Bhopal disaster

The Bhopal disaster is widely considered the world's worst industrial accident. It occurred in Bhopal, a city in Madhya Pradesh, India.

The event centered on a pesticide plant owned by Union Carbide India Limited (UCIL). The factory produced a pesticide called Sevin, which is the brand name for carbaryl. To create carbaryl, the plant used a highly toxic chemical called methyl isocyanate, or MIC.

Because the leak was so massive, it changed how the world views industrial safety and chemical management.

The chemical process at the Bhopal plant was specific and complex. It involved reacting methylamine with phosgene to form MIC. This MIC was then reacted with 1-naphthol to produce the final product, carbaryl. This method differed from other manufacturers, such as Bayer, who used an MIC-free route. In the MIC-free process, phosgene reacts with 1-naphthol first to form a chloroformate ester. That ester is then reacted with methylamine later in the sequence. While the Bhopal method was different, it required the storage of large amounts of dangerous MIC.

The disaster was caused by a runaway exothermic reaction inside a storage tank. The facility used three underground tanks, labeled E610, E611, and E619, to hold liquid MIC. In late October 1984, tank E610 lost its nitrogen gas pressure. This meant the 42 tons of MIC inside could not be pumped out. On the night of December 2, 1984, water entered tank E610 through a side pipe during cleaning attempts. This contact between water and MIC triggered a rapid increase in heat and pressure. The reaction was accelerated by high temperatures and iron from corroding steel pipes.

Several critical safety systems failed to prevent the gas from escaping into the air. A refrigeration system meant to keep the MIC tanks cool had been shut down in 1982. Because of this, the high-temperature alarms had been disconnected. A flare tower, designed to burn escaping MIC gas, was also out of service for maintenance. Additionally, a vent gas scrubber was in "standby" mode and lacked enough caustic soda to neutralize a large leak. These failures allowed approximately 30 to 40 tonnes of MIC to escape into the atmosphere.

The history of the plant shows a pattern of warnings and smaller incidents. In 1976, local trade unions complained about pollution at the site. In 1981, a worker died after being splashed with phosgene gas. Throughout 1982, several leaks occurred, including one that caused severe burns to a chemical engineer. A journalist named Rajkumar Keswani even warned the public that Bhopal was on the edge of a volcano. Despite these signs, the plant continued to accumulate unused MIC in the early 1980s as pesticide demand fell.

The scale of the human impact was devastating and remains a subject of study. Over 500,000 people living near the plant were exposed to the toxic gas. While the official immediate death toll was 2,259, other estimates suggest 8,000 died within two weeks. Many more people died later from diseases caused by the gas exposure. A 2006 government affidavit stated that the leak caused approximately 558,125 injuries. These included 3,900 cases of severe and permanent disability.

Legal and corporate changes followed the disaster over many decades. In 1989, the Union Carbide Corporation (UCC) paid $470 million to settle litigation. In 2001, the Dow Chemical Company purchased UCC. In 2010, an Indian court convicted seven former UCIL employees for death by negligence. They were sentenced to two years in prison and a small fine.

The disaster remains a landmark case in the study of industrial responsibility and the importance of emergency communication between corporations and local governments.