FOR decades it has been known that the drinking water of large populations across South Asia contains dangerous levels of arsenic, but now a new study has established that even in Pakistan the number of people exposed could be as high as 60m. Arsenic is a naturally occurring element, but many deeper aquifers are free from it, and much of the clay that forms the surface across many parts of South Asia has been naturally cleansed of it over a long period of time due to the passage of large amounts of water across the subcontinent every year. The fact that it is now being found in dangerous quantities could well be connected to the growing amount of effluent that vends its own way into informal industrial clusters around the country. Whether found in agricultural chemicals or leather tanneries or dyes, arsenic once in the water supply will naturally leach into ground water. The deadliest avenue for its entry into the human body is through drinking water, which can carry it in quantities large enough to do serious health damage.

Now scientists from the Swiss Federal Institute of Aquatic Science and Technology tell us that after testing water from 1,200 wells around the country, from depths ranging from three to 70 metres, they found that almost two-thirds of them contained arsenic beyond 10 micrograms per litre, which WHO has recommended as the maximum permissible level. In many areas along the Indus, they found people consuming water with almost 200 micrograms of arsenic, while 50m to 60m people could be drinking water containing 50 micrograms of the deadly element. Arsenic poisoning can lead to skin lesions, cardiovascular disease and cancer. It can also interfere with cognitive development. In short, the problem is vast and the public health risks it poses are serious. The good news is that it is relatively easy these days to treat water to remove arsenic. Usually a simple reverse osmosis filter can do the job, even the ones that are attached to individual taps at home. But for this to be a proper solution, the provincial governments need to pay more attention to water contamination from industrial and agricultural chemicals, and then ensure that filters are regularly replaced in treatment plants. This is by no means a difficult target, and the authorities must make it a priority.

Published in Dawn, August 25th, 2017