Chapter 38 - Arsenic toxicity and its clinical manifestations in Murshidabad district with some potential remedial measures

Abstract

Arsenic is a toxic metalloid responsible for fatal health hazards throughout the world. Murshidabad district of West Bengal (India) has severe arsenic toxicity of geogenic origin. Blocks of Murshidabad district located on the eastern banks of Bhagirathi show higher contamination of soil and groundwater compared to the blocks on the western bank. Twenty-four out of the 26 blocks of Murshidabad district show above 50ppb arsenic in groundwater samples used for consumption, thereby exceeding the maximum permissible limit prescribed by the WHO. Tube wells in these blocks have arsenic concentration ranging from 3 to 3000ppb with an average concentration of 240ppb. Arsenic is detected in the cultivated food crops and in hair, nail, and urine samples of the residents of arsenic affected blocks, thereby showing the biomagnification of arsenic in the food chain. Government, UNICEF, NGOs, and Research Institutes have taken the initiative of marking unsafe tube wells and establishing domestic and community arsenic filtration units, which partially address the problem of arsenic contamination of groundwater. Some of the widely used methods for arsenic removal include ion exchange, electrochemical treatment, membrane filtration, reverse osmosis, coagulation-flocculation, oxidation, and adsorption. Considering the financial and environmental costs and the learning curve, these methods could be supplemented by different tools of bioremediation like bioaccumulation, bioadsorption, biovolatilization, and biotransformation. In these methods, arsenic-resistant bacteria, fungi and plants are used to remove (by accumulation or adsorption), volatilize, or transform (to less toxic forms) arsenic, resulting in mitigation of arsenic toxicity. Indigenously developed arsenic filtration units based on nanotechnology and innovative adsorption technology are showing promising results in Murshidabad. These ultra low-cost filtration units do not require power supply for functioning, work with minimal maintenance, and possess effective sludge disposal strategies without contaminating the environment. There are several instances where biofilters have been developed based on bioremediation processes, which have proved efficient and cost-effective in treatment of arsenic-contaminated groundwater and wastewater. Similarly, soils contaminated with arsenic are remediated by phytoremediation, mycoremediation, and a combinatorial approach amalgamating various bioremediation techniques.