March 13, 2009

The control of rodents such as rats and mice around structures, including homes, food plants, and farm buildings, is essential in protecting human health and the quality of our food and feed.

Rodent urine, feces, and hair can contaminate food products, and rodents can spread diseases such as plague, rickettsialpox, leptospirosis, rat bite fever, trichinosis, salmonellosis, and Hantavirus.

Rodent Control Options

Common toxicants used for rodent control have included anticoagulants (agents that prevent blood from clotting) and non-anticoagulants. Non-anticoagulants include bromethalin, cholecalciferol, and zinc phosphide. Anticoagulants are divided into first generation (warfarin, chlorophacinone, and diphacinone) and second generation (brodifacoum bromadiolone, difenacoum and difethialone) products.

With first generation anticoagulants usually a rodent must feed several times to receive a toxic dose. Second generation anticoagulants are more toxic than first generation products and usually only require a single feeding to be lethal. Second generation products also are effective in controlling rodents that have become resistant to first generation anticoagulants.

New Rodenticide Restrictions

Recently, new consumer and application restrictions have been placed on some anticoagulant rodenticides. Second generation products or loose pellet formulations are no longer available to consumers. All consumer products will be sold in tamper-resistant bait stations with solid bait blocks. This will reduce the risk of non-target poisoning to wildlife, children, or pets.

Loose baits provide easier access and more chance of exposure, especially if used by consumers unfamiliar with proper handling and use of these products. As an added precaution, second generation anticoagulants will not be sold through "consumer" stores, such as hardware supply stores.

Second generation anticoagulants for use in and around agricultural buildings will be sold in 8 lb or larger containers. These rodenticides are not intended for use inside occupied homes. Pesticide applicators will be required to use tamper-resistant stations: 1) for indoor applications if non-target exposure, such as to children and pets, is a possibility, and 2) for all above ground, outdoor use. These same restrictions apply to second generation anticoagulants sold in 16 lb or larger containers, and those used by professional pesticide applicators inside homes.

Resource

For more information on rodenticides and any recent regulation changes concerning them, visit EPA's Web site at http://epa.gov/pesticides/reregistration/rodenticides/.

Erin Bauer
Extension Assistant
Clyde Ogg
Pesticide Safety Educator