations were also reduced below detection limits in bench-scale tests. These metals included arsenic, cadmium, chromium, lead, nickel, mercury, and silver. 

Concern over dioxins originally arose over one particular dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). This was found to produce clinical effects (chloracne) in workers exposed to it through industrial accidents.35 It is also toxic to some species of laboratory animals. A few PCBs have been shown in experimental systems to exert a number of toxic responses similar to those observed for TCDD. In consequence, the total concentrations of both dioxins and PCBs in environmental media, including food, are now commonly determined as part of the same chemical analysis, and each cannot be discussed now without reference to the other. 

CDDs = chlorinated dibenzo-p-dioxins CDFs = chlorinated dibenzofurons EPA = Environmental Protection Agency FIpCDD = heptachlorodibenzo-p-dioxin HpCDF = heptachlorodibenzofuran FIxCDD = hexachlorodibenzo-p-dioxin FIxCDF = hexachlorodibenzofuran NA = not applicable PeCDD = pentachlorodibenzo-p-dioxin PeCDF = pentachlorodibenzofuran TCDD = tetrachlorodibenzo-p-dioxin TCDF = tetrachlorodibenzofuran TEQ=Toxicity equivalency concentration... 

Calvert GM, Wille KK, Sweeney MH, et al. 1996. Evaluation of serum lipid concentrations among U.S. workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin. Arch Environ Health 51 100-107. 

Faqi AS, Dalsenter PR, Merker H-J, et al. 1998. Reproductive toxicity and tissue concentrations of low doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin in male offspring rats exposed throughout pregnancy and lactation. Tox Appl Pharmacol 150 383-392. 

Kennedy SW, Lorenzen A, Norstrom RJ. 1996. Chicken embryo hepatocyte bioassay for measuring cytochrome P4501A-based 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent concentrations in environmental samples. Environ Sci Technol 30 706-715. 

Seo B-W, Li M-H, Hansen LG et al. 1995. Effects of gestational and lactational exposure to coplanar polychlorinated biphenyl (PCB) congeners or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on thyroid hormone concentrations in weanling rats. Toxicol Lett 78 253-262. 

Vos JG, Kreeftenberg JG, Engel HWB, et al. 1978. Studies on 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced immune suppression and decreased resistance to infection endotoxin hypersensitivity, serum zinc concentrations and effect of thymosin treatment. Toxicology 9 75-86. 

Recent studies have indicated that humans may be exposed to 2,3,7,8-tetrachlorodibenzo-p- dioxin(2,3,7,8-TCDD), a toxic and teratogenic substance in laboratory animals (1). A fraction of beef fat samples from cattle known to have grazed on pasture treated with herbicide 2,4,5-T (which contains trace quantities of 2,3,7,8-TCDD) have been reported to contain low part per trillion (ppt) levels of 2,3,7,8-TCDD (2,3) Two studies of bovine milk reported no detectable chlorodioxins however (4,5). Combustion processes have been reported to produce chlorinated dioxins which enter the air as fly ash and soot (6.7.8). Three different studies of human milk have been carried out by various workers to determine if humans contain detectable concentrations of 2,3,7,8-TCDD (9,20,22). 

All components behave as if they were simple dilutions by a factor g of this first chemical hence, all concentrations of component 2. .. n can be rescaled to the first chemical, independent of the considered effect level. A widely used application of this approach is the toxic equivalence factor (TEF) concept for the assessment of mixtures of polychlorinated dioxins and furans (PCDDs/Fs). Here, concentrations (or doses) of specific PCDD/F isomers are all expressed in terms of the concentration of a reference chemical, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), needed to induce the same effect ( equivalent or equi-effective concentration). The assessment of the resulting combined effect is obtained simply by adding up all TCDD-equivalent concentrations. 

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