Elevated arsenic levels in contaminated groundwater-irrigated crops in West Bengal have been documented. The soil of the affected zone of West Bengal has also been shown to act as a major sink of arsenic inflow to agroecosystems, thereby reducing the availability of the toxicant to the cropped species. The cellular metabolism of arsenic in plants and microbes, as well as the interaction of root exudates with arsenic, along with its effect on soil biota in the crop rhizosphere are yet to be examined in this country. However, a significant difference in the uptake pattern and load of arsenic among several land races (more than 200) of rice crop has recently been observed by the arsenic research group at BCKV.
However, the integrated research effort on health effect of humans (and animals) due to arsenic exposure through food-chain are yet to be conducted systematically. In contrast to health effects, arising from drinking arsenic contaminated water in West Bengal, which are well characterized and documented, the reports of such studies characterizing the effect of arsenic intake through food on human health are lacking. Nevertheless, higher (than permissible) arsenic levels in the urine samples of humans, having no history of consuming arsenic contaminated drinking water, have been observed by workers. Indeed, this observation assumes an added significance in view of the intensive programme, launched by the Government of West Bengal to supply arsenic-free drinking water to the affected villages, while no restriction is in force on the use of contaminated groundwater for irrigation. Therefore, potential of exposure of humans (and ruminants, birds and fish) to arsenic through food-chain would exist in the region, and is worth investigating.
The impact of arsenic contamination in groundwater beyond the WHO permissible limit on livestock health is not known. Indeed, no systematic and detailed study has been undertaken till date to address the issues of pathogenesis symptoms, haematobiochemical profiles and histopathological changes, diagnosis and effective therapy of arsenic toxicity in animals under field condition.
Aquatic organisms such as bacteria, phytoplankton and fish/molluscs are known to play critical role in arsenic cycle in marine environment. Arsenic has been reported to induce genotoxicity in zebra fish (Danio rerio) at environmentally realistic concentrations (0.395 to 0.630 mg As/L) which are reported from the affected belt of West Bengal. However, effect of arsenic on fish, molluscs and other aquatic organisms at lethal and sub-lethal concentration is largely unknown, especially in the freshwater environment and needs to be examined.
The present project attempts to bridge the knowledge gaps, mentioned above, in terms of the following :
• Mechanism of arsenic transport, storage and interaction with other molecules in arsenic tolerant or minimal-uptake plants and genotypes.
• Mechanism and genes of soil microbes responsible for transformation of highly toxic inorganic arsenic species to less toxic and volatile organic arsenic forms (e.g., DMAA, MMAA).
• Quantification of human intake of arsenic through cereals, vegetables, fish, meat and dairy products in the arsenic endemic areas.
• Health effect, covering pathophysiological changes, in humans, ruminants, and fish in arsenic endemic areas exposed to arsenic through food-chain.
Since there have been recent reports of arsenic contamination of groundwater in several other states of the Eastern and other parts of India (e.g., in Jharkhand, Bihar, Uttar Pradesh, Chattisgarh, Punjab) and elsewhere (e.g., Nepal), the results of the present research are expected to be of help to a large number of population (in addition to those already at risk level in West Bengal, India and Bangladesh) residing in these states as well.
