Drinking water is derived from a variety of sources depending on local availability. These resources include, Surface water (rivers, lakes, reservoirs, ponds), Groundwater (aquifers), and Rain water. The presence of arsenic varies in each source. Higher arsenic contamination is found in ground waters as a result of the influence of water-rock interactions or where favorable physical and geochemical conditions are present for arsenic mobilization and accumulation in the aquifer. Drinking water probably poses the greatest threat to human health due to the various sources of arsenic in the environment. In natural waters arsenic is mostly found as oxyanions of trivalent arsenite [As (III)] or pentavalent [As (V)]. Arsenic enters the atmosphere through inputs from wind erosion, volcanic emissions, low temperature volatilization from soils, marine aerosols, pollution and is returned to the earth’s surface by wet and dry deposition. Arsenic is present in copper and lead ores and smelting these metals can release airborne arsenic compounds to settle on the ground and solubilize by rain to contaminate the soil and groundwater (DEQ, 2003). A number of large aquifers in various parts of the world have been identified with problems of arsenic contamination with concentrations above 50 ppb, the most noteworthy occurrences are in parts of Argentina, Bangladesh, China, Northern China, Hungry, India (West Bengal), Mexico, Romania, Taiwan and many parts of the USA.

Arsenic contaminated water may lead to serious health hazards when used for drinking, washing and food preparations. Arsenic is difficult to detect while ingesting, as it is tasteless, odorless and colorless. The effects are not immediately visible and people can absorb significant quantities of Arsenic without any immediate health complications. Generally, a healthy person will withstand the arsenic poison for a longer period than an undernourished or weak person who will perish quickly. Similarly, children are more vulnerable sensitive. Arsenic can damage the nervous system and is also carcinogenic as it can cause various types of cancer. It is also Teratogen as it can enter the metabolic system of newborn children. According to EPA in Arsenic Rule Benefit Analysis, August 9, 2001 (Aapo Saak, 2001), following diseases are suspected to be caused or aggravated by arsenic in drinking water.

1. Cancer of the lungs, bladder, skin, prostate, kidney, nose and liver

2. Still births

3. Post neonatal mortality

4. Ischemic heart diseases (heart attack)

5. Diabetes mellitus

6. Nephritis (chronic inflammation of kidneys)

7. Nephritis (degenerative kidney diseases)

8. Hypertension, hypersensitive heart disease

9. Emphysema, Bronchitis

10. Chronic airway obstruction

11. Lymphoma (tumors in the lymph)

12. Black foot disease and Developmental deficit.

The Department of Health and Human Services (DHHS), USA has determined that arsenic is a known carcinogen. Breathing inorganic arsenic increases the risk of lungs cancer (Tahir, M.A, 2000). Ingesting inorganic arsenic increases the risk of skin cancer and tumors of the bladder, kidney, liver and lungs. According to a news report in April 19, 2001, a team of EPA scientists at Carolina has discovered a direct link between DNA damage and arsenic compounds presence. The research demonstrates how a human cells own metabolic response to arsenic exposure produce compounds that cause genetic damage. Early clinical symptoms of acute intoxication include:

• Abdominal pain, vomiting, diarrhea

• Muscular pain and weakness

• Flushing of the skin

Signs of chronic arsenicalism include dermal lesions (corns or warts on the palm, soles and torso), Peripheral neuropathy, Skin cancer and Lymphoma. Peripheral vascular disease has been observed in population ingesting arsenic contaminated drinking water (Figure-3).

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Fig.-3: Symptoms of skin cancer and Lymphoma caused by Higher Arsenic concentration in drinking water

In March, 1999 the National research Council (NRC) of USA has released a new study suggesting that there may be increased risk of long-term health effects from exposure to arsenic at levels as low as 2 ppb (James and Patrick, 1999).

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