20 per cent of India has toxic levels of arsenic in groundwater

New Delhi: Almost 20 per cent of India's total land area has toxic levels of arsenic in its groundwater, exposing more than 250 million people across the country to the poisonous element, says a new IIT Kharagpur study which used artificial intelligence (AI)-based prediction modelling. According to the researchers, the findings suggest a much greater extent of the high arsenic zones and total population exposed than already known from arsenic sampling exercises and reports by various governmental and non-governmental organisations.

The research, published in the journal Science of the Total Environment, indicates the need for much more rigorous sampling of arsenic levels across India than what exists.

Arsenic is highly toxic in its inorganic form, with long-term exposure to the element from drinking-water and food potentially causing cancer and skin lesions, among other disorders, according to the World Health Organisation (WHO WHO).

The current study noted that these high arsenic areas are mostly located along the Indus-Ganga-Brahmaputra river basin and in pockets in Peninsular India. It said the states of Punjab (92 per cent), Bihar (70 per cent), West Bengal (69 per cent), Assam (48 per cent), Haryana (43 per cent), Uttar Pradesh (28 per cent), and Gujarat (24 per cent) show the highest areal extent of elevated groundwater arsenic zones.

These are followed by sporadic occurrences in the states of Madhya Pradesh (9 per cent), Karnataka (8 per cent), Odisha (4 per cent), Maharashtra (1 per cent), and south-eastern part of Jammu & Kashmir (1 per cent), the researchers said. Apart from these, all other states are found to have negligible or mostly no arsenic hazard, they added.

"A total of more than 250 million people are estimated to be exposed to high arsenic in India," said Abhijit Mukherjee, Associate Professor at the Indian Institute of Technology Kharagpur, West Bengal. "Our study indicates a strong influence of irrigational abstraction (of groundwater) and regional geology on arsenic distribution patterns within India," Mukherjee, the lead author of the study, told PTI.

In the study, the scientists used advanced AI to model the occurrence of arsenic above its national permissible limit of 10 microgrammes per litre (µg/L) in the groundwater across India based on the various geologic, hydrogeologic and anthropogenic factors that have been known to control the groundwater arsenic distribution in the aquifers.