Arsenic in drinking water: 60 million in Pakistan at risk

According to a new study in the journal Science Advances, up to 60 million people living in Pakistan's Indus Plain are at risk of being affected by high levels of arsenic in the region's groundwater supply.

An international team of scientists created a "hazard map" of locations at risk using water samples collected from almost 1,200 sites across the country, the majority of them from hand and motor pumps.

Team also assessed environmental factors that may affect the movement of arsenic and calculated the size of populations at risk of exposure. They concluded that there was widespread arsenic contamination in the Indus Plain, from where 50 million to 60 million people get their groundwater.

The study found arsenic levels in groundwater in parts of Pakistan’s Indus Valley to be more than 20 times the safe level of 10 micrograms per liter of water recommended by the World Health Organization (WHO). Pakistan’s government has a higher safety level of 50 micrograms per liter.

Almost two thirds of the wells exceeded the WHO recommendations. Extremely high concentrations of more than 200 micrograms per liter were found in the Indus Valley, the area surrounding the Indus River that flows through northern Pakistan and the Punjab region before reaching the Arabian Sea at the country’s southern edge. The study identified the major cities of Hyderabad and Lahore, two of the biggest cities in Pakistan, as major risk hotspots.

Arsenic is a heavy metal that occurs naturally in soil. The chemical gets into water supplies when it is leached from rocks and sediments. Arsenic is more likely to leach into groundwater supplies if the earth is young, since most of the chemical in older aquifers—bodies of permeable rock that can transmit groundwater—has likely already been washed away into the sea.

Arsenic does not have a smell or a taste, and there are no short-term symptoms after consuming it. However, drinking contaminated water regularly could lead to serious illnesses including lung cancer and cardiovascular diseases

The World Health Organization estimates that 200 million people worldwide are affected by arsenic contamination. The organization's guidelines for concentration of arsenic in drinking water permit up to 10 micrograms per liter; Pakistan's guidelines allow up to 50 micrograms per liter.

This alarmingly high number of people likely affected demonstrates an urgent need to test all drinking water wells in the Indus Plain. But Pakistan government has certain other priorities to work upon. As long as people may have to wait.