Correspondence Address:
Dipankar Chakraborti
School of Environmental Studies, Jadavpur University, Kolkata - 700 032, West Bengal
India

Full Text

Dear Sir,

Millions of people from different developing countries in the world heavily rely on groundwater for drinking and cooking. Geogenic arsenic contamination of groundwater has been identified in 105 countries with an estimate of the exposed population of >200 million worldwide. In Ganga-Meghna-Brahmaputra plain alone, currently >100 million people are potentially at risk from groundwater arsenic contamination. Arsenic is a toxic metalloid being identified as human carcinogen (International Agency for Research of Cancer). The WHO guideline value of arsenic in drinking water is 10 ppb. At present, in most of the arsenic-affected Asian countries, the permissible limit of arsenic in drinking water is 50 ppb. Considering area and population potentially at risk from arsenic danger in world's arsenic scenario, India appears to be at the top of the list. It is important to note that the WHO guideline value of arsenic in drinking water 10 ppb is on the basis of 2 L of drinking water per day whereas in tropical arsenic-affected states in India, the average direct drinking water consumption is about 4 L of water and total water intake (direct and indirect) is about 6 L/day. [1] In arsenic-affected areas of India, arsenic-contaminated groundwater is in use for agriculture and thus food is also arsenic contaminated, an additional source of arsenic to the consumer. It is also reported that better nutrition status can resist arsenic toxicity and in arsenic-affected states of India, 80% of the population living in affected areas are suffering from malnutrition with poor literacy rate.

WHO permissible limit for fluoride in drinking water is 1.5 ppm. For India, on the basis of the factors discussed above, WHO suggested to reduce the permissible limit of F in drinking water of India from 1.5 to 1.0 ppm and India accepted it. However, the permissible limit of arsenic in drinking water in India remains 50 ppb. On the basis of the reasons discussed above, the permissible limit of arsenic in drinking water in India logically should be <5 ppb. Further regarding the danger of cancer, it is reported that the cancer risk to those drinking arsenic-contaminated water at 50 ppb and 1.0 L/day is 1.3/100. [2] A group of scientists also opined that for pregnant mothers and children, WHO limit may not be safe. [3] In the meantime, some parts of the world considering the danger of the guideline value of arsenic 10 ppb already have reduced their permissible level of arsenic. New Jersey and South Carolina of USA accepted 5 ppb level for their drinking and cooking water. For Australia, it is 7 ppb.

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