A review on the stereospecific fate and effects of chiral conazole fungicides

The production and use of chiral pesticides are triggered by the need for more complex molecules capable of effectively combating a greater spectrum of pests and crop diseases, while sustaining high production yields. Currently, chiral pesticides comprise about 30% of all pesticides in use; however, some pesticide groups such as conazole fungicides (CFs) consist almost exclusively of chiral compounds. CFs are produced and field-applied as racemic (1:1) mixtures of two enantiomers (one chiral center in the molecule) or four diastereoisomers, i.e., two pairs of enantiomers (two chiral centers in the molecule). Research on the stereoselective environmental behavior and effects of chiral pesticides such as CFs has become increasingly important within the fields of environmental chemistry and ecotoxicology. This ismotivated by the fact that currently, the fate and effects of chiral pesticides such as CFs that arise due to their stereoselectivity are not fully understood and integrated into risk assessment and regulatory decisions. In order to fill this gap, a summary of the state-of-the-art literature related to the stereospecific fate and effects of CFs is needed. This will also benefit the agrochemistry industry as they enhance their understanding of the environmental implications of CFs which will aid future research and development of chiral products. This review provides a collection of >80 stereoselective studies for CFs related to chiral analyticalmethods, fungicidal activity, non-target toxicity, and behavior of this broadly used pesticide class in the soil environment. In addition, the review sheds more light on mechanisms behind stereoselectivity, considers possible agricultural and environmental implications, and suggests future directions for the safe use of chiral CFs and the reduction of their environmental footprint. (C) 2020 Elsevier B.V. All rights reserved.