title: Identification of fipronil metabolites by time-of-flight mass spectrometry for application in a human exposure study.
abstract: Fipronil is a phenylpyrazole insecticide commonly used in residential and agricultural applications. To understand more about the potential risks for human exposure associated with fipronil, urine and serum from dosed Long Evans adult rats (5 and 10mg/kg bw) were analyzed to identify metabolites as potential biomarkers for use in human biomonitoring studies. Urine from treated rats was found to contain seven unique metabolites, two of which had not been previously reported-M4 and M7 which were putatively identified as a nitroso compound and an imine, respectively. Fipronil sulfone was confirmed to be the primary metabolite in rat serum. The fipronil metabolites identified in the respective matrices were then evaluated in matched human urine (n=84) and serum (n=96) samples from volunteers with no known pesticide exposures. Although no fipronil or metabolites were detected in human urine, fipronil sulfone was present in the serum of approximately 25% of the individuals at concentrations ranging from 0.1 to 4ng/mL. These results indicate that many fipronil metabolites are produced following exposures in rats and that fipronil sulfone is a useful biomarker in human serum. Furthermore, human exposure to fipronil may occur regularly and require more extensive characterization.
authors: ORISE fellow at the United States Environmental Protection Agency, National Exposure Research Laboratory, Research Triangle Park, NC, United States.
authors: Rebecca L
authors: RL
authors: McMahen
authors: United States Environmental Protection Agency, National Exposure Research Laboratory, Research Triangle Park, NC, United States. Electronic address: strynar.mark@epa.gov.
authors: Mark J
authors: MJ
authors: Strynar
authors: ORISE fellow at the United States Environmental Protection Agency, National Exposure Research Laboratory, Research Triangle Park, NC, United States.
authors: Sonia
authors: S
authors: Dagnino
authors: United States Environmental Protection Agency, National Health and Environmental Effects Research Lab, Research Triangle Park, NC, United States.
authors: David W
authors: DW
authors: Herr
authors: United States Environmental Protection Agency, National Health and Environmental Effects Research Lab, Research Triangle Park, NC, United States.
authors: Virginia C
authors: VC
authors: Moser
authors: National Institute for Environmental and Health Sciences, Research Triangle Park, NC, United States.
authors: Stavros
authors: S
authors: Garantziotis
authors: United States Environmental Protection Agency, National Exposure Research Laboratory, Research Triangle Park, NC, United States.
authors: Erik M
authors: EM
authors: Andersen
authors: United States Environmental Protection Agency, National Health and Environmental Effects Research Lab, Research Triangle Park, NC, United States.
authors: Danielle L
authors: DL
authors: Freeborn
authors: National Caucus and Center on Black Aged Employee, United States Environmental Protection Agency, National Exposure Research Laboratory, Research Triangle Park, NC, United States.
authors: Larry
authors: L
authors: McMillan
authors: United States Environmental Protection Agency, National Exposure Research Laboratory, Research Triangle Park, NC, United States.
authors: Andrew B
authors: AB
authors: Lindstrom
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D015415:Biomarkers / Q000097:blood / Q000652:urine; D004781:Environmental Exposure / Q000032:analysis; D004784:Environmental Monitoring; D005260:Female; D006798:Housing; D006801:Humans; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D008875:Middle Aged; D023421:Models, Animal; D010575:Pesticides / Q000097:blood / Q000652:urine; D011720:Pyrazoles / Q000097:blood / Q000652:urine; D051381:Rats; D020318:Rats, Long-Evans; D055815:Young Adult
chemical_list: D015415:Biomarkers; D010575:Pesticides; D011720:Pyrazoles; C534368:fipronil sulfone; C082360:fipronil
keywords: Biomarker; Fipronil; Human exposure; LC/TOF; Metabolism