1 / 13

Ashley Watts

Ashley Watts. Aquatic Toxicology. Physical & Chemical Properties. 1,1,1-trichloro-2,2-bis- (p- chlorophenyl ) ethane Technical grade DDT 65–80% was the active ingredient, 4,4’-DDT 15–21% of the nearly inactive 2,4’-DDT 4% of 4,4’-DDD 1.5% of 1-(p- chlorophenyl )-2,2,2-trichloroethanol

heidi
Download Presentation

Ashley Watts

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ashley Watts Aquatic Toxicology

  2. Physical & Chemical Properties • 1,1,1-trichloro-2,2-bis-(p-chlorophenyl) ethane • Technical grade DDT • 65–80% was the activeingredient, 4,4’-DDT • 15–21% of the nearly inactive 2,4’-DDT • 4% of 4,4’-DDD • 1.5% of 1-(p-chlorophenyl)-2,2,2-trichloroethanol • Degrades into 2,4’-DDE, and 2,4’-DDD 4,4’-DDE

  3. Physical & Chemical Properties

  4. Physical & Chemical Properties Half-life 3-10 years

  5. DDT Timeline • Discovered in 1939 • U.S. used in WWII • Control vectors of malaria and typhus • 1945 - Agricultural pesticide for 30 years • 1.3 billion pounds used • 1959 – use declined greatly • 1974 – banned

  6. Degradation Pathway DDT DDD DDE

  7. Environmental/Organismal Entry • Introduced as a powder, emulsion, encapsulation • Long term persistence in soil • Dispersed via runoff • Erosion • Volatilization • Solubility in lipids results in concentrated amounts in aquatic organisms • Biomagnification results in all levels of the food chain being affected

  8. BiomagnificationDDT and DDE are readily stored in fats of vertebrates

  9. Toxic Effects • Insects • Death • Fish • Reproductive effects • Neurotoxin effects • Birds • Eggshell thinning • Mammals • Localized liver and kidney damage • Neurotoxin effects • Teratogenic effects (mice) • Carcinogenic effects are likely

  10. Molecular Interactions • How it kills insects • Na ion channels stay open, resulting in random neuron fire and death “DDT Jitters” • Those with a mutation or up-regulated CYP-450 genes are resistant • DDE mimics the  action of estradiol causing a decline in androgen synthesis in some vertebrates • DDE inhibits the Ca2+ -ATPase or Ca2+-Mg2+ ATPase activity in the eggshell gland

  11. Biochemical Breakdown and Removal • DDE and DDD formed • In the presence of NADPH and NADH • In anaerobic conditions • Dechlorination is catalyzed enzymatically by cytochrome P450  • DDT and DDE are further oxidized to form DDA which is the major excreted product in animals.

  12. Detoxification • Insects • DDTasecan render the compound more water soluble. DDT -> DDE • Mammals • DDT is dehalogenated to DDD and DDE is produced also in small amounts • DDD is produced and stored in liver • DDE found excreted in milk • Fish • DDT is highly resistant to metabolism and very little is excreted

  13. References • Agency for Toxic Substances & Disease Registry http://www.atsdr.cdc.gov/toxprofiles/tp35-c4.pdf • DDT Regulatory History: A Brief Survey (to 1975) http://www.epa.gov/history/topics/ddt/02.htm • Davies, T. Field, L., Usherwood, P., Williamson, M. 2007. DDT, Pyrethrins, Pyrethroids and Insect Sodium Channels. Life, 59(3): 151 – 162. • Lundholm, C. 1997. DDE-Induced Eggshell Thinning in Birds:Effectsof p,p’-DDE on the Calcium and Prostaglandin Metabolism of the Eggshell Gland. Comp. Biol. Physiol. Vol. 118C, No. 2, pp. 113-128. • Kitamura, S. Shimizu, Y., Shiraga, Y., Yoshida, M., Sugihara, K.,Ohta,S.2002. Reductive Metabolism ofp,p′-DDT ando,p′-DDT by Rat Liver Cytochrome P450. DMD,30.2.113. • Low, W.Y. et al. Recognition and Detoxification of the Insecticide DDT by Drosophila melanogaster Glutathione S-TransferaseD1. J. Mol. Biol. (2010) 399, 358–366, • Whiting, F. Et al. 1968. Detoxification of DDT by the Perfused Bovine Liver. Journal of Dairy Science. 51.10, 1612-1615. • Wang, X., Wang, W. Uptake, absorption efficiency and elimination of DDT in marine phytoplankton, copepods and fish. Environmental Pollution 136 (2005) 453e464. • Loomis&Thomas. Effects of Estrogens and Xenoestrogens on Androgen Production by Atlantic Croaker Testes In Vitro: Evidence for a Nongenomic Action Mediated by an Estrogen Membrane Receptor.. April 1, 2000 vol. 62 no. 4995-1004.

More Related