ISLAMABAD: Lives of about 70 million people of Pakistan are at stake due to drinking water polluted with arsenic.
The World Health Organization (WHO) study report said that at least 70 million people of Pakistan residing across the four provinces, Azad Jammu Kashmir (AJK) and Gilgit-Baltistan (GB) were exposed to contaminated water polluted with arsenic.
Previous studies had revealed that groundwater in some areas of Pakistan also contained high levels of arsenic. But the extent of those risks was unknown, says Joel Podgorski, an environmental scientist at the Swiss Federal Institute of Aquatic Science and Technology in Dübendorf and lead author of the new study.
Podgorski’s team started by measuring arsenic levels in groundwater samples collected from about 1200 wells throughout Pakistan at depths of 3 to 70 meters. Nearly two-thirds exceeded the WHO-recommended threshold, and extremely high concentrations—above 200 micrograms per liter—were found along the Indus River valley. The higher concentrations tended to occur in areas with higher soil pH and near sand and clay younger than 10,000 years. Older sediments have been exposed to so much water over geological time that most of their arsenic has already washed out to sea. Under specific chemical conditions, the arsenic in younger sediments can dissolve in water and contaminate it, Podgorski says.
Next, the team created the region’s first risk map for arsenic, which shows the probability of dangerous concentrations in every part of the country. By estimating the number of people relying on groundwater for drinking, the team reports in Science Advances that 50 million to 60 million people might use water that contains more than 50 micrograms per liter of arsenic, five times the WHO guideline.