Seveso Disaster 1976

The Seveso disaster of 1976

The Seveso Disaster of 1976 serves as an example of the critical importance of thorough process safety measures.

Cause

The accident was triggered by the unintended overheating of a reaction mixture in the 2,4,5-trichlorophenol (TCP) production process due to steam condensation in the reactor’s shell. This led to an exothermic reaction, resulting in the formation of TCDD dioxin, leading to a runaway effect (Lees, 1996).

Consequences

Efforts to conceal the causes and the insufficient intervention of those responsible caused a delay in informing the public and a delay in the rescue work resulting in:

• 3,300 animals died, another 78,000 were euthanised.

• Around 5,000 residents required medical supervision due to delayed evacuation.

• "Chlorine acne" in 193 scholars and health issues in others.

• Pregnant women in the area miscarried within the next months.

• TCDD's harmful effects emerged in subsequent years (Jelemenský et al., 2012).

Lesson learnt

The conclusions of the accident investigation revealed the necessity to assess in advance:

• Possibility of side reactions (especially exothermic).

• Possibility of the formation of extremely dangerous substances (toxic, flammable, explosive).

• Chemical reactor design (construction, operating conditions, regulation).

• Sufficiency of protective mechanisms.

• Appropriateness of location of dangerous facilities.

• Threat to the population (public threat control).

• Preparedness for an accident (countermeasures immediately after the occurrence of an accident).

• Training and motivation of workers (compliance with technological regulations) (Jelemenský et al., 2012).

Policy response

In response to the Seveso disaster, the European Union enacted directives known as "Seveso I", later "Seveso II" and "Seveso III". These directives aimed at preventing and controlling industrial accidents proactively, reflecting a commitment to enhancing process safety at a regulatory level (Nerin, et al., 2024).

This tragic event serves as a reminder of the imperative to prioritize process safety across all industrial operations, ensuring the protection of both human life and the environment.

References

Lees F. P. (1996). Lee's loss prevention in the process industries : hazard identification assessment and control (2nd ed.). Boston: Elsevier Butterworth-Heinemann.

Jelemenský et al., (2012).Hodnotenie nebezpečenstva chemických procesov. Bratislava. Slovak University of Technology in Bratislava.

Nerin, C. et al. (2024) The Seveso Disaster and the European Seveso Directives, Elsevier eBooks, pp.477–481. https://doi.org/10.1016/b978-0-12-824315-2.00013-0