Lethal aftermath

Published : Jul 02, 2010 00:00 IST

December 15, 1985: People exposed to the gas leak in December 1984 receiving treatment a year after the disaster.-GAMMA

December 15, 1985: People exposed to the gas leak in December 1984 receiving treatment a year after the disaster.-GAMMA

IN the context of the Chief Judicial Magistrate's verdict more than 25 years after the Bhopal tragedy, in the criminal case filed against the eight key employees of Union Carbide of India Ltd (UCIL) for causing death by negligence, to talk about the health effects and the continuing long-term impact of the poisonous methyl isocyanate (MIC) gas may not have direct relevance. But it helps to put matters in perspective, especially as a retrospective assessment of the out-of-court settlement amount of $470 million arrived at in 1989 in the civil case against the parent United States company, Union Carbide Corporation (UCC), filed by the Government of India on behalf of the victims. This is just over 15 per cent of the original claim of $3 billion in the lawsuit.

The Supreme Court upheld the settlement in October 1991, dismissing petitions against it. The court ordered the Indian government to purchase a group medical insurance policy to cover 100,000 affected persons. Official estimates put the immediate death toll at around 2,500 and the total number of deaths related to the tragedy at around 4,000. Other estimates put the total death toll at around 15,000. But several thousands have been condemned to long-term morbidity. In fact, there are more than 500,000 registered survivors of the worst chemical disaster in the world.

The Bhopal Gas Tragedy and Rehabilitation Department of the Madhya Pradesh government claimed that by October 2003, compensation had been awarded to 554,895 people for injuries and 15,310 survivors of those killed. But according to reports, very little money from the settlement amount actually reached the survivors. Indeed, even the insurance cover, as directed by the court, was never bought by the government. In July 2004, the Supreme Court ordered the Indian government to release the remaining settlement funds to the victims by April 30, 2006. The final compensation was reported to be Rs.25,000 for grievous personal injury and Rs.62,000 for death claims. By 2007, the number of cases in which compensation was awarded was 574,304 and the total compensation awarded was about Rs.1,560 crore, according to the State government. An unspent amount of over Rs.1,500 crore is still lying with the government. Activist groups have been demanding that the compensation amount be enhanced given the enormity of the long-term health effects and the steep inflation in the interim period. Sadly, these demands have gone unheeded.

At the time of the disaster, there was no law in the country that laid absolute liability on the operator of a hazardous unit or provided for immediate payment of compensation. The Public Liability Insurance Act of 1991 was passed to address this issue in case of accidents involving non-nuclear hazardous substances. The Act, however, despite the experience of the Bhopal tragedy, only allows for an award of Rs.25,000 for a death claim and a total relief of Rs.25,000 towards medical expenses and rehabilitation in case of permanent or partial injury or serious sickness. Even today there is no comprehensive law relating to chemical accidents, which can be far more serious than other accidents as Bhopal has shown. A draft Green Tribunal Bill is reported to be awaiting passage into an Act.

The medical follow-up study by the Indian Council of Medical Research (ICMR), based on diverse multi-institutional projects over a 10-year period between January 1984 and May 1994, on the communities that were exposed to the leak provides a reasonably comprehensive perspective on both short- and long-term health effects. Epidemiological studies formed the core of the study that included 25 research projects, including two multidisciplinary ones on pathology and toxicology to determine the effects of inhaling noxious gases. The investigations also included clinical and toxicological studies. The work was coordinated by the Bhopal Gas Disaster Research Centre (BGDRC).

The settlement came well before the completion of this study, and it is not known if the findings up to 1989 were taken into account to arrive at the amount. What is even more intriguing is that the results of the study were not made public until 2004, and even that was because of the perseverance of a few retired ICMR scientists, particularly the late S.S. Sriramachari. Moreover, the report apparently does not include the results of some important studies on children, N.R. Bhandari, who led these studies, has alleged in the wake of the recent verdict.

About 42 tonnes of MIC (and other gaseous products of the runaway reaction) are believed to have leaked from the storage tank in the UCIL plant in December 1984. Nearly three-fourths of the eight-lakh strong population at that time were exposed to the leak. Different sections of the population were exposed in different degrees, depending on their distance from the plant and atmospheric factors. A total number of 80,000 individuals were studied at severely, moderately and mildly exposed areas and compared with controls from unexposed areas. Of the total population, 3.9 per cent was affected severely, 8.6 per cent moderately and 50.1 per cent mildly, while 37.4 per cent was not affected. Most people included in the study had no fixed occupation or fixed source of income. Nearly 70 per cent of the people in the severely affected as well as control areas (areas where the gas had not spread) lived in kuccha houses, and prevalence of the smoking habit ranged from 0.2 to 14.3 per cent.

According to the ICMR report, nearly three-fourths of the deaths occurred within the first 72 hours of the leak, which occurred around the midnight of December 2-3, 1984. In the first 48 hours, the death rate in some of the worst affected areas was as high as 30 per thousand. In fact, for the month of December 1984, the death rate was 24 per thousand, against the national average of 1 for the corresponding period. The worst affected were children under five years, and the death rate was 33 per thousand; the rate was 15 for the age group above 15. The number of deaths declined rapidly, but the extent of the health impact on the survivors could not be gauged at all because nothing was known about the toxic effects of MIC, so no antidote could be administered, the report says.

Suppression of critical information

Besides MIC, which constituted the primary gas leak, a mixture of other toxic gases that escaped with it compounded the havoc, unlike in other chemical disasters. The exact nature of the leak was also unknown, and it came in the way of evolving an appropriate course of clinical management of the victims. The early recourse was limited to symptomatic treatment. Even though UCIL had been engaged in the manufacture of MIC since 1980, it apparently had no information on its toxicity or its antidote in case of severe exposure. This could be the fallout of pressure from the parent company because UCC all along underplayed the toxicity of MIC and even resorted to misinformation that led to confusion and controversy among Indian medical professionals.

The issue of cyanide toxicity' and the administration of sodium thiosulphate (NaTS), the known antidote to cyanide poisoning, was particularly controversial. A criminal charge against UCIL/UCC officials can certainly be made over this suppression of critical medical information. But it seems that the Central Bureau of Investigation (CBI), which brought the charges, did not press this particular charge in the criminal case that has just concluded.

It was later determined, through gas chromatography and mass spectroscopic studies of the tank residue and the blood of victims, autopsies of tissues, and tests on the tissues of survivors, that the aerosol inhaled by the affected contained a mixture of 21 chemicals. These included MIC and its dimers and trimers as well as aqueous and thermal decomposition products, including hydrogen cyanide, or HCN. The Medicolegal Institute in Bhopal conducted autopsies on 837 bodies it received in December 1984.

Lung was the primary target

The most important finding of these initial autopsies was that the lung was the primary target organ, and its weight increased two- to threefold after the victim inhaled the poisonous gas. A series of pathological changes were seen in the entire respiratory tract, including severe pulmonary oedema (accumulation of fluid in the lungs), enlarged air sacs and haemorrhages, general visceral congestion, cerebral oedema and anoxic brain damage.

A puzzling feature was a characteristic cherry red discolouration of the lung tissues, which was thought, and later proved, to be caused by cyanide toxicity. The mechanism of this development is now understood as the binding of MIC to terminal end amino acid of haemoglobin and its involvement in biochemical processes known as N-carbamoylation and S-carbamoylation. The latter, in particular, has been argued to be responsible for maintaining a constant circulating cyanogens pool in the body, thus affecting key enzymes and their body functions and resulting in long-term health effects and related morbidities.

According to the study, most deaths occurred owing to asphyxia caused by acute lung injury or acute respiratory distress syndrome (ARDS). Later studies, from four months to one year and beyond, showed the development of diffuse pulmonary fibrosis. The report emphasises that a large fraction of the exposed population continues to be chronically ill with respiratory, gastrointestinal tract (GIT), reproductive, musculoskeletal, ocular, neurological, psychological and other disorders. It also highlights the need for continued investigations on long-term effects, which include impaired immune competence. An increase in miscarriages has also been noted in a large pregnancy outcome study in the severely affected areas. Sriramachari had stressed the importance of follow-up studies on the incidence of cancer among the victims. There are, of course, questions like genetic and teratogenic effects that need to be studied.

Post-exposure phases

Depending upon the varying clinical features, the different post-exposure phases have been classified in the study as acute (first month of exposure), subacute (one to three months) and chronic (more than three months). Most symptoms during the acute period were related to the effects of the gas(es) on the eyes and the respiratory tract. The ocular symptoms, however, got cleared with prompt treatment, notes the report. In the acute phase, in addition to respiratory complaints, including chest pain and breathlessness, there were complaints of muscle weakness, listlessness, febrile illness and vomiting. The blood samples in this phase revealed increased white blood cells and higher than normal haemoglobin levels.

Persistent morbidities, suggesting multi-organ involvement, started manifesting in the subacute phase. As many as 40 per cent of the persons attending hospitals complained of respiratory problems even two months after the exposure. A significant finding was that the severity of respiratory problems did not correlate at all with physical and X-ray results of the lung function. A significant number also presented gastrointestinal symptoms in this phase. Though it was found that ocular symptoms arose mainly from effects of the gas in the anterior of the eye, which could be treated, a proportion of patients could end up with corneal opacities requiring surgery on corneal tissues. Ophthalmic complaints were present in 80 per cent of the subjects residing 0.5 km from the plant and in 40 per cent of the people residing 8 km away.

Psychological problems

Psychological consequences were also found to be significant in this phase. Over a tenth of the exposed population displayed psychological symptoms. While these were predominantly anxiety and depression, cases of disturbed sleep, gas phobia and feeling of hopelessness were also reported. These problems were more prevalent among bereaved, widowed and orphaned individuals, and many families were found to be unable to cope with the tragedy, the report notes.

In the chronic phase, irrespective of the severity of the exposure, a majority continued to display respiratory symptoms and severe muscle weakness, body aches, abdominal pain, loss of appetite, disturbed vision, disturbed sleep and severe loss of capacity to work. Even if victims improved clinically following treatment, cough, chest pain and dyspnoea (laboured breathing) and weakness persisted. Most significantly, says the report, it was in this phase that many developed symptoms of wheezing. Abnormalities in lung function tests (LFTs) were also seen as a common feature, and the severity of respiratory symptoms did not correlate with the radiological symptoms, LFTs and physical examination like before. Neuromuscular defects, such as tingling, numbness, sensation of pins and needles in extremities, and muscle aches have continued among the victims, according to the study.

A random survey of 10 hospitals three to five months after the disaster found a high 22.6 per cent to be suffering from mental disorders. People suffered from anxiety, neurotic depression and other psychological problems. Of the 208 people suffering from psychological problems, 45 per cent suffered from neuroses, 35 per cent from anxiety and 9 per cent from accentuated adjustment problems. A separate study in the chronic phase found impairment of auditory and visual memory, attention, response speed and vigilance. A follow-up study after one year found associated learning and motor speed and precision to be significantly impaired. Yet another study found the psychological disorders to have set in even among children of seven years and above.

In 1986, deaths due to respiratory causes were high in both the severely and moderately affected areas, whereas in the mildly affected areas digestive tract causes were also significant. In 1992, deaths due to respiratory causes became the highest in all the three exposed areas. Significantly, in the mildly affected areas, 20 per cent of the deaths were because of neurological or circulatory disorders. In 1993, the overall death rates among males in the mildly affected areas were seen to be high. This was partly because of the very high death rates among the elderly (60 years and above). Lung- and eye-related morbidities have been dominant (over 95 per cent) in all the three categories of the exposed population. About 75 per cent have experienced GIT disorders, which, according to the study, came down to 12 per cent in males and 17 per cent in females after one year in the severely affected areas.

According to the report, morbidity rates in the variously affected areas showed distinct trends. In the severely affected area, the rates were low up to 1988. Later, the rates tended to increase in surveys up to May 1991 and showed a decrease thereafter. The increase was seen in the moderately and mildly affected areas as well, but the peak came a little earlier in May-November 1990 and in November 1989-May 1990, respectively. In general, says the report, morbidity studies showed that there was a multi-system involvement. Data based on 40 symptoms showed that there was persistent high overall morbidity along with high respiratory, ocular and GIT-related morbidities in the affected areas with the highest rates seen in the severely affected area. Respiratory disorder has been the main cause of higher morbidity followed by ocular morbidity, which seems to have worsened after 1991.

The increase in the morbidity rate in the mildly affected areas in the 1990s showed that all the exposed areas, irrespective of the distance from ground zero, had been rendered vulnerable by the long-term toxicity of the gases, though the timing of the sequence of effects (including death) was dependent on the spread of gases in the atmosphere and the inhaled concentrations of various gases by the victims. The ICMR report has also ascribed the cause of the higher mortality rate seen in moderately and mildly affected areas as compared to the severely affected areas during 1992-93 to the unknown pattern of the spread of the toxic gas mix and inhaled quantities. Significantly, the ICMR report noted that the mortality and morbidity rates did not decline close to the level of the control areas even 10 years after the tragedy.

Effect on women's reproductive health

Some epidemiological studies have continued beyond the ICMR study period. For instance, a recent study has found that 20 years after the disaster, menstrual abnormalities, vaginal discharge and premature menopause have emerged as common problems among women exposed to the gas and their girl children. Besides affecting the reproductive health of women, these conditions also lead to social problems, notes a recent review by P.K. Mishra of the Bhopal Memorial Hospital and Research Centre (BMHRC) and others in the International Journal of Occupational Medicine and Environmental Health. Girls who were exposed to the leak in infancy and those who were then in their mother's wombs, says the review paper, are now experiencing menstrual chaos.

The incidence of miscarriages was found to be 24.2 per cent among pregnant women exposed to the gas as compared with those in the control areas. The ICMR report had also found a higher rate of miscarriages in the initial years in addition to menstrual problems. Other indicators of adverse reproductive outcome, such as the rate of stillbirths and congenital malformations, were found to be different in the affected areas. An anthropometric survey on exposed adolescents carried out 16 years after the exposure showed that there was a selective retardation in boys but not in girls. This was also noted among children born to exposed parents, says the review.

Long-term effects, says the ICMR report, of this one-time injury to the respiratory tract and the ophthalmic system would continue to produce recurrent and episodic respiratory illness, and possibly disability, for a long time to come. In particular, people with pre-existing lung disorders (about 5 per cent of the population) and smokers would have suffered more, the report notes. The Bhopal population today is more vulnerable; pulmonary fibrosis has accentuated, there is occlusion of bronchioles, Siramachari, who edited the report, observed some time ago.

The ICMR report may have seen the light of day a decade after it was completed, but its findings must have been known to the agencies concerned. These, however, do not seem to have been used systematically for clinical management of the affected people. The monitoring of these 80,000-odd people, Sriramachari pointed out, should be an ongoing process, and the State health authorities should use this data as a base and take steps such as deploying mobile units with blood gas apparatus, lung function tests and oxygen concentrators. Such measures can extend therapeutic support for chronic respiratory illnesses.

It is debatable whether these long-term effects could have been greatly reduced if MIC toxicity was better understood, particularly the cyanide toxicity and the use of NaTS antidote therapy during the acute phase. Given the controversy, NaTS therapy was discontinued under official pressure. However, from the perspective of the evident chronic illnesses and the continuing morbidities, the criminal act of suppression of vital information by UCC, and probably UCIL, also assumes significance.

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