Seveso disaster
The Seveso disaster was an industrial accident that occurred around 12:37 pm July 10, 1976, in a small chemical manufacturing plant approximately 15 km (9.3 mi) north of Milan
Milan is the second-largest city in Italy and the capital city of the region of Lombardy and of the province of Milan. The city proper has a population of about 1.3 million, while its urban area, roughly coinciding with its administrative province and the bordering Province of Monza and Brianza ,...

 in the Lombardy
Lombardy is one of the 20 regions of Italy. The capital is Milan. One-sixth of Italy's population lives in Lombardy and about one fifth of Italy's GDP is produced in this region, making it the most populous and richest region in the country and one of the richest in the whole of Europe...

 region in Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

. It resulted in the highest known exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in residential populations which gave rise to numerous scientific studies and standardized industrial safety regulations. The EU industrial safety regulations are known as the Seveso II Directive.


The Seveso disaster was so named because Seveso
Seveso is a town and comune in the Province of Monza and Brianza, in the Region of Lombardy. The economy of the town has traditionally been based around the furniture industry....

, with a population of 17,000 in 1976, was the community most affected. Other affected neighbouring communities were Meda
Međa is a village located in the Žitište municipality, in the Central Banat District of Serbia. It is situated in the Autonomous Province of Vojvodina...

 (19,000), Desio
Desio is a town and comune in the Province of Monza and Brianza, Italy.-History:In 1277 it was the location of the battle between the Visconti and della Torre families for the rule of Milan. It is also known as the birthplace of Pope Pius XI and the Arsenal goalkeeper, Vito Mannone...

 (33,000), Cesano Maderno
Cesano Maderno
Cesano Maderno is a town and comune of c. 37,110 inhabitants in the province of Monza and Brianza, Lombardy, northern Italy. The town borders with the towns of Seveso in the North, in the South with Bovisio-Masciago, in the East with Desio and Seregno, and in the west with Ceriano Laghetto and...

 (34,000) and to a lesser extent Barlassina
Barlassina is a comune in the Province of Monza and Brianza in the Italian region Lombardy, located about 20 km north of Milan.-External links:*...

 (6,000) and Bovisio-Masciago
Bovisio-Masciago , is a comune in the Province of Monza and Brianza in the Italian region Lombardy, located about 15 km north of Milan.-Geography:...

 (11,000). The industrial plant, located in Meda, was owned by the company ICMESA (Industrie Chimiche Meda Società Azionaria), a subsidiary of Givaudan
Givaudan is a Swiss manufacturer of flavorings and fragrances. As of 2008, it is the world's largest company in the industry.-Background:The company's scents and flavors are developed most often for food and beverage makers, but they are also used frequently in household goods, as well as grooming...

 which in turn was a subsidiary of Hoffmann-La Roche
Hoffmann-La Roche
F. Hoffmann-La Roche Ltd. is a Swiss global health-care company that operates worldwide under two divisions: Pharmaceuticals and Diagnostics. Its holding company, Roche Holding AG, has shares listed on the SIX Swiss Exchange....

 (Roche Group). The factory building had been built many years earlier and the local population did not perceive it as a potential source of danger. Moreover, although several exposures of populations to dioxins had occurred before, mostly in industrial accidents, they were of a more limited scale.

Chemical events

The accident occurred in building B. The chemical 2,4,5-trichlorophenol
A trichlorophenol is any organochloride of phenol that contains three covalently bonded chlorine atoms. Trichlorophenols are produced by electrophilic halogenation of phenol with chlorine. Different isomers of trichlorophenol exist according to which ring positions on the phenol contain chlorine...

 (2) was being produced there from 1,2,4,5-tetrachlorobenzene (1) by the nucleophilic aromatic substitution
Nucleophilic aromatic substitution
right|300px|Aromatic nucleophilic substitutionA nucleophilic aromatic substitution is a substitution reaction in organic chemistry in which the nucleophile displaces a good leaving group, such as a halide, on an aromatic ring...

 reaction with sodium hydroxide. The 2,4,5-trichlorophenol was intended as an intermediate for hexachlorophene
Hexachlorophene, also known as Nabac, is a disinfectant. The compound occurs as a white to light-tan crystalline powder, which either is odorless or produces a slightly phenolic odor. In medicine, hexachlorophene is very useful as a topical anti-infective, anti-bacterial agent, often used in soaps...

, although it can also be used as an intermediate for the herbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...

 2,4,5-T (2,4,5-trichlorophenoxyacetic acid
2,4,5-Trichlorophenoxyacetic acid
2,4,5-Trichlorophenoxyacetic acid , a synthetic auxin, is a chlorophenoxy acetic acid herbicide used to defoliate broad-leafed plants. It was developed in the late 1940s and was widely used in the agricultural industry until being phased out, starting in the late 1970s due to toxicity concerns....


This reaction must be carried at a temperature above that of the normal process utilities that were available, so it was decided to utilize the exhaust steam from the electricity turbine on site, and pass that around an external heating coil on the reactor. This exhaust steam was at 12 bar and 190°C, resulting in a reaction mixture at 158°C (with a boiling point of 160°C). Safety testing showed onset of an exothermic
Exothermic reaction
An exothermic reaction is a chemical reaction that releases energy in the form of light or heat. It is the opposite of an endothermic reaction. Expressed in a chemical equation:-Overview:...

 side reaction at 230°C. On this occasion the batch process was interrupted prior to finishing the final step of removal of ethylene glycol
Ethylene glycol
Ethylene glycol is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colorless, syrupy, sweet-tasting liquid...

 by distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....

, due to an Italian law requiring shutdown of plant operations over the weekend. Other parts of the site started to close down as batches finished, and no more were started. This caused the load on the turbine to fall dramatically, resulting in the exhaust steam temperature rising to around 300°C, heating the reactor wall above the level of the liquid to the same temperature. (No steam temperature reading was available to the plant operators.) This batch was then stopped by isolating the steam, and turning off the stirrer. The residual heat in the jacket then heated the upper layer of the mixture next to the wall to the critical temperature (which was actually only 180°C, 50°C lower than believed), starting a slow runaway decomposition, and after seven hours a rapid runaway reaction
Thermal runaway
Thermal runaway refers to a situation where an increase in temperature changes the conditions in a way that causes a further increase in temperature, often leading to a destructive result...

 ensued when the temperature reached 230°C.

The relief valve eventually opened and 6 tonnes of material were distributed over an 18 km² (6.9 sq mi) area, including 1 kg of 2,3,7,8-tetrachlorodibenzodioxin
2,3,7,8-Tetrachlorodibenzo-p-dioxin is a polychlorinated dibenzo-p-dioxin . It is the most potent compound of the series and became known as a contaminant in Agent Orange, a herbicide used in the Vietnam War, as well as the Seveso disaster...

 (TCDD) (3) – which is normally seen only in trace amounts of less than 1 ppm (parts per million). However, in the higher-temperature conditions associated with the runaway reaction, TCDD production apparently reached 100 ppm or more.

Immediate effects

The affected area was split into zones A, B and R in decreasing order of surface soil concentrations of TCDD. Zone A was further split into 7 sub-zones. The local population was advised not to touch or eat locally grown fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

s or vegetable
The noun vegetable usually means an edible plant or part of a plant other than a sweet fruit or seed. This typically means the leaf, stem, or root of a plant....

  • 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.

Within days a total of 3,300 animals were found dead, mostly poultry and rabbits. Emergency slaughtering commenced to prevent TCDD from entering the food chain
Food chain
A food web depicts feeding connections in an ecological community. Ecologists can broadly lump all life forms into one of two categories called trophic levels: 1) the autotrophs, and 2) the heterotrophs...

, 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
Chloracne is an acne-like eruption of blackheads, cysts, and pustules associated with over-exposure to certain halogenated aromatic compounds, such as chlorinated dioxins and dibenzofurans...

. An advice center was set up for pregnant women of which only 26 opted for an abortion, which was legal in special cases, after consultation. Other 460 women brought on their pregnancies without problems, their children not showing any sign of malformation or pathologies. Herwig von Zwehl (Technical Director of ICMESA) and Paolo Paoletti (director of production at ICMESA) were arrested. Two government commissions were established to develop a plan for quarantining and decontaminating the area, for which the Italian government allotted 40 billion lire. This amount would be tripled two years later.

Studies on immediate and long-term health effects

A 1991 study
14 years after the accident sought to assess the effects to the thousands of persons that had been exposed to dioxin. The most evident adverse health effect ascertained was chloracne
Chloracne is an acne-like eruption of blackheads, cysts, and pustules associated with over-exposure to certain halogenated aromatic compounds, such as chlorinated dioxins and dibenzofurans...

 (193 cases). Other reversible early effects noted were peripheral neuropathy and liver enzyme induction. The ascertainment of other, possibly severe sequelae of dioxin exposure (e.g., birth defects) was hampered by inadequate information; however, generally, no increased risks were evident.

A study published in 1998
concluded that chloracne (nearly 200 cases with a definite exposure dependence) 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, possibly related to the psychosocial
For a concept to be psychosocial means it relates to one's psychological development in, and interaction with, a social environment. The individual needs not be fully aware of this relationship with his or her environment. It was first commonly used by psychologist Erik Erikson in his stages of...

 consequences of the accident in addition to the chemical contamination. An 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. Results cannot be viewed as conclusive, however, because of various limitations: the lack of individual exposure data, short latency period, and small population size for certain cancer types.

A 2001 study
observed no increase in all-cause and all-cancer mortality. However, results support that dioxin is carcinogenic to humans and corroborate the hypotheses of its association with cardiovascular- and endocrine-related effects. In 2009, an update including 5 more years (up to 1996) found the expected increase in "lymphatic and hematopoietic tissue neoplasms" and increased breast cancer.

Cleanup operations

In January 1977, an action plan consisting of scientific analysis, economic aid, medical monitoring and restoration/decontamination was completed. Shortly after ICMESA began to pay the first compensations to those affected. Later that spring decontamination operations were initiated and in June a system epidemiological health monitoring for 220,000 people was launched. In September The International Steering Committee was created, staffed with "renowned experts from all over the world", in order to assess the scientific data generated. In February, 1984 The International Steering Committee released its final report stating that "with the exception of chloracne, no ill effects can be attributed to TCDD".

In June 1978, the Italian government raised its special loan from 40 to 115 billion lire. By the end of the year most individual compensation claims had been settled out of court. On February 2, 1980 Paolo Paoletti - the Director of Production at ICMESA - was shot and killed in Monza
Monza is a city and comune on the river Lambro, a tributary of the Po, in the Lombardy region of Italy some 15 km north-northeast of Milan. It is the capital of the Province of Monza and Brianza. It is best known for its Grand Prix motor racing circuit, the Autodromo Nazionale Monza.On June...

 by a member of the Italian radical left-wing terrorist organization Prima Linea
Prima Linea
Prima Linea was an Italian Marxist-Leninist terrorist group of the 1970s. It was formed in 1976 by members of hard-line factions within the far left, extra-parliamentary organization Lotta Continua, which disbanded that year, together with members of Potere Operaio and of other far left groups...

. On December 19, 1980 representatives of the Region of Lombardy/Italian Republic and Givaudan/ICMESA signed a compensation agreement in the presence of the prime minister of Italy, Arnaldo Forlani
Arnaldo Forlani
This article is about the Italian legislator. For the similar name used as an alias by terrorist Ramzi Yousef for Philippine Airlines Flight 434, see Ramzi Yousef....

. The total amount would reach 20 billion lire
Italian lira
The lira was the currency of Italy between 1861 and 2002. Between 1999 and 2002, the Italian lira was officially a “national subunit” of the euro...


Waste from the cleanup

The waste from the clean up of the plant was a mixture of protective clothing and chemical residues from the plant. This waste was packed into waste drums which had been designed for the storage of nuclear waste. It was agreed that the waste would be disposed of in a legal manner.

To this end, in spring 1982, the firm Mannesmann Italiana was contracted to dispose of the contaminated chemicals from Zone A. Mannesmann Italiana made it a condition that Givaudan would not be notified of the disposal site which prompted Givaudan to insist that a notary public certify the disposal. On September 9 41 barrels of toxic waste left the ICMESA premises. On December 13, the notary
Notary public
A notary public in the common law world is a public officer constituted by law to serve the public in non-contentious matters usually concerned with estates, deeds, powers-of-attorney, and foreign and international business...

 gave a sworn statement that the barrels had been disposed of in an approved way.

However, in February 1983, the programme "A bon entendeur" on Télévision Suisse Romande
Télévision Suisse Romande
Télévision Suisse Romande is a TV network with 2 channels: TSR 1 and TSR 2. They are the main French language channels in Switzerland, part of SRG SSR idée suisse...

, a French language
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...

Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

 TV channel, followed the route of the barrels to Saint-Quentin
Saint-Quentin, Aisne
Saint-Quentin is a commune in the Aisne department in Picardy in northern France. It has been identified as the Augusta Veromanduorum of antiquity. It is named after Saint Quentin, who is said to have been martyred here in the 3rd century....

 in northern France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 where they disappeared. A public debate ensued in which numerous theories were put forward when it was found that Mannesmann Italiana had hired two subcontractors to get rid of the toxic waste. On May 19 the 41 barrels were found in an unused abattoir (slaughterhouse) in Anguilcourt-le-Sart
Anguilcourt-le-Sart is a commune in the department of Aisne in Picardy in northern France.-Population:-References:*...

, a village in northern France. From there they were transferred to a French military base near Sissonne
Sissonne is a commune in the Aisne department in Picardy in northern France.-Population:...

. The Roche Group (parent firm of Givaudan) took it upon itself to properly dispose of the waste. On November 25, over nine years after the disaster, the Roche Group issued a public statement that the toxic waste consisting of 42 barrels (1 was added earlier that year) had all been incinerated in Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

. According to New Scientist
New Scientist
New Scientist is a weekly non-peer-reviewed English-language international science magazine, which since 1996 has also run a website, covering recent developments in science and technology for a general audience. Founded in 1956, it is published by Reed Business Information Ltd, a subsidiary of...

 it was thought that the high chlorine content of the waste might cause damage to the high temperature incinerator used by Roche, but Roche stated that they would burn the waste in the incinerator and repair it afterward if it were damaged. They stated that they wanted to take responsibility for the safe destruction of the waste.

Criminal court case

In September 1983, the Criminal Court of Monza sentenced five former employees of ICMESA or its parent company, Givaudan
Givaudan is a Swiss manufacturer of flavorings and fragrances. As of 2008, it is the world's largest company in the industry.-Background:The company's scents and flavors are developed most often for food and beverage makers, but they are also used frequently in household goods, as well as grooming...

, 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 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, even though the prosecuting attorney had called for their acquittal.


The safety operations handled by the company's directors and local government were badly coordinated and to some extent incompetent. At least a week passed before it was publicly stated that dioxin had been emitted and another week passed before evacuation began. Few scientific studies had confirmed the level of danger TCDD posed and there were scant industrial regulations to be followed. As a result the local population was caught unaware when the accident happened and in such an insecure situation became very frightened. Confrontation with an invisible poison possibly extremely hazardous to human health was a very traumatic experience for small rural communities.

"In the context of such heightened tensions, Seveso became a microcosm where all the existing conflicts within society (political, institutional, religious, industrial) were reflected. However, within a relatively short time such conflicts abated and the recovery of the community proceeded. In Seveso accident the responsible party was known from the outset and soon offered reparation. Moreover, the eventual disappearance of the offending factory itself and the physical exportation of the toxic substances and polluted soil enabled the community to feel cleansed. The resolution of the emotional after-effects of the trauma, so necessary for the recovery of a community, was facilitated by these favourable circumstances."

Industrial safety regulations were passed in the European Community in 1982 called the Seveso Directive which imposed much harsher industrial regulations. The Seveso Directive was updated in 1999, amended again in 2005 and is currently referred to as the Seveso II Directive (or COMAH Regulations in the United Kingdom).

Treatment of the soil in the affected areas was so complete that it now has a dioxin level below what would normally be found. The whole site has been turned into a public park, Seveso Oak Forest park. Some say that Seveso is now the least polluted place in Italy.

It could be argued that Seveso is a disaster that has not yet produced identifiable disastrous consequences. Several studies have been completed on the health of the population of surrounding communities. It has been established that people from Seveso exposed to TCDD are more susceptible to rare cancers but when all types of cancers are grouped into one category, no statistically significant excess has yet been observed.

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
Chloracne is an acne-like eruption of blackheads, cysts, and pustules associated with over-exposure to certain halogenated aromatic compounds, such as chlorinated dioxins and dibenzofurans...

 sufferers (1985).

The Seveso disaster gives valuable comparative insight into the effects of Agent Orange
Agent Orange
Agent Orange is the code name for one of the herbicides and defoliants used by the U.S. military as part of its herbicidal warfare program, Operation Ranch Hand, during the Vietnam War from 1961 to 1971. Vietnam estimates 400,000 people were killed or maimed, and 500,000 children born with birth...

 on flora
Flora is the plant life occurring in a particular region or time, generally the naturally occurring or indigenous—native plant life. The corresponding term for animals is fauna.-Etymology:...

 and fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...

 in Vietnam, not to mention Vietnamese people as TCDD was a significant contaminant in Agent Orange.

The documentary "Gambit" is about Joerg Sambeth, the technical director of ICMESA, who was sentenced to five years in the first trial, and had his sentence was reduced to two years and was paroled on appeal.

External links

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