Scientists identify genetic vulnerability to arsenic-related cancers

Exposure to arsenic occurs through contaminated drinking water Copyright: Linda Roberts

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[DHAKA] People at greater risk of developing debilitating or fatal diseases related to arsenic exposure could be prioritised for treatment, following a study by Bangladeshi and US researchers.

Exposure to arsenic through contaminated drinking water is a major public health issue affecting millions of people, mostly in South Asia.

A previous study had linked as many as one in five deaths in Bangladesh to arsenic exposure, and the WHO has called the phenomenon "the largest mass poisoning" in history.

The new study — published in PLoS Genetics last month (23 February) — looked at why some people are more susceptible to arsenic poisoning, with a view to establishing whether there is a genetic basis to their susceptibility.

Researchers studied the entire genomes of 3,000 people in Bangladesh and found that those who developed arsenic-related skin lesions shared a common area of their genomes. Such lesions are an indicator of overall susceptibility to other arsenic-related diseases.

The researchers said their findings suggested that up to a third of the Bangladeshi population carries the genetic variation.

"The precise risk estimates are being investigated," said lead author Habibul Ahsan, an epidemiology professor at the University of Chicago, United States.

Ahsan told SciDev.Net that the discovery could inform the design of targeted screening programmes to identify those most at risk of developing arsenic-related illness.

"Since millions of exposed people can’t realistically be treated, our findings will help identify susceptible sub-groups that can be provided with specific medical treatments," Ahsan said.

At present, he said, people with the genetic disposition have no alternative but to avoid contaminated water, although he acknowledged this was not always possible.

But he added that a range of treatments are being investigated, including low-cost therapies using vitamin E, selenium and folic acid, all of which are in clinical trials.

Once treatments become available, Ahsan said, those with the genetic susceptibility could be prioritised for treatment.

"We know from Chile and Taiwan that the risk of arsenic-related cancers and death remains high for the rest of [the lives of arsenic-affected people] — even after the exposure [risk] is removed by the provision of safe water," he said.

The researchers plan further large-scale studies, with a view to persuading the Bangladeshi government to engage more actively with the issue.

"This will help our doctors in curative and preventive management of arsenic-exposed patients," said Sudhir Kumar Ghosh, superintendent engineer at the Department of Public Health Engineering, in Bangladesh.

Link to full paper in PLoS Genetics  [563kB]


PLoS Genetics doi:10.1371/journal.pgen.1002522 (2012)