1. Cyclodiene Insecticide Michelle Nakamura Biol 468

2.  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)  Highly soluble in fats, waxes, oils, and other organic solvents

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

4.  Atmospheric deposition  Does not leach into the groundwater, but will volatilize off the fields  High wind dispersal  Some river runoff

5.  Photo-oxidation  Sunlight degrades aldrin to dieldrin  Physical half-life: 1.5 - 5 years

6.  Mode of entry into organism  Direct contact (gills, epidermis)  Ingestion  96h LC 50 (for fish): 2-53 µg/L  Toxic effects noted:  Damage to the central nervous system ▪Convulsions  Liver cancer

7.  Aldrin competes with GABA molecules for the binding site on the GABA 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.  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.  Biotransform aldrin  dieldrin  Dieldrin is slightly more polar than aldrin, but is still hydrophobic  Bioaccumulates in fatty tissues

10.  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.  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.