Under an Environmental Protection Agency Experimental Use Permit, a pelleted bait containing 0.0025% (25 ppm) of the new anticoagulant difethialone was tested to determine the effectiveness in controlling Norway rats (Rattus norvegicus) and house mice (Mus musculus). Sixteen (16) individual field studies were conducted in five (5) geographical locations of the United States. The results were conclusive in showing that difethialone bait formulated at 25 ppm was both palatable and efficacious in controlling both Norway rats and house mice under actual field conditions.

Cholecalciferol is an acute (single-feeding) and/or chronic (multiple-feeding) rodenticide toxicant with unique activity for controlling commensal rodents including anticoagulant-resistant rats. Cholecalciferol differs from conventional acute rodenticides in that no bait shyness is associated with consumption and time to death is delayed, with first dead rodents appearing 3-4 days after treatment.