Bhopal disaster (1984)

Summary of background and causes

The Union Carbide India, Limited (UCIL) factory was established in 1969 near Bhopal. 51% was owned by Union Carbide Corporation (UCC) and 49% by Indian authorities. It produced the pesticide carbaryl (trademark Sevin). Methyl isocyanate (MIC), an intermediate in carbaryl manufacture, was also used. In 1979 a plant for producing MIC was added to the site. MIC was used instead of less toxic (but more expensive) materials, and UCC was aware of the substance's properties and how it had to be handled.[6][7][8]

During the night of December 2–3, 1984, large amounts of water entered tank 610, containing 42 tonnes of methyl isocyanate. The resulting 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. 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.