In May 2008, the EPA added restrictions on the sale of difethialone in consumer-use rodenticide products and also for exterior use by commercial applicators.[3][4]
^Saravanan K, Kanakasabai R, Thiyagesan K (June 2003). "Field evaluation of difethialone, a new second generation anticoagulant rodenticide in the rice fields". Indian Journal of Experimental Biology. 41 (6): 655–8. PMID15266918.