Question: In the 1960s there was seen to be a need to improve India's agricultural productivity and the use of pesticides was promoted as a key component in a ‘Green Revolution'. This led to the construction of an industrial facility at Bhopal in central India by the Union Carbide Corporation (UCC), a company with headquarters in Connecticut, USA. This plant produced pesticides using the chemical methyl isocyanate (MIC). It is important in understanding this case to know that MIC has a boiling point of 39 °C, that is it exists as a gas at a possible ambient temperature for the city. As a gas it has a density twice that of air, and therefore will tend to keep close to the ground. It is highly toxic and reacts violently with other substances, including water, producing heat which in turn speeds up the reaction. Such properties make it of great value in industrial scale chemical reactions but also make it highly dangerous to living populations. For this reason it was stored at Bhopal in stainless steel, refrigerated tanks, partly below ground and covered by earth and concrete.
Bhopal is an industrial city and major rail junction with a population of around 800,000, some living in poorly constructed accommodation within 100 m of the chemical facility. The Indian Government saw the production of pesticides in India to be of value not only in terms of the product but also in the development of engineering expertise essential to the country's future. It has also been noted by some commentators that as the Bhopal facility included the storage of MIC in substantial quantities rather than its immediate use it is possible that other uses were intended, for example, by the military. The plant was designed and funded by UCC and operated by Union Carbide India Ltd (UCIL), a subsidiary of UCC. Despite the incentives of operating in India (including lower labour costs and the operation of local safety protocols) the plant did not meet the financial expectations of UCC. The locally managed UCIL provided management training and ongoing operational management. It would be obvious to any chemical engineer that stringent safety measures must be designed to be in place to prevent the escape of MIC. An analysis (see Fortune and Peters 1995) shows that ten such measures were designed:
1. Safety valves
2. ‘Slip bind' metal sheet
3. Refrigeration unit (to keep MIC in its liquid form)
4. High-temperature warning alarm
5. Pressure gauge on the MIC tank
6. Pump to move MIC back to an earlier stage in production
7. Pump to move material to a reserve tank
8. Vent gas scrubber
9. Flare tower to burn off the gas
10. Gas alarm.
Late in the evening on 2 December 1984 water entered a tank containing MIC, probably due to an inexperienced technician flushing out a nearby pipe incorrectly. This produced a reaction in the tank, increasing heat and pressure and resulting in the escape of MIC gas for around an hour into the still air surrounding the facility. In the early hours of 3 December, an MIC gas cloud rolled slowly and quietly over the parts of Bhopal adjoining the plant. As large numbers of people tried to obtain medical assistance for a variety of symptoms (including burning sensation in the eyes and choking), local doctors were unsure of the cause of the problem as there was no past history of treating the effects of MIC poisoning in the city and no standard procedures in place to identify and deal with this problem.
By the time the cloud had dissipated, over 3000 people had died, though the eventual official death toll is 5325 with some estimates nearer 15000. It is estimated that at least 250,000 have suffered permanent disability with around 100,000 still seriously ill 10 years later. Typical long-term damage includes impairment to the respiratory system, miscarriages, children with birth defects, breathing problems and mental illness from the memory of the incident and its effects as well as the fear that other problems (cancers and genetic damage) will be revealed in the long term. If we look back at the safety measures which should have been in place to stop such an event occurring, we note the following:
1. Safety valves (not used correctly or not working)
2. ‘Slip bind' metal sheet (not used)
3. Refrigeration unit (to keep MIC in its liquid form) (not operational since June)
4. High-temperature warning alarm (incorrectly set)
5. Pressure gauge on the MIC tank (showed pressure but not how it was changing)
6. Pump to move MIC back to an earlier stage in production (process not running)
7. Pump to move material to a reserve tank (reserve tank full)
8. Vent gas scrubber (faulty meter)
9. Flare tower to burn off the gas (corroded pipe to tower; closed for repair)
10. Gas alarm (sounded at 01.00, long after the leak had started).