‘In the absence of adequate data on humans’: animal bioassay and the transnational machinery for controlling carcinogens

Abstract From the 1960s onwards, a growing number of national and international organizations began working to define more precisely what constitutes a carcinogenic exposure. The central question for these new groups of experts soon became what kinds of data authorities should rely on to govern chemicals and their uses. Drawing on new archival material from the World Health Organization’s International Agency for Research on Cancer, this paper examines the dramatic rise and contested decline of the animal bioassay for carcinogenicity in this domain. The legitimation of this type of study was inseparable from the very emergence of the institutional machinery responsible for controlling carcinogens. During the 1970s and 1980s, establishing the animal bioassay as evidence of carcinogenicity became a way for scientific and regulatory institutions to stabilize relations among themselves. But what had been done could also be undone. The validity of animal studies was challenged on the ground of possible high-dose artefacts in rodents, as well as on that of the emergence of new cellular tests promising to be quicker, cheaper and more precise. These criticisms destabilized the institutional order linked to the animal bioassay standard, even as actors managed to contain the threat – allowing these studies to remain at the core of the field.