Clearing the Fog: The Bhopal Gas Tragedy

December 2nd 2014 marks the 30th anniversary of the world’s worst industrial disaster. In the central Indian city of Bhopal, a chemical reaction at a pesticide factory released 42 tons of methyl isocyanate, better known as MIC. In one night between 3,000 and 10,000 lives were lost.

MIC is one of the deadliest substances used in the chemical industry. It destroys the respiratory system, causes blindness and burns the pigment of the skin. Union Carbide, the owners of the factory along with their Indian subsidiary, UCIL, commissioned studies of MIC in 1963 and 1970. They showed that under heat, MIC breaks down into several molecules, including deadly hydrocyanide gas. In Bhopal MIC was used in the production of the pesticide Sevin. When stored as a liquid, the introduction of water to MIC can set off a dangerous chemical reaction. This is exactly what happened 30 years ago.

The prevailing theory is that during routine pipe cleaning, water was able to leak into MIC tank 610. This was made possible by a combination of faulty valves, the non-insertion of metal disks designed to seal the pipes, a jumper line that allowed water to pass through two headers and onto tank 610 and one of four drainage valves being blocked. The media and several studies endorse this explanation. A report by UCC’s intermediary Arthur D. Little Inc. challenges this theory with several claims. The most compelling being that even if all the valves to the tank were open, the water pressure would not be sufficient to climb the 3.1 metres (10.4 ft) needed to reach tank 610. With three drainage valves open, the hose could not generate more than 21 cm (0.7 ft) of hydraulic head. Not enough to make the climb. However, for some time just two drainage valves were flowing. It might be that before the third drainage valve was unblocked, the water made the climb.

The report casts some doubt on the water washing theory, but since Arthur D. Little Inc. was retained by UCC, it was not impartial. The report suggests sabotage as the cause of the disaster. It has three pieces of evidence that directly indicate this:

1) A sketch found, which may have shown a hose attached to an instrument tank.

2) A plant employee reported that on the morning of the 3rd the local pressure indicator for tank 610 was missing and there was a rubber hose next to it. The tank manhead, where the gauge belonged, was one of the places where a hose could be directly attached to tank 610.

3) A worker at another part of the plant overheard MIC operators saying that water entered through a pressure gauge.

These accounts are suspicious, but not conclusive. Due to poor maintenance, many pieces of plant equipment were missing at the time of the accident. The report does not say who the plant worker was, or whom he overheard. The report also repeatedly discredits eyewitness accounts, but relies on others to support the sabotage theory. There are other questions, too; UCC claims to know who the saboteur was and yet they never pursued the matter legally. Also, why would he put himself, his family and almost everybody he knew in serious danger?

Unfortunately due to government incompetence or corruption, as well as Union Carbide’s lack of cooperation with legal investigations, many questions remain unanswered. What is known is that from the beginning UCC and the Indian authorities ignored important safety considerations. The plant posed a direct danger to the city and planning permission should have been denied. However, UCC did not mention the dangers of MIC in their application. From the start, the state government was in bed with UCC. There was a suite at a lavish guest house on permanent reserve for Madhya Pradesh’s chief minister. The minister and other officials were constantly wined and dined. It is no wonder the Indian government have been accused of being complicit in the accident; they owned a 22 per cent stake in UCIL and violated their own safety laws by not taking action after two accidents at the plant before December 1984.

India was under great pressure to industrialise, which outweighed the need to regulate business. An industrial disaster was more likely, because lack of knowledge placed safety entirely in the hands of Union Carbide. The Madhya Pradesh government insisted that the plant be heavily reliant on manual labour. The plant’s European and American counterparts had computerised safety systems capable of detecting the smallest leak. In Bhopal, staff noses were given the job of detecting leaks.

The factory had been designed to create more Sevin pesticide than the Indian market could absorb. As the plant lost money, UCC ordered its Indian subsidiary to cut costs. Large-scale redundancies meant safety checks were done less regularly. The MIC team was cut by half and other staff were used as ‘floaters’, moving from one area to another, despite having no expertise in that area. Safety training in the MIC unit was cut from six months to 15 days and the position of night-shift MIC supervisor was axed.

At the time of the disaster, the MIC unit was storing 63 tons of methyl isocyanate; 42 of which were in tank 610. Regulations stated that tanks should be at most half full, but 610 was almost full. Before budget cuts all MIC had to be refrigerated. The refrigeration unit had been shut down and the Freon drained. On the night of the disaster none of the safety systems in the MIC unit were working. A burner, designed to burn off any gas leaks, and a scrubber cylinder designed to decontaminate leaks, were both switched off. They could not be switched back on, as they had had parts removed for maintenance. Once airborne, methyl isocyanate can be neutralized by water. However, the water hose designed for this purpose could not reach the MIC leak. If tank 610 had not been so full, it may have been able to contain the reaction inside. In French and German plants, half a ton was the maximum permissible storage limit. Union Carbide’s website admits that even if safety systems had been operational, they would not have been able to cope with the quantity of gas. Once the leak in tank 610 began, there was nothing to stop it from forming a deadly cloud. The MIC broke down into monomythylamine ammonia, hydrocynic acid, and phosgene gas. There was no alarm for the city; residents had no idea what was about to happen.

The Arthur D. Little report concedes that there were readily available hoses that could be connected to any of the MIC tanks and that acts of sabotage at chemical plants are common. Industry experts point out that if the system was so vulnerable that someone could simply unscrew one pipe and replace it with another, there were serious safety issues. Mechanical error or sabotage, Union Carbide built a chemical bomb with a hair trigger in the middle of a city. It was just a matter of time until it went off. 

Thomas Benge has a Masters degree in International History from Staffordshire University, and taught full curriculum in Seoul for three years.