Residents Exposed to Methyl Isocyanate in Bhopal Gas Disaster Continue Showing DNA Damage

New tests conducted on those exposed to the chemical show that the frequency of aberrations within damaged cells has increased with time.

Aligarh: Victims of the Bhopal gas disaster continue to suffer damage in their DNA, a new study has revealed.

Methyl isocyanate (MIC), which was released from the Union Carbide plant in December 1984, is known to damage human DNA by interacting with proteins. Such damage had been recorded in studies undertaken by the Indian Council of Medical Research (ICMR) in the years following the gas leak.  

Now, a team of scientists from MGM New Bombay Hospital has performed fresh tests on people who were exposed to MIC and found that the chemical compound’s damage continues its havoc. Researchers used the same categorisation that was used by the ICMR, grouping people as severely exposed, moderately exposed or unexposed. They collected blood samples from 156 people. Of them, 130 yielded readable data and the anomalies thus detected were classified. Finally, they compared the results with ICMR’s screening performed in the period 1985-1988. 

The study has revealed two trends. Even though people who were severely exposed to the gas now possess fewer abnormal cells, the frequency of aberrations within such cells has increased with time. The researchers also found that the number of aberrations in chromosomes had increased even among people who had not been exposed or moderately exposed to the gas. This could be due to several reasons. The study says:

A number of confounders, including lifestyle, environment, nutritional factors, drinking water, occupational exposures and inherent genetic conditions interact. Additionally, continuous soil contamination by chemical wastes dumped in the Union Carbide India limited site might have augmented the genetic changes through interaction with other biologic and abiologic factors.

Hit Kishore Goswami, a former founder-chairman of the department of genetics at Bhopal University (now Barkatullah University) and a member of previous studies in Bhopal, said, “Many follow up studies have been performed by individual groups, each differing slightly in their approach. This study also does the same. It manages to expose the complications of chemical contact with better techniques.”

However, V. Ramana Dhara, an adjunct clinical professor at the Rollins School of Public Health, Emory, said that, “given problems with the study design and a lack of clear exposure-response, it does little to advance the knowledge of methyl isocyanate toxicity.”

The study was conducted by Bani B. Ganguly and Shaouvik Mandal from the MGM Centre for Genetic Research and Diagnosis, MGM New Bombay Hospital. It was published in the journal Mutation Research-Genetic Toxicology and Environmental Mutagenesis

Sarah Iqbal is a senior research fellow at the department of biochemistry, Aligarh Muslim University.