Environmental, economic and health perspectives of arsenic toxicity in Bengal Delta

Arsenic is a metalloid of great environmental concern because of its highly toxic nature and wide abundance. Arsenic contamination in groundwater has been reported in Bangladesh, India, China, Taiwan, Vietnam, USA, Argentina, Chile and Mexico. The clinical symptoms of arsenic toxicity in human body include skin itching to sun rays, burning and watering of the eyes, weight loss, loss of appetite, weakness, fatigue, limited physical activities and working capacities, chronic respiratory problems, moderate to severe anemia etc. The Bengal basin is regarded to be the most acutely arsenic infested geological province in the world. Heavy withdrawal of groundwater for fulfilling the needs of the increasing population in Bengal Basin resulted in increased arsenic level in the groundwater. Mobilization of arsenic in Bengal delta is further interfered by microbial activities and interactions. Different microbial strains have been isolated from Bengal Delta which can tolerate, transform and resist arsenic. The use of arsenic contaminated groundwater for irrigation purpose in crop fields elevates arsenic concentration in surface soil and in the plants grown in these areas. Several plant species have been studied for their ability to accumulate arsenic in the Bengal Delta. Rice is generally grown in submerged flooded condition, where arsenic bioavailability is high in soil. As arsenic species are very much toxic to plants and can execute oxidative stresses, they can also affect the overall production of rice and other vegetables, and can affect the agricultural and economic development of Bengal Basin. Cattle population also consume arsenic infested water in those areas and usually eat edible plants contaminated with arsenic, which, in turn, can further increase the toxicity level in their bodies and also can increase the arsenic bioaccumulation in meat and milk. In the rural areas of the Bengal Delta, arsenic contamination raised a number of social problems which are continuously weakening the structural integrity of rural society. Uses of phytoremediation and microbial remediation technologies, rainwater harvesting, use of arsenic resistant plant varieties for cultivation are some sustainable methods which can be applied for arsenic remediation. Besides, nano-agglomerates of mixed oxides have been synthesized and successfully employed for arsenic removal from aqueous solutions. Intensive investigation on a complete food chain is urgently needed in the arsenic contaminated zones, which should be our priority in future researches.