The authors have reviewed studies of human health effects that resulted from exposure
to methyl isocyanate gas that leaked from the Union Carbide plant in Bhopal, India,
in 1984. The studies were conducted during both the early and late recovery periods. Major
organs exposed were the eyes, respiratory tract, and skin. Although mortality was initially
high, it declined over time, but remained elevated among the most severely exposed population.
Studies conducted during the early recovery period focused primarily on ocular and
respiratory systems. Major findings included acute irritant effects on the eyes and respiratory
tract. In follow-up studies, investigators observed persistent irritant effects, including ocular
lesions and respiratory impairment. Studies conducted during the late recovery period
focused on various systemic health endpoints. Significant neurological, reproductive, neurobehavioral,
and psychological effects were also observed. Early and late recovery period
studies suffered from several clinical and epidemiological limitations, including study design,
bias, and exposure classification. The authors herein recommend long-term monitoring of
the affected community and use of appropriate methods of investigation that include welldesigned
cohort studies, case-control studies for rare conditions, characterization of personal
exposure, and accident analysis to determine the possible components of the gas
cloud.