Defenders of Wildlife and Audubon of Kansas, which filed the federal lawsuit last week in Washington, D.C., say the chemicals threaten the endangered black-footed ferret, which feeds on prairie dogs. Prairie dogs can compete with livestock for forage.
The lawsuit says the EPA is violating the Endangered Species Act and other federal laws. It also says the EPA failed to heed warnings from the U.S. Fish and Wildlife Service that said the chemicals have "known and potential impacts to wildlife."
The EPA says it will release a notice next week related to the lawsuit and that once it has evaluated comment, it will determine how to proceed.