Fate and distribution of fipronil on companion animals and in their indoor residences following spot-on flea treatments

Abstract

Use of fipronil {5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-trifluoromethyl)sulfinyl]-1H-pyrazole-3-carbonitrile CAS 120068–37-3} topical pet products on dogs and cats introduces low level residues into residences. Distribution and fate studies of fipronil on pets and in residences were performed to evaluate potential determinants of human exposure. Fipronil, desulfinyl fipronil, fipronil sulfone and fipronil sulfide were measured on hair clippings and brushed hair. The derivatives usually represented <10% of fipronil applied. Cotton gloves worn over impervious nitrile gloves, cotton cloths placed indoors in locations frequented by pets, and cotton socks worn by residents as direct dosimeters collected fipronil and its derivatives listed above in low amounts during 4-week study periods. Subsequent acid hydrolysis urine biomonitoring did not reveal significant excretion of biomarkers at ppb levels. The human exposure potential of fipronil is low relative to levels of health concern.

Keywords:

• Fipronil
• companion animals
• flea control
• biomonitoring
• exposure assessment

Acknowledgments

The enthusiastic assistance, cooperation and compliance of all study participants and their companion animals was essential to the completion of this research. Analytical standards were generously provided by BASF Corporation. This research of the University of California Citrus Experiment Station, Riverside was augmented by unrestricted gifts to the Regents of the University of California in support of the Personal Chemical Exposure Program. The registrant of Frontline® provided no direct or indirect support of this research.