An huge cloud of poisonous gas


In the early hours of December 3rd, 1984, an huge cloud of poisonous gas began spewing out of the Union Carbide pesticide factory in Bhopal, India. This poisonous substance, stored in tank number 610 of the factory was later found to be Methyl Isocynate(MIC), which had got contaminated with water. As around forty tons of this gas spread to the city. The expected death of this accident is believed to have been between 2500 and 5000 people, with up to 200,000 injured. Union Carbide had sent an investigative team to India to offer help and to determine the cause of the accident. The team had difficulty interviewing plant employees or obtaining access to records concerning the accident. According to Union Carbide, the investigative team was prohibited from interviewing the employees because the Indian Central Bureau of Investigation (CBI) was conducting its own investigation. Whether the accident was the result of intentional sabotage, as claimed by Union Carbide, or the result of a mistake of an inadequately trained employee and poor maintenance, the result will be the same. There was thousands of people death in this accident.

1. Introduction

Union Carbide Corporation is the world's largest manufacturer of ethylene glycol that commonly use as antifreeze. The world's most widely use plastic; polyethylene also is manufactured by Union Carbide Corporation. In the late 60's, Union Carbide India Limited (UCIL) had set up a chemical plant at Bhopal, India. The aim of the chemical plant being set up in Bhopal is for supplying pesticide to protect Indian agricultural production. In 1979 a methyl isocyanate (MIC) production plant was added to the site. MIC, an intermediate in carbaryl manufacture, was used as an alternative of less hazardous but more expensive materials.

Sevin and Temik was the trade names of Union Carbide's. Dupont's Lannate and Shell Chemical Co.'s Nudrin make up more than half of the pesticide market for soybean producers. In 1984, massive fatal disaster of pesticide had happened in Bhopal. This is because of a relief valve on a storage tank containing highly toxic methyl isocyanate (MIC) lifted which cause a cloud of MIC gas flow to nearby housing. These had cause of approximately 2000 people died within a short period and tens of thousands were injured. This was further compounded by the fact that the hospitals were unaware as to which gas was involved or what its effects were. Until know, the exact numbers of dead and injured are uncertain because people have continued to die of the effects.[3] Shortly after the disaster, manufacturers looked at alternative methods of manufacturing pesticides to stay away from using of toxic raw materials such as methyl isocyanate.

We study the chemical disaster that happened at the Union Carbide plant in Bhopal, India. The effect of the Bhopal disaster to health, environment and ecology, and compensation cost. We also need to identify what are the improvements in the management systems so to prevent the accident from occurring.

2. Management and operation

The Union Carbide India, Limited (UCIL) plant was established in 1969. 51% was owned by Union Carbide Corporation (UCC) and 49% by Indian authorities. The plant was "backwards" integrated from a formulation plant to a fully integrated chemical plant in the late 1970's.Methyl isocyanate (MIC) was produced at Bhopal plant by reacting monomethylamine and phosgene in the plant's MIC production unit. The refined MIC was then transferred to a separate MIC storage area where it was stored in two horizontal, mounded, 15 000-gallon, and stainless-steel tanks. There is a third storage tank that was kept empty for emergencies use or for off-specification material waiting reprocessing. The MIC was used to make SEVIN carbaryl and several other carbonate pesticides.

The aim of Union Carbide set up the plant is for supplying pesticide to protect Indian agricultural production. The main product was Sevin, a carbonate insecticide involving methyl isocyanate in its production. Initially, MIC shipped from the States was used in Sevin production, but in the late 70's a plant was constructed locally for manufacturing methyl isocyanate at Bhopal. This plant was located on the outskirts of Bhopal. A densely populated shantytown had grown up near the plant, with an estimated 100,000 people living within a 1 km radius of the plant at the time of the tragedy. [2]

3. Industrial process

MIC is a highly volatile toxin. It is a chemical intermediate. It is combined with other chemicals to produce a pesticide. Phosgene, which is made by combining carbon monoxide and chlorine, is reacted with monomethylamine to form MIC. MIC is used in the production of the agricultural pesticides carbaryl and aldicarb, generally known as carbonates.

Process for making methyl isocyanate comprising thermally dehydrochlorinating a solution of methyl carbamyl chloride in an aprotic nonpolar solvent, condensing the gases thereby formed at a temperature above the boiling point of methyl isocyanate so as to liquify at least part of said gases which are condensable at said temperature, removing HCl gas by condensing the remaining condensable gases at a temperature below the boiling point of methyl isocyanate, and separating methyl isocyanate from the condensate obtained in said first condensation step.[5]

At least three separate activities involves in the pesticide manufacturing. First synthesized in a chemical factory, then formulated in the same place or sent to a formulator who prepares the liquis or powder form.

First, a new pesticide is manufactured on a small scale in a laboratory. If the substance proves viable, then production will be start in the factory. Batch or continuous manufacturing insures a high volume, perhaps as much as 500 kilograms per cycle. The fundamental procedure entails altering an organic molecule to form a pesticide. A number of specific reagents and catalys and often must take place in a controlled climate for example within a certain temperature range will involve. Once synthesized, the active ingredient is packed and sent to formulator. Liquid insecticides will be moved in tank trucks or 200-liter drums.

Secondly, a formulator accepts the active ingredient. The proper amount need to be measures out and mixes it with carrier if it is to be a liquid pesticide or with inert powders or dry fertilizers if it is to be a dust pesticide. After that, bottles or packages it. If a large-scale farmer is the anticipated customer, liquid pesticides are packaged in 200-liter drums or 20-liter jugs for small-scale operation. Dry formulations will be packages into 5 to 10 kilogram plastic or plastic-lined bags. An emulsified formulation is usually concentrated to render transport easier (the active ingredient typically makes up 50 percent of the emulsified concentrate), but granulated and dry pesticides are ready to use. [6]

4. Cause of accident

The Bhopal tragedy was cause by the failure of a "trigger-man" to block the line leading to tank e-610 during routine washing of the line with water to remove the residue. As result water was allowed to enter the tank where it reacted with highly volatile contents. This is because, the "trigger-man" was just transferred into the unit that makes and stores MIC for two month. He had less that the background and training originally required to fill his job as an operator.

Furthermore, three safety systems on the MIC tank were simultaneously out of order. Firstly, was the refrigeration unit for cooling the tank in an emergency. The refrigeration unit had been shutting down in June 1984 as a cost cutting measure. Secondly, the caustic flow indicator on the scrubber is malfunctioning, making it difficult to know whether the unit is still operating or not. Moreover, the scrubber designed to neutralize escaping MIC vapour with caustic soda solution was switched to a standby position and could not be activated during the disaster. Last, the corroded pipe leading to the flare tower that had been removed has not been replaced yet.

All above system were designed as manually operated systems with specific insistence of Indian govt to above affect that maximum employment many be given to Indians. Cost-cutting measures directed by the Danbury Headquarters of Union Carbide included reducing the production crew is cut from 12 to 6 workers and maintenance crew from 6 to 2 workers. Moreover, the operator needs to monitors about 70 panels, indicators and controllers in the control room. The period of safety training for workers in the MIC unit is brought down from six months to 15 days. [4]

In May 1984, the process safety system included a design modification was installed. This 'jumper line', a cheap solution to a maintenance problem, connected a relief valve header to a pressure vent header and enabled water from a routine washing operation to pass between the two, on though a pressure valve, and into MIC storage tank 610.[12]

Besides, the environment of the working condition was very bad even it had been complaint for so many times. For example, in August 1984 the general secretary of the Union Carbide Karamchari Sangh (Workers' Union), a union of the Bhopal plant workers, writes to the works manager of the Bhopal plant raising concerns about air and noise pollution and workers' exposure to hazardous substances. "We have complained so many times against the rising pollution of air and noise in different departments of our factory but we are disappointed that ... it is increasing day by day in an uncontrolled manner," the letter says.[4] In such a terrible condition it was impossible to storage the MIC because MIC will react with almost anything. It was possible to produce Sevin without producing MIC. The reason of cost adapted to the process of more hazardous product. Moreover, because of the cost consideration led to the bulk production of MIC.

5. Consequences of the effect of the accident

The gas leak triggered a disaster that is now widely recognized as the world worst industrial catastrophe. Apart from MIC, the gas cloud may have contained phosgene, hydrogen cyanide, carbon monoxide, hydrogen chloride, oxides of nitrogen, monomethyl amine (MMA) and carbon dioxide, either produced in the storage tank or in the atmosphere. This made the streets of Bhopal was littered with human corpses and the carcasses of buffaloes, cows, dogs and birds. There were more than 200000 persons exposed to the MIC gas. In Nov 1989, the Department of Relief and Rehabilitation, Government of Madhya Pradesh, placed the death toll at 3598 and by 1994 the toll was estimated at 6000. More than two decades on, over 20,000 people have died and 100,000 more still suffer severe, chronic and disabling illnesses

The MIC gas not only because mortality, is also causes ocular problems. Resulting from the intensely irritating affect of MIC on the cornea included severe ocular burning, watering, pain and photophobia. Besides, MIC also causes the respiratory toxicity that MIC attack on tissues. Reports in early 1985 indicated that menstrual cycle disruption, leukorrhea, and dysmenorrhea had occurred in gas-exposed women. In pregnant women, the fetus was at risk from exposure to the gas, as well as from factors such as stress, anoxia, and ingestion of various prescription drugs (e.g., antibiotics, bronchodilators, analgesics). [8] It has resulted in many children being born with genetic defects and mutations and mental retardation. It has also had a long term impact on the reproductive cycle of affected women and the quality of their breast milk. Peoples in Bhopal also are facing the problem of neuromuscular toxicity, immunotoxicity, psychological, neurobehavioral toxicity, genotoxicity and carcinogenicity.

Besides the effects on people, according to environmentalists, the impact it has had on the ecology of that area is also far reaching. There are still thousands of tons of toxic waste on the abandoned and dilapidated site, lying in piles exposed to the weather, which could lead to a continuous poisoning of the soil as well as ground water. These chemicals have leached into the earth, contaminating the groundwater source for 25,000 Bhopal is who live nearby. People have no other water supply and have been forced to drink that poison. The people do not have pure water to drink, they have no means of employment, they are not getting any medical treatment from the government, and they are living a miserable life there. [9]

The Government of India passed the Bhopal Gas Leak Disaster Act that gave the government rights to represent all victims in or outside India. UCC had offered US$ 350 million, the insurance sum for the victim of the Bhopal disaster as compensation but the government of India claimed US$ 3.3 billion from UCC. Total of US$ 470 million (the insurance sum, plus interest) in a full and final settlement of its civil and criminal liability was agreed in 1989 between Union Carbide and the Indian government. And much of this money has found its way into the hands of corrupt government officials rather than those who suffered in the disaster.[10] When UCC wanted to sell its shares in UCIL, it was directed by the Supreme Court to finance a 500-bed hospital for the medical care of the survivors. Bhopal Memorial Hospital and Research Centre (BMHRC) was inaugurated in 1998. It was obliged to give free care for survivors for eight years.[11]

6. Improvement and prevention

The Bhopal tragedy is a very serious disaster. We need to do some improvement to prevent this tragedy to happen again. As we all know, the Bhopal plant was all on one single manhole and no computerized control. So, we need to improve the plant to become lines and instruments spread out over whole tank and computerized the control system. Besides, we need to add a unit storage tank between MIC manufacture and large storage tank to check purity. We also need to make sure that the PVH and RVVH lines from storage tank direct to VGS and flare tower.

When the Bhopal tragedy happens, the refrigeration was shutdown since May 1984. The refrigeration been shut down because of the power saved and reduced the cost of MIC vapour loss. So, to prevent the same misfortune to happened again the MIC storage temperature need to make sure less than or equal to 5C [42F].

Moreover, to prevent the same disaster to happen once more we require giving sufficient training for the worker. The operation and maintenance crew to be under trained and experienced staff. The numbers of worker also need to be adequate. We cannot reduce the worker and their training time as a result of cost-cutting. Furthermore, we need to arrange hospital, train, road, river transport, police, civic administration that can be informed if any emergency happened.

We need to clean up the factory site, which continues to contaminate the soil, water and much more so that the people that stay near to there can get a clean water to drink. We can also offer alternate livelihood to the victims who cannot pursue their work because of exposure- related illness. Improving the standard of living and the health of the people in Bhopal, some fund is necessary to be set up such as medical care, health monitoring regimens and research studies.

7. Conclusion

The Bhopal disaster happened in the early hours of December 3rd, 1984. More than 40 tons of methyl isocyanate gas leaked from a pesticide plant in Bhopal, India. This accident, immediately killing at least 3,800 people and causing significant morbidity and premature death for many thousands more. Over the last two decades, more than 20,000 additional people have died as a result of the original exposure, and an estimated 120,000 still suffer significant health impacts. People continue to die each month from the long-term effects of the poisoning.

We had learnt a lot from this accident. We learned the preventative strategies to avoid similar accidents and a better state of preparedness to meet future industry disaster. Besides, hiring worker that is experience and give training to the worker is a very important in a plant. The technology that use in the plant and the maintenance of the plant is a very important issue to prevent for such a disaster. In India, a number of changes were made in the Indian Factories Act and environmental legislation. Since the disaster, India has experienced rapid industrialization.

8. Reference







7. "Bhopal Methyl Isocyanate Investigation Team Report", Union Carbide Corporation, Danbury, Connecticut, U.S.A., March 1985.

8. Bang R, Sadgopal M. Effect of Bhopal disaster on women's health: an epidemic of gynecological diseases. In: Distorted Lives: Women's Reproductive Health and Bhopal Disaster. Part I. Medico Friend Circle, Oct. 1990.



11. Browning, Jackson (1993). Jack A. Gottschalk. ed (PDF). Union Carbide: Disaster at Bhopal. Crisis Response: Inside Stories on Managing Image Under Siege. Detroit. "Union Carbide's former vice-president of health, safety and environmental programs tells how he dealt with the catastrophe from a PR point of view."


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