The fear of a poisoned world is being increasingly pressed, debated, debunked, and reiterated from many disciplinary vantage points: medicine, political science, history, sociology, economics, and ethics among others. Seldom however is toxicity discussed as a discourse. This essay aims to define the forms, origins, uses, and critical implications of toxic rhetoric, conceiving it as an interlocked set of topoi whose force derives partly from the exigencies of an anxiously industrializing culture, partly from deeperrooted Western attitudes. In order to make this analysis pointed and manageable, and not to outrun the limits of my knowledge, I shall focus on the United States, although many of my points apply to Anglophone settler cultures worldwide, if not also to other regions (and few remain untouched) influenced by Western environmental institutions. As we shall see, toxic discourse challenges traditional understandings of what counts as an environmentalist movement or ethos. It calls for a new history of US environmentalism that would place the wilderness preservationist John Muir and the urban social reformer Jane Addams in the same narrative. It insists on the interdependence of ecocentric and anthropocentric values. It underscores the point that environmentalism