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Objectives: In 1984, nearly 500,000 inhabitants of Bhopal city, India, were exposed to toxic gases that leaked from a nearby pesticide manufacturing plant. In 1985, four cohorts were established to assess the long-term health impact of exposure, namely, mild, moderate, severely exposed and unexposed groups. The self-reported morbidity data of these cohorts were collected by follow-up cross-sectional surveys at regular intervals over the last 35 years. The present study aimed to analyse the long-term trend of chronic (duration of symptoms >3 months) respiratory morbidity in the four cohorts, stratified by age groups., Study Design: The design of this study is a longitudinal analysis of cross-sectional respiratory morbidity data., Methods: Chronic respiratory morbidity data within the cohorts were analysed at 5-year intervals (first recorded data from 1986). Based on age at the time of exposure, subjects were stratified into four age groups: children (aged <10 years), teenagers (aged ≥10 to <20 years), younger adults (aged ≥20 to <40 years) and older adults (aged ≥40 years)., Results: During the first decade, after exposure to the toxic gases, chronic respiratory morbidity in children and teenagers was high (up to 9.1%), which declined thereafter. Progressively increasing chronic respiratory morbidity was observed in both the younger and older adult age groups within all cohorts during the initial 5-10 years after exposure. Respiratory morbidity in both the younger and older adult age groups remained high for 15-20 years and thereafter recorded a declining trend. The highest respiratory morbidity observed during this study in the younger and older adult age groups was 38.6% and 59.5%, respectively; these values were both recorded in the severely exposed cohort., Conclusions: Exposure to toxic gases released during the Bhopal gas disaster has resulted in chronic respiratory morbidity of the exposed population; this morbidity has continued over decades. The age of the individuals at the time of exposure and exposure severity were crucial determinants of the long-term trend of respiratory morbidity., (Copyright © 2020 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.)

Following the 1984 Bhopal methyl isocyanate (MIC) gas disaster, genetic alterations were sporadically reported on small cohorts. However, the outcome of the multi-center cytogenetic screening conducted at that time remains unknown and no follow-up studies on the long-term effects of MIC exposure have been published. The present work examines genetic changes in the exposed population,with the aim of identifying any long-term effects of MIC. G-Banded metaphases were studied in lymphocytes of 130 individuals. Chromosomal aberrations (CA) were broadly grouped as abnormal cells (Abc), aberrations (Abn), and aberration/abnormal cell (Abn/Abc). From the previous multi-center screening, 946 records were retrieved, from which CA, sister chromatid exchanges (SCE), and cell-cycle kinetics (RI) were computed. In our analysis of the previous study, Abc and Abn were higher in the moderately and severely exposed groups than in the unexposed population. Abc appeared uniform in all groups of the present study, although Abn and Abn/Abc were higher in the exposed groups. Aberrations were now significantly higher in the unexposed and moderately exposed groups than in the previous screening. Although Abn and Abc now appeared lower in severely exposed subjects, the Abn/Abc ratio was higher, perhaps due to more rearrangements and damage in a smaller number of Abc. This result may be attributed to differences between the methods used in the studies, then and now. Elevated SCEs and reduced RI were seen in the severely exposed population shortly after exposure, and stable/clonal rearrangements were seen 30 y later. Follow-up of index cases and their progenies is needed., (Copyright © 2017 Elsevier B.V. All rights reserved.)

There is a vital need to understand details of the methylisocyanate (MIC) release that occurred at the 1984 Union Carbide Ltd. pesticide plant in Bhopal, India in order to avoid or respond to such releases in the future. However, we believe there are serious deficiencies in currently available dispersion predictions of the impact of toxic materials on humans and animals downwind of the plant. Specifically, cloud densities have been underestimated due to failure to account for the presence of a liquid/solid aerosol that would have been produced by the chemical reactions that caused the problem. Using data reported in Union Carbide's own investigation of the accident, which included chemical reaction data, we estimated aerosol compositions and cloud densities, then modeled the Bhopal release, simulating potential exposure levels at various locations under a number of wind-condition scenarios. For the worst-case (low wind speed and high aerosol densities), our predicted MIC concentrations at ground level are at least one order of magnitude greater than any previously published estimates. The centerline elevation of the jetting plume released at 33 m elevation is predicted to rise to about 41 m before falling, resulting in a 40 ppm (Immediately Dangerous to Life or Health, IDLH) concentration contour that reaches the ground at about 410 m downwind of the release location. This is consistent with observations that the plant environs were not hard-hit while the public immediately downwind of the plant perimeter was severely exposed. Concentrations on the order of 1000 ppm are predicted at some ground-level locations, which are more consistent than previous estimates with the reported large numbers of deaths and injuries of humans and animals., (Copyright © 2012 Elsevier B.V. All rights reserved.)