Authorizing to prohibit: the manufacture of knowledge about molecules and their risks in the European REACH regulation.

Summary How to regulate chemical substances in spite of old, incomplete, but above all unevenly shared data? Since the adoption of the Toxic Substances Control Act in the United States in 1976, information asymmetries and the multiplication of uses of industrial chemicals seemed to have made their control impossible. To this long unsolvable problem, the European regulation REACH, adopted in 2006, proposes an original answer: the authorization procedure. This thesis examines the way in which the authorization procedure has changed the way in which "prohibition" is carried out, despite the asymmetries of information. This procedure now gives public authorities the possibility of banning "substances" on the basis of their classification, while certain "uses" of these molecules can then be authorized on the basis of individual requests made by companies. In order to continue to use them, these companies then put into circulation toxicological and exposure data and, above all, socio-economic evaluations that had never been produced before. While authorization inherits part of the previous regulatory system, in which regulatory activities involved the production of lists of chemical substances, it above all reconfigures the relationship between public authorities and companies, modifies the objects over which they have control and transforms the ways in which the regulatory knowledge that supports decision making is developed.