By all accounts the Bhopal Gas leak on the night of 2-3 December 1984 is the worst chemical disaster in history. It took a heavy toll of human lives. People started dying within hours and more than 2000 lives were lost in the first few days.
According to Dureja and Saxena one of the earliest of the ‘Rescue Teams’ to reach Bhopal when panic was at its peak at major hospitals of the city, the patients could be graded symptomatically into four categories: (i) Minor eye ailments, throat irritation and cough, (ii) Severe conjunctivitis, keratitis, acute bronchitis and drowsiness, (iii) Severe pulmonary oedema leading to cardio-respiratory distress, and (iv) Convulsions, followed by cardio-respiratory arrest. Intense fatigue and muscular weakness was another common feature.
Several thousand survived with a variety of morbidity and permanent disabilities. According to the recent press reports, there are a large number of survivors, with lingering ailments and incapacity to work.
Non-availability of any information about the toxicity of even the parent compound, MIC (methyl isocyanides), was a great impediment to institute ‘detoxication measures’ and lay down guidelines for therapeutic intervention and management of the victims. Hence there was an urgent need to generate de novo, authentic scientific evidence and information. The ICMR rushed to the scene and tried to fill the void.
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It funded, amongst 24 other projects, two comprehensive studies on toxicology and a collateral project on PFT (pulmonary function tests)/blood gas analyses. Both these projects rapidly transformed themselves into multidisciplinary and multi-institutional investigations.
Nature of the Toxic Gases in Bhopal
Devkumar and Mukherjee drew public attention to the high reactivity of MIC. It was followed by more authoritative accounts in the Varadarajan Committee Report.
According to the report, there was a massive leak of MIC stored for a long period in the incriminated Tank 610 of the Pesticide Plant of Union Carbide of India Ltd (UCIL). Several hypotheses attributed for this disaster include, ‘prolonged bulk storage of 42 tons of MIC, non-functioning refrigeration system, failure of safety measures and malfunctioning of neutralization facilities’.
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One or more of these factors might have contributed to the accidental and uncontrolled runway reaction. From all accounts, quite unlike leakage of a single chemical like ammonia, sulphuric acid, phosgene or hydro cyanic acid, the gas release in Bhopal is not due to mere leakage of cold MIC.