The Bhopal disaster (also referred to as the Bhopal gas tragedy) is the world's worst industrial catastrophe. It occurred on the night of December 2--3, 1984 at the Union Carbide India Limited (UCIL) pesticide plant in Bhopal, Madhya Pradesh, India. A leak of methyl isocyanate gas and other chemicals from the plant resulted in the exposure of hundreds of thousands of people. Estimates vary on the death toll. The official immediate death toll was 2,259 and the government of Madhya Pradesh has confirmed a total of 3,787 deaths related to the gas release. Other government agencies estimate 15,000 deaths. Others estimate that 3,000 died within weeks and that another 8,000 have since died from gas-related diseases. A government affidavit in 2006 stated the leak caused 558,125 injuries including 38,478 temporary partial and approximately 3,900 severely and permanently disabling injuries.
UCIL was the Indian subsidiary of Union Carbide Corporation (UCC). Indian Government controlled banks and the Indian public held 49.1 percent ownership share. In 1994, the Supreme Court of India allowed UCC to sell its 50.9 percent share. The Bhopal plant was sold to McLeod Russel (India) Ltd. UCC was purchased by Dow Chemical Company in 2001.
Civil and criminal cases are pending in the United States District Court, Manhattan and the District Court of Bhopal, India, involving UCC, UCIL employees, and Warren Anderson, UCC CEO at the time of the disaster. In June 2010, seven ex-employees, including the former UCIL chairman, were convicted in Bhopal of causing death by negligence and sentenced to two years imprisonment and a fine of about $2,000 each, the maximum punishment allowed by law. An eighth former employee was also convicted but died before judgment was passed.
The Bhopal disaster is often studied by officials as an example of what could happen should a massive industrial accident or terrorist attack occur at a chemical plant.
A word about methyl isocyanate.
Methyl iscoyanate is an extremely dangerous chemical. In fact, it is one of the most toxic substances in the world. This particular chemical is said to give pause and cause fear even among chemists who have extensive experience working with other toxic chemicals.
Methyl isocyanate (MIC) is a clear, colorless, lachrymatory, sharp-smelling liquid. It is highly flammable, boils at 39.1°C and has a low flash point. Methyl isocyanate is soluble in water to 6–10 parts per 100 parts, but it reacts with the water.
The threshold limit value set by the American Conference on Government Industrial Hygienist was 0.02 ppm. MIC can damage by inhalation, ingestion and contact in quantities as low as 0.4 ppm. Damage includes coughing, chest pain, dyspnea, asthma, irritation of the eyes, nose and throat, as well as skin damage. Higher levels of exposure, over 21 ppm, can result in pulmonary or lung edema, emphysema and hemorrhages, bronchial pneumonia and death. Although the odor of methyl isocyanate cannot be detected at 5 ppm by most people, its potent lachrymal properties provide an excellent warning of its presence (at a concentration of 2–4 parts per million (ppm) subject's eyes are irritated, while at 21 ppm, subjects could not tolerate the presence of methyl isocyanate in air).
Proper care must be taken to store methyl isocyanate because of its ease of exothermically polymerizing and its similar sensitivity to water. Only stainless steel or glass containers may be safely used; the MIC must be stored at temperatures below 40 °C (104 °F) and preferably at 4 °C (39 °F).
The Fire Diamond (NPFA 704) ratings hazard for MIC reads as follows:
Health (Blue) - 4
Fire (Red) - 3
Reactivity (Yellow) - 2
Special Hazard (White) - "W" with a line through it (water prohibited)
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