Cytogenetic studies in human populations exposed to gas leak at Bhopal, India.

Abstract

Frequencies of chromosomal abnormalities, sister chromatid exchanges, and replicative index were assessed following peripheral lymphocyte culture in 129 individuals from Bhopal, India. Of these, 83 persons (40 male and 43 female) had been exposed directly to the methyl isocyanate (MIC) gas after the accident at the Union Carbide plant on December 2 and 3, 1984. The remaining 46 samples were taken from age-matched unexposed persons in the same city. Chromosome aberrations were recorded at first cycle metaphase (M1) and sister chromatid exchanges, at second cycle metaphase (M2), following standard schedule. The frequency of chromosomal aberrations was, in general, higher in individuals from the exposed populations, with the females showing a higher incidence. Nondisjunction of chromosomes or laggard was rare. The frequencies of sister chromatid exchanges and depression in mitotic and replicative indices could not be related to exposure or sex. The persistence of chromosomal abnormalities in the form of replicating minutes and exchange configurations, even 1114 days after exposure to the gas, may indicate a residual effect on T-cell precursors.

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

“…Therefore, it is evidenced that MIC can establish some genetic effect on T-cell precursors; however, the knowledge about the extent of genetic alterations and their clinical impact is very meager. The spectrum of SCEs in Ghosh et al [26] study could not be correlated to exposure status or sex, which was in agreement with others [28]. However, elevated SCEs were reported by Goswami [27] and Mason et al [31].…”

“…Nondisjunction of chromosomes or laggard was rare resulting in absence of aneuploidy. The persistence of CA in the form of replicating double minutes and exchange configurations, even 1114 days post-exposure to MIC, indicated a residual effect on T-cell precursors [26]. None of them had been exposed to any other known clastogenic agents except a single chest X-ray.…”

“…All genetic studies were carried out in peripheral lymphocytes with a view to evaluating MIC-induced chromosomal alterations as guided by EHC [24,25]. The author had studied over 1000 individuals from different distances from UCIL plant from which an excerpt of the data on 129 individuals was reported [26].…”

“…Genetic damage in human lymphocytes was measured on MICexposed population immediately after the accident by Goswami [27], Deo et al [28], Saxena et al [29] and later by Ghosh et al [26] Ischemia of rat brain leading to cerebral hypoxia; growth of muscle fibers and death of fibroblast and myoblasts in rats; higher doses caused muscle aches and repeated episodes of extreme muscular weakness; persistent muscle weakness, lasting from 1-60 months following exposure to CO 2-5 ppm exposure reduced foetal and placental weight; complete loss of all fetuses in mice exposed to 9 and 15 ppm for 3 h; 0, 1, 3 ppm/6 hrs/day during 14-17d gestation lowered survival in Swiss (CD-1) mice; inhalation of 1.3 ppm/6 hrs/day for 4 days to mice of both sexes revealed no effect on mating/fertility after 1/ 8/17 weeks post exposure reported a higher frequency of chromosome aberrations (CA) and sister chromatid exchanges (SCEs) in MIC-exposed individuals compared to controls [27]. SCE frequencies were tripled in MIC-exposed persons in that study.…”

“…Ghosh et al [26] assessed frequencies of CA, SCE, and replicative index following peripheral blood lymphocyte culture in 129 individuals (83 exposed: 40 male and 43 female, and 46 unexposed from Bhopal) from Bhopal, 1114 days after the disaster. CA was recorded in first cycle metaphases (M1) and SCEs at second mitotic cycle (M2), following standard phytohemagglutinin (PHA)-stimulated blood culture protocol [30].…”