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It’s 20 years since the world witnessed the worst ever chemical, industrial and environmental disaster at Bhopal in central India. On a cold wintry night of December 02/03, some 40 tonnes of methyl isocyanate (MIC) and other toxic gases leaked from the Union Carbide factory, killing thousands instantaneously and maiming several thousand others. The health effects of exposure to the deadly cocktail of gases continue to unfold even after such a long time.
The Indian Council of Medical Research (ICMR) that followed up a cohort of over 80,000 gas victims from 1985 to 1994, has published its first report recently listing some of the adverse effects of the gas exposure. The council’s report has reiterated that the disaster can not be attributed to MIC alone. The aerosol of toxic gases inhaled by the victims possibly contained a mixture of over 20 aqueous and thermal decomposition products, and a host of reactant chemicals and polymers of MIC- including Hydrogen cyanide (HCN) - generated due to a runaway reaction in the tank at very high temperature.
This has been proved by both analysis of residues in Tank 610 and MIC, HCN and other chemicals to blood and viscera of dead and living exposes have been tracked down. For the first time, chemicals have been traced in human bodies after a massive chemical disaster, say scientists involved in research in Bhopal. Double blind clinical trials also showed that administration of sodium thiosulphate helped in relieving symptoms of cyanide poisoning and excretion of urinary thiocyanate.
The report has concluded that toxic gas inhalation caused injuries to respiratory tracts and ophthalmic systems of the people. But long-term research needs to be continued to study potential hazards of cancer and long-term involvement of other organs. After ICMR concluded its research work, it passed on the database to Centre for Rehabilitation Studies, set up by Madhya Pradesh government. The Bhopal Memorial Hospital and Research Centre (BMHRC), set up from proceeds of Union Carbide shares in 2000, also plans to undertake long-term research on MIC exposure. The BMHRC has recently established a Department of Epidemiology and Biostatics to take up public health research in both MIC related and other public health issues. It also proposes to launch studies on possible genetic mutations, especially among the offspring of the gas victims.
Clinical and toxicological studies have shown that MIC is a potent toxin. Chronic inflammation of the eye and respiratory tract account for a major portion of its adverse impact. Experts say that these damaged organs could become more susceptible to other environmental inflictions such as infections, irritants, and allergens. For instance, a person with airway damage may be more prone to infections or respond adversely to smoke and dust. Pulmonary function limitation may preclude survivors from working on jobs which require moderate or strenuous activity. Progressive pulmonary fibrosis and restrictive lung disease appear to be a major cause for concern among the gas-exposed.
While hearing a petition on the medical follow up of the gas victims, the Supreme Court has appointed an advisory panel, to be headed by director general of ICMR, to develop treatment protocols for gas-related disorders after examining current practices in Bhopal hospitals as well as to suggest research to find out long-term health impact of the exposure. The research includes effect on children born to gas-affected parents. The court constituted another panel to monitor functioning of healthcare facilities in Bhopal and to look into complaints from gas-affected patients. Both the panels are supposed to report back to the court every six months.
Yet another problem Bhopal faces is the toxic legacy leftover by Union Carbide at the factory site. A series of investigations by Indian and international agencies have found evidence of contamination of subsoil and groundwater with heavy metals and persistent organic pollutants from the abandoned pesticide plant. Chemicals such as carbon tetrachloride, chloroform, trichloroethene, tetrachloroethene and dichlorobenzene, in concentrations ranging from 5 to 600 times prescribed limits, have been found in groundwater. Only a carefully drafted remediation plan can prevent further damage to the environment and make the site safe for future use.
Calling the Bhopal disaster man-made, the ICMR report has concluded that it could have been averted if the Union Carbide factory did not have any inhabitation within four kilometer of the site, and if proper monitoring and safety devices had been maintained. It also says that MIC should not have been stored for such a long time, as was done. The gas was stored for six weeks, which was against the company’s own norms.
It is a striking fact to note that much of the mortality and morbidity could have been averted by the simple measure of covering the face with a wet cloth. MIC would have been decomposed on contact with the water. Unfortunately, the community was never informed of the existence of such a potent chemical in the factory and contingency measures to be taken in the event of a leak. This is perhaps the biggest lesson one can learn from Bhopal. We need to have emergency planning and disaster preparedness at every level to prevent such mishaps. Countries also have to exercise caution to see that only safe technologies are allowed and that multinational companies don’t follow double standards of safety and environment protection. At the same time, research on hazardous compounds – both primary and intermediate chemicals – should be carried out. All these issues have gained greater importance than 1984, because of globalisation phenomenon that we are witnessing today.
*Science Writer
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