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Dwight Causey DDT DDE DDD Chemical Properties DDT DDE DDD Molecular Weight 354.49 318.03 320.05 Appearance/ Physical State Colorless Crystals, white powder Crystalline Solid Colorless Crystals, white powder Melting Point (oC) 109 89 109-110 Solubility (at 25oC) 0.025 mg/L 0.12 mg/L 0.090 mg/L Log Kow 6.91 6.51 6.02 Log Koc 5.18 4.7 5.18 Henry’s Law constant 8.3x10-6 atmm3/mol 2.5x10-5 atmm3/mol 4.0x10-6 atmm3/mol History First synthesized in 1874 Insecticidal properties discovered in 1939 by Paul Hermann Müller Won Noble Prize in Physiology and Medicine in 1948 Used to control insect-borne diseases (i.e. malaria and typhus) Peak of usage in 1962 Registered for use on 334 agricultural commodities 85,000 tons produced Cumulative estimated world usage is 2 million tons History Used in homes for mothproofing and lice control Still used today in developing countries to control malaria and lice Silent Spring by Rachel Carson in 1962, questioned the widespread use of DDT Mode of Entry into Water Indirectly Agricultural runoff ○ Binds strongly to soil and organic matter Volatized into the atmosphere ○ Redistributed through particulate matter Directly Water pollution plants (sewer pipes to the ocean) 1,000,000 kg (~227 tons) from Montrose Chemical Company to Palos Verdes shelf Reactivity Slightly soluble in water Very lipophillic Physical Half-life: 2-15 years Increases with time Sequestered in micropores Biological Half-life: 8 years Biodegraded into DDE and DDD under aerobic and anaerobic conditions, respectively DDT Derivatives DDE is the major metabolite Both resist to biodegradation in aerobic and anaerobic conditions Very long half-lives in water Hydrolysis is a minor process in degradation Photolysis of DDE is a major process Half-life: 15-26 hours DDD Toxicity 96 hour LC50: Glass shrimp: 2.4 µg/L Rainbow trout: 70 µg/L Largemouth bass: 42 µg/L Walleye: 14 µg/L 48 hour LC50: Daphnid: 4.5 µg/L DDE Toxicity 96 hour LC50: Rainbow trout: 32 µg/L Atlantic Salmon: 96 µg/L Bluegill: 240 µg/L Egg shell thinning Mallard: 3 µg/g Brown pelican: 3 µg/g Toxic Effects Weak estrogenic activities In the brain: Inhibition of ATP-based reactions Hepatic enzyme induction Disruption of hormonal mechanisms Inhibition of Na+/K+ ATPases in the gills Thinning of egg shells in raptors Reduction in cortisol production Mode of Entry into Organisms Majority enters through food Some enters through absorption from water through body surfaces (i.e. gills), not believed to be significant when compared to amount entering through food Very Lipophillic, bioaccumulates Some organisms retain 90%+ of ΣDDT in their food source Molecular Mode of Interaction Egg shell thinning in Raptors, 2 possibilities: DDE inhibits prostaglandin synthesis in the shell gland mucosa, limiting calcium and bicarbonate transport across the mucosa Embryonic exposure alters shell gland carbonic anhydrase expression, causing eggshell thinning In fish, no known molecular mechanism is known Believed to involve ATPases in the central nervous system and gills In Insects, causes the irreversible opening of voltage gated Na+ channels along the axon Biochemical Metabolism and Breakdown DDT metabolized into DDE and DDD by microorganisms Mixed-function oxidases may induce the dechlorination of DDT to DDE in fishes In some mammals, DDE is converted to 2methylsulfonyl-DDE and 3-methylsulfonylDDE Acted on by phase I CYP2B enzymes Followed by conjugation with glutathione during phase II Then through the mercapturic acid pathway, 2SH-DDE and 3-SH-DDE are formed Detoxification Up-regulation of CYP6G1 gene in Drosophila melanogaster Secretion through urine, feces, semen, and breast milk Clams shown to dechlorinate DDE to DDMU under methanogenic or sulfidogenic conditions Dried and ground seaweed has been shown to increase DDT biodegradation by 80% after 6 weeks, further degradation of DDD also seen Bibliography Cal/Ecotox Toxicity Data for Brown Pelican (Pelecanus occidentalis) . Office of Environmental Health Hazard Assessment. 1999. http://www.oehha.ca.gov/cal_ecotox/report/pelectox.pdf The Comparative Toxicogenomics Database. Mount Desert Island Biological Laboratory. 2008. http://ctd.mdibl.org/ Denholm I, Devine GJ, Williamson MS (2002). Evolutionary genetics. Insecticide resistance on the move. Science 297 (5590): 2222–3. Evans, D. H. (1987). The Fish Gill: Site of Action and Model for Toxic Effects of Environmental Pollutants. Environmental Health Perspectives 71, 47-58. Hazardous Substances Data Bank. National Library of Medicine TOXNET System. 2008. http://toxmap.nlm.nih.gov/toxmap/home/welcome.do Handbook of Acute Toxicity of Chemicals to Fish and Aquatic Invertebrates. U.S. Fish and Wildlife Services. 1980. Kantachote D., Naidu R., Williams B., McClure N., Megharaj M., Singleton I. (2004). Bioremediation of DDT-contaminated soil: enhancement by seaweed addition. Journal of Chemical Technology & Biotechnology, 79 , 6, 632-638. Lacroix M., Hontela A. (2003). The organochlorine o,p’-DDD disrupts the adrenal steroidogenic signaling pathway in rainbow trout (Oncorhynchus mykiss). Toxicology and Applied Pharmacology 190, 197-205. O’Reilly A.O., Khambay B.P.S., Williamson M.S., Field L.M., Wallace B.A., Emyr Davies T.G. (2006). Modelling insecticide-binding sites in the voltage-gated sodium channel. Biochemical Journal, 396, 255263. U.S. Department of Health and Human Services. Toxicological Profile for DDT, DDE, and DDD. Agency for Toxic Substances and Disease Registry. 2002. World Health Organization. DDT and its Derivatives – Environmental Aspects. Environmental Health Criteria 83. 1989. http://www.inchem.org/documents/ehc/ehc/ehc83.htm World Health Organization. DDT and its Derivatives. Environmental Health Criteria 9. 1979. http://www.inchem.org/documents/ehc/ehc/ehc009.htm