Proceedings of the Vertebrate Pest Conference

The development of second-generation anticoagulant rodenticides for commensal rodent control arose from the need to overcome genetic resistance to earlier anticoagulants, to improve efficacy, and to reduce hazard over older acute rodenticide materials. Over the past three decades, the second-generation anticoagulant products have become the principal commensal rodenticides used in the U.S. and elsewhere. During this long usage, individual cases of human and nontarget wildlife exposure have been documented, and the significance has been debated. Following a lengthy re-registration and review process, the U.S. Environmental Protection Agency in January 2007 proposed restrictions on the use of second-generation anticoagulant rodenticides for commensal rodent control. The proposed restrictions would shift emphasis to other rodenticides, including those with inherent problems that were the basis for developing second-generation anticoagulants. Reduced efficacy, prolonged public exposure to rodents, limitations in bait formulations and placements, increased genetic resistance, and greater application rates (exposure) are anticipated if these restrictions are adopted. Various nontarget concerns will remain with alternative products and use patterns by professional users and consumers, including use of products without specific antidotes. These impacts would occur amidst increasing rodent problems in many U.S. municipalities with declining management resources and aging infrastructure. Alternative measures should include use of human taste deterrents in baits and revised label statements to limit the use of all commensal rodenticide from sensitive areas, including placement along fence lines, and bordering natural habitats.