On Sunday, 11 July 1976 in the afternoon the Mayor of Seveso, Francesco Rocca, received the visit of two ICMESA technicians who reported to him about an accident that happened the day before inside the factory.
“They were brief in describing the incident – the Mayor recalled – and gave a rather technical description of it. It was the first time I had ever heard about “tetrachlorophenol or TCP.”
«It is a basic intermediate chemical,» Dr. Paoletti immediately explained. «You can also find it at the drugstore, and it serves also as a herbicide. And precisely the reactor that produces this exploded. Nobody really knows why. Yesterday morning at six, the shift ended and as on every Saturday, they had let the reactor cool down. Tomorrow the production of TCP would have resumed as usual if it wasn’t for this uncontrollable reaction inside, which slowly caused the temperature and pressure to rise, until it exploded around midday.»