The Bhopal disaster was an industrial catastrophe that took place at a pesticide plant owned and operated by Union Carbide (UCIL) in Bhopal, Madhya Pradesh, India on December 3, 1984. Around 12 AM, the plant released methyl isocyanate (MIC) gas and other toxins, resulting in the exposure of over 500,000 people. Estimates vary on the death toll. The official immediate death toll was 2,259 and the government of M P has confirmed a total of 3787 deaths related to the gas release. Other government agencies estimate 15,000 deaths. Others estimate 8000 to 10,000 died within 72 hours and 25,000 have since died from gas-related diseases.
Some 25 years after the gas leak, 390 tonnes of toxic chemicals abandoned at the UCIL plant continue to leak and pollute the groundwater in the region and affect thousands of Bhopal residents who depend on it, though there is some dispute as to whether the chemicals still stored at the site pose any continuing health hazard. There are currently civil and criminal cases related to the disaster ongoing in the United States District Court, Manhattan and the District Court of Bhopal, India against Union Carbide, now owned by Dow Chemical Company, with an Indian arrest warrant pending against Warren Anderson, CEO of Union Carbide at the time of the disaster. No one has yet been prosecuted.
The UCIL factory was established in 1969 near Bhopal. 50.9 % was owned by Union Carbide Corporation (UCC) and 49.1 % by various Indian investors, including public sector financial institutions. It produced the pesticide carbaryl (trademark Sevin). In 1979 a methyl isocyanate (MIC) production plant was added to the site. MIC, an intermediate in carbaryl manufacture, was used instead of less hazardous but more expensive materials. UCC understood the properties of MIC and its handling requirements.
During the night of December 23, 1984, large amounts of water entered tank 610, containing 42 tonnes of methyl isocyanate. The resulting exothermic reaction increased the temperature inside the tank to over 200 °C (392 °F), raising the pressure to a level the tank was not designed to withstand. This forced the emergency venting of pressure from the MIC holding tank, releasing a large volume of toxic gases into the atmosphere. The reaction sped up because of the presence of iron in corroding non-stainless steel pipelines. A mixture of poisonous gases flooded the city of Bhopal, causing great panic as people woke up with a burning sensation in their lungs. Thousands died immediately from the effects of the gas and many were trampled in the panic.
Theories of how the water entered the tank differ. At the time, workers were cleaning out pipes with water, and some claim that owing to bad maintenance and leaking valves, it was possible for the water to leak into tank 610. In December 1985 the New York Times reported that according to UCIL plant managers the hypothesis of this route of entry of water was tested in the presence of the Central Bureau Investigators and was found to be negative. UCC also maintains that this route was not possible, and that it was an act of sabotage by a "disgruntled worker" who introduced water directly into the tank. However, the company's investigation team found no evidence of the necessary connection.
The 1985 reports give a picture of what led to the disaster and how it developed, although they differ in details.
Factors leading to this huge gas leak include:
-The use of hazardous chemicals (MIC) instead of less dangerous ones
-Storing these chemicals in large tanks instead of over 200 steel drums.
-Possible corroding material in pipelines
-Poor maintenance after the plant ceased production in the early 1980s
-Failure of several safety systems (due to poor maintenance and regulations).
-Safety systems being switched off to save money - including the MIC tank refrigeration system which alone would have prevented the disaster.