Bhopal continues to bear the brunt of toxic disaster
Disastrous health effects of methyl isocyanate (MIC) gas that leaked from the Union Carbide factory in Bhopal continue to unfold even after a quarter of a century.
The absence of long-term follow up of the survivors and their offspring by any medical research agency of the government has left large gaps in knowledge about the long-term effects of MIC. Small research studies and anecdotal evidence point out continued effect of the gas among those exposed as well as among children born to gas-affected parents and, in some cases, in the third generation as well.
The health impacts range from stunted growth to cleft lips.
The Indian Council of Medical Research (ICMR) had followed up over 80,000 people exposed to the gas from 1985 to 1994, but published its first report only in November 2004.
After survivors approached the judiciary demanding medical follow up, the council last year decided to re-start research work in Bhopal. But its call for research proposals has received only lukewarm response.
More than half a million people were exposed to MIC, and around 1.2 lakh of them continue to suffer from chronic respiratory, ophthalmic, reproductive, endocrine, gastro-intestinal, musculo- skeletal, neurological, and mental disorders.
The diversity of symptoms prompted the ICMR to conclude that MIC alone could not have been responsible. 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 byproducts of MIC - including hydrogen cyanide (HCN) - generated in runaway reactions in the tank at very high temperature.
It was for the first time that chemicals including high levels of cyanides were traced in human bodies after a massive chemical disaster.
A study done by Sambhavana Trust Clinic provided the first evidence of selective growth retardation in boys - but not in girls - who were either exposed as toddlers or were born to gas-exposed parents.
The main chemical that escaped from the plant was MIC, which is readily degraded on contact with water and in the body. One of the degradation products of MIC is trimethylamine, which has been reported to produce selective growth retardation of male progeny of mice.
Scientists believe it is possible that similar hormonal effects were produced by MIC, its metabolites or other substances.
The clinic has subsequently undertaken a large study among children born to exposed parents, but its results are yet to be published.
"We are analysing the results of this study which involved about one lakh children in different categories," said Rachna Dhingra of Sambhavana.
Experts feel long-term monitoring of the affected community needs to be done for the next several decades. At present, no genetic studies are going on. The only long-term follow-up is in the form of a population- based cancer registry.
Continuous follow up of the gas-affected could help agencies take important decisions about action on detoxification, short-term and long-term treatment, long- term health consequences, and the implementation of a programme to compensate the victims.
Yet another problem Bhopal faces is the toxic remains of the Union Carbide factory.
A series of investigations by Indian and international organisations have found evidence of contamination of the subsoil and groundwater with heavy metals and persistent organic pollutants from the abandoned pesticide plant.
Greenpeace has found chemicals such as carbon tetrachloride, chloroform, trichloroethene, tetrachloroethene, and dichlorobenzene, in concentrations ranging from five to 600 times the safety limits.
Such chemicals stay in the environment for tens of thousands of years and have known health effects on the liver and kidney, while some are carcinogenic.