ABSTRACT
The notorious name of Seveso reminds that the chemical industry has been dramatically affected by several accidents that resulted in the formation and dispersion of undesired products as a consequence of the loss of control of chemical processes. As a matter of fact, a large number of undesired products may be formed and released as a consequence of ‘‘out of control’’ conditions in a chemical system of industrial interest. The ‘‘secondary substances’’ that may be formed may be very different from the substances present in normal operating conditions, and in particular may be more harmful for the humans and the environment. Although the negative consequences of these events are confirmed by the experience (e.g. the Seveso accident), a throughout analysis of this kind of accidental scenarios is seldom undertaken in the safety assessment of industrial processes. As a matter of fact, even the actual understanding of the hazards of the potential accidents may result quite difficult. No robust and widely accepted assessment method exists up to date for the comparison between the hazards of the original substances and those of their decomposition products. All this, despite the inherent hazards connected to the possible decomposition products and to the possible
undesired reactions, is one of the elements that should be considered in the Material Safety Data Sheets of the substances and in the plant inventory, according to the European Directives 67/548/EEC and 96/82/EC.
