Photo by Michael Berg.

Around 65 percent of wells in Vietnam’s Red River Delta contain arsenic, manganese, selenium and barium at unsafe levels, posing a serious health threat to about 7 million people, according to a research done by Swiss scientists, released on January 17.

The pollution in the Red River Delta is at the same scale with Bangladesh, which is considered the worse arsenic polluted area in the world.

According to Bloomberg, the research was published in the Proceedings of the Swiss National Academy of Sciences.

Vietnamese authorities should seek alternative sources or install better treatment technology to ensure the safety of drinking water, researchers led by Michael Berg at the Swiss Federal Institute of Aquatic Science and Technology wrote in the journal.

The contamination is likely the result of  pumping the water from deep aquifers for more than a century, causing naturally occurring arsenic in groundwater to seep downward, they said.

The findings are “alarming,” the authors wrote.

According to researchers, the Red River Delta is one of the world’s most densely populated regions, with about 1,160 people per square kilometer. Of the delta’s 16.6 million people, 11 million have no access to public water and depend on other sources such as private wells, they wrote.

Berg and colleagues analyzed samples from 512 private wells between May 2005 and January 2007. Arsenic contaminates 27 percent of the region’s wells and about 1 million people use water with concentrations that are five times the World Health Organization’s safety standard, according to the report.

Arsenic poisoning can cause vomiting, abdominal pain, bloody diarrhea and is linked to cancer of the skin, lungs, bladder and kidney, according to the WHO. Natural arsenic contamination is “a cause for concern” in countries including Argentina, Bangladesh, Chile, China, India, Mexico, Thailand and the U.S., the WHO said on its website.

Manganese is the second-greatest health concern related to the well water in Vietnam, the study found. About 44 percent of wells have unsafe levels of manganese, and an estimated 5 million people consume water with health-threatening levels of the chemical.

While manganese is needed in small quantities for the body to function correctly, chronic exposure to excessive levels may cause neurological effects.

PV