Toxic groundwater threatens millions

The study, conducted by a team led by Joel Podgorski from the Swiss Federal Institute of Aquatic Science and Technology, measured arsenic concentrations from 1200 sites across the country, most of them hand- and motor-operated pumps.The largest ever assessment of water quality in Pakistan has found that as many as 60 million people are at risk because of high concentrations of arsenic in ground water on the Indus Plain.

Using the test results, Pogorski and colleagues then constructed a “hazard map”, factoring in statistical estimates of arsenic movement through groundwater. The results suggest that much of the Indus Plain contains arsenic levels above the maximum recommended by the World Health Organisation (WHO).

The study – published in the journal Science Advances – confirms and extends the results of recent previous, smaller studies.

In February this year the journal Environment International published a paper assessing the health risks posed by consuming a diet based on arsenic-laced water in Pakistan.

The research, led by Hifza Rasheed of the University of Leeds, UK, used questionnaires to establish the average intake of water, rice and wheat per person. It found that daily water and wheat consumption were both higher than current WHO recommendations, while rice intake was below par.

The study concluded that the standard Pakistani diet represented a significantly high cumulative cancer risk – although a smaller one than those posed by standard diets in Bangladesh and India, where arsenic contamination is also present and rice consumption higher.

Another study, published in the journal Environmental Quality and Health this month, reported on arsenic concentrations on water drawn from tube wells in the Tehsil Mailsi region of the Punjab.

The research, conducted by a team led by Atta Rasool of the Chinese Academy of Sciences, found that arsenic levels ranged between 12 and 448.5 micrograms per litre – well above the WHO-recommended maximum dose of 10 micrograms per litre.

The high level of arsenic in the water of the Indus Plain is a result of both natural and anthropogenic sources.

Arsenic is the twelfth most common element on Earth, and background levels vary wildly from place to place. A 2008 study estimated that naturally occurring arsenic contributed 40% of Pakistan’s total burden. Manmade sources contributed the rest.

The following year, another study, measuring arsenic levels in groundwater in the Punjab, concluded that much of surface level deposits were the result of “the contribution of air pollutants derived from coal combustion and the use of fertilizers”.

All the research – including the latest by Podgorski’s team – underlines the stark fact that Pakistan is facing a water crisis of unprecedented proportions.

In a blog post published this month, analysts at US think-tank The Wilson Centre said “the country will face absolute water scarcity (insufficient water supply to meet demand) as soon as 2025.”

Contributing factors included difficulties in controlling water quality because Pakistan’s three major rivers all rise beyond its borders. Internal migration is also placing extreme pressure on water supplies, and various factors, including climate change, are causing the water table beneath Islamabad to decrease by more than half a metre every year.

The authors refer to multiple studies that all found the “vast majority” of water samples “were considered unsafe due to contamination—either by harmful bacteria or by arsenic from industrial pollution”.

In their conclusions Podgorski and colleagues call for urgent additional testing across the Indus Plain, coupled with health intervention strategies and an urgent search for new sources of fresh water.