Regulatory agencies and industry argue that BPA is harmless 'when used as intended' and that populations' exposure through contaminated food is 'well below levels considered harmful'. It was this concern that Druckrey and Truhaut fuelled and mobilized to try to develop international expertise on food additives and contaminants. Authors will now take a closer look at how this happened, by examining the work carried out within the most visible of these expert committees on food additives and contaminants that depended on international organizations in the late 1950s and early 1960s, the JECFA. After evaluating the work already performed by the JECFA, the Second Joint FAO/WHO Conference on Food Additives, in June 1963, added another task to those of the expert committee: 'To recommend acceptable maximum daily intake levels'. Author's second point is that the analysis of the construction of certain tools for assessing and regulating food additives and contaminants shows the high level of fragility of experts and their expertise.