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close this bookThe Long Road to Recovery: Community Responses to Industrial Disasters (UNU, 1996, 307 p.)
close this folder4 Seveso: A paradoxical classic disaster
View the document(introduction...)
View the documentIntroduction
Open this folder and view contentsOverview
Open this folder and view contentsThe European Community's institutional response to Seveso
Open this folder and view contentsThe lessons of Seveso
View the documentConclusion: ''Seveso'' - A paradoxical symbol
View the documentAcknowledgements
View the documentChronology
View the documentNotes
View the documentReferences



Saturday 10 July. In building B of the ICMESA factory located in Meda, an increase in pressure due to an exothermic reaction in the TCP vessel causes the rupture disk of the safety valve to burst. As a consequence, a toxic cloud escapes into the air.

Sunday 11 July (accident day + 1). ICMESA managers inform local authorities of the escape of a "cloud of herbicide that causes harm to agriculture" (Ufficio speciale... 1984). They state that "in all likelihood the aerosol mixture which escaped consists of sodium trichlorphenate, caustic soda and solvent, but possibly other toxic substances as well" (Roche Magazin 1986) and they request the authorities to warn the population. Samples are sent by courier for examination in Switzerland.

12 July (+2). Nearby residents are warned not to eat any vegetables from their gardens.

14 July (+4). First symptoms on skin of children, and deaths of small animals. According to Roche (Roche Magazin 1986: 10), Dr. Sambeth, the Technical Director of Givaudan in Geneva, informs von Zwehl, the Technical Director of ICMESA, that the samples contain traces of TCDD. Authorities will be informed only much later.

15 July (+5). The factory workers are examined by the factory doctor. The Mayor of Seveso issues "Ordinanza 43," on the basis of indications by the Deputy Health Officer, declaring as contaminated the area to the south of the ICMESA factory (about 12 hectares and 200 residents). Warning signs and fences are to be erected. The Mayor of Meda issues a similar decree. Dr. Giuseppe Reggiani, Director of Clinical Research at Roche Basle, is instructed by the management of Roche to investigate the possible effects of the accident on workers and population and to take necessary measures. During a first meeting in the Municipio (Town Hall), ICMESA managers show maps, but are generally reticent.

16 July (+6). Increasing skin reactions: 13 children hospitalized. The LPIP (Laboratorio provinciale di igiene e profilassi) begins to collect vegetable samples for analysis. The Mayor of Seveso informs Il Giorno, a national newspaper. During a meeting in the Municipio, the ICMESA managers show new maps, indicating concentrations which they judge below the danger threshold for humans (Rocca 1980). They claim ignorance of the substance involved. Factory workers mobilize and accuse authorities of hiding facts. The local prefecture (representing the national government) is called in by the Mayor; they support his actions.

17 July (+7). First articles in the national press based in Milan (Il Giorno, Corriere della Sera). According to Roche accounts, the ICMESA Technical Director announces the release of dioxin (Roche Magazin 1986: 12). According to other sources, this information was delivered a few days later (see below, Pocchiari, Silano, and Zapponi 1987).

18 July (+8). The investigating magistrates seal building B of ICMESA, where the accident occurred. The Mayor of Meda orders that all other buildings are sealed as well. First news of the accident on television.

19 July (+9). For the first time, Givaudan admits that TCDD was found, in notification to local authorities (Pocchiari, Silano, and Zapponi 1987).

20 July (+10). In Geneva, Givaudan makes a public statement on the accident and the Givaudan chemists confirm, to the public health doctors caring for the children, that TCDD was found; they send a map showing where dioxin was found. The Mayor of Seveso hears for the first time that dioxin may be involved. This comes from a television journalist who was informed by a doctor at a research institute in Milan. In the evening this was confirmed by the Health Officer, who had gone to Zurich to get information. He decides not to release this information at the meeting that same evening in the Municipio (Rocca 1980).

21 July (+11). Banner headlines in the newspapers. The Technical Director and the Director of Production of ICMESA are arrested. The public health doctors inform the prefecture of Milan, who call a meeting with the Regional Health Department for 24 July. According to Roche Magazin (1986: 12), Dr. Reggiani contacts other companies that had accidents with dioxin and recommends evacuation to the Italian authorities. The Head of the Regional Health Department is reluctant. First official press release from the Lombardy Region. The Milan Province offers assistance; subsequently they are put in charge of decontamination.

22 July (+12). Eighty children from Seveso are sent away to a holiday camp belonging to the province. A census of all dead animals is ordered. A dermatological clinic is opened in Seveso to monitor exposed people.

23 July (+13). Dr. Reggiani has the first meeting with the authorities, including the Head of the Regional Health Department. With the Mayor of Seveso, he insists on an evacuation (Roche Magazin 1986: 12). For the first time, the mayors of Desio and Cesano Maderno are involved (Rocca 1980).

24 July (third week). First meeting at the Lombardy regional government office, chaired by the Head of the Regional Health Department, with experts, civil servants, and scientists of the Region, along with those of the LPIP, the national Ministry of Health, the ISS (Istituto Superiore della Sanit and a representative of Givaudan. The so-called zone A (more than 50 micrograms of TCDD per square metre), about 15 hectares, was defined for evacuation, fencing-off, and prohibited entry. (Later, zone A was further divided into seven subzones according to the severity of contamination. The evacuated people often violated the zone, and on two occasions, in October and December, reoccupied their homes.) First public meeting.

26 July. Local authorities with the aid of armed forces accomplish the evacuation of 225 people (170 from Seveso, 55 from Meda). Following new laboratory results, it was decided to extend the evacuation zone, enlarging the area to 71.8 hectares. Approximately 3,300 animals died. Many others will eventually be slaughtered, a total of 81,000.

28 July. The Regional Health Department establishes four committees of scientific and technical experts to investigate different aspects of the accident. Their tasks are to define health problems and define measures for protection of public health; to define procedures for data, sampling, and interpretation; to study decontamination measures; and to investigate causes of animal deaths.

29 July. The contamination zone is further extended to 108 hectares and a total of 730 people are evacuated; 198 families are temporarily housed in two "residences" in the suburbs of Milan and in hotels and private houses in the vicinity of the affected area.

2 August (fourth week). Following further tests, a second zone (B) is defined (between 5 and 50 micrograms per square metre), comprising about 270 hectares in the municipalities of Cesano Maderno and Desio. Regional authorities decree that children under 12 and pregnant women within the third month should not stay in the affected area during the day. Strict rules are issued on food and water consumption. All productive activities are suspended in zone B. Health authorities give consent to abortion, in spite of its illegality at the time. Therapeutic abortion was allowed in special cases, including pregnancies that would be psychologically traumatic for the mother, following the judgement of the Constitutional Court no. 27 of 18 February 1975. (This case was later used politically in the debate that resulted in the law 194 of 1988, which legalized abortion, later confirmed by a popular referendum in 1981.)

4 August. The President of the Italian Council of Ministers nominates a governmental technical-scientific commission, to explore possible decontamination measures. It will be known as "Commissione Cimmino," after its Chairman.

5 August. First regional legislation to aid the affected population.

10 August (second month). The Italian government grants a loan of 40 billion liras to the region to finance necessary measures (it was raised to 115 billion in 1978).

11 August. In a press conference in Geneva, Roche commits itself to cover the costs of the damage.

13 August. The regional government sets up the Giovanardi Commission, which is to implement the proposals of the national Cimmino Commission.

14 August. The Cimmino Commission recommends the establishment of a third zone (R; 1400 hectares), where levels of contamination are below 5 micrograms per square metre.

15 August. The Regional Health Department completes the mapping of the affected zones. The epidemiological monitoring was extended to five more municipalities (Lentate sul Seveso, Seregno, Varedo, Muggiova Milanese), for a total of 220,000 inhabitants. First cases of chloracne (there would eventually be 193, some very serious, taking years to clear, with permanent scars).

August-December. Several measures for decontamination are suggested and attempted (e.g. spreading of olive oil preparations on contaminated lots). The region studies the possibility of constructing a high-temperature incinerator in the area. The affected communities react angrily: the region joins Givaudan as the enemies to be fought by local residents. An agreement is reached between Lombardy and Givaudan for removal and disposal of chemicals and raw materials from the factory. The ICMESA workers are re-employed in the area.


January (six months after disaster). Decontamination work begun, to enable resumption of productive activities: removal of leaves, grass, and agricultural produce. Decontamination of schools. Hydrological studies; studies of incineration plant. Experimental studies for rehabilitation of buildings in zones furthest from ICMESA. Holidays and financial aid for special classes: children, pregnant women, elderly people.

February. First compensation payments made by ICMESA to private individuals.

Spring. Public protest about unorthodox methods of cleaning adopted by Milan Province; much pressure on President of province (Rocca 1980).

June. The region sets up the Ufficio Speciale di Seveso (Special Bureau for Seveso), located first in Seveso, then in Milan. It is responsible for putting the five action programmes into practice. (Closed in 1987, archive established in 1992.)

July (one year after disaster). Official promulgation of special legislation for Seveso (Regione Lombardia 1977), articulating five operational programmes: (1) analysis of soil, water, and vegetation plus measures for reclamation; (2) aid and medical monitoring programmes in the health sector; (3) social and educational aid; (4) rehabilitation of buildings; (5) aid for trade and industry.

Epidemiological monitoring programmes established as follows (with termination dates): abortions (1982); malformations (1982); tumours (1997); deaths (1997). Health monitoring of workers at ICMESA and on decontamination projects, and chloracne sufferers (1985).

Laboratory research undertaken, to improve knowledge of metabolic and toxic effects, for later development of health monitoring programmes.

Ghetti, Head of the Seveso Health Department, shot in the legs in a terrorist attack.

September. International Steering Committee established to assess toxicological and epidemiological data and findings of the monitoring programme. This was officially named "comitato dei garanti," as it represented international scientific authority and probity. Parliamentary Committee of Enquiry established.

October. Decontamination of zone A; return of first 511 evacuated persons. Decision to demolish most heavily contaminated houses and to rebuild. Start of decontamination of zone B


July (two years after disaster). Report by Parliamentary Committee of Enquiry, criticizing ICMESA and regional authorities. Settlements of private claims, the majority amicably, out of court.


Decontamination continues. Zone R released for agricultural use. After long negotiations, an agreement between ICMESA, the Italian Government, and the Lombardy Region on the settlement of claims is signed. Poletti, the Director of Production at ICMESA at the time of the accident, is shot and killed in a terrorist attack. Disposal site in zone A approved by the Cimino Committee.

1981 (five years after disaster)

Out-of-court settlement with the municipalities of Desio and Cesano Maderno: ICMESA pays 1.45 and 2.85 billion liras, respectively. Preparation of plan for disposal of contaminated building B of ICMESA by ENEA (Italian state energy agency).


June. Start of the mystery of the lost barrels of contaminated materials. According to Roche Magazin (1986: 18), they were eventually discovered in a barn in France.

September. Reactor where explosion occurred, emptied. Out-of-court settlement with Meda (ICMESA pays 1.3 billion liras).


Out-of-court settlement with Seveso (ICMESA pays 15 billion liras).


Health Report of the International Steering Committee: no human effects other than 193 cases of chloracne. Decontamination of zone A totally completed; zone B authorized for construction. Incineration of barrels begins in Switzerland; in the following year, officially said to be completed (see December 1992).


Court of Appeals in Milan confirms criminal convictions of two of the five accused - the Director of ICMESA and the Technical Director of Givaudan. Demolition of the ICMESA premises, converted to a public park and community facilities.

1991 (15 years after disaster)

September. The newspaper La Repubblica (1991) reports a judgement by the civil court of Milan, requiring Givaudan to pay 2 million lira to each of 21 inhabitants of the zones B and R. for their material and psychological injuries. The plaintiffs belonged to a committee called "5d," composed of 300 citizens who were initially excluded by the courts from the civil suit for damages because they had not suffered material harm. They were disappointed by the amount awarded and will appeal. But they are satisfied by the court's acceptance of the principle that any exposed person is potentially entitled to damages. The court's judgement states: "The exposure to an unknown quantity of dioxin, the restrictions on liberty of actions and of life, the oppressive public-health measures, all constitute causes for disturbance and moral damage." Their advocate had argued that they had suffered inconvenience and distress caused by the discrimination they had experienced merely because they were from Seveso.


December. The newspaper Il Corriere della Sera (1992) reports on a documentary on German television channel "Ard." They spoke of 150 tons (336,000 lb) of dioxincontaminated material that had been put in a dump in Schoenberg, in the former East Germany, by the Italian firm Mannesmann, and which were described in the documents as "sodium chloride," or salt. According to the German television programme, the supposed destruction in Switzerland was only a diversion. The region of Mecklenburgh-Pomerania, where Schoenberg is located, has started an enquiry, requesting the participation of the Italian and French authorities.


March. The newspaper Il Corriere della Sera (Magni 1993) reports that 850 citizens of the contaminated area have started legal procedures against Givaudan in order to be compensated for "moral and biological" damage.

November. On the initiative of the regional Director for the Environment, the Lombardy regional government nominates a Commission of Enquiry, with powers to re-examine the Seveso archives, with special reference to three issues. The first is the amount of dioxin released: it was generally accepted that some 200-300 grams were emitted, but even at the time some experts spoke of much higher quantities, even 40 kg or more. The second point concerns the 41 barrels: the official story that they had been burned in Basle has been questioned by the discovery of a stock of similar barrels in a site in Schoenberg. Third, what was ICMESA really producing? This question may be very difficult to answer.