Bhopal, India, methyl isocyanate accident

We may all say accidents happen. However, their occurrence may not only take human lives, destroy millions of dollars in property and lost business, they may also cost us our jobs and reputations. The Bhopal, India, accident in 1984 released methyl isocyanate and caused over 2500 fatalities. A petroleum refinery blew up in Houston, Texas, in 1989, killing 23 workers and damaging properly totaling U.S. 750 million, spewing debris from the explosion over an area of 9 km. Many thought that after the Three Mile Island nuclear accident in the United States in 1979 and the Chernobyl nuclear power plant disaster in Ukraine in 1986, we would finally get a handle on how to prevent accidents. Unfortunately, the Fukushima nuclear accident in 2011 proved otherwise (see Picture 2.1). 

There are three types of TAP emissions continuous, intermittent, and accidental. Both routine emissions associated with a batch process or a continuous process that is operated only occasionally can be intermittent sources. A dramatic example of an accidental emission was the release of methyl isocyanate [624-83-9] in Bhopal, India. As a result of this accident, the U.S. Congress created Tide III, a free-standing statute included in the Superfund Amendments and Reauthorization Act (SARA) of 1986. Title III provides a mechanism by which the pubHc can be informed of the existence, quantities, and releases of toxic substances, and requires the states to develop plans to respond to accidental releases of these substances. Eurther, it requires anyone releasing specific toxic chemicals above a certain threshold amount to aimuaHy submit a toxic chemical release form to EPA. At present, there are 308 specific chemicals subject to Title III regulation (37). 

Naphthol is mainly used in the manufacture of the insecticide carbaryl (59), l-naphthyl A/-methyicarbamate/ iJ-2j5 - (Sevin) (22), which is produced by the reaction of 1-naphthol with methyl isocyanate. Methyl isocyanate is usually prepared by treating methylamine with phosgene. Methyl isocyanate is a very toxic Hquid, boiling at 38°C, and should not be stored for long periods of time (Bhopal accident, India). India has developed a process for the preparation of aryl esters of A/-alkyl carbamic acids. Thus l-naphthyl methylcarbamate is prepared by refluxing 1-naphthol with ethyl methylcarbamate and POCl in toluene (60). In 1992, carbaryl production totaled > 11.4 x 10 t(35). Rhc ne-Poulenc, at its Institute, W. Va., facihty is the only carbaryl producer in United States. 

The study of the accidents in chemical facilities, during transportation, storage and others, the research of the chemical products, which are produced and stored, are important points in the preparation of the defence against chemical terrorism. An example of such an accident is the explosion at the Union Carbide pesticide manufacturing plant (Dec. 3, 1984), which scattered toxic methyl isocyanate (MIC) over the city of Bhopal, India. During the first few days up to 4000 people died of painful, harrowing deaths [10],... 

On December 3, 1984, a toxic gas release from a pesticide plant in India killed nearly 3000 people and injured at least 100,000 others. The chemical that leaked was methyl isocyanate, a chemical intermediate that was supposed to be stored in a cooled bunker near the plant s outer boundary. The vapor is highly toxic and causes cellular asphyxiation and rapid death. Despite engineering and procedural provisions to prevent its release, a total system breakdown resulted in the release of 40 tons of the deadly material into the densely populated community of Bhopal. Because of this incident, the plant was dismantled and ultimately the parent corporation. Union Carbide, was forced to make a number of organizational changes. The occurrence is considered by many to have been the most tragic chemical accident in history. 

Methyl isocyanate is a very dangerous chemical. It was responsible for the deaths of over 2,500 people, perhaps as many as 10,000 people, in the worst industrial accident ever, that of the carbamate insecticide plant in Bhopal, India on December 3, 1984. It is a very toxic chemical. This tragedy is discussed in more detail in Chapter 25. Methyl isocyanate can be made from phosgene and methylamine, which would circumvent use of the isocyanate. Phosgene is made from chlorine and carbon monoxide, but it is also very toxic and dangerous. 

Bhopal, the site of the largest chemical accident in the past 50 years, wasn t an explosion but rather an uncontrolled reaction. The plant in Bhopal, India, owned jointly by Union Carbide and the Indian government, was producing methyl isocyanate as an intermediate for a pesticide. Water was admitted into a storage tank containing this chemical, which caused it to hydrolyze and produce CO, HCN, and unreacted MIC, which spread downwind into a crowded slum nearby and caused many deaths and casualties. The desired reaction to synthesize MIC was... 

Methyl isocyanate was the toxic agent involved in the most catastrophic industrial accident of all time, which took place in Bhopal, India, on December 2, 1984. This accident occurred when water got into a tank of methyl isocyanate, causing an exothermic reaction that built up pressure and ruptured a safety valve. This resulted in the release to the atmosphere of 30 to 40 tons of the compound over an approximately 3-h period. Subsequent exposure of people resulted in approximately 3,500 deaths and almost 100,000 injuries. 

One of the worst industrial accidents occurred in Bhopal, India, on December 2 and 3, 1984. It was due to the leakage of methyl isocyanate (MIC) released from the Union Carbide pesticide manufacturing plant. More than 3,000 people who resided in areas adjacent to the manufacturing plant died within a few hours after exposure to MIC. Death was attributed to severe pulmonary toxicity, followed by... 

The sensitivity of isocyanates toward hydrolysis to give primary amines and C02 achieved sad fame with the largest chemical accident in history. In 1984 in Bhopal, India, water penetrated into or was conducted into a large tank full of methyl isocyanate. The result was a massive hydrolysis of the following type ... 

On December 3 and 4, 1985, a chemical release causing a massive toxic gas cloud occurred at the Union Carbide India, Ltd, plant in Bhopal, India. (Union Carbide is now a part of The Dow Chemical Company.) The process involved used methyl isocyanate (MIC), an extremely toxic chemical, to make Sevin, a pesticide. According to various authoritative reports, about 1,700-2,700 (possibly more) people were killed, 50,000 people were affected seriously, and 1,000,000 people were affected in some way. The final settlement may involve billions of dollars. It was one of the worst industrial accidents in history. The accident occurred when about 120-240 gallons of water were allowed to contaminate an MIC storage tank. The MIC hydrolyzed, causing heat and pressure, which in turn caused the tank rupture disk to burst. 

The accident involving the generation of heat and the leakage of methyl isocyanate (MIC) that happened in Bhopal, India, from midnight of December 2 through Dec. 3, 1984, developed into the greatest industrial disaster in history. The death toll was reportedly 2,500, and it was said that more than 10,000 people suffered health-disorders as after-effects. Approximately 200,000 people in total were affected by the leaked gas. 

As discussed earlier, nuclear accidents liave not been die only accidents to occur in recent times. Other disasters at chemical plants have been responsible for a much greater loss of life. Tlie worst disaster in the recent history of the chemical industry occurred in Bhopal, in central India, on December 3, 1984. A leak of methyl isocyanate (MIC) from a chemical pkint, where it was used as an intermediate in the manufacture of a pesticide, spread into tlie adjacent city and caused the poisoning dcatli of more tlian 2500 people apja-oximately 20,000 others were injured. 

Methyl isocyanate (MIC) is the smallest member of the isocyanate family and the most reactive and toxic of all. MIC was almost unheard of until the fateful night December 3, 1984, when nearly 30 metric tons of this poisonous chemical spewed out of the Union Carbide India Ltd (UCIL) pesticide plant within a period of 45-60 min (Jayaraman, 1984). Bhopal turned into a city of death , wrote the fortnightly India Today (December 30, 1984). The journal Nature (Opinion, 1984) vented its anger thus ... the anguish vividly carried round the world by the television cameras seems not to have matured into the anger, even hysteria, there would have been had the [Bhopal] accident occurred on the edge of a European city - or in Connecticut (the headquarters of Union Carbide was in Danbury, Connecticut, USA). 

In 1982, the European Union s Council Directive 82/501/EEC on the major-accident hazards of certain industrial activities, also known as the Seveso Directive, was adopted. The Directive was mostly designed to promote information flow and created the requirement that each Member State (i.e., each country belonging to the European Union) appoint a Competent Authority to oversee safety issues. The Seveso Directive was amended twice, following major accidents at the Union Carbide chemical factory in Bhopal, India in 1984 (a leak of methyl isocyanate caused thousands of deaths), and at the Sandoz chemical warehouse in Basel, Switzerland in 1986 (fire-fighting water contaminated with mercury, organophosphate pesticides and other chemicals caused massive pollution of the Rhine River and the death of hundreds of thousands of fish). Both amendments, broadened the scope of the Directive, in particular to include the storage of dangerous substances. 

Although toxic releases, in general, are not the principal cause of major accidents (relative to fire and explosion) associated with the chemical industry, they are a just cause of "considerable public apprehension" [1327a]. This concern has been compounded by an event which occurred in Bhopal, India in December 1984, in which over 2500 people were killed by a single toxic release of methyl isocyanate. 

The chemical industry received a wake-up call for improved safety when 40 tons of methyl isocyanate escaped from a pesticide plant into a densely populated area of Bhopal, India on Dec. 3,1984. This resulted in 3500 deaths and 150,000 injuries.85 According to one reviewer86 the accident... 

Certain chemical disasters have prominent places in medical history. In 1976, a chemical reactor explosion in Seveso, Italy, released 2,3,7,8-tetrachlorodibenzo-p-dioxin, which contaminated thousands of acres, killed 100,000 animals, and caused the evacuation of hundreds of people (Melius and Binder 1989). In 1984 in Bhopal, India, a carbamate pesticide plant released 30 tons of methyl isocyanate, causing more than 3,000 deaths and 50,000-300,000 injuries (Melius and Binder 1989). The Three Mile Island and Chernobyl nuclear accidents during the 1980s were the culmination of a string of eight nuclear accidents since 1952 (Melius and Binder 1989). Other chemical disasters severely affected local communities but did not generate widespread attention (De La Paz 1997 Withers 1988). 

India currently has a better record of environmental compliance, although one need only look at the covers of back issues of Chemical Engineering News to find pictures of polluted effluent from Indian manufacturers. The industrial accident followed by the airborne dispersal of methyl isocyanate at Bhopal was not so long ago and was perhaps the event that triggered the Indian industry to better manage its processes and effluent. 

Note An industrial accident during the manufacture of carbaryl in Bhopal. India on December 3, 1984 resulted in the leakage of an unknown amount of methyl isocyanate into the air. Over 2,000 people died and an estimated 200,000 were exposed to the vapor Chetn. A Eng. News 62, 6 (Dec. 10, 1984) ibitL 63, 14 (Feb. 11, 1983). Series of articles on follow -up studies on survivors Indian J. Exp. Biol 26, 149-176, 201 -204 (1988). 

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