Those who survived the Bhopal Gas Tragedy faced an increased risk of premature death in addition to experiencing a reduced lifespan, according to a study published last year.
Victims exposed to the toxic methyl isocyanate (MIC) gas leak suffered the most, especially individuals aged 21 and older. Men were found to be more affected than women, as per the study published in July 2023 in the PubMed journal.
The analysis, titled Survival Analysis for Cohort of Bhopal Gas Disaster Victims During 1985-2015, was published in July 2023. It evaluated the survival patterns of individuals exposed to MIC.
The study also compared the survival rates of affected individuals to those who were not exposed to the gas to analyse how factors like gas exposure, gender, and age influenced mortality rates.
The researchers analysed data from 92,320 individuals over 30 years (365 months) using various statistical models. The findings revealed that men and individuals aged 21 and above in the gas-affected cohort experienced significantly higher mortality rates.
Over the 30-year study period, 6,609 deaths were recorded, equating to a mortality rate of 7.2 per cent. The median age at death was 40 years. Among these, 5,540 deaths occurred in areas exposed to the gas, while 1,159 deaths were reported from unaffected areas.
The average survival time for gas-affected individuals was found to be 344.5 months, compared to 349.5 months for those not exposed, indicating a five-month reduction in lifespan for the affected group.
While this difference in mortality rates appeared less pronounced over the three decades, mortality rates were significantly higher during the initial years following the disaster. The trend later stabilised, likely due to improved medical facilities and government interventions.
The analysis divided the 30-year period into three phases. For Phase 1 (0-100 months), the survival rate was notably lower for the gas-affected group. The survival rate remained lower for the affected group in Phase 2 (101-300 months). In Phase 3 (301-400 months), mortality rates between the affected and unaffected groups became almost identical.
This indicates that the initial post-disaster years were the most critical for the affected population, with mortality rates leveling off in subsequent decades.
The study found that women had a higher survival rate compared to men. Additionally, individuals aged 21 and older exhibited lower survival rates than those younger than 20 years.
Individuals exposed to the gas had a 1.30 times higher risk of death compared to those who were not exposed. Between 1986 and 2000, respiratory illnesses were the leading cause of death among gas victims, while their prevalence was significantly lower in the unaffected group. Over time, an increase in deaths due to circulatory system diseases and nervous system-related disorders was observed.
The study underscored the long-term impact of biological factors such as age and gender on mortality. It also highlighted the need for ongoing healthcare support for individuals exposed to the gas leak.
As survivors now fall within the age range of 30 to 99 years, they face heightened risks of age-related health issues such as cardiovascular diseases, stroke, diabetes, and cancer.
The research was conducted by a team from the Indian Council of Medical Research-Indian Institute for Research in Environmental Health, Bhopal, including Sushil Singh, Dharamraj, and Yogesh Sabde, along with Rajnarayan Ramshankar Tiwari. They collaborated with Madhanraj Kalyanasundaram from the School of Public Health, ICMR-National Institute of Epidemiology, Chennai.
The findings offer valuable insights into the long-term health consequences of industrial disasters and stress the importance of comprehensive healthcare strategies for affected populations.