Genotoxic and Carcinogenic Effects of Methyl Isocyanate (MIC) Reviewed on Exposed Bhopal Population and Future Perspectives for Assessment of Long-Term MIC-Effect

Abstract

MIC disaster has been established as one of the largest industrial disasters which claimed>10000 lives and seriously jeopardized lives of millions. Besides acute illness and multi-system complications, genetic damage at chromosomal level was indicative of long-term illness as demonstrated in individual reports. Presence of self-replicating minutes detected after 1114 days indicated persistence of rearrangements in the exposed individuals. Among the systemic complications, respiratory, ophthalmic and reproductive systems were significantly affected then and now. Some of the females with elevated chromosome abnormalities had history of fetal loss and high incidence of perinatal and neonatal mortality. Several in vivo and in vivo experiments concluded that MIC may exert geno-toxicity by binding of carbamoylating agents to nuclear proteins. The cancer-incidence among the MIC-exposed survivors is calculated from hospital records. Moreover, continuous soil contamination by multiple of chemical wastes in the site might have augmented the genetic changes through interaction with other biologic and a-biologic factors. Owing to variable latency period of chemicals, and also unavailability of genetic information measured in stratified cohorts immediately after the disaster, it is worthy of screening genetic condition in the exposed survivors and their progenies, though 32 years have gone. This review further pays importance to compounding effects of multiple confounding variables on the exposed individuals. Nevertheless, comparison of a current genetic screening with the previous genetic condition would actually discuss about the long-term genotoxic effect of MIC on Bhopal population; however, such exercise would not be a straightforward approach due to interaction of several confounders.