The Bhopal disaster
World's worst industrial disaster from a toxic gas leak.
The Bhopal disaster unfolded on the night of 3 December 1984, when over half a million people living near the Union Carbide India Limited pesticide plant in Bhopal, Madhya Pradesh, were exposed to the highly toxic gas methyl isocyanate. This event is widely regarded as the world’s worst industrial disaster. The plant, built in 1969, originally produced the pesticide Sevin using methyl isocyanate as an intermediate, with a dedicated MIC production unit added in 1979. The chemical process involved reacting methylamine with phosgene to create MIC, which was then combined with 1-naphthol to form the final product. Unlike some other manufacturers who later adopted MIC-free routes at greater cost, UCIL continued using this method. By the early 1980s, falling demand for pesticides led to an accumulation of unused MIC at the site. The facility housed three underground liquid MIC storage tanks, each meant to be filled no more than 50% (about 30 tons) and pressurized with nitrogen gas to prevent contamination. In late October 1984, one tank lost its ability to hold nitrogen pressure, trapping 42 tons of MIC. Production was halted for maintenance, including repairs to a corroded pipe in the flare tower, but carbaryl production resumed in late November using MIC from the remaining tanks. Prior to the disaster, there had been multiple smaller leaks: a fatal phosgene exposure in 1981, a phosgene leak affecting 24 workers in January 1982, an MIC leak affecting 18 workers in February 1982, a severe MIC burn in August 1982, another MIC leak in October 1982, and various combined leaks of MIC, chlorine, and other gases throughout 1983 and 1984.
- location
- Bhopal, Madhya Pradesh, India
- company_involved
- Union Carbide India Limited (UCIL)
- parent_company
- Union Carbide Corporation (UCC)
Quick Facts
- Date
- 1984 · 12 · 2 · 1984 · 12 · 3 · df=y
- Location
- Bhopal, Madhya Pradesh, India
- Also Known As
- Bhopal gas tragedy
- Cause
- Methyl isocyanate leak from the E610 storage tank on the Union Carbide India Limited plant
- Deaths
- At least 3,787; over 16,000 claimed
- Injuries
- At least 558,125
Facts from the source article.
Lore & Background
By the early 1980s, demand for pesticides had fallen, but production continued, leading to an accumulation of unused MIC at the site. In the months before the leak, tank E610 lost its ability to contain nitrogen gas pressure, leaving 42 tons of liquid MIC trapped inside. Safety systems, including a refrigeration system, flare tower, and vent gas scrubber, were malfunctioning or inoperable. The pressure rose rapidly, and by 12:40 a.m. on 3 December, the emergency relief valve burst, releasing about 30 tonnes of MIC gas into the atmosphere over four hours.
Reader's Guide
The Bhopal disaster, occurring on 3 December 1984, exposed over 500,000 people near the Union Carbide India Limited pesticide plant to methyl isocyanate gas. A 2006 government affidavit recorded approximately 558,125 injuries, including 38,478 temporary partial injuries and 3,900 severely and permanently disabling injuries. Official immediate deaths numbered 2,259, though other estimates suggest 8,000 died within two weeks and another 8,000 or more from gas-related diseases. The plant, built in 1969, produced the pesticide Sevin using methyl isocyanate as an intermediate, with an MIC production unit added in 1979. The process involved methylamine reacting with phosgene to form MIC, then reacting with 1-naphthol to produce carbaryl. After the plant was built, other manufacturers produced carbaryl without MIC, though at higher cost. By the early 1980s, falling pesticide demand led to accumulated unused MIC on site. The facility had a history of leaks: a 1981 phosgene leak killed a worker; a January 1982 phosgene leak exposed 24 workers; a February 1982 MIC leak affected 18; an August 1982 liquid MIC exposure burned a chemical engineer; and an October 1982 MIC leak severely burned the supervisor and two workers. Throughout 1983 and 1984, leaks of MIC, chlorine, monomethylamine, phosgene, and carbon tetrachloride occurred. The disaster’s cause involved three underground liquid MIC storage tanks. Tank E610 lost nitrogen pressure in late October 1984, preventing pumping of its 42 tons of MIC. MIC production then halted for maintenance, including repair of a corroded pipe on the inoperable flare tower. Carbaryl production resumed in late November using MIC from the other tanks. In 1989, Union Carbide Corporation paid $470 million to settle litigation. The factory was majority-owned by UCC, with 49.1 percent held by Indian public and government-controlled banks. UCC sold its stake in 1994 to Eveready Industries India Limited, which merged with McLeod Russel. Eveready ended site clean-up in 1998, turning control over to the state government. Dow Chemical purchased UCC in 2001. US civil and criminal cases against UCC and its CEO Warren Anderson were dismissed and redirected to Indian courts between 1986 and 2012. In June 2010, seven former UCIL employees, including chairman Keshub Mahindra, were convicted in Bhopal of causing death by negligence, receiving two-year se
Did You Know?
- The Bhopal plant's MIC storage tank E610 held 42 tons of liquid MIC when the leak occurred.
Common Misconceptions (Editorial)
Some people mistakenly believe the Bhopal disaster was solely the fault of the parent company, Union Carbide Corporation (UCC), but the facts show the plant was operated by Union Carbide India Limited (UCIL), though UCC was the parent company. Another common misconception is that the leak was a sudden, unforeseeable event; in fact, the facts indicate that safety systems such as the refrigeration system, flare tower, and vent gas scrubber were malfunctioning or inoperable prior to the leak, and tank E610 had already lost its ability to contain nitrogen pressure, making the disaster foreseeable.
Why It Matters (Editorial)
The Bhopal disaster endures as a stark reminder of the catastrophic consequences when industrial safety is neglected in pursuit of profit. Its legacy continues to shape global environmental and chemical safety regulations, underscoring the urgent need for corporate accountability and the protection of vulnerable communities from industrial hazards.
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