Presence of arsenic in drinking water can be from the following sources:
Natural Geological Formation
Arsenic presents naturally in underground rocks and soils worldwide. It binds to rust particles (iron oxides) and stays in solid forms.
When there is no oxygen, iron-reducing bacteria that present in the soil will transform solid phase iron oxides Fe (III) to soluble iron Fe (II). Then it releases Arsenic that binds to it.
When the rocks and soils is in contact with underground water, the inorganic salts of arsenic dissolved and release into the underground water.
Two forms of arsenic are As(III) and As (V).
The dissolved arsenic salts can be transported from:
This natural process of reaching the aquifer would take at least 100 years.
Industrial Discharges
Arsenic and arsenical compounds is used in the following industries:
Argricultural Run-off
Arsenic is used in some of the insecticides and fungicides manufacturing. Insecticide and other pesticides are used in the farm and agricultural lands.
What is the health risk of having arsenic in drinking water?
Arsenic is tasteless and odourless. It is toxic and can cause cancer (carsinogen) and may act as co-carcinogen.
Table 1. Summary of various studies published in the scientific journal all around the world.
| Type of Risk | Concentration of Arsenic in Drinking Water | Quantity of Drinking Water Consumed | Risk | Source |
|---|---|---|---|---|
| Death caused by various cancers: Liver cancer, Lung cancer, Bladder cancer, Kidney cancer | 50 ppb | 1 litre per day | 13 in 1000 persons | Environmental Health Perspectives, 97, 259-267. (1992) |
| Bladder cancer, Lung cancer | 3 ppb | Daily | 1 in 1000 persons | Arsenic in Drinking Water: 2001 Update. National Research Council |
| Blood Vessel Diseases: Heart attack, Strokes, Atherosclerosis, Blackfoot disease | 3 times the risk of atherosclerosis as people who were not exposed to arsenic. | Science Daily (Mar. 28, 2002) | ||
| Neuro-sensory effect (nervous system) | 150 -170 ppb | Daily | Reduce vibrotactile thresholds | Journal of Water Health, 04, 39-48. (2006) |
| Neuro-sensory effect (nervous system) | 400 ppb | Daily | Reduce pain thresholds | Journal of Water Health, 04, 29-37.(2006) |
| Skin lesions | 50 ppb | Daily | Journal of Water Health, 03, 101-107. (2005) | |
| IQ of girls | 100 ppb | IQ decreased | Journal of Hygiene Research, 36 (3), 347-349. (2007) | |
| Liver cancer in children | Increase in childhood mortality | Cancer Epidemiology, Biomarkers & Prevention, 17 (8), 1982-1987. (2008) | ||
| Bronchiectasis (lung disease ) | Epidemiology, 16 (6), 760-765. (2005) | |||
| Circulatory system diseases, Diabetes mellitus (type 2 diabetes), Cerebro-vascular diseases, Kidney diseases | Average 11 ppb | Elevated mortality rates | Environmental Health, 6, 4. (2007) |
Notes:100 ppb = 100 [micro]g per litre = 0.10 mg per litre of drinking water
Table 2. Example of Contamination of Arsenic in Well and Underground Water
| Area | Concentration of Arsenic | Source | Summary of Survey |
|---|---|---|---|
| Tainan (Taiwan) | 600 -2000 ppb | Journal American Water Works Association, 65(9), 543-548. (1973) | 244 deaths due to blackfoot disease. |
| Cordoba (Argentina) | 900 -3400 ppb | Biological and Environmental Effects of Arsenic, B.A. Fowler (ed.), Elsevier Science Publishers, Amsterdam, 6, 199-232. (1983) | 165 deaths due to cancer of the respiratory system and gastrointestinal tract. |
| West Bengal (India) | Above 50 ppb | Analyst, 120(3), 643-650, 917-924. (1995) | 175,000 people showing arsenical skin lesions. |
Notes:100 ppb = 100 [micro]g per litre = 0.10 mg per litre of drinking water
So, what is the permitted level / guideline of arsenic allowed in drinking water?
Notes: 10 ppb = 10 [micro]g per litre = 0.010 mg per litre of drinking water
However, the presence of arsenic in drinking water should be reduced to as close as possible to zero.
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