Arsenic, which is commonly found in well water worldwide, is responsible for one out of every 20 deaths in Bangladesh. Many villagers have now discovered a simple way to overcome this problem.
“Groundwater is popular as a water source because it is generally free of bacterial pathogens, unlike surface water,” explained Alexander van Geen of Columbia University‘s Lamont-Doherty Earth Observatory.
As groundwater makes its way through rocks and sediments, most harmful bacteria is filtered out. However, the same process adds minerals to the water, including arsenic in some of the shallow wells of Bangladesh.
Sarah Ruth is a director of the National Science Foundation’s (NSF) Dynamics of Coupled Natural and Human Systems program, which funded the research.
“Millions of people rely on water supplies that are contaminated with arsenic,” said Ruth. “Consumption of arsenic-contaminated water, and the rice crops irrigated with it, can have severe health effects, including a variety of cancers and increased child mortality.”
In 2000, van Geen and a team of researchers surveyed 6,000 wells in Bangladesh, and then conducted a health study of 12,000 people. In 2013, the survey was extended to 50,000 wells that served 350,000 people.
The study revealed that government wells more than 150 meters deep were usually low in arsenic. The researchers also found that wells more than 900 meters deep were not accessible to the wider public, but only to the well-connected or the elite.
Some villagers have found a way to hack into this clean water. “People in the study area now understand that deeper is better,” said van Geen. They have been drilling deeper wells and finding low-arsenic water above a depth of 150 meters.
A survey of the water in the study area demonstrated a recent jump in the proportion of safe drinking water. While only 25 percent of wells were safe in 2000, a total of 70 percent were deemed safe by World Health Organization standards in 2018.
“That’s good news,’ said van Geen. “Arsenic data from urine samples confirm that villagers aren’t just telling us what we’d like to hear. Most of the decline is attributed to households reinstalling wells at their own cost.”
“Some villagers have figured this out, but others still have not. The region’s geochemistry causes the problem, but it’s also the solution. Arsenic is avoidable without having to resort to water treatment.”
Van Geen will present the research at the 2018 meeting of the Geological Society of America (GSA).
By Chrissy Sexton, Earth.com Staff Writer
Image Credit: Imtiaz Choudhury, University of Dhaka