Posted on: March 24, 2010 Posted by: Diane Swarts Comments: 0

The world’s worst process disaster occurred in 1984 when a water reaction caused pesticide gas to escape from a Union Carbide production plant in Bhopal, India.

The disaster claimed public 3000 fatalities, and some 100 000 injuries. Methyl isocyanate (MIC) gas was the active ingredient accidentally released. A sodium hydroxide scrubber was not working during the incident.

The International Medical Commission on Bhopal estimated in 1994 that 50 000 people remained partially or totally disabled as a result of exposure to MIC.

Bhopal was a reactive chemistry incident. MIC reacts exothermically with water. An MIC storage tank was contaminated with water, and the reaction generated heat and pressure causing a relief valve to open.

Safety systems had been taken out of service without doing a management of change evaluation, or the systems were unable to deal with the release. Some 40 tons of highly toxic MIC was released into the community, exposing tens of thousands of people in a densely populated area.

It was just after midnight, December 3, 1984 in Bhopal, when a succession of events at Union Carbide led to the release.

The basic cause has been agreed upon by most experts who investigated the event, as a significant quantity of water that entered the MIC storage tank. Even today, the water source remains controversial. The release occurred near midnight.

•    Source; CCPS Process Safety Incident Database,
•    Source; Process Safety Beacon,

* PHOTO; funeral photos of some of 3000 people killed by pesticide gas.


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