Arsenic contamination or arsenic poisoning is a widely common phenomenon in many parts of India. In some states, arsenic is naturally found along with high contents of fluoride but the consumption of water with presence of such elements in high concentration is a matter to worry about.
I had the opportunity to get in touch with one of my seniors, Ms Sonal Bindal from TERI SAS, New Delhi, whose doctoral thesis was on arsenic contamination of groundwater in Uttar Pradesh. A total of 40 districts in the state are exposed to high concentration of arsenic in groundwater. Balia, Barabankhi, Gorakhpur, Ghazipur, Gonda, Faizabad and Lakhimpur Kheri are the worst affected districts. Majority of them are in the floodplains of Ganga, Rapti and Ghaghara rivers.
Ten other districts with moderate risk of arsenic contamination are Shahjahanpur, Unnao, Chandauli, Varanasi, Pratapgarh, Kushinagar, Mau, Balrampur, Deoria and Siddharthnagar. About 78% of the population in the state lives in rural areas and depends on ground water for irrigation, drinking, cooking and other domestic use. The risk of exposure to arsenic is much higher in rural areas than cities as piped water supply is not available in most villages. The study was led by one of the professors named Dr CK Singh from TERI SAS and Sonal was involved in the study as well. The results of the study were published in the journal Water Research.
Arsenic (As) is an odourless and tasteless metalloid widely distributed in the earth’s crust. Arsenic and its compounds occur in crystalline, powder, amorphous or vitreous forms. It usually occurs in trace quantities in all rocks, soil, water and air. Exposure to arsenic in the environment can happen via both natural and anthropogenic means.
Naturally, it can happen through leaching of ambient arsenic in groundwater from sediments containing arsenic bearing minerals; leaching and percolation of arsenic in soils. Through anthropogenic activities, it can happen via agrochemicals, wood preservatives, industrial sources, mineral processing, acid mine drainage, burning of fossil fuels, etc. Arsenic exposure has cause skin lesions, skin cancer, bladder, lungs and cardiovascular diseases as well as reduced intellectual function in children.
In South Asia, arsenic contamination in groundwater in the Ganga-Brahmaputra fluvial plains in India and Padma-Meghna fluvial plains in Bangladesh has been found to have a huge impact on human health and its consequences have been reported as the world’s biggest natural groundwater calamities. In India, West Bengal, Jharkhand, Bihar, Uttar Pradesh in the flood plains of the Ganga, Assam and Manipur in the flood plains of the Brahmaputra and Imphal rivers and Rajnandgaon village in Chhattisgarh have been reported to be affected by arsenic contamination in groundwater. (Ghosh and Singh, nd)
According to WHO prescribed limits, the current recommendation of arsenic in drinking water is 10 µg/L. However, developing countries like India and Bangladesh are exposed to limits exceeding 100 µg/L. The permissible limit of arsenic in India in absence of an alternative source is – 0.05 mg/l (50 μg/l).
The presence of arsenic in drinking water is called arsenicosis. It is interesting to note that some foods, especially of marine origin, have high concentrations of arsenic and the consumption of such food items also results in a surge in the concentration of arsenic in urine. Arsenic accumulates very fast in the hair and nails compared to other tissues as a result of surface contamination.
The most viable options to tackle arsenic contamination of groundwater resources are as follows:
- In-situ remedy of aquifers by decontaminating arsenic from infested aquifers.
- Use of groundwater after ex-situ treatment by arsenic removal devices.
- Use of surface water source as an alternate to the contaminated groundwater source.
- Exploring possibilities of tapping risk free deeper aquifers for supply of arsenic free groundwater.
- Increasing awareness to encourage people to invest in rainwater harvesting.
It is interesting to note that all the areas worst affected by arsenic are located in eastern and north eastern parts of India along with neighbouring Bangladesh, thereby exposing millions of people to groundwater arsenic woes. It is also important to note that all these areas are extremely vulnerable owing to its proximity to coastal areas.
Its topography, geography, high population density, low socio-economic conditions are factors to be considered, apart from dealing with regular natural calamities like floods, cyclones, earthquakes, and tropical diseases to name a few.
It is about time we shifted our focus on this public health menace and demand to have rightful policy intervention in place.