Ground water is an important source  of domestic water in West Bengal and Bangladesh, but it is now clear that much of the ground water in these areas is contaminated with naturally occurring arsenic. Out of 20 countries in different parts of the world where ground water arsenic contamination and human sufferings have been reported so far, the magnitude is considered highest in Bangladesh, followed by West Bengal. About 6 million people in West Bengal and 25 million in Bangladesh are at present drinking water contaminated with arsenic at a level above 50ppb.

Sources of arsenic pollution

Arsenic is a naturally occurring element in the earth’s crust. It occurs as a major constituent in more than 200 minerals, including elemental arsenic, arsenides, sulphides, oxides, arsenates and arsenites. In West Bengal and Bangladesh, it is believed that arsenic is largely due to the erosion from local rocks. Increased ground water extraction has caused this problem by dropping the ground water level in much of the region.

Effected locations

High concentrations of arsenic have been reported in eight districts of West Bengal and one district each from Bihar and Madhya Pradesh. Bangladesh is also adversely affected by high arsenic content in ground water. Out of a total of 188 million people in West Bengal and Bangladesh, 136 million people live in arsenic affected districts where ground water contains arsenic level above 50ppb. Detailed description of arsenic affected areas and population in West Bengal and Bangladesh are given in the table provided below.

Guidelines and Standards
 There is a big argument about the permissible limits of arsenic in drinking water in India and Bangladesh. Both the countries have a standard of 0.05mg/l, but WHO guidelines value is 0.01mg/l. There are two key arguments in the debate. The WHO guideline value is derived from the studies of health effects of arsenic, and is based on a 70 Kg person drinking two litres of water a day over his/ her life span. However, people in rural India and Bangladesh tend to drink more than this because of the heat and lack of cheap alternatives. There is also evidence that people with poor nutrition levels are more affected by arsenic contamination than healthy people. Therefore, a given level of arsenic in drinking water in India and Bangladesh, where there are millions of malnourished people drinking large quantities of water daily, is likely to be far more dangerous than a similar concentration in Europe or the USA, and thus arsenic standards in India and Bangladesh should be lower than the international standards.
The second argument makes a case for keeping the current standard of 0.05mg/l, due to practical and economic difficulties associated with a lower standard, and the risk of adverse social impact. 

Impacts of arsenic contamination

The main arsenic ingestion mediums are drinking water, food and road side dust, while contribution of road side dust is very small; the other two play a very-very important role. Long term ingestion of high arsenic concentration (>50ppb) water results in Arsenicosis, Hyperpigmentation, Depigmentation, Keratosis and peripheral vascular disorders are the most commonly reported symptoms of chronic arsenic exposure. It is estimated that in West Bengal two million people are at health risk due to ingestion of arsenic water. 

Status of monitoring and Surveillance efforts

The major challenge is how to rapidly reduce and monitor the arsenic consumption of millions of people scattered over a huge area. The respective governments, external support agencies and non-governmental organizations are already pooling their resources to determine the extent of ground water contamination, and develop long term solutions to the problem. However, it has been estimated that it may take 10 to 15 years to provide sustainable arsenic free water supply options to all the threatened areas.

One of the current priorities is to check existing tube wells for arsenic contamination, and to set up sustainable arsenic monitoring systems. In addition arsenic removal technologies need to be monitored to ensure that arsenic is consistently removed to below permissible limits. 

Need for extensive monitoring

Arsenic is poisonous even at extremely low concentrations. Standards for safe levels of arsenic in drinking water vary from around five parts per billion to 50 parts per billion. The standard set by WHO is 0 parts per billion and BIS is 50 parts per billion. Thus, devices that can reliably measure arsenic down to these levels are essential.

Development Alternative’s initiative

 Keeping all this in view, the Environment Systems Branch at Development Alternatives has developed an Arsenic field testing potable kit for determining the presence of Arsenic and proper monitoring.

Salient Features of the kit
Jal-TARA Arsenic kit is cost effective, potable, compact and easy to operate. This kit will help in identifying the problematic water sources and enable communities to take the appropriate safety measures to treat water for removal of Arsenic. The various components of the kit have been packaged in a sturdy, elegant and water proof bag. The kit contains enough reagents to test 50 samples and the shelf life of the various reagents is over six months. For each test, appropriate safety measures are given in the user’s manual. Arrangement has been made for refilling the reagents.

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