Chapter 3 asks what is counted and who comes to count in the enactment of epidemiological knowledge. It explores the presence and absence of injury in statistics, blood, chromosomes, memory, and radiation records, and asks how those exposed to toxic environmental harm experience and evaluate epidemiological accounts of their health. It also examines how scientists who use epidemiological reasoning in toxic exposure studies understand and enact the ethics of their practice. It charts how test veterans grappled with the troubling evidentiary burdens of exposure upon which claim-making depends. In attempting to contest accounts of ‘safe’ radiation exposure embedded within government records, test veterans condemned some epidemiological studies and praised others. ‘Good’ numbers were emergent if they were temporally responsive, appropriately connected and detached from study subjects, separable from the state’s influence, epistemically humble, future focused, and contextualized within the practices of their production. ‘Bad’ numbers, by contrast, were those that perpetuated and exacerbated the injuries they denied.