2, 3, 7, 8,-Tetra chlorodibenzo-p-dioxin

Figure 3. Photolysis rate of 2,3,7,8-tetra-chlorodibenzo-p-dioxin (5 mg/liter in methanol) in sunlight (20), 1971 by AAAS...

Female Wistar rats treated orally with 0.125-16 jug/kg/day of 2,3,7,8-tetrachlorodibenzo-p-dioxin (8-D), 50-800 jug/kg/day of 1,2,3,4-tetra-chlorodibenzo-p-dioxin (4-D , and 250-2000 /xg/kg/day of 2,7-dichloro-dibenzo-p-dioxin (2-D) and 1,000-2,000 /xg/kg/day of 2,3-dichlorodi-benzo-p-dioxin or 2-chlorodibenzo-p-dioxin during 6—15 days of gestation (first morning of a positive vaginal smear was designated as day 1) were assessed for prenatal effects of the compounds on their progeny. 

Figure 2. Excretion of activity by rats following a single oral dose of 50 fJig/kg (0.14 iCi/kg) 2,3J,8-tetra-chlorodibenzo-p-dioxin. Each point represents the mean SE for three rats.

An environmental protocol has been developed to assess the significance of newly discovered hazardous substances that might enter soil, water, and the food chain. Using established laboratory procedures and C-labeled 2,3,7,8-tetra-chlorodibenzo-p-dioxin (TCDD), gas chromatography, and mass spectrometry, we determined mobility of TCDD by soil TLC in five soils, rate and amount of plant uptake in oats and soybeans, photodecomposition rate and nature of the products, persistence in two soils at 1,10, and 100 ppm, and metabolism rate in soils. We found that TCDD is immobile in soils, not readily taken up by plants, subject to photodecomposition, persistent in soils, and slowly degraded in soils to polar metabolites. Subsequent studies revealed that the environmental contamination by TCDD is extremely small and not detectable in biological samples. 

Ankley, G.T., D.E. Tillitt, J.P. Giesy, P.D. Jones, and D.A. Verbrugge. 1991. Bioassay-derived 2,3,7,8-tetra-chlorodibenzo-p-dioxin equivalents in PCB-containing extracts from the flesh and eggs of Lake Michigan chinook salmon (Oncorhynchus tshawytscha) and possible implications for reproduction. Canad. Jour. Fish. Aquat. Sci. 48 1685-1690. 

Hanberg, A., Nilsson, C. B., Trossvik, C., and Hakansson, H. (1998). Effect of 2,3,7,8-tetra-chlorodibenzo-p-dioxin on the lymphatic absorption of a single oral dose of [3H]retinol and on the intestinal retinol esterification in the rat. /. Toxicol. Environ. Health A 55, 331-344. 

Poland A, Glover E, Kende AS. 1976. Stereospecific, high affinity binding of 2,3,7,8-tetra-chlorodibenzo-p-dioxin by hepatic cytosol. Evidence that the binding species is receptor for induction of aryl hydrocarbon hydrolase. J Biol Chem 251 4936-4946. 

Calculate the aqueous activity coefficients,, and the excess free energies in aqueous solution, G (in kJ mol1), of (a) w-decane (n-C ioH22), (b) 2,3,7,8-tetra-chlorodibenzo-p-dioxin, and (c) bromomethane (CH3Br) at 25°C using the data provided in Appendix C. 

De Krey GK, KerkvlietNI. 1995. Suppression of cytotoxic T lymphocyte activity by 2,3,7,8-tetra-chlorodibenzo-p-dioxin occurs in vivo, but not in vitro, and is independent of corticosterone elevation. Toxicology 97 105-112. 

Koshakji RP, Harbison RD, Bush MT. 1984. Studies on the metabolic fate of [14C]2,3,7,8-tetra-chlorodibenzo-p-dioxin (TCDD) in the mouse. Toxicol Appl Pharmacol 73 69-77. 

Blaylock B, Holladay S, Comment C, Heindel J, Luster M (1992) Exposure to tetra-chlorodibenzo-p-dioxin (TCDD) alters fetal thymocyte maturation. Toxicol Appl Pharmacol, 112 207-213. 

Widholm, J.J., Seo, B.W., Strupp, B.J., Seegal, R.F., Schantz, S.L. (2003). Effects of perinatal exposure to 2,3,7,8-tetra-chlorodibenzo-p-dioxin on spatial and visual reversal learning in rats. Neurotoxicol. Teratol. 25 459-71. 

Fernandez-Salguero PM, Hilbert DM, Rudikoff S, Ward JM, Gonzalez FJ. 1996. Aryl-hydrocarbon receptor-deficient mice are resistant to 2,3,7,8-tetra-chlorodibenzo-p-dioxin-induced toxicity. Toxicol. Appl. Pharmacol. 140 173-79... 

Kramer S, Arthur K, Denison MS, Smith WL, DeWitt DL. 1996. Regulation of prostaglandin endoperoxide H synthase-2 expression by 2,3,7,8-tetra-chlorodibenzo-p-dioxin. Arch. Biochem. Biophys. 330 319-28... 

Henschler has reviewed the toxicity of organochlorine compounds.32 Many are carcinogens (e.g., vinyl chloride, which is associated with liver and biliary tract cancers and angiosarcomas).33 One of the most toxic is 2,3,7,8-tetra-chlorodibenzo p dioxin (3.3). 

The Times Beach Dioxin Research Station was constructed in 1984 under the direction of the University of Missouri and the Missouri Department of Natural Resources. The station offers investigators the opportunity to conduct experiments under field conditions on a well characterized soil. During the Summer of 1984, a series of six experiments were established by Monsanto at the station to study the environmental transport of 2,3,7,8-tetra-chlorodibenzo-p-dioxin (TCDD) under field conditions. 

B09. Cohen, G.M., W.P. Bracken, R.P. Iyer, D.L. Berry, and T.J. Slaga Anticarcinogenic effects of 2,3,7,8- tetra-chlorodibenzo-p-dioxin on benzo[a]pyrene and 7,12 dimethylbenz[a]anthracene tumor initiation and its relationship to DNA binding Cancer Res. 39 (1979) 4027 033. 

Tomaszewski, K. E., C. A. Montgomery, and R. L. Melnick. 1988. Modulation of 2,3,7,8-tetra-chlorodibenzo-p-dioxin toxicity in F344 rats by di(2-ethylhexyl) phthalate. Chem. Biol. Interact. 65(3) 205-22 cited in Chem. Abstr. CA 109(9) 68399m. 

There are many dioxin congeners, and the toxicity of the congeners varies depending on the number and positions of the chlorine substituents. 2,3,7,8-Tetra-chlorodibenzo-p-dioxin (2,3,7,8-TCDD) shows the highest toxicity to mammals. Values for dioxin toxicity were reassessed by the World Health Organization in 2005 [1]. The toxic equivalency factor (TEF) of dioxin congener represents its toxicity relative to that of 2,3,7,8-TCDD, which is defined as having a TEF value of 1. Another parameter is the toxic equivalent quantity (TEQ), which is the total toxicity of a mixture of compounds represented as the sum of the concentrations of each compound multiplied by its TEF. Dioxin contamination is usually represented in terms of TEQ values. 

Mufti NA, Shuler ML. 1998. Different in vitro systems affect CYPIAl activity in response to 2,3,7,8-tetra-chlorodibenzo-p-dioxin. Toxicol. In Vitro 12 259. 

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