The nuclear disaster at Fukushima in March 2011 has led to a burst of research on the role of uncertainty in social and scientific knowledge production. This line of research is not limited to the special uncertainties of radioactive contamination. In fact, from the 1960s to today, a loosely affiliated group of antipollution thinkers and activists have been exploring the relationship of human society to its environment in extremely creative and fruitful ways. Beginning with the methylmercury poisoning called “Minamata disease” of the 1950–70s, this group began what they called “Minamata studies” (Minamatagaku, 水俣学) as a way to develop new modes of analysis and remediation of toxic sites. This article focuses on the key category of the lived site, the genba (現場), and the role it plays in the politics and medicine of environmental disease. Finally, this article explores an apparent repetition compulsion at work in the series of toxic disasters in modern Japanese history from Ashio to Fukushima.