A new body of evidence is building. Study after study shows widely prescribed drugs such as Prozac, Effexor and Celexa disrupt the natural order when they are excreted into the water. Scientists in Mississippi discovered antidepressants are interfering with the way tadpoles develop into frogs. They also interfere with the ability of tiny minnows to escape predators. Experts say these early signs could point to long-term problems for the aquatic food chain as a whole.