Isomerization of chiral pesticides in the environment

The most biologically active stereoisomer(s) of a chiral pesticide should be used favorably when stereoisomers exhibit different activities on target species, not only to reduce the unnecessary burden of inactive ones to the environment but also to remove unjustified dietary and ecological risks as possible. However, the isomerization of a chiral pesticide, if it occurs in the environment, deteriorates the advantage of using chirally purified pesticide. The isomerization of a chiral pesticide should be examined in hydrolysis, photolysis, and metabolism in soil and plants to estimate enantioselectivity in its environmental fate and any ecotoxicological effects from the viewpoint of more precise risk assessment. (C) Pesticide Science Society of Japan