Assessment of the hazard footprint of substances formed in the loss of control of chemical systems

The analysis of past accidents involving chemical systems shows that the loss of control of a chemical process often results to lead to undesired release of substances. In particular, substances that are more dangerous than the original ones may be formed, as dramatically occurred in Seveso in 1976. Nevertheless, no robust and widely accepted method still exists to characterize the compounds that may be formed under accidental conditions and to assess their inherent hazards. The present study addresses the issue on two levels. Firstly, a specific set of experimental protocols is defined on the base of different calorimetric and analytical techniques for the identification of the products suspected to be formed in the loss of control of a chemical process. Then, a parametric approach for the assessment of the hazards deriving from the emission of dangerous compounds is introduced. The hazard assessment is based on toxicological, physical and chemical properties of the substances and it allows to describe the behaviour of a compound with respect to specific endpoints: acute toxicity, ecotoxicity, chronic toxicity and carcinogenicity. A simplified approach based on the chemical structure of the substances is also proposed in case of lack of data. The application of the described approach confirms the tool effectiveness for the assessment and the comparison of the hazards deriving by undesired release of substances in accidental scenarios.