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Arsenic is considered as one of the oldest, most dangerous poisons, and is a well defined contaminant, which has various acute and chronic health effects on the human health. Cf. chapter 2. The Adverse Health Effects and [Kim R. Adamsen: Arsenic Impact, Internal NEWAH note, 2001]

Arsenic is a shiny metalloid, but dissolved in water or on gaseous form, humans cannot detect its presence. We cannot see, taste, or smell, if the water or food we drink or eat is contaminated with Arsenic compounds. We can however feel it, since Arsenic compounds depending on the intake severely damages human health, and the sight of its effects is not pleasant. Ultimately infected persons die, either immediately and acutely from a variety of effects caused by the very poisonous substance or indirectly after a chronic exposure, which eventually causes skin and internal cancers, since Arsenic by the US Environmental Protection Agency (USEPA) have been classified as a highly carcinogenic compound. [WHO: Environmental Health Criteria 224, Arsenic and Arsenic Compounds,http://www.inchem.org/documents/ehc/ehc/ehc224.htm 2001], [USEPA: Proposed Arsenic in Drinking Water Rule: Regulatory Impact Rule, 2000]

Various Arsenic compounds occur naturally in the environment in different concentrations. Activities by humans can furthermore lead to an unintentional release of Arsenic components considered unhealthy for life in general and specifically for humans. These activities includes among others (Cf. this chapter below) the industrial activities (Cf. Appendix 5:page 64) and the activities to provide safe drinking water to the population. (Cf. chapter 3.1, explanation A, page 19.)

Arsenic is ubiquitous in nature and occurs in all environments. The concentration in the earth's crust is on average 2 mg/kg. The well known natural processes like weathering of rocks, biological and volcanic activities are the dominant natural processes of arsenic release in the environment, whereas smelting of non-ferrous metals, manufacture of various arsenic compounds, burning of fossil fuel, incineration of arsenic containing substances and the extensive use of arsenical pesticides, fertilizers, herbicides and pharmaceuticals cause the anthropogenic release of arsenic in the earth's environment. Since arsenic is indestructible in nature it can travel through the various pathways and can enter from one segment to another segment of the environment. [Kim R. Adamsen: Arsenic memo, Internal NEWAH note, 2001]

Groundwater is the dominant source of potable water. The anthropogenic processes of arsenic contamination are the seepage of arsenic enriched industrial effluents through the ground, leaching of solid wastes, rich in arsenic and intrusion of contaminated water into the groundwater aquifer through the contaminated water bodies like lake, river and sea. Furthermore, extensive use of arsenical pesticides, herbicides, fertilizers, etc. in agricultural land as well as the continuous dry and wet depositions of arsenic into the ground from contaminated air will enrich the soil with arsenic compounds. Leaching of enriched soil by precipitation create the contamination of groundwater with arsenic. Cf. Appendix 5:, page 64. [Kim R. Adamsen & Dinesh Bajracharya: Arsenic memo, Internal NEWAH note, 2001]

Despite all these prevailing anthropogenic activities, the dominant source of arsenic contamination in ground water throughout the world is still the natural processes. As the earth's crust consists of arsenical compounds in trace levels, the rock - water interactions lead to the contamination of groundwater with arsenic compounds. Dissolution of arsenic in groundwater however, primarily influenced by the oxic and anoxic conditions of the groundwater aquifers (See. chapter 3 page 19) as well as secondarily affected by the level and type of arsenic compounds present in the adjoin rock of the particular region. [Kim R. Adamsen & Dinesh Bajracharya: Arsenic memo, Internal NEWAH note, 2001]

Taken from the report "The Arsenic Contamination of the Drinking Water in Nepal" by Anil Pokhrel, head of technical section of NEWAH & Kim Rud Adamsen, hydrology adviser of NEWAH

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