title: Enantioselective toxicity, bioaccumulation and degradation of the chiral insecticide fipronil in earthworms (Eisenia feotida).
abstract: The enantioselective acute toxicity to earthworms of racemic fipronil and its individual enantiomers was studied. R-(-)-fipronil was approximately 1.5 times more toxic than the racemate and approximately 2 times more toxic than S-(+)-fipronil after 72 and 96 h of exposure, respectively. Assays of fipronil enantiomer bioaccumulation and degradation in earthworms were conducted. The bio-concentration factors (BCFs) were slightly different between the two enantiomers. The enantiomeric fraction (EF) values in earthworms in the bioaccumulation period were approximately 0.5, which indicated there was no enantioselective bioaccumulation. In contrast, the degradation of fipronil in earthworms was enantioselective: the t1/2 values for R- and S-fipronil were 3.3 and 2.5 days, respectively, in natural soil, and 2.1 and 1.4 days, respectively, in artificial soil. The results of soil analyses showed that the degradation of fipronil was not enantioselective, which suggested that the enantioselectivity of fipronil in earthworms results from the organism's metabolism. The study also demonstrated that the presence of earthworms could accelerate the degradation of fipronil in soil.
authors.affiliation: Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China.
authors.forename: Han
authors.initials: H
authors.lastname: Qu
authors.affiliation: Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China.
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China.
authors.forename: Rui-Xue
authors.initials: RX
authors.lastname: Ma
authors.affiliation: Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China.
authors.forename: Xing-Xu
authors.initials: XX
authors.lastname: Qiu
authors.affiliation: Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China.
authors.forename: Peng
authors.initials: P
authors.lastname: Xu
authors.affiliation: Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China.
authors.forename: Zhi-Qiang
authors.initials: ZQ
authors.lastname: Zhou
authors.affiliation: Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China. Electronic address: liudh@cau.edu.cn.
authors.forename: Dong-Hui
authors.initials: DH
authors.lastname: Liu
mesh_terms: D000818:Animals; D001681:Biological Assay; D007306:Insecticides / Q000737:chemistry / Q000633:toxicity*; D007928:Lethal Dose 50; D009835:Oligochaeta; D011720:Pyrazoles / Q000737:chemistry / Q000633:toxicity*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry / Q000633:toxicity*; D013237:Stereoisomerism
chemical_list: D007306:Insecticides; D011720:Pyrazoles; D012987:Soil; D012989:Soil Pollutants; C082360:fipronil
keywords: Bioaccumulation; Degradation; Enantioselectivity; Fipronil; Toxicity