Early in the morning of December 3, 1984, a Union Carbide pesticide plant leaked around 40 tons of methyl isocyanate gas into the air of Bhopal, a town in Madhya Pradesh, India. More than 500,000 people were exposed to the highly toxic substance. This resulted in around 3,800 people, who were mostly living in the slums around the plant, believed to have been killed instantly.
What is Methyl Isocyanate?
Methyl isocyanate, abbreviated as MIC, is an intermediate used in the manufacturing of pesticide products, polyurethane foam and plastics. The substance is colorless but has a strong, sharp odor. It is highly flammable and quickly evaporates when exposed to the air. Methyl isocyanate is produced through the reaction of monomethylamine and phosgene, the latter of which is a deadly poisonous gas that was used in World War I. Methyl isocyanate gas is highly toxic and exposure to it can cause a burning sensation in the eyes and body. It removes oxygen from the lungs, resulting in chest tightness and difficulty breathing. Additionally, exposure to the gas causes cyanide to build up in the body, which can lead to cardiac arrest and ultimately, death.
History of the Chemical Plant
In the 1970s, the Indian government started sourcing for foreign companies to invest in local industry. One of those companies was Union Carbide Corporation, which built a chemical plant in Bhopal to manufacture Sevin, a pesticide commonly used in the region. Bhopal was chosen as the location for the plant due to its central location and access to transport infrastructure. However, the site of the plant in Bhopal was not meant for such hazardous industries dealing with poisonous substances, but rather for light industrial and commercial use.
Although the chemical plant was initially only approved to handle small quantities of pesticide components, such as methyl isocyanate, the local subsidiary Union Carbide India Limited felt pressure with the competition arising from the chemical industry. A “backward integration” process was implemented, where both raw and intermediate materials were processed in the same factory and manufactured into the final product. As such, larger amounts of components were stored in the plant, such as the three tanks of methyl isocyanate from which the gas leak occurred.
In the 1980s, farmers in the region saw many crop failures. The lower income led to a decreased demand for pesticides and the chemical plant was only producing a quarter of its usual output. The plant was meant to be closed and scheduled to be sold in July 1984, but there were no takers. While Union Carbide planned to dismantle some parts and ship it to other countries, the plant continued to operate, but below desirable safety standards. Although the government was aware of this, they did not enforce heavy regulations on the plant to avoid economic consequences since Union Carbide was such a large employer.
How Did It Happen?
Late in the night on December 2, 1984, a worker at the chemical plant noticed that one of the storage tanks was leaking methyl isocyanate and its pressure was increasing. Several key safety components in the plant were not operational:
- The vent gas scrubber, a safety device meant to neutralize toxic discharge from the methyl isocyanate, had been shut down for maintenance three weeks earlier.
- The refrigeration unit meant to cool methyl isocyanate and prevent chemical reactions had been drained of its coolant, which was being used in another part of the plant.
- The flare tower had not been functional for three months.
- Also, the water valves were faulty, allowing one ton of water intended for cleaning pipes to mix into the methyl isocyanate storage system.
The water mixing with methyl isocyanate resulted in a violent exothermic reaction taking place inside the tanks, emitting pressure and heat. When methyl isocyanate is exposed to temperatures of 200 degrees, it turns into degraded methyl isocyanate which contains hydrogen cyanide, a more deadly substance. Whether the gas in the tank did turn into degraded methyl isocyanate is unknown – while there is evidence that the tank did reach such high temperatures, Union Carbide Corporation vigorously denied the presence of hydrogen cyanide.
Eventually, due to the extreme pressure and heat, a safety valve on the storage tank gave way and the lethal gas was released into Bhopal’s air. It took only hours for the streets to be full of the corpses of humans, cattle and domestic animals.
Aftermath of the Incident – How Were People Affected?
Many of the 500,000 residents exposed to the toxin woke up vomiting and in coughing fits. Most of the initial deaths were from cardiac arrest and respiratory failure. An estimated 10,000 people were believed to have succumbed to the plume within the first few days of the leak, with the total number of casualties amounting to at least 38,000. The workers who picked up the bodies in the streets in the days after the disaster estimated handling around 16,000 bodies in total. While neither Union Carbide nor the company that later acquired it ever made public the facts of the gas leak, the blood and viscera of the victims exhibited a cherry-red color suggesting acute cyanide poisoning.
In addition to the direct effects of methyl isocyanate, the mercury levels in Bhopal also rose to between 20,000 and 6 million times the normal amount. Additionally, the gas leak contaminated the water around the area, causing 50 times the safe limits of trichloroethene – a chemical that impairs fetal development – to build up in freshwater bodies. As such, many of those exposed also suffered other adverse health effects, including blindness, brain damage, cancer, gynecological disorders and birth defects.
Unfortunately, the effects of the Bhopal Disaster did not stop there – the consequences would still be evident three decades later. The mortality of the population exposed to the gas was drastically increased, with 15,000 to 20,000 premature deaths reportedly occurring in the first two decades after. However, these numbers are expected to be under-representative of the actual affected population, as many who were exposed fled from Bhopal immediately after the disaster and were not followed up on.
To this day, many of the survivors of the Bhopal Disaster are still reportedly suffering from the effects of the tragedy, such as partial or complete blindness, respiratory problems, gastrointestinal problems, impaired immune systems and post-traumatic stress. The survivors have also seen an abnormally high stillbirth rate, spontaneous abortions and children born with congenital disorders as a result of their parents’ exposure to the toxic gas.
Union Carbide Corporation, the owner of the pesticide factory, alleged that the incident happened due to sabotage, while the Indian government argued that poor maintenance and negligence contributed to the disaster. In 1989, Union Carbide reached a partial agreement with the government, resulting in the company paying $470 million in compensation – a measly sum when spread out among the half million affected, amounting to just about $350 per victim. However, this figure was partly based on the erroneous fact that only 3,000 people were killed and 102,000 became permanently disabled.
The case was further pursued by the victims of the disaster. By 2003, the Bhopal Gas Tragedy Relief and Rehabilitation Department stated that 554,895 people who suffered permanent injuries and 15,310 survivors of the casualties had been granted compensation for their losses.