title: Enantioselective toxicity and degradation of the chiral insecticide fipronil in Scenedesmus obliguus suspension system.
abstract: Fipronil is an effective insecticide, but it presents highly toxic effects in nontarget aquatic organisms. The present study examined the enantioselective toxicity and degradation of fipronil enantiomers in a freshwater algae Scenedesmus obliguus suspension. There was a substantial difference in the acute toxicity of the enantiomers to S. obliguus, with 72-h median effective concentrations (EC50s) of 0.29 mg L(-1) and 1.50 mg L(-1) for the R-fipronil and S-fipronil, respectively. The influences on the concentration of chlorophyll a, chlorophyll b, and carotenoids were determined, and the effects of fipronil on the concentration of chlorophyll a and chlorophyll b were also enantioselective. The degradation of fipronil in algae suspension was enantioselective, with half-lives for R-fipronil and S-fipronil of 2.9 d and 3.2 d, respectively, and the enantiomer fraction reaching 0.65 at the day 17. The enantiomeric differences should be taken into consideration for fipronil risk assessment.
authors: Department of Applied Chemistry, China Agricultural University, Beijing, People's Republic of China.
authors: Han
authors: H
authors: Qu
authors: Rui-Xue
authors: RX
authors: Ma
authors: Dong-Hui
authors: DH
authors: Liu
authors: Peng
authors: P
authors: Wang
authors: Le-Dan
authors: LD
authors: Huang
authors: Xing-Xu
authors: XX
authors: Qiu
authors: Zhi-Qiang
authors: ZQ
authors: Zhou
mesh_terms: D001681:Biological Assay; D002338:Carotenoids / Q000737:chemistry; D002734:Chlorophyll / Q000031:analogs & derivatives / Q000737:chemistry; D000077194:Chlorophyll A; D007306:Insecticides / Q000378:metabolism / Q000633:toxicity*; D010788:Photosynthesis; D011720:Pyrazoles / Q000378:metabolism / Q000633:toxicity*; D015203:Reproducibility of Results; D018570:Risk Assessment; D044444:Scenedesmus / Q000187:drug effects*; D013237:Stereoisomerism; D013535:Suspensions; D013997:Time Factors
chemical_list: D007306:Insecticides; D011720:Pyrazoles; D013535:Suspensions; D002734:Chlorophyll; C085815:chlorophyll a'; D002338:Carotenoids; C037184:chlorophyll b; C082360:fipronil; D000077194:Chlorophyll A
keywords: Degradation; Enantioselectivity; Fipronil; Scenedesmus obliguus; Toxicity