Poisons

Rats thrive around humans, for good reason: They feed off crops and garbage and readily adapt to many settings, from farms to the world’s largest cities. To control them, people often resort to poisons. But chemicals that kill rats can also harm other animals. The most commonly used poisons are called anticoagulant rodenticides. They work by interfering with blood clotting in animals that consume them. These enticingly flavored bait blocks are placed outside of buildings, in small black boxes that only rats and mice can enter. But the poison remains in the rodents’ bodies, threatening larger animals that prey on them. My colleagues and I recently reviewed studies from around the world that sought to document wild mammal carnivores’ exposure to anticoagulant rodenticides. Many animals tested in these studies were already dead; others were alive and a part of other studies. Researchers detected rodenticides in about one-third of the animals in these analyses, i...