Chiral selectivity in the environmental fate of pyrethroids

Pyrethroids are a family of chiral pesticides with a large number of stereoisomers. Following the discovery of significant differences in non-target toxicities between pyrethroid enantiomers, enantioselectivity during degradation and analysis have been investigated in recent studies to better understand their fate and ecotoxicological effects. Enantioselective degradation occurs frequently for pyrethroids in various field matrices and under laboratory conditions. Enantiomerization, which may contribute to the enantioselectivity in the environmental fate and effects of pyrethroids, is common in pyrethroids with the α-cyano carbon when exposed to alcohols and other conditions. Results suggest that the fate and effects of individual stereoisomers, instead of the racemic compound, should be considered for pyrethroids to better predict their environmental impacts. In addition, rigorous analytical methods and pesticide handling procedures should be developed to prevent the artifacts caused by enantiomerization.