Methyl Isocyanate is best known industrially induced disaster which occurred at the Union Carbide pesticide plant in Bhopal, India in December 1984. The plant started to produce the pesticide SEVIN or Carbaryl in 1969 and MIC is an intermediate chemical in SEVIN production. The process uses a cost efficient one step-process using the highly toxic methyl isocyanate gas.

The MIC release was suggested to accrue the violent reaction from inappropriate introduction of water into the storage tanks of MIC. Introduction of water to MIC resulted in a highly exothermic reaction generating CO2, which would have led to a rapid increase in pressure which could have caused the release of 40 metric tons of MIC into the atmosphere. Normally, this release of MIC would be harmless as it would be passed through NaOH ‘scrubbers’ in the exhaust lines but unfortunately on that very day, the scrubbers were not working and the toxic was emitted into the surrounding town. As a result, the casualty rate was over 3000 and the major cause of death was pulmonary edema. The secondary cause was respiratory infections like bronchitis and pneumonia. There was over 100 000 injuries and significant damage was done to livestock and crops. An estimated 50 000 people remained partially or totally disabled. In addition, there were reproductive effects like leukorrhea, pelvic inflammatory disease, and an increase in the number of stillbirths and spontaneous abortions of the survivors of the Bhopal incident. After extensive negotiations in 1989, the Indian government, on behalf of the Bhopal victims, were awarded with $470 million in compensation from the Union Carbide.

Methyl Isocyanate