Climate breakdown will put tens of millions of people in Bangladesh at heightened risk of cancer from contaminated well water, according to research.
Sea level rises, unpredictable flooding and extreme weather caused by the climate heating up will accelerate the release of dangerous levels of arsenic into the country’s drinking water, say scientists.
The result, the researchers say, will be an intensification of a public health crisis already gripping the country, where millions have skin, bladder and lung cancers as a result of arsenic poisoning.
“Chronic arsenic poisoning from drinking water … is a real problem, not a theoretical exercise,” said the lead researcher, Dr Seth Frisbie, an emeritus professor of chemistry at Norwich University, in a recent presentation of the findings. “I once walked into a village where no one was over 30 years old.”
The origins of the arsenic water contamination crisis date back to the 1970s, when Bangladesh had one of the world’s highest rates of infant mortality due to polluted surface water.
UN aid agencies and NGOs sponsored a vast programme of deep tube well boring to provide clean water for domestic use, crop irrigation and fish farming. The new wells reduced rates of child deaths by curtailing the spread of waterborne diseases, but by the 1990s it became clear that water drawn from sedimentary rocks beneath Bangladesh contained high levels of naturally occurring arsenic.
The first case of chronic arsenic poisoning from drinking well water was diagnosed in Bangladesh in 1993 and the World Health Organization would go on to describe it as the “largest mass poisoning of a population in history”.
“Arsenic is naturally occurring, and it’s washed down the sediments from the Himalayan uplift,” Frisbie said. “So all the sediments from the Ganges, Brahmaputra, Meghna, Irrawaddy [and] Mekong river basins are rich in naturally occurring arsenic.
“It wasn’t a problem when people drank surface water, because the surface water is in communication with the oxygen in the atmosphere and that makes the arsenic insoluble and removes it from the water. But the deep well water does not communicate as well with the oxygen in the atmosphere. And that’s why all of a sudden giving people access to these deep water wells has been a tremendous public health crisis.”
Chronic arsenic poisoning leads to a buildup of arsenic inside the bodies of those affected. It manifests externally through keratinisation of skin on the palms and the soles of the feet. Similar processes are also under way inside, and deposits gather in their lungs and other internal organs, causing cancers.
Wells in about 49% of areas contained drinking water that exceeded the maximum WHO limit of 10 parts per billion, Frisbie said. About 45% contain water with at least five times that much arsenic. During his fieldwork, Frisbie tested water from one well with an arsenic concentration of 448 parts per billion.
“My current estimate is about 78 million Bangladeshis are exposed, and I believe a conservative estimate is that about 900,000 Bangladeshis are expected to die from lung and bladder cancer,” Frisbie said.
Climate breakdown risks making the problem much worse. As sea levels continue to rise, Bangladesh, which sits on one of the world’s biggest river deltas, is expected to be disproportionately affected by flooding, which will change the chemistry of the underlying aquifer through a process known as “reduction” to leach even more arsenic from its sediment.
At the same time, seawater ingress into the aquifer, another result of rising sea levels, will increase its salinity, another chemical change that will increase the rate that arsenic leaches into the water, via a process known as “the salt effect”.
“These changes in aquifer chemistry are expected to increase the release of arsenic into Bangladesh’s drinking well water … [and] this increased exposure to arsenic is expected to increase the rates of death and disease from chronic arsenic poisoning,” write Frisbie and colleagues in their study, published on Wednesday in the journal Plos One.
The implications of the change in the underlying chemistry of aquifer water caused by climate breakdown are not limited to Bangladesh – they will be felt throughout the world. “These chemical processes are global,” Frisbie said. “There’s this reduction of arsenic in Manchester, there’s the salt effect in Louisiana [because of] floods like Hurricane Katrina. So because these are universal chemical processes, this is a global problem.”
