Abstract. The Precautionary Principle implies the adoption of a set of rules aimed at avoiding possible future harm associated with suspected, but not ascertained, risk factors. Several philosophical, economical and societal questions are implied by precaution-based public health decision making. The purpose of the present paper is to specify the scope of the principle examining the notion of uncertainty involved, and the implication of different approaches to the decision-making process. The Bayesian-utilitarian approach and the approach based on the maximin principle will be considered, and the different meaning of prudence in the two settings will be discussed. In the Bayesian-utilitarian approach the small number of attributable cases will end up in a low average expected value, easily regarded as acceptable in a cost-benefit analysis. In a maximin approach, on the other hand, the issue will be to consider the high etiologic fraction of a rare disease in the highest category of exposure. In the light of the aforementioned cautions in interpretation, the core difference between the two approaches has to do with the choice between averaging knowledge or equitably distributing technological risks. The Precautionary Principle implies adoption of a set of rules aimed at avoiding possible future harm associated with suspected, but not ascertained, risk factors A recent World Health Organization (WHO) workshop extensively discussed a central issue in the implementation of the Precautionary Principle, namely to define what is meant by "prudent approach to risk" [2]. It was stated, among other things, that adoption of the Precautionary Principle implies some sort of immediate action followed by a second stage of undertakings, including scientific investigations and search for alternatives. Action inspired by precaution is characterized by uncertainty, and the policy framework should thus regularly be reviewed
