Seveso incident

A reaction at the interface caused by a loss of mixing can eventually lead to a runaway itself. Examples include nitration processes and the well-known Seveso incident where agitation stopped in a reactor during the manufacture of trichlorophenol this led to higher than normal temperatures and increased production of the undesirable side product 2,3, 7,8-tetrachlorodibenzo-p-di-oxin (commonly referred to as "dioxin"), ultimately resulting in a vapor release to the atmosphere. 

Another development is due to the interest in polychlorodibenzofurans, spurred by their occurrence as environmental contaminants. Polychloro-phenols are manufactured in large amounts (150,000 tons per annum) and find a wide range of uses. The usual method of manufacture involves the hydrolysis of chlorobenzenes, and side reactions, favored by high temperature, can lead to the production of polychlorodibenzofurans and poly-chlorodibenzo-p-dioxins. The Seveso incident is well known." Polychloro-biphenyls are also widely used industrial chemicals, particularly in heat exchange systems, and their pyrolysis leads to the formation of polychloro-dibenzofurans. Polychlorodibenzofurans have also been detected in the fly ash and flue gases of incinerators and industrial heating plants. The most toxic of the polychlorodibenzofurans are 2,3,7,8-tetra-, 1,2,3,7,8-penta-, and 2,3,4,7,8-pentachlorodibenzofuran, and an extensive literature exists on the environmental pollution and the results of human exposure to these substances. A particularly tragic example of the latter occurred in 1968 in the Fukuoka prefecture of Japan after consumption of rice oil contaminated with a commercial polychlorobiphenyl. 

The part played by DSC in the investigation of the Seveso incident has been discussed [3]. A critique of DSC for screening reactions suggests a somewhat larger scale alternative, also capable of showing pressure generation [4]. 

The immune status of children exposed to 2,3,7,8-TCDD in the Seveso incident was also examined (Mocarelli et al. 1986). The group consisted of 44 children, 20 of whom had chloracne. The results of the testing showed no abnormalities in serum immunoglobulin concentrations, levels of circulating complement, or lymphoproliferative responses to T- and B-cell mitogens. However, a different cohort of... 

Bertazzi PA, Zocchetti C, Pesatori AC, et al. 1989b. Ten-year mortality study of the population involved in the Seveso incident in 1976. Am J Epidemiol 129 1187-1200. 

The first safety cases prepared for the process industries were those developed for North Sea offshore oil and gas operations following the Piper Alpha disaster that occurred in the year 1988. The Cullen report (Cullen, 1990) that was written following that accident was highly critical of offshore operating practices and recommended that a safety case approach be implemented. The Seveso incident that occurred in Italy further prompted the increased use of safety cases. Since that time the use of safety cases has spread to other industries (such as mining and railway operations) and to other nations, primarily in Europe and Australasia. (It is notable that the safety case regime approach has not been taken up for offshore oil and gas operations in the Gulf of Mexico—instead a more prescriptive approach based on industry consensus standards is used.)... 

A publication summarises all the then available technical evidence related to the Seveso accident, and recommends operational criteria to ensure safety in commercial processes to produce trichlorophenol [4], All the plant scale incidents were characterised [ 1 ] by the subsequent occurrence of chloracne arising from the extremely toxic and dermatitic compound 2,3,7,8-tetrachlorodibenzodioxin (structure IX, p. S-3), formed dining the thermal runaway reaction and dispersed in the ensuing explosion. It is also extremely resistant to normal chemical decontamination procedures, and after the 1968 explosion, further cases occurred after transient contact with plant... 

Lodi, New Jersey incident, 8, 159-160 management practices, 67-68 Paterson, New Jersey incident, 160-161 Seveso, Italy incident, 4 Springfield, Massachusetts incident, 7 Toulouse, France incident, 4,5 Castleford, UK incident, 11,156-158 Center for Chemical Process Safety (CCPS), 183... 

Self-accelerating decomposition temperature (SADT), screening methods, 56 Self-reactive materials chemical reactivity hazard, 1,2 screening methods, 54-58 Seveso, Italy incident, 4 Seveso II Directive, 5-6,27 Shelf life... 

On July 9, 1976, in Meda, Italy, near Seveso, a chemical reactor incident caused a release of dioxin (TCDD), which is a highly toxic chemical. The regulatory requirements developed as a result of this incident are referred to as the Seveso Directive. 

There have been occasions in which relatively large quantities of dioxins were released as the result of chemical or industrial accidents. Explosions at chemical plants in Seveso, Italy, in 1976 and at Bhopal, India, in 1984 are examples of such incidents. High levels of dioxin have also been found in animal feed on a few occasions the source and mechanism of this contamination have not always been clear. 

The Seveso accident in 1976 also involved the glycol-based process, but differed fundamentally from the 1968 incident. While the latter apparently involved a thermal runaway initiated during the hydrolysis reaction by application of excessive heat by the faulty hot oil system [7], the process design adopted by Icmesa at Seveso featured heating the reaction vessel by steam at 12 bar (192°C if saturated) to ensure a minimum 40°C safety margin below the known decomposition temperature of 230°C [5]. At Seveso the exothermic hydrolysis reaction had been completed, but... 

The chemical industry, more than any other industry, is perceived as a threat to humans, society, and the environment. Nevertheless, the benefits resulting from this activity cannot be negated health, crop protection, new material, colors, textiles, and so on. This negative perception is more enhanced after major accidents, such as those at Seveso and Bhopal. Even though such catastrophic incidents are rare, they are spectacular and retain public attention. Thus, a fundamental question is raised What risk does society accept regarding the benefits of an activity, of a product Such a question assumes that one is able-a priori-to assess the corresponding risk. 

Residential/Environmental Exposures. Several incidents in which populations were exposed to potentially high levels of 2,3,7,8-TCDD include an industrial accident that occurred during the production of 2,4,5-TCP at the ICMESA plant in Seveso, Italy and the spraying of roads and other places... 

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