In 1861, the utopian artist William Morris started to produce block-printed wallpapers to defend the Pre-Raphaelite ideals of pre-industrial artisanal production. Often celebrated as a pioneer of environmentalism and hailed by E.P. Thompson as a prominent socialist thinker, Morris was however also a shareholder and member of the board of directors of the copper mine Devon Great Consols, which produced arsenic as a by-product. This article explores the divergence between Morris’s critique of environmental pollution and his use of toxic arsenical pigments in his workshops between 1864 and 1872. Placing Morris’s ideas within the broader context of contemporary debates on the toxicity of arsenic and on the causes of disease, it explains how environmental risks tied to the production of these wallpapers could be minimized by Morris and his peers, while also redefining Morris’s environmentalism.