Abstract
Quantitative health risk assessment is a procedure for estimating the likelihood that exposure to environmental contaminants will produce certain adverse health effects, most commonly cancer. One instance of its use has been a California air toxics public “right-to-know” law. This article examines the ways in which credible health risk measurements were produced and challenged during the implementation of the California public policy. Fieldwork and documentary analysis finds that stakeholders negotiated within the formal constraints of the risk assessment procedures but still expressed their competing visions for the implementation of the risk communication policy. The abstract results of the method were contextualized according to different time frames and allocations of uncertainty. Furthermore, the article demonstrates that the political process privileged consistency of measurement over accuracy, revealing political negotiations at a fundamentally technical level. The struggle and variation in interpretations can be explained best by the demand to organize the program around the discordant values of democratic accountability and technical efficiency.