Difenacoum

Difenacoum is an anticoagulant of the 4-hydroxycoumarin vitamin K antagonist type. It has anticoagulant effects and is used commercially as a rodenticide. It was first introduced in 1976 and first registered in the USA in 2007.
Formulation.
Difenacoum is sold as blue-green and red pellets.
Uses.
Difenacoum was first introduced in 1976 as a rodenticide effective against rats and mice which were resistant to other anticoagulants.
Safety and toxicity.
Because other species of mammals and birds may prey upon affected rodents, or directly ingest rodenticide bait, there is a risk of primary, secondary or tertiary exposure; examples are described in a 2012 publication on veterinary toxicology.
Using radiolabeled isotopes, difenacoum (and/or its metabolites) has been shown to be distributed across many organ tissues upon oral ingestion, with the highest concentrations occurring in the liver and pancreas.
Difenacoum has been shown to be highly toxic to some species of freshwater fish and green algae despite the fact that difenacoum is weakly soluble in aqueous solutions.