Rising sea levels increase arsenic risk in drinking water: study

Rising sea levels fueled by climate change may trigger the release of more arsenic into drinking water, scientists said this week, citing the instance of Bangladesh.

With 21% of Bangladesh flooding annually during monsoons, rising sea levels are expected to increase the area and duration of these floods, the new study published in Plos One said.

The study explores this impact of climate change on the country’s already vulnerable water source.

In the study, scientists said climate change will trigger the release of more arsenic into drinking water through two processes: reduction and the salt effect.

The team of scientists have meticulously collected water samples across Bangladesh, analyzing not only arsenic levels but also dissolved oxygen and other elements. Their findings demonstrate a clear correlation: decreasing dissolved oxygen, a consequence of rising sea levels, coincides with rising arsenic concentrations.

These changes, including decreased oxygen levels (reduction) and increased salinity (salt effect) due to freshwater from its rivers mixing with the saline water from the Bay of Bengal, can further mobilize arsenic, thus increasing its release into drinking water wells.

Arsenic, a potent carcinogen, can be found underneath the surface of many countries, including Bangladesh, Argentina, and India.

The study’s chilling conclusion, as Dr Seth Frisbie of Norwich University in the US states, is that increased arsenic exposure is likely to translate to higher rates of death and disease from chronic arsenic poisoning.

This unfolding crisis, Dr Frisbie warns in an interview with The Independent, extends beyond Bangladesh’s borders. Similar processes are likely to release arsenic from sediments into the drinking water wells of neighboring West Bengal as well.

Decades ago, a public health crisis unfolded in Bangladesh. Contaminated surface water was a breeding ground for waterborne diseases, leading to tragically high child mortality rates. 

To address this, a collaborative effort by the government, United Nations (UN) agencies, and NGOs saw the installation of around 10 million drinking water wells. 

Since the 1970s, groundwater has become the primary source of drinking water in Bangladesh, replacing surface water. This shift was driven by the installation of millions of wells by the government, United Nations International Children’s Emergency Fund (UNICEF), and NGOs. 

This intervention successfully curbed the spread of waterborne diseases, drastically reducing child deaths.

However, an unforeseen consequence emerged. The groundwater accessed through these wells, drawn from sedimentary rocks, contained high levels of inorganic arsenic. 

This discovery in the 1990s revealed a new threat to public health, impacting a staggering 97% of the Bangladeshi population who still rely on well water. 

Today, Bangladesh grapples with the legacy of this well-intentioned solution.

Over 165 million people in Bangladesh face this growing threat as nearly half of Bangladesh’s area, according to this study, has well water exceeding the World Health Organization’s (WHO) guideline of 10 micrograms per liter for arsenic.

This exposes millions to serious health risks like increased rates of skin, bladder, liver, lung cancers, and vascular diseases, for which climate change will be directly responsible.