Science Inventory

Identification of fipronil metabolites in rodents by time-of-flight mass spectrometry for application in a human exposure study


McMahen, R., M. Strynar, S. Dagnino, D. Herr, V. C. Moser, S. Garantziotis, E. Andersen, D. Lyke, L. McMillan, AND A. Lindstrom. Identification of fipronil metabolites in rodents by time-of-flight mass spectrometry for application in a human exposure study. ENVIRONMENTAL SCIENCE AND TECHNOLOGY. John Wiley & Sons, Ltd., Indianapolis, IN, 78:16-23, (2015).


The National Exposure Research Laboratory’s (NERL’s) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA’s mission to protect human health and the environment. HEASD’s research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA’s strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.


Fipronil is a phenylpyrazole insecticide commonly used in residential and agricultural applications. To understand more about the potential risks associated with fipronil, dosed Long Evans rats were evaluated for metabolites to develop a set of biomarkers for use in human exposure studies. Urine from treated rats was found to contain seven unique metabolites, two of which had not been previously reported. Rat serum was found to contain relatively low concentrations of the parent fipronil whereas the primary metabolite, fipronil sulfone varied from 500 - 3500 ng/mL in a dose and time-dependent manner. The fipronil metabolites identified in animal studies were then evaluated in matched human urine and serum 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 0.1-4 ng/mL. These results indicate that many fipronil metabolites are produced following exposures in rats and that fipronil sulfone could be a useful biomarker in human serum. Furthermore, human exposure to fipronil may occur regularly and require more extensive characterization.


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Record Details:

Product Published Date: 05/01/2015
Record Last Revised: 05/13/2015
OMB Category: Other
Record ID: 307953