2. INTRODUCTION 10 July 1976 Seveso, Lombardy, Italy ICMESA (Industrie Chimiche Meda Società Azionaria) Run-away reaction Desired product :2,4,5 trichlorophenol sodium salt (TCP) side product :2,3,7,8 tetrachloro dibenzo dioxin (TCDD) Death toll : no people died as an immediate result,Around 3,300 domestic animals (including poultry) perished within days and another 80,000 were slaughtered

3. Company Overview ICMESA (Industrie Chimiche Meda Società Azionaria) subsidiary of Givaudan, which in turn was a subsidiary of Hoffmann-La Roche (Roche Group) : A swiss company ICMESA had manufactured 2,4,5-trichlorophenol (TCP) since 1971 TCP a toxic substance used in herbicides and for the preparation of cosmetics.

4. TCP 2,4,5 tri chloro phenol sodium salt used in medicated soaps, shampoos and cosmetics manufactured by alkaline hydrolysis of 1,2,4,5 tertachloro benzene reaction is carried out temp about 135- 160 0 C

5. TCDD 2,3,7,7 tetrachlorodibenzo paradioxin dioxin have no common uses highly toxic formed as a by product in the manufacturing of TCP (herbisides) Absorbed by plants and soil

6. TCDD formation Reaction

7. Manufacturing method of TCP Tetrachlorobenzenes is heated to 135 to 160 0 C Reaction with NaOH Solvent is ethylene gycol xylene addition and azeotropic distillation at 160 0 C Removal of remaining xylene by distillation 50% ethylene glycol recovery under reduced pressure conditions Termination of manufacturing by cooling the product to 50 0 C by addition of water

8. Reactor Design

9. What actually went wrong ? Stopping of the uncompleted process Addition of water was not carried out hence temp remained 158 0 C Stopping of agitation process and cooling process. Operator left the site

10. UNDESIRED REACTION Steam valve was closed so superheated steam present in the jacket continued to heat the reactor Stopping of agitation caused the local temp rise Triggering of an Exothermic reaction Rupture disc operation Release of the gas containing TCP, TCDD to the atmosphere

11. Chemical Events Operation course leading to leakage At 8:00 PM Friday july 9, 1976 batch reaction which caused the incident is started At 4:37 AM Saturday july 10,1976 reaction and distillation process of the batch finished (only 15% recovery of glycol) steam valve was closed and agitation was stopped and plant was shut down during the weekend according to Italion law and the Operator went home At 12:37 PM rupture disc suddenly operated and reactor contents began to leak

13. Cause of Operation of Rupture Disc and Leackage of Contents At that time it was thought runaway reaction would not occur temp less than 230 0 C so operator stopped the operation at 158 0 C. Further it was found in research exothermic reaction can occur at 180 0 C Superheated steam remained in the jacket continued to heat the liquor and cause the temp increase over 180 0 C locally. An exothermic reaction began in the liquid and expanded throughout the reactor

14. Continued..... Rupture Disc was directy open to the atmosphere. Company did not refer to other accidents that had occured before this accident so it is thought that the contravention of instructions might not happen either and study had not been conducted seriously. There were at least 14 other similar accidents at other TCP manufacturing plants at minor scale. 1949 Monsanto (USA); 1953 BASF (Germany); 1960 Dow Chemicals (USA); 1963 Phillips Duphar (Netherlands); 1968 Coalite Chemical Productions (UK)

15. Course after the Leakage July 10, 1976 technical manager of the company advised the locals not to touch or eat locally grown fruits and vegetables. On Monday july 12,1976 first signs of health hazard appeared By july 14th Locals hospitals were filled with patients. On july 15th the parent company found a high concentration of TCDD in the leacked material but did not announce this outside the company including the local government untill they reconfirmed the existence of TCDD on 20th july. on 24th july local government ordered the evacuation from the A area and further it was expanded

16. Zone A had a TCDD soil concentration of > 50 micrograms per square metre (µg/m²), it had 736 residents. Zone B had a TCDD soil concentration of between 5 and 50 µg/m², it had about 4700 residents. Zone R had negligible or a TCDD soil concentration of < 5 µg/m², it had 31,800 residents.

17. Immediate Effects Within days a total of 3,300 animals, mostly poultry and rabbits, were found dead. Emergency slaughtering commenced to prevent TCDD from entering the food chain, and by 1978 over 80,000 animals had been slaughtered. 15 children were quickly hospitalised with skin inflammation By the end of August, Zone A had been completely evacuated and fenced, 1,600 people of all ages had been examined and 447 were found to suffer from skin lesions or chloracne and blurred vision. Italian government allotted 40 billion lire (US $47.8 million) for quarantining and decontaminating the area. This amount would be tripled two years later.

18. Long Term Effects A study published in 1998 concluded that chloracne was the only effect established with certainty. Early health investigations including liver function, immune function, neurologic impairment, and reproductive effects yielded inconclusive results. An excess mortality from cardiovascular and respiratory diseases was uncovered, and excess of diabetes cases was also found. Results of cancer incidence and mortality follow- up showed an increased occurrence of cancer of the gastrointestinal sites and of the lymphatic and hematopoietic tissue. A 2001 study confirmed in victims of the disaster, that dioxin is carcinogenic to humans and corroborate its association with cardiovascular- and endocrine-related effects. In 2009, an update including 5 more years (up to 1996) found an increase breast cancer. Seveso and its residents continue to function as a kind of "living laboratory" into the effects of dioxin exposure on people and animals

19. ompensation and Criminal Court Case Compensation and Criminal Court Case On 17 december 1980 Italian Republic and Givaudan/ICMESA signed a compensation agreement in the presence of the prime minister of Italy, Arnaldo Forlani. The total amount would reach 20 billion lire (approx 24 million USD) On September 1983, the Criminal Court of Monza sentenced five employees of ICMESA or its parent company, Givaudan, to prison sentences ranging from 2.5 years to 5 years. They all appealed. In May 1985, the Court of Appeal in Milan found three of the five accused not guilty; the two was still facing prosecution appealed to the Supreme Court in Rome. On May 23, 1986, the Supreme Court in Rome confirmed the judgment against the two remaining defendants.

20. Aftermath ICMESA was completely shut down. Industrial safety regulations were passed in the European Community in 1982 called the Seveso Directives Purpose of the “Seveso” Directive is to set up a procedure to ensure that major hazards are prevented and that their consequences are mitigated.

21. Seveso Directives Operators should have a general obligation to take all necessary measures to prevent major accidents, to mitigate their consequences and to take recovery measures. The operator should provide competent authourity a safety report. The Safety Report should contain details of …. possible major accident scenarios and risk analysis, prevention and intervention measures and the management systems available in order to prevent and reduce the risk

22. Safety Report Contents ? The Safety Report shall provide Information on the management system and the organisation; Information on the Plant and the Site; Information on the technological and process aspects; Identification and accidental risk analysis and prevention methods; Information on measures for protection and mitigation.

24. References 1) Explosion of chemical plant in seveso, Italy, Mitsuo kobayashi, failur knowledge database 2) http://www.legislation.gov.uk/uksi/2015/483/contents/made 3) Sharing Experience in Process Safety and SEVESO Directive,Giovanni Uguccioni, 2014 4)B. De Marchi; S. Funtowicz; J. Ravetz. "4 Seveso: A paradoxical classic disaster". United Nations University 5)https://www.siznursing.be/index.php?preaction=joint&id_joint=7179 0

25. Thank you !