This paperwork deals with the social construction process of the international norm in the chemical safety realm. The point of departure was a local reality -- the occurrence of a major industrial accident --- and its impacts on the international environment. The perception of that reality as a social fact, constructed from a wider environmental awareness or collective acquiescence, was essential. The constitution of that collective awareness is part of the referred social construction process and was politically strengthened by the international community when it assembled in the Stockholm Convention (1972) and the Rio Convention (1992). Following certain constructivist theoretical parameters, the wider ideational and normative scenario, related to environmental questions in the contemporary international relations, was first analysed. Afterwards, the focus was directed towards the social construction of the accident and the norm negotiated. In relation to the civil society organisation and mobilisation, as well as to its influence on state behaviour, it was given emphasis on the role of agents of environmental protection and chemical safety ideas and its organisational platforms. As per its social and empirical importance, it was chosen as object of analysis the major industrial accident, occurred in 1984, in Bhopal, India, and the Convention 174 of the International Labour Organization concerning the Prevention of Major Industrial Accidents.