DDT had been used during the Second World War against insects carrying typhus and malaria, and spread through agriculture afterwards; its discoverer received a Nobel Prize in 1948. By the 1950s mass aerial spraying was routine in the United States. Rachel Carson spent four years matching the observations reaching her in letters — birds found dead in gardens after spraying — against the published research.

The concept at the centre of Silent Spring, published in 1962, is bioaccumulation: fat-soluble DDT is not excreted but concentrates at each step of the food chain until it reaches the predators at the top. The thinning eggshells and population collapses in eagles and herons were explained this way. Carson did not call for a total ban on pesticides; what she argued for was measuring the ecological cost of widespread, unmonitored use.

The chemical industry ran an intense campaign against the book, attacking Carson's expertise and — by way of her sex — her 'emotionalism'. Kennedy's science advisory committee nevertheless upheld the substance of her claims in 1963. The United States created the Environmental Protection Agency in 1970 and banned agricultural DDT in 1972; eagle populations recovered over the following thirty years. The book's lasting effect is methodological rather than chemical: the idea that a technology must be judged by its indirect consequences within a system, not only by its intended effect, runs from chemical and climate regulation to environmental impact assessment. DDT's place in malaria control remains a separate and continuing argument; the World Health Organization still permits limited indoor use.