Description:
Permethrin is a synthetic insecticide of the pyrethroid family. Pyrethroids are derived from botanical pyrethrins. Approximately 2 million pounds of permethrin are applied annually for agricultural, residential, and public health use in the United States (US EPA, 2009). Like other pyrethroid insecticides, permethrin has a higher insect to mammal ratio of toxicity than organochlorine or organophosphate insecticides ([http://www.ncbi.nlm.nih.gov/pubmed/19853000|Laffin et al., 2010]). Permethrin biodegradation begins with ester hydrolysis ([http://www.ncbi.nlm.nih.gov/pubmed/3145715|Maloney et al., 1988]), an initial step widespread in pyrethroid metabolism, to produce 3-phenoxybenzyl alcohol and the side chain carboxylate. 3-Phenoxybenzyl alcohol is oxidized to 3-phenoxybenzoate, a major intermediate in pyrethroid insecticide metabolism. It then undergoes angular 1,6 dioxygenation by phenoxybenzoate dioxygenase. The resulting dihydrodiol spontaneously cleaves its ether to produce phenol and 3,4-dihydroxybenzoate ([http://www.ncbi.nlm.nih.gov/pubmed/10820337|Halden et al., 2000]). The other product of the initial esterase hydrolysis, 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate, is mineralized to CO2, but the pathway and organisms that perform these steps are not known ([http://www.ncbi.nlm.nih.gov/pubmed/7069133|Jordan et al., 1982]).