Arsenic in groundwater

“ Beware of arsenic in drinking water” Bombay times, 8th May 2011 is nothing new. It seem that the editor has asked his juniors to fill this space ( other wise going empty!!) with some sensitizing news and the youngster unaware of the worldly problems, filled this void with this news. Arsenic contamination in groundwater in West Bengal and Bangladesh is a global calamity! Why USA and Bangladesh, there are half dozen top Institutes in India working on this problem and suggesting remedial measures. The reporter should have called some one with this knowledge and filled this void space with better and updated news instead of publishing stale news. Some recent updates are given below for those keen in getting knowledge beyond what is casually reported in the above news paper. Let us be concerned with the state within our own country first and what ever is applicable to West Bengal is true to Bangladesh as well,  since both regions have more or less similar geological formations and both the regions are drained by the rivers originating from the Himalayas.

 Both West Bengal and Bangladesh are affected by arsenic and for over couple of decades, people in WB and BD are drinking groundwater with high arsenic levels. The permissible limit of arsenic in drinking water is prescribed by the World Health Organization is 10 to 50 µg/L. 10 µg/L being the limit for developed countries while 50 µg/L is for the developing countries. Countries like India and China were following 50 µg/L limit but recently China has reduced the limit to 10 µg/L.   Let us not debate on why some of the countries are not following 10 µg/L limit now (it is a issue related to commercial vs political lobby)

 Arsenic is a killer element. Groundwater in West Bengal and Bangladesh is contaminated with arsenic and people are drinking arsenic contaminated water for the last several decades. Since it is tasteless, millions drink such water unknowingly and succumb to its poisonous effect. Nearly 40 % of 80 million people in West Bengal are suffering from arsenic related diseases like conjunctivitis, melanosis, hyperkeratosis, and hyper pigmentation. In certain areas gangrene in the limb, malignant neoplasm and even skin cancer have also been observed. Children are the worst affected. In West Bengal, Nadia, Hoogly, 24 Parganas (N & S), Murshidabad, Burdwan and Malda are the seven districts that are worst affected. The arsenic content in groundwater in West Bengal is ~ 3200 µg/L.  According to WHO this problem in West Bengal and Bangladesh is termed as global problem and several scientific bodies are seeking solution to this problem.  Wrst Bengal and Bangladesh has now become a field laboratory with several international organizations working on this problem. A few of the organizations include: Royal Institute of Technology – KTH, Stockholm Sweden, Government of the Netherlands, Commonwealth Science Council/ Science and Technology Division, University of  Karlsruhe, Germany, UNICEF, CARE, WHO, Dainichi Consultants Japan, London Arsenic Group, University of California, Berkeley, USGS, British Geological Survey and several institutes from India.

 During eighties, to prevent cholera and typhoid menace from surface water bodies that were extensively used by the population to meet their daily needs, UNICEF advocated using groundwater. Arsenic was not detected earlier but during the course of routine quality, check arsenic was detected at levels above permissible level for drinking water. But by then it was too late and several thousands of people of earlier generation were affected. Thus by accident high levels of arsenic was detected in groundwater. Now diseases related to arsenic fom groundwater are affecting third or fourth generation in West Bengal.

 When bore well culture was introduced in West Bengal, it became shot in hand for the farmers since bore-well irrigation started giving the farmers comfortable life and they were able to rise crops through-out the year. This feel-good factor encouraged extensive bore-well irrigation and the number of bore wells increased from about 20,000 in 1976 to 5,50,000 in 2001.  Since then this number started growing beyond expectation.  Thus bore-well irrigation practice made the rural population to exploit groundwaters without any control.  Arsenic that was found only in the groundwater earlier  has now entered the food chain.

 Thus from groundwater arsenic menace has entered the food chain through irrigation practice. A large number of bore wells operate continuously pumping groundwater from different depths to rice fields. The amount of water required is quite large since 90% of the land in West Bengal is under rice cultivation.  The arsenic content in the water pumped for irrigation is same as that mentioned above ( 3200 µg/L). A recent study conducted in parts of West Bengal has revealed that paddy crop has maximum concentration of arsenic scavenged from groundwater. The arsenic content in rice grain is 0.3 mg/L, in husk it is 1 mg/L and in the steam and leaves it is > than 2 mg/L. The root accumulate large amount of arsenic. In the present study it was found to be as high as 169 mg/L. Except roots, all parts of rice plant is eaten by humans and animals. Now we are in an arsenic web!! This problem is no longer confined to West Bengal and Bangladesh. Besides rice, the vegetable cultivated through irrigation also have high levels of arsenic.  Common leafy vegetable like Red Spinach, Amaranth, Chinese Spinach, Indian Spinach have arsenic content > 0.3 mg/L. 

 Thus while countering one disease ( cholera/typhoid) the then advisors gifted West Bengal and Bangladesh with a major and irreversible catastrophe. Perhaps the wisest thing that could have been done is to boil the surface water and drink to counter cholera and typhoid.  Because of bore-well irrigation the entire aquifer (s) are contaminated.

 Remedial measures that are suggested to the rural population by the multinationals are too expensive.

 Now arsenic is also found in amount larger than 50 µg/L in all the NE states of India ( Manipur, Assam, Tripura, Arunachal Pradesh, Meghalaya and Nagaland) and it also slowly surfacing in other parts of the country.  Arsenic contaminated groundwater is reported within the Godavari sub-basins bordering Chattisgarh.  Millions of population depend on groundwater in the rural areas. Both arsenic and fluoride has become a nightmare to rural population.