Rachel Carson, founder of the modern environmental movement, began work on her seminal book Silent Spring in the late 1950s, when a dizzying array of synthetic pesticides had come into use. Leading this chemical onslaught was the insecticide DDT. Effective against crop pests as well as insects that transmitted human diseases such as typhus and malaria, DDT had at first appeared safe. But as its use expanded, alarming reports surfaced of collateral damage to fish, birds, and other wildlife. Silen...