Synthetic Pyrethroids: Toxicity and Metabolism

Synthetic Pyrethroids are synthetic analogs of naturally occurring pyrethrins, found in extract from Chrysanthemum flowers. They were launched as a replacement of highly toxic class of pesticides like DDT and Organophosphates in 1980s. Major success of pyrethroids lies in the low toxicity of them towards mammals as well as humans and due to which they have wide range of applications right from agricultural fields, as household pesticides to veterinary applications. Low toxicity of pyrethroids is mainly defined by high rate of metabolism reaction via ester hydrolysis and oxidation at certain position depending on the structure which are mediated by carboxylesterase and CYP isoforms. These metabolites further undergoes either hydrophilic or lipophilic conjugate formation based on the structure of molecule. One of the drawback of pyrethroids is toxicity to aquatic organism and bees which limits their use for crops like paddy, chestnut etc.