Union Carbide leak in Bhopal, India

On the night of December 2nd, 1984 (and into the morning of December 3rd) a leak of methyl isocyanate occurred in a Union Carbide pesticide plant in Bhopal, India. The leak killed 2500 people and injured several thousand more.

The immediate cause of the accident was an influx of water into a tank storing methyl isocyanate, compounded by having a disconnected flare tower and an inoperable refridgeration plant. Although Union Carbide scientists believed the pesticide plant to be a model facility, and that it provided the latest technology and many layers of protection, much of this was made ineffective by failures in maintenance, safety management and configuration change control.

Management were lax in enforcing safety policies, and there were severe reductions in staff, training and maintenance. When problems were fixed, the causes of the problems were not always investigated. When safety audits found problems, corrective actions were not always undertaken. Responsibility for safety was also uncertain, and complex relationships with the parent company and an ineffective organisational structure exacerbated matters.


The incident was made all the worse by the quantities of methyl isocyanate, an intermediate product which could have been produced as needed rather than stockpiled, failing to apply the principle of intensification.


Disabling of layers of protection also contributed to the Piper Alpha oil platform inferno.