The EPA is considering whether to cancel registrations for granular labels for fipronil products, according to a recent email sent this week to some Extension faculty, USDA researchers, state government officials and customers by Bayer Environmental Science representatives.
According to the email, "In 2001, EPA granted a 5-year conditional registration for broadcast granular products containing fipronil insecticide such as TopChoice® for fire ant control. Since that time, the conditional registration for these products has been extended until May, 2009. The EPA has recently indicated their intention to cancel the registration for fipronil broadcast applications when the conditional registration expires."
If so, this would mean that popular insecticides like TopChoice® and Over N Out® would go away, probably for good. Top Choice® is currently the best option for control of mole crickets in the southern U.S., and both these products find use as a once-a-year treatment for fire ant control.
Although the EPA is not talking on the record about the reasons for a possible cancellation of registration, the official I spoke with noted that the agency has been concerned with the ecological impact of fipronil, especially in aquatic environments. The persistence of fipronil in the environment, and possible biomagnification in some food chains are additional issues for the agency. A review of the ecotoxicology of fipronil by Tingle et. al in 2003 will give you some idea of environmental and health concerns with this product.
Whether granular fipronil remains on the market will depend on how strong a case Bayer Environmental Science can make as well as input received from end users. As far as I can tell the registration of fipronil for termite and ant control is not currently at risk, and may never be. Fire ant baits certainly offer a strong alternative to fipronil granules for fire ant control. But turfgrass managers will miss fipronil as an option for mole cricket control.
The scientific issue at stake is what use pattern might result in fipronil toxicity issues in aquatic environments. It has been well documented that effluent from treated rice fields can impact many aquatic invertebrates and even fish (see for example Gunasekara and Troung 2007. and Stehr et. al 2006) Less well known is how much fipronil might be leaching from treated golf courses or home lawns. As a pest management specialist I would hate to lose fipronil as a tool for turfgrass management. But as an environmentalist and one who realizes the importance of water quality to our quality of life, I don't want to see pesticides eroding the health of our streams and estuaries. Let's hope the EPA uses sound science to make the right decision.