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Aldrin

Cyclodiene Insecticide. Aldrin. Michelle Nakamura Biol 468. Physical and Chemical Properties. Aldrin (C 12 H 8 Cl 6 ) MW: 364.91 Appearance: Pure – white powder Commercial grade – tan powder Low water solubility (< 27 ng/L) No reaction with water Hydrophobic! (log K ow = 7.4)

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Aldrin

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  1. Cyclodiene Insecticide Aldrin Michelle Nakamura Biol 468

  2. Physical and Chemical Properties • Aldrin (C12H8Cl6) • MW: 364.91 • Appearance: • Pure – white powder • Commercial grade – tan powder • Low water solubility (< 27 ng/L) • No reaction with water • Hydrophobic! (log Kow = 7.4) • Highly soluble in fats, waxes, oils, and other organic solvents

  3. Production History • 1950s - 1970s: widely used as an insecticide • 1987: EPA banned all uses of aldrin • Uses and Applications • Pesticide for soil and crops -mostly corn, some cotton • Termite control • Does not occur naturally in the environment

  4. Mode of Entry in Aquatic Environment • Atmospheric deposition • Does not leach into the groundwater, butwill volatilize off the fields • High wind dispersal • Some river runoff

  5. Physical Half-Life • Photo-oxidation • Sunlight degrades aldrin to dieldrin • Physical half-life: 1.5 - 5 years

  6. Toxicity to Aquatic Life • Mode of entry into organism • Direct contact (gills, epidermis) • Ingestion • 96h LC50 (for fish): 2-53 µg/L • Toxic effects noted: • Damage to the central nervous system • Convulsions • Liver cancer

  7. Molecular Mode of Toxic Interaction • Aldrin competes withGABA molecules forthe binding site on theGABA receptor • When GABA binds,Cl- channels open,inhibits firing of new action potentials • When aldrin binds, Cl- channels stay closed,action potentials keep firing*INCREASES pre-synaptic neurotransmitter release!

  8. Biomechanical Metabolism • Aldrin is rapidly converted to dieldrin by CYP450 found on the endoplasmic reticulum of liver cells • Biotransformation takes only 12-24 hrs • Result: very little aldrin found in the blood or tissues • Mediated by the mixed-function mono-oxygenase (MFO) system

  9. Defense Strategies for Detoxification • Biotransform aldrin  dieldrin • Dieldrin is slightly more polar than aldrin, but is still hydrophobic • Bioaccumulates in fatty tissues

  10. Summary of Aldrin • Soil pesticide for crops • No longer produced • Hydrophobic • Can be absorbed by direct contact or ingestion • Causes convulsions and liver cancer • Rapidly converted to dieldrin in the body  bioaccumulates in fatty tissues

  11. Bibliography • Aldrin and Dieldrin. (2002). Agency for Toxic Substances and Disease Registry. 1-2. • Brooks, G. T. Interactions with the Gamma-Aminobutyric Acid A-Receptor: Polychlorocycloalkanes and recent congeners. (2001). Handbook of Pesticide Toxicology (Second Edition. 1131-1156. • Connell, D. W., Miller, G., & Anderson, S. (2002). Chlorohydrocarbon pesticides in the Australian marine environment after banning in the period from the 1970s to 1980s. Marine Pollution Bulletin. 45, 78-83. • Grun, G. L., MacDonald, R. M., Verge, J., & Aube, J. (2008). Long-term atmospheric deposition of current-use and banned pesticides in Atlantic Canada; 1980-2000. Chemosphere. 71(2), 314-327. • Guo, Y. G., Meng, X., Tang, H., & Zeng, E. (2007). Tissue distribution of organochlorine pesticides in fish collected from the Pearl River Delta, China: Implications for fishery input source and bioaccumulation. Environmental Pollution. 1-7. • Jorgenson, J. L. (2001). Aldrin and Dieldrin: A review on their production, environmental deposition and fate, bioaccumulation, toxicology, and epidemiology in the United States. Environmental Health Perspectives. 109(1), 114-139. • Mason, Z. Phase II metabolism [lecture]. 15 Apr. 2008. • Pomes, A., Rodrigues-Fare, E., & Sunol, C. (1994). Disruption of GABA-dependent chloride flux by cyclodienes and hexachlorocyclohexanes in primary cultures of cortical neurons. The Journal of Pharmacology and Experimental Therapeutics. 271(3), 1616-1623. • Sanchez-Bayo, F. Comparative acute toxicity of organic pollutants and reference values for crustaceans, I. Branchiopoda, Copepoda and Ostracoda. (2006). Environmental Pollution. 139(3), 385-420. • Singh, P. B., & Singh, V. (2008). Pesticide bioaccumulation and plasma sex steroids in fishes during breeding phase from north India. Environmental Toxicology and Pharmacology. 25(3), 342-350. • Zhou, R., Zhu, L., & Kong, Q. (2007). Persistent chlorinated pesticides in fish species from Qiantang River in East China. Chemosphere. 68(5), 838-647.

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