Enantiomer-specific toxicity and bioaccumulation of alpha-cypermethrin to earthworm Eisenia fetida
Journal of Hazardous Materials, Volume 192, Issue 3, 15 September 2011, Pages 1072–1078
Jinling Diao1, Peng Xu1, Donghui Liu, Yule Lu, Zhiqiang Zhou
Alpha-cypermethrin, a synthetic pyrethroid, is highly effective against a wide range of chewing and sucking insects in crops, and it is a racemic mixture of two enantiomers ((+)-1R-cis-αS + (−)-1S-cis-αR). Studies about the toxicity of alpha-cypermethrin to non-target organisms are mainly focused on aquatic organisms, whereas information regarding terrestrial organisms is relatively much less. Very little report about its enantioselective toxicity is known, so the present study tested the enantiomer-specific acute toxicity to earthworm Eisenia fetida. Experiment about bioaccumulation of two enantiomers in soil was conducted, peak-shaped accumulation curves were observed for both enantiomers, and the calculated biota to soil accumulations factor (BSAF) have significant difference between the two enantiomers. It was obvious that earthworm can uptake alpha-cypermethrin enantioselectively, preferentially accumulating (−)-(1S-cis-αR)-enantiomer. Great difference in toxicity to earthworm between two enantiomers was found, and the calculated LC50 values for (+)-(1R-cis-αS)-, (−)-(1S-cis-αR)-, and rac-alpha-cypermethrin were 49.53, 1663.87 and 165.61 ng/cm2, respectively. The acute toxicity of alpha-cypermethrin enantiomers was enantioselective.
► (+)-(1R-cis-αS)-alpha-cypermethrin was 30 times more toxic than the (−)-isomer to earthworm.
► The chiral HPLC analysis method for alpha-cypermethrin in earthworm tissue was established.
► The bioaccumulation of alpha-cypermethrin in earthworm was enantioselective.
Corresponding author at: Department of Applied Chemistry, China Agricultural University, Yuanmingyuan West Road 2, Beijing 100193, PR China. Tel.: +86 10 62733547; fax: +86 10 62733547.