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 the undesired formation and release of hazardous substances. In particular, substances that are more dangerous than the original ones may be formed, as occurred in the well known Seveso accident. Nevertheless, no robust and widely accepted method yet exists to characterize the compounds that may be formed in the loss of control of chemical systems. The present contribution focused on the analysis of the inherent hazard due to the possible unwanted formation of hazardous decomposition products. A specific set of experimental protocols is defined, based on the coupling of different calorimetric and analytical techniques for the identification of the products that may be formed in the loss of control of a chemical process. The results were the input to a hazard assessment procedure aiming to quantify the potential risk deriving from the possible emission of dangerous compounds formed in the loss of control of chemical systems. The hazard assessment is based on toxicological, physical and chemical properties of the substances and allows the assessment of an hazard footprint of the decomposition products, based on the description of their behaviour with respect to specific endpoints: acute toxicity, ecotoxicity, chronic toxicity and carcinogenicity. The application of the approach described to specific case-studies confirms the effectiveness of the tool for the assessment and the comparison of the hazards deriving by undesired release of substances in accidental scenarios.