As you know, the world's worst industrial disaster, the Bhopal disaster was occurred in December 1984. Bhopal industrial disaster, also referred as Bhopal gas tragedy, was a gas leak incident occurred at the Union Carbide India Limited (UCIL), more than 40 tons of methyl isocyanate gas leaked from a pesticide plant in Bhopal, Madhya Pradesh state. As per the Government records more than 3750 peoples were dead, approximately 3,900 severely and permanently disabling injured and 38,478 temporary partial injured.
Causes and consequence of Bhopal disaster in 1984
The cause of the disaster remains under debate (Wikipedia). There are two main lines of argument involving the disaster. The "Corporate Negligence" point of view argues that the disaster was caused by a potent combination of under-maintained and decaying facilities, a weak attitude towards safety, and an under trained workforce, culminating in worker actions that inadvertently enabled water to penetrate the MIC tanks in the absence of properly working safeguards.
The "Worker Sabotage" point of view argues that it was not physically possible for the water to enter the tank without concerted human effort, and that extensive testimony and engineering analysis leads to a conclusion that water entered the tank when a rogue individual employee hooked a water hose directly to an empty valve on the side of the tank. This point of view further argues that the Indian government took extensive actions to hide this possibility in order to attach blame to UCC.
Theories differ as to how the water entered the tank. At the time, workers were cleaning out a clogged pipe with water about 400 feet from the tank. They claimed that they were not told to isolate the tank with a pipe slip-blind plate. The operators assumed that owing to bad maintenance and leaking valves, it was possible for the water to leak into the tank.
However, this water entry route could not be reproduced despite strenuous efforts by motivated parties. UCC claims that a "disgruntled worker" deliberately connecting a hose to a pressure gauge connection was the real cause.
Early the next morning, a UCIL manager asked the instrument engineer to replace the gauge. UCIL's investigation team found no evidence of the necessary connection; however, the investigation was totally controlled by the government, denying UCC investigators access to the tank or interviews with the operators
Ref : Wikipedia