The overarching theme of "Silent Spring" is the powerfuland often negativeeffect humans have on the natural world. Carson's main argument is that pesticides have detrimental effects on the environment; she says these are more properly termed "biocides" because their effects are rarely limited to solely targeting pests. DDT is a prime example, but other synthetic pesticidesmany of which are subject to bioaccumulationare scrutinized. Carson accuses the chemical industry of intentionally spreading disinformation and public officials of accepting industry claims uncritically. Most of the book is devoted to pesticides' effects on natural ecosystems, but four chapters detail cases of human pesticide poisoning, cancer, and other illnesses attributed to pesticides. About DDT and cancer, Carson says only: