This paper exposes the New Zealand (NZ) government’s longstanding campaign to silence evidence of health impacts from dioxin-containing emissions during the production of the herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in New Plymouth in the 1960s. Our analysis of official documentation and related literature between 1960–2005 reveals a series of investigations engaging various silencing mechanisms that have culminated in a case of historical pollution. By doing so, they have intensified the acute injuries, chronic disease and multigenerational impacts stemming from the emissions, while discounting the lived experiences of suffering. We argue that silencing be seen as an epistemic violence that is intertwined with, but stands in evidence of, actions to ignore and deny harms that could be utilized in securing the long overdue acknowledgement and appropriate assistance for the Paritutu community.