Surface water not always the answer to Bangladesh arsenic polluti...( BOSTON -- In a preliminary st...)

BOSTON -- In a preliminary study of arsenic pollution in Bangladesh drinking water sources, Duke University hydrologists have found evidence that surface waters can also be contaminated with the substance. Thus, say the scientists, abandoning polluted wells in favor of ponds and surface reservoirs, as is advocated by the World Health Organization (WHO) and the Bangladeshi government, will not always solve the problem.

"Our analyses found that surface waters as well as ground waters have arsenic in excess of WHO standards, especially in areas of significant irrigation," said associate professor Stuart Rojstaczer, who led the study. "This finding means that groups advocating surface water over ground water must be very cautious. They should not assume a priori that arsenic levels in the surface waters will be negligible."

The scientists' early data also suggested that soil arsenic levels may vary greatly between nearby sites, suggesting that re-siting new wells even close to contaminated wells may be a useful strategy to reduce arsenic levels. The scientists' studies were supported by funds from a National Science Foundation Presidential Young Investigator award to Rojstaczer.

Arsenic contamination in Bangladesh ground water has been called perhaps the most widespread mass poisoning in history, exposing at least 10 million people to arsenic levels that cause eye disorders, skin lesions such as gangrene, and cancer. Ironically, the population's massive exposure to arsenic resulted from efforts begun in the 1960s by international aid organizations to reduce exposure to pathogens in drinking water by sponsoring the sinking of millions of shallow tube wells into underground aquifers.

However, not until 1993 did health experts realize that the sediments found throughout the country contain high levels of natural arsenic that leach into ground water.

In a paper delivered Thursday at the American Geophy
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Contact: Dennis Meredith
Dennis.meredith@duke.edu
919-681-8054
Duke University
3-Jun-1999