Arsenic is the most favourite murder weapon Agatha Christie used. Make no mistake, it was not a random selection, it was very deliberate. Arsenic has limited rivals in terms of its toxicity and how it affects the human body. Arsenic is a potent poison! Then who gave us the right to poison almost the entire population of the Northeast by forcing them to drink arsenic-laced water?
Arsenic is a naturally occurring metalloid (i.e., it has properties intermediate between a metal and non-metal). Most of the arsenic present in groundwater is from geological sources while there may be anthropogenic sources like pesticides and industrial discharges. The World Health Organization (WHO) and the Bureau of Indian Standards (BIS) have set a limit for total arsenic in drinking water as 10 micrograms per litre. To put things in perspective, if you take one teaspoon of sugar (4 g) and divide it into 4 lakh parts, then one part will be 10 micrograms. More than that of arsenic in one litre of water is toxic to humans.
Arsenic in drinking water causes skin lesions and cancer of the skin and internal organs (liver, kidney, lung and bladder). It may lead to cardiovascular disease, diabetics and impacts cognitive development in children.
About 220 million people in 50 countries are affected by groundwater arsenic contamination and the number is increasing rapidly. One-fifth of India’s population is vulnerable to arsenic poisoning. The journal Science (2020) predicts that more people will be affected as more groundwater is pumped out to support the growing population. The same study puts Assam as one of the most vulnerable spots. At least 24 districts in Assam are already affected by arsenic in drinking water since we first reported a case in 2004. In the Northeast, Arunachal Pradesh, Assam, Manipur, Nagaland and Tripura are badly affected so far. People in Assam and the Northeast are suffering because of the presence of toxic arsenic in drinking water.
Assam’s aquifer is part of the geology where arsenic is present naturally. Researchers have suggested that low concentration arsenic present in river water has infused arsenic into the Brahmaputra Valley groundwater over thousands of years. The pumping of water from the aquifer changes the geobiochemistry of the arsenic deposits and it finds its way to our wells. The more water we pump, the more arsenic we get in our water. Deep-wells are not exceptions.
The complexity of arsenic treatment makes it difficult to propose ‘a solution’ that will solve the arsenic problem across the board. Simple filtration and boiling do not remove arsenic at all. Arsenic can neither be destroyed nor transformed into a benign form, it always retains its extreme toxicity. The only thing we can do to alleviate the arsenic problem is to manage it well.
Adsorption, ion-exchange, and reverse osmosis (RO) are considered the most effective processes to remove arsenic from water. The presence of iron in the Northeast water is an advantage. Iron is one of the natural adsorbents of arsenic. If the groundwater contains 20 times more iron than arsenic then we may be able to design affordable arsenic removal processes. Any iron-based material works well for arsenic removal. The IIT Bombay promoted an arsenic removal unit in Titabor where they used commercial pure iron nails as the filter media to remove arsenic. The RO system also works well provided there is proper maintenance. Specific technology to be adopted will depend upon the geochemistry of the water, geographic location and, most importantly, acceptance by the stakeholders.
While there are governmental schemes for drinking water, there has been an erosion in confidence in the government. There is a clear lack of leadership in the system. We, the powerful middle-class, have also failed the people who are suffering. Are they the children of a lesser God? We should have stepped up to fill the leadership void. We are better than this, we can do better.
With the lack of confidence in the government, community ownership is a way to go. The example of Kothora village in Nalbari can be emulated. The village groundwater is affected by arsenic. Local Gramya Vikash Mancha (GVM) has initiated an awareness programme and helped the community install an ion-exchange unit with support from the Tata Water Mission (Tata Trusts). The GVM volunteers sensitized and organized the water users to form a water management committee. The committee now manages the treatment system and takes management decisions. The unit produces about 4,650 litres of arsenic-free drinking water every day. The land for the unit came from one of the villagers. The villagers pay Rs 210 per month to get 20 litres of water a day. Each household gets a ‘Water ATM’ card to ‘withdraw’ the 20 litres of water. Once you swipe your ATM card, 20 litres of water will come out from one of three designated outlets of your choice. With the money collected, the monthly salary for the operator is paid and a part of the money is saved for annual maintenance. There are a few economically challenged families in the village and they get free ATM cards with each loaded with Rs 210 worth of water. Kothora is a Jal tirtha.
We are seeing sufferings from arsenic contamination in the Northeast, but the triumphs of overcoming the demon in Kothara inspire us all. Kothora tells us that it is time to start working at the grassroots level and empower the small communities to have access to safe drinking water. While the enormous surface water resources (rivers) should be our primary sources of drinking water, it may take some time to have the facilities to treat surface water for drinking purposes, and till then we need to invest our resources to ensure that our current supply of drinking water (even if it is from groundwater) is free from contaminants like arsenic.