December 3, 1984
Over 20,000 deaths resulted from the release of toxic gas, 40 tons of methyl isocyanate gas, used in the manufacture of the pesticide Sevin, made by Union Carbide, now a part of the Dow Chemical Company.
25 years later the disaster site remains toxic and contaminated.
A few informative websites:
Dow Chemical Company accepts full responsibility for Bhopal (video)