In a reply to a question in the Lok Sabha, the Union ministry of water resources said 239 million people across 153 districts in 21 states drink water that contains high levels of arsenic.
That’s around a fifth of the country’s population, and by any standards, that’s an appalling statistic.
The actual number could be higher. India pegs arsenic concentrations above 50 parts per billion as harmful; in the US, it is 10 parts per billion. Arsenic is one of the 10 chemicals classified as a public health concern by the World Health Organization; it slowly poisons the body, potentially causing skin lesions, damage to the peripheral nerves, gastrointestinal ailments, diabetes, renal (kidney) failure, cardiovascular disease, and cancer. At least half the people who were known to be at risk of arsenic contamination live in the Ganga-Brahmaputra basins of Bangladesh and India (across the states of West Bengal, Bihar, Jharkhand, Uttar Pradesh, Assam, Manipur and Chhattisgarh).
Groundwater contamination, India’s hidden crisis
The number of habitations affected by arsenic in India has increased from 3,728 in 2012-13 to 7,535 in 2015-16. This is because of the overuse of groundwater for irrigation and drinking. Arsenic previously occurred in a harmless insoluble conjugate with iron called arsenopyrite. Overuse has split this compound, contaminating groundwater with a soluble ionic form of arsenic. Over-exploitation of groundwater started in India in the 1970s when millions of tube wells were installed in the Ganga delta to prevent diarrhoea from surface water sources such as tanks, ponds and open wells. Today, India has over 30 million groundwater extraction points.
Groundwater is also used for irrigation. This means arsenic poisoning affects not just the people of the area but also those who consume the produce of the affected region. In food, rice has the highest sensitivity to arsenic followed by vegetables. In most arsenic-affected states rice is the staple.
Despite the crisis, groundwater contamination , either by arsenic or other pollutants such as fluorides, does not get the attention it deserves, especially when compared to surface water contamination because the latter is visible. Moreover, there is no law yet to check groundwater withdrawal.
This severe environmental-health crisis has to be contained quickly before it can expand. Along with periodic testing of water in affected areas and individualised testing of each hand pump or tubewell (marking it as safe/unsafe), it is important to encourage people to opt for low-cost, local solutions such as rainwater harvesting that can ensure clean drinking water. States such as Bihar have set up filtration units but the maintenance of filters has always been a problem.This needs to be addressed. Additionally, governments have to curb the use of groundwater and keep a strict control on agricultural and industrial effluents that pollute aquifers that recharge groundwater