73 S.J.S. Flora (Ed): Handbook of Arsenic Toxicology. DOI: © 2015 Elsevier Inc. All rights reserved. 2015 http://dx.doi.org/10.1016/B978-0-12-418688-0.00003-4 Arsenic and Fluorescent Humic Substances in the Ground Water of Bangladesh: A Public Health Risk 3 Shafi M. Tareq DEPARTMENT OF ENVIRONMENTAL SCIENCES, JAHANGIRNAGAR UNIVERSITY, DHAKA, BANGLADESH; SCHOOL OF BIOSCIENCES, THE UNIVERSITY OF NOTTINGHAM MALAYSIA CAMPUS, JALAN BROGA, SELANGOR DARUL EHSAN, MALAYSIA CHAPTER OUTLINE 3.1 Introduction ................................................................................................................................ 73 3.2 Materials and Methods.............................................................................................................. 74 3.3 Results and Discussion ............................................................................................................... 77 3.4 Conclusion .................................................................................................................................. 90 References ......................................................................................................................................... 91 3.1 Introduction Drinking water should be thoroughly purified to ensure the quality of the water and to protect the health of consumers. Consumption of surface water for drinking purposes has been a pri- mary source of waterborne disease in developing countries like Bangladesh. Over the past few decades, ground water has become an important alternative source for the inhabitants of the Ganges-Brahmaputra-Meghna (GBM) floodplains. Unfortunately, much of the water extracted from the alluvial aquifers contains naturally occurring As (arsenic) from the alluvium sedi- ments deposited in these floodplains [1–3]. Arsenic contamination in ground water of deltaic aquifers of Bangladesh represents the most serious public health concern in terms of global population density [3–5]. Resultant health problems were first identified in West Bengal in the 1980s but the first diagnosis in Bangladesh was not made until 1993 [5–7]. In ground water, arsenic is primarily found in its inorganic forms, either As(III) or As(V). Both inorganic forms are toxic for the human body, where in As(V) is reduced to As(III). The mechanisms of causing toxic effects are based on the inhibition of various mitochondrial enzymes by As(III) and the uncoupling of oxidative phosphorylation. The affinity of As(III) for