Enantioselectivity in environmental safety of current chiral insecticides
AUTOR(ES)
Liu, Weiping
FONTE
National Academy of Sciences
RESUMO
Chiral pesticides currently constitute about 25% of all pesticides used, and this ratio is increasing as more complex structures are introduced. Chirality occurs widely in synthetic pyrethroids and organophosphates, which are the mainstay of modern insecticides. Despite the great public concerns associated with the use of insecticides, the environmental significance of chirality in currently used insecticides is poorly understood. In this study, we resolved enantiomers of a number of synthetic pyrethroid and organophosphate insecticides on chiral selective columns and evaluated the occurrence of enantioselectivity in aquatic toxicity and biodegradation. Dramatic differences between enantiomers were observed in their acute toxicity to the freshwater invertebrates Ceriodaphnia dubia and Daphnia magna, suggesting that the aquatic toxicity is primarily attributable to a specific enantiomer in the racemate. In field sediments, the (-) enantiomer of cis-bifenthrin or cis-permethrin was preferentially degraded, resulting in relative enrichment of the (+) enantiomer. Enantioselective degradation was also observed during incubation of sediments under laboratory conditions. Enantioselectivity in these processes is expected to result in ecotoxicological effects that cannot be predicted from our existing knowledge and must be considered in future risk assessment and regulatory decisions.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=545578Documentos Relacionados
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