On 3 December 1984, a Union Carbide Corporation pesticide plant in Bhopal leaked around 32 tons of toxic gases, including methyl isocyanate gas which led to the worst industrial disaster to date. The official death toll was initially recorded around 5,000. Many figures suggest that 18,000 died within two weeks, and it is estimated that around 8,000 have died since then of gas-poisoning-related diseases. The Greenpeace organization cites a total casualty figure of 20,000 as its own conservative estimate. Many more were rendered sick and have been facing chronic health problems such as psychological and neurological disabilities, blindness, skin, vision and breathing disorders and the newborn children still suffer from serious birth defects, even after generations. The soil and ground water near the factory site has been contaminated by the toxic wastes and other chemicals still leaking out from the factory. The Indian government, however, maintains that no such pollution has taken place or that any such toxins are even present at the site. The Bhopal disaster is often cited as the world's worst industrial disaster. December 3 is annually observed as the official day of mourning, and every year, all government offices in Bhopal remain closed on this day.
The Union Carbide India Limited (UCIL) plant was established in 1969 in the Eastern part of the City. Fifty-one per cent of it was owned by Union Carbide Corporation (UCC) and 49% by Indian authorities, although UCC was responsible for the technique and design. It manufactured carbaryl pesticide (trade mark Sevin). Methyl isocyanate (MIC), an intermediate in carbaryl manufacture, was also used, and in 1979 a plant for producing MIC was added to the site.
On the night of 3 December 1984, large amounts of water entered the chemical storage tank E610, which contained about 40 tonnes of methyl isocyanate. The resulting reaction increased the temperature of the liquid inside the tank to 200 �C (400 �F). As a result, a large volume of mixed toxic gases leaked from the MIC containing tank, forcing the emergency release of pressure. Consequently there was massive panic among common people as they woke up in a cloud of noxious gases that burned their lungs. About nine thousand people died immediately, and many more were trampled under others who were fleeing.