Arsenic (As) is semi-metal of p Block, having Atomic Number 33 of Group 15 of Period 4 with Electronic Configuration [Ar] 3d104s24p3. A little amount of arsenic is found in its native condition either it is mainly found with minerals. The arsenic-containing mineral is arsenopyrite is wide spread in Earth Crust. Arsenic occurs in two solid states (Elemental form) as Grey (or metallic) and Yellow, having specific gravities of 5.73 and 1.97 respectively.
2- In Drinking Water
The main basis of arsenic concentration in ground water is arsenic-rich rocks through which the water has passed; it is highly toxic in its inorganic form. Fate of Arsenic contamination in Ground Water through the dissolution of rocks, minerals and ores, from industrial effluents and through mining wastes. In oxygenated surface waters, arsenic (V) is generally present under reducing conditions commonly, where as in deep lake sediments or in groundwater, the principal form is arsenic (III).
3- Exposure to Human Health
People are exposed to high levels of inorganic arsenic through drinking water which contains high level of Arsenic concentration, using unhygienic water in food preparation and irrigation of food crops, industrial processes, eating contaminated food and smoking tobacco.
4- Health Effect
According to Indian Standard the prescribed limit for Arsenic concentration in drinking water is 0.01mg/l to max. 0.05mg/l. Its effect on human health is both Acute as well as long term. The health effect of arsenic poisoning thickening and discoloration of the skin, stomach ache, nausea, vomiting, diarrhea, deadness in hands and feet, partial paralysis, and blindness symptoms is shown by the patient. Whereas in case of long-term exposure to high levels of inorganic arsenic contamination are frequently observed in the skin and comprise alteration in pigment, skin lesions and hard patches on the palms and soles of the feet (hyperkeratosis) . This takes place after a minimum exposure of approximately five years and may be a forerunner to skin cancer. As well as skin cancer, long-term exposure of arsenic contamination may also lead to cancers of the bladder and lungs.
5- Control and Avoidance
I – The steps towards the prevention of exposure to arsenic by the prerequisite of a safe water supply for drinking in affected communities/Habitat.
II – Installation of Arsenic Removal Units – In Centralized System or at Domestic level with ensuring the appropriate disposal of the removed arsenic. Various technologies such as oxidation, coagulation–precipitation, absorption, ion exchange and membrane techniques can be used in removal of Arsenic.