Bhopal's water is still contaminated 20 years on. Credit: Reuters/Kamal Kishore

Indian scientists have released a report on the gas leak in Bhopal, a decade after the studies ended, and nearly 20 years after the disaster.

On 3 December 1984, 40 tons of methyl isocyanate leaking from a Union Carbide pesticide plant killed more than 3,000 people and left hundreds of thousands with chronic lung, eye and gynecological problems.

The Indian Council of Medical Research (ICMR) initiated 24 research projects, including long-term epidemiological, toxic and clinical studies on 80,000 persons from severely, moderately and mildly exposed areas and control unexposed areas. But it abruptly terminated the studies in 1994, without any explanation.

As a result of a legal battle with Union Carbide, the Indian government also blocked release of the studies in scientific journals and elsewhere.

The ICMR finally released the results in November 2004, by which time four members of the research team have passed away. “The results are possibly outdated,” says Samavedam Sriramachari, scientist emeritus at ICMR and one of the investigators.

“[The long delay] violates the objectives of the exercise as well as the ethics of research,” says Satinath Sarangi, a spokesperson for Sambhavna Trust, a Bhopal-based nongovernmental organization that assists survivors.

[The long delay] violates the objectives of the exercise as well as the ethics of research , Satinath Sarangi, Sambhavna Trust

The ICMR report says most deaths were due to asphyxia resulting from acute lung injury, chemical pneumonia and acute respiratory distress syndrome caused by cyanide poisoning. The affected areas had a persistent high death rate between 1984 and 1993, primarily from respiratory disorders, and high rates of respiratory, ophthalmic and gastrointestinal disorders.

Ingrid Eckerman, a public health expert from Sweden, says the study design is flawed, and research is rudimentary or missing in some fields. Eckerman and 12 other researchers from international agencies served on the International Medical Commission on Bhopal, which in 1994 conducted an independent survey on the health, economic and social consequences of the disaster. Eckerman also notes that little research has been done on female reproduction, or on chromosomal aberrations, post-traumatic stress disorder or the health of children born after the disaster.

The ICMR report calls for more follow-up studies, especially on possible cancers—but in the past 20 years, many members of the original cohort have died or migrated. “We have done the maximum possible studies,” says Sriramachari.

Venkata Ramana Dhara, an occupational and environmental health researcher at Emory University in Atlanta, has proposed a simulation of the disaster at a US Department of Energy test site in the Nevada desert to study the gas cloud and how it spread into the environment. But such a test is “unlikely to yield any information applicable to the survivors,” notes Sriramachari.

Meanwhile, toxic wastes are still lying at the pesticide plant—now owned by Dow Chemicals—contaminating groundwater in nearby areas. Organizations such as Greenpeace, Sambhavna and a recent BBC team have highlighted the adverse health effects resulting from the contamination.

“It is high time the government and other agencies undertook the responsibility of clearing the wastes, instead of getting caught in legal wrangles over who should pay for the removal,” says Sriramachari.