This article examines how politics and with questions of illness, safety, and disposal. To gain science interacted against a background of uncertainty influence over those institutions, dissatisfied individto shape policy in the case of environmental conuals and groups then turned the PBB contamination tamination by polybrominated biphenyls (PBB) in into a political controversy. The final section of the Michigan. In 1973, between 500 and 1,000 pounds of present article analyzes how science and politics interthe flame retardant PBB were accidentally shipped acted in: the ways bureaucratic organizations defined and used instead of the dairy feed additive magnesium the three problems of contamination; the role political oxide, resulting in the widespread contamination of controversy played in redefining problems and influanimal feeds, animals, and human food products. The encing policy; and the political roles of scientists in contamination was initially perceived as the private controversies over environmental contamination. (Am trouble of a single farmer. The problem next became a J Public Health 1983; 73:302-313.) public issue as public and private institutions grappled