It started with spots dappled across people’s chests and backs. Unusual hard patches on the skin of their palms and soles of their feet. For some, a blackening of their toes.

Doctors and researchers began noticing patients in Bangladesh presenting with these kinds of symptoms in the 1980s. It soon became clear what they were seeing: classic signs of arsenic poisoning.

In a tragic irony, the reason was eventually traced back to an otherwise hugely successful public-health program.

In the 1970s, children in Bangladesh were dying in high numbers from diseases such as dysentery and cholera after drinking dirty water from rivers, lakes and streams. In response, Bangladesh’s government, along with aid agencies spearheaded by UNICEF, launched a huge effort to tap into cleaner water underground.

Now, in a cruel twist, the situation could be set to worsen. New evidence suggests the impacts of the human-caused climate crisis — including flooding and sea level rise — are changing the water chemistry underground and pushing up arsenic levels even further.

Read more at the link in our bio.

📷: Munir Uz Zaman/AFP/Getty Images; Seth H. Frisbie