Although no arsenic-related health problems have been reported there yet, more than 11 million people are potentially exposed to the tainted water, according to Michael Berg, a research team leader from the Swiss Federal Institute for Environmental Science and Technology and the Centre of Environmental Chemistry at the Hanoi University of Science. The report is the first scientific evidence identifying previously unknown and potentially hazardous arsenic levels in drinking water pulled from shallow wells in the country, he said
The problem flows largely from "tubewells," which pull water from depths of between approximately 30 feet and 120 feet, according to the researchers. The wells, designed to provide safe drinking water by avoiding polluted surface waters, inadvertently tapped into arsenic-contaminated underground aquifers, Berg said.
Arsenic is found naturally in rocks, soils and the waters in contact with them. Consuming arsenic can cause skin disease, cardiovascular and neurological problems. Long-term exposure has been shown to increase the risk of lung, bladder, liver and prostate cancer, according to the U.S. Environmental Protection Agency.
Measuring the ground (and, in this case, drinking) water in 69 wells over a nearly 500 square mile area in the Red River delta near Hanoi, researchers found average arsenic levels more than three times the nation's 50-microgram per liter health standard with peaks up to 3,000 micrograms per liter in groundwater. Nearly half of the well water samples contained arsenic levels above the standard and approximately 20 percent exceeded 150 micrograms per liter, he reported.
Berg's group compares the arsenic levels in Vietnam with an area between India and Bangladesh where tainted groundwater contributed to what a World Health Organization report called the "largest poisoning of a population in history."
"We would like to emphasize that the arsenic contamination levels in aquifers of Vietnam are of the same order of magnitude as in Bangladesh," he said. "In rural areas, the untreated groundwater is consumed directly as drinking water, hence several million totally unaware people are at immediate risk."
The researchers have suggested to the Vietnamese government that early warning of the problem might allow it to make people aware of the elevated arsenic levels and to put systems in place that could mitigate the severity of the exposure. The population near the India-Bangladesh border — which has arsenic levels equivalent to northern Vietnam's — has experienced severe health problems attributed to the arsenic, according to WHO.
Less than one percent of groundwater in the United States exceeds the same 50 microgram standard, according to the U.S. Geological Survey. The U.S. EPA has proposed lowering the maximum arsenic level in drinking water to 10 micrograms per liter of water, the standard recommended by the WHO, a measure currently being evaluated.
The research cited above was funded by the Swiss Agency for Development and Cooperation.
— By Jonathan Lifland
A feature article based on this research will be available after the July 1 publication.
The online version of the research paper cited above was initially published July 1 on the journal's Web site. Journalists can arrange access to this siteor the research paper by sending an email to newsroom@acs.org or calling the contact person for this release.
Michael Berg, Ph.D., is an environmental chemist at the Swiss Federal Institute for Environmental Science and Technology (EAWAG) in Duebendorf, Switzerland.
Journal
Environmental Science & Technology