Concerns over continued detections in urban watersheds of fipronil, a broad-spectrum insecticide commonly used against ants and other pests, led to the U.S. Environmental Protection Agency (EPA) and the California Department of Pesticide Regulation (DPR) asking companies to modify the labels of liquid formulations of fipronil to reduce negative impacts of this pesticide on the environment. These use restrictions apply to surface applications along foundation perimeters of structures.
Pre- or post-construction subsurface termite treatments and bait formulations are exempt from the new limitations.
Two nationwide changes to labels of liquid fipronil products were approved by the EPA in April 2017, with the goal of keeping this active ingredient out of watersheds. These new restrictions are:
- Do not allow application to enter or runoff into storm drains, drainage ditches, gutters, or surface waters.
- Do not apply directly to sewers or drains, or to any area like a gutter where drainage to sewers, storm drains, water bodies, or aquatic habitats can occur, except as directed by this label.
In addition to these nationwide label amendments, there are some California-specific label changes. These came about through discussions among DPR, the Pest Control Operators of California (PCOC), the registrants of Termidor SC and Taurus SC, and the University of California, Riverside. The California-specific amended label was accepted by DPR in November 2017.
In California, surface applications of liquid fipronil products along foundation perimeters of structures will be further restricted as noted below.
- Applications prohibited on any date between November 1st and February 28th.
- Maximum of 4 applications per year.
- Minimum of 60 days between applications.
- No applications during active precipitation or when rain is predicted within 48 hours post-application.
- Do not apply to garage doors, driveways, vertical surfaces above driveways and garage doors, or to cracks and crevices leading to or adjacent to driveways (such as the expansion joint between driveways and garages).
- Do not apply spray bandwidth at greater than 6 inches out or up from where the foundation meets the ground.
- For foundation exterior perimeter treatments, apply the product as a low-pressure (25 PSI or less at the nozzle) coarse general surface spray (must be limited to 6 inches out and up, as above).
- Only the 0.03% dilution rate may be applied, at 1 quart per 160 feet.
UC Riverside considered these application restrictions in an applied research project and concluded that there were no significant effects on pest control efficacy and that the runoffoff potential was low. During field efficacy trials conducted by PCOC using these new restrictions, there were no noticeable changes in callbacks observed.
Containers with the revised label have been available in California since December 2017. According to California law, registrants can continue selling product with the old label until October 2019, which is 18 months after the US EPA's acceptance of the new label. Enforcement of product labels is based on the actual product label in hand. If an applicator legally obtained a product with the old label, then they can continue to use it under those label directions.
The new label restrictions for structural perimeter applications of liquid formulations are hoped to reduce the amount of fipronil detected in urban surface water systems.