People's genes could help determine how likely they are to become ill after being exposed to arsenic, according to research in the current issue of the International Journal of Cancer.
The study, led by Ashok Giri of the Indian Institute of Chemical Biology, is the first to link a specific gene to people's susceptibility to arsenic poisoning — a major public health problem in parts of South Asia.
Giri's team studied more than 400 people in West Bengal, India, where arsenic levels in drinking water can be 5-80 times above the World Health Organization's safe limit.
They found that people lacking a gene called GSTM1 were less likely to have the skin lesions that are among the commonest symptoms of arsenic poisoning.
GSTM1 is known to play a role in detoxifying compounds in tobacco smoke but, paradoxically, people with the gene had a significantly higher risk of skin lesions, says Giri.
Previous studies have shown that the complete loss of GSTM1 can help protect people from other disorders ranging from chronic inflammation of the pancreas to lung cancer.
Giri points out that in addition to GSTM1, other genes are also likely to affect people's susceptibility to arsenic.
Allan Smith, director of arsenic research at the University of California at Berkeley's school of public health, says that while the study suggests that people could one day undergo tests to assess their susceptibility to arsenic, reducing people's exposure to the toxin is more important.
"Some people may have more genetic susceptibility than others, but arsenic exposure should be reduced or kept low for all," he says.
In India and neighbouring Bangladesh, more than 100 million people are at risk of arsenic poisoning. Over 300,000 people in West Bengal have symptoms of exposure, ranging from lesions to cancers of the skin and internal organs.
Reference: International Journal of Cancer 118, 2470 (2006)