Fipronil is a phenylpyrazole insecticide frequently used for structural pest control in California. As a result, fipronil and its primary degradation products (<i>fipronils</i>)—fipronil desulfinyl, fipronil sulfide, and fipronil sulfone—are commonly detected in surface water as a consequence of use in urban environments. The contamination of surface water by these compounds is associated with non-target aquatic invertebrate toxicity, necessitating the reduction of runoff loads of fipronils. In an effort to achieve this goal, the present study was undertaken. The standard application method dictated on the label of professional fipronil formulations requires that fipronil be applied as a spray around the perimeter of homes and on the garage one foot up the wall and one foot out from the wall (1 foot * 1 foot; treatment A1). This method was compared to three alternative application regimes on 20 treated homes in Riverside, California and on 18 treated constructed wall-concrete pad segments located on campus: 1 foot * 1 foot around the house with a 1 inch * 1 inch band in front of the garage (treatment A3), 1 inch * 1 inch around the house and in front of the garage (treatment C2), and 1 foot * 1 foot around the house with no garage application (treatment G). Runoff water was collected from the residential driveways and from the constructed wall-concrete pad segments and analyzed for the four fipronils. Treatment G showed the lowest concentrations of all four application methods. Urban dust, soil, and concrete wipe samples were also collected from the 5 homes receiving treatment A1 in order to understand the contribution of these compartments to the urban runoff of fipronils and the persistence of fipronils around real homes. The results of this study indicate that runoff of fipronils can be reduced through simple and cost-effective mitigation strategies.

Urban surface water runoff mitigation of Fipronil and its primary degradation products

253rd National Meeting (2017)

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