A pragmatic & translational approach of human biomonitoring to methyl isocyanate exposure in Bhopal.

Human biomonitoring has evolved beyond margins to ascertain exposure-response relationship in environmental associated human diseases. As occupational ailments continue to dominate global concerns, biomonitoring strategies have evolved better in terms of evaluating health risks associated with systemic uptake from chronic (long-term) environment exposures. Even though contributions of acute toxic exposures (short-term) towards initiation of disease processes have been gradually recognized, a comprehensive approach delineating mechanistic insights of such an implication remains elusive. Molecular biomonitoring in a strictly selected defined surviving cohort of the infamous Bhopal gas tragedy “as a model”, could provide an unparallel opportunity to discern the long standing implications of acute exposures. Besides comprehending clinical significance of isocyanate toxicity, the results might provide a framework for understanding the molecular repercussions pertaining to a host of other such acute environmental exposures. The investigative strategy might also be helpful in identification of biomarkers with potential for translational research.

Long term morbidity in survivors of the 1984 Bhopal gas leak.

BACKGROUND: The extent and nature of long term health sequelae among survivors of the Bhopal gas disaster are not known. In 1994 an International Medical Commission was set up with the aim of assessing respiratory, neurological and other health effects attributable to gas exposure. METHODS: An epidemiological survey of a representative sample of gas-exposed inhabitants of Bhopal was conducted in January 1994; for reference, a group of unexposed persons in the same city were surveyed. Questionnaires regarding health and exposure were administered to 474 persons, and a random sample (n=76) were subjected to respiratory and neurological testing. Responses to the questionnaire and the results of clinical testing were analysed according to a measure of individual gas exposure. RESULTS: A large number of subjects reported general health problems (exposed v. unexposed; 94% v. 52%) and episodes of fever (7.5/year v. 2.5/year); adverse outcome of pregnancy (e.g. still-births, 9% v. 4%) and respiratory symptoms (81% v. 38%), with a strong gradient by exposure category. This was not accounted for by differences in smoking, and was consistent with the results of spirometric testing. Neurological and psychiatric symptoms were reported more frequently by subjects in high exposure categories and the results of neurological examination and testing tended to confirm this finding. Ophthalmic symptoms demonstrated a similar pattern. Although a number of other symptoms were reported (with the possible exception of gastrointestinal disease), there was no clear evidence of other organ system damage attributable to gas exposure. CONCLUSION: The gradient of reported symptoms and clinical test results with estimates of exposure among these survivors of the gas leak suggests that a proportion of their current respiratory and neurological disease was due to gas exposure.