Seventy phosphogypsum stacks are scattered throughout the United States, concentrated in low-wealth and Black, indigenous, and people of color communities. These radioactive waste heaps have a long history of failures, and present a substantial hazard and unreasonable risk of harm. The U.S. Environmental Protection Agency (EPA) should swiftly move to regulate these environmental and public health hazards. This Article examines the regulatory failures that have given rise to the proliferation of phosphogypsum stacks in vulnerable communities and sensitive environments in the United States.