Arsenic is one among 10 important poisonous chemical substances: Lead, Mercury, Vinyl Chloride, Benzoic, Polycyclic, Aromatic Hydrocarbon, Polychlorinated Bylines Cadmium, Banzopyrin and Benz Florynathine.
Arsenic is found in rocks, soil, water, air, plants and living organisms in natural form. It is a bright, grey and brittle substance having metallic and non-metallic qualities.
Arsenic is a cumulative poison which is rarely found in form of an element of nature. It is mostly found in compound form with oxygen, chlorine, sulphur, carbon, hydrogen, lead, gold and iron.
In compounds, arsenic is in trivalent and pentavalent position. Compounds made from carbon and hydrogen existing in plants and living organisms are called carbonic-arsenic compounds.
Carbonic arsenic compounds are less poisonous as compared to non-carbonic arsenic compounds. Arsenic converts into other forms in the environment but it does not get destroyed, neither does it evaporate. By burning arsenic mixed things, it reaches in the air. Arsenic in the air stays in soil or dissolves in rain. Most of the compounds of arsenic dissolve in water.
Different sources of concentration of arsenic in nature and human related conditions are as under:
Sources of Arsenic in Water:
1. Geographical processes like rock slipping, mineral leakage and volcanic bursting
2. Flow of domestic and industrial effluent
3. Arsenic existing in air-from rain and dry concentrates
4. Soil
Sources of Arsenic in Air:
1. Volcanic outburst
2. Fire in forests
3. Burning of fuel
4. Industrial processes like metal melting, heating, burning and other production processes
5. Use of pesticides in agriculture
6. Thermal power generation
7. Micro organic processes in soil
Sources of Arsenic in Soil:
1. Use of pesticides in agriculture
2. Contact of air containing arsenic
3. Use of water containing arsenic in irrigation water
4. Volcanic outburst
5. Weathering of rocks containing arsenic
6. Mineral leakage
Source of Arsenic in Man:
1. Use of arsenic polluted food
2. Use of arsenic polluted water
3. Breathing in arsenic polluted air
4. Working area for example working in industries and mines
5. Burning of arsenic painted fuel for safety and breathing in its fuel dust
6. Living near uncontrolled arsenic affected poisonous waste
7. Living near rocks containing higher quantity of arsenic
Arsenic moves mostly in conscious and sub-conscious forms of air, water and soil due to flexible and reactive reactions, where it makes different types of chemical and biochemical changes, e.g., oxidation, reduction, mithilation and de-mithilation. Finally, arsenic reaches the sea through air, water, soil, man etc.
Uses of Arsenic:
Arsenic is harmful but it is useful also, as in United States of America 90 per cent arsenic is used in chemicals utilized for safety of wood and 10 per cent arsenic is used in manufacture of paints, drugs, dyeing, soap, metal, semi-conductors and other products. In the field of agriculture, arsenic is used for manufacture of insecticides. It is also used for manufacture of lead. Though arsenic is poisonous for man, but in the field of medicine also, it cures many diseases like skin disease, spirochetes infections, blood discrepancies etc.
Global Problem of Arsenic:
In Novaskotia area of Canada, arsenic is found in a majority of rocks as well as groundwater. In New Mexico and Arizona regions of United States of America, local residents get drinking water from far off area by tanker because local water contains arsenic. Arsenic is affecting the health of native people in many areas due to its presence in large quantities in the groundwater in Argentina, China, Taiwan, Thailand, Mexico, America, Ghana, Hungary, England, Chile, New Zealand and Russia.
In some areas of Argentina, concentration of arsenic in groundwater is 100 to 2,000 microgram per litre. According to health related tests, wherever presence of arsenic was more than 0.3 milligram per litre, problems from black spots on skin to skin cancer was found. In China, deep hand pumps in many areas were found to contain arsenic in high concentration. This problem was not found in less deeper hand pumps. Concentration of arsenic in deeper handpumps ranged from 0.6 to 1.2 milligram per litre.
In Thailand, the main reason for presence of arsenic in groundwater is the chemical composition of natural rocks and storage of arsenic affected waste in large quantities. The concentration of arsenic in less deep hand-pumps also was more than 0.5 milligram per litre, but in deeper hand pumps there was low concentration.
In Taiwan, reports regarding high concentration of arsenic are coming since 1968 and a large section of population is suffering from problems of skin diseases. In Taiwan, water of almost 19 per cent tube-wells contains more than 50 microgram per litre concentration of arsenic, whereas in the rest of the tubewells, the concentration of arsenic was found to range from 10 to 1820 microgram per litre.
In the United States of America, the states of Nevada, Arizona and California have more than normal arsenic concentration in groundwater due to natural reasons. In many tube wells and five community water supply schemes of Nevada, arsenic concentration is more than the prescribed norm of 0.5 milligram per litre. About six crore population of America is affected because of this problem.
At many places of North Mexico, a large proportion of population is suffering from skin diseases, skin cancer and problems of digestive system due to arsenic. In some areas, the average concentration of arsenic in groundwater is 0.4 milligram per litre.
In the South-eastern area of Hungary, the health of about four lakh citizens is being affected due to extreme use of insecticides containing arsenic. In the Cornwall area of England, the concentration of arsenic in groundwater was found to be between 10 to 50 micrograms. Aluminum hydroxide is used for curing such water. It neutralizes gray arsenic so that it does not reach water supply system.
In Chile, concentration of arsenic is more in surface water like rivers and lakes. In the water supply for Antofagasta city in Chile, average concentration of arsenic is 0.8 milligram per htre. It has been affecting skin of children there. In New Zealand and Japan also, water in some areas contain higher concentration of arsenic
In India, the water of six out of 17 districts of West Bengal contains arsenic concentration more than the permissible standard of 0.5 milligram per litre. In Bangladesh, 59 out of 64 districts contain arsenic concentrations in groundwater that is more than the permissible standard of 0.5 milligram per litre.
Of the two crore and 40 lakh people residing there, 7,600 persons in all suffer from arsenocosis disease and one lakh from skin diseases. About 11.2 lakh tube wells contain water having higher concentration of arsenic. In America, 90 per cent arsenic affected water is utilized in production of chemicals for safety of wood.
The remaining 10 per cent is used in paint, medicine, dye, soap, metal, semi conductor and other industries. For safety of wood, chromate copper and arsenate chemicals are used on a large scale. For the last few years, many organizations have been demanding ban on production of chemicals containing arsenic for domestic use. Ecology Security Agency of America categorizes arsenic as ‘cancerous material’.
Though no concrete proof of evil effects of chromate copper arsenate on health has found, but three important American companies manufacturing it – Osmos, Archwood Protection and Chemical Specialties – had decided to stop its manufacture for domestic use up to the end of 2003. However, the production for occupational use was not stopped.
Effects of Arsenic on Human Health:
Although arsenic affects human health but It depends how much, m what manner and in what form it enters the body and as a result of it, how the body responds to it. Even a little quantity of non-carbonic arsenic harms the health of our body. It causes nausea, vomiting, leads to decrease in formation of red and white blood corpuscles, damage of blood vessel, and has the effect of paralysis in hands and feet.
If arsenic concentrate water is used for a long time, it can also cause cancer of skin, lungs, liver, kidney and urinary tract. It also brings dryness of skin and change in colour of skin. However, water affected with arsenic does not cause any harm while washing hands, bathing and wearing clothes washed with such water in laundry because the water does not enter the skin.
As compared to normal persons, the maximum effect of arsenic is caused to infants in the womb, newly born infants, persons sick a since long time, AIDS patients, cancer patients and old and imbalanced persons taking little food.
Some health problems out of the above are also caused by diseases. Hence, the poisonous effect of arsenic does not become clear m the beginning. When people take water containing arsenic, the effects take place slowly. It becomes visible after a duration of 8 to 14 years. If its awareness is generated earlier, its effects can be minimized.
The level of effect of arsenic can be measured through examination of blood, urine, hair and nails. Arsenic stays in the body for a very short time, hence testing of the effect of arsenic should be done through urine examination as early as possible since it is more trustworthy. Extreme arsenic contact can be measured through testing of nails and hair within 6 to 12 months. Lesser quantity of arsenic contact cannot be measured by these tests and neither can these tests tell us about the harmful effects of arsenic on our health.
Problem of Arsenic in Drinking Water in India:
In India, about 53.6 lakh persons in West Bengal are residing in arsenic affected areas and are compelled to drink water containing arsenic. The reason of this problem is geographical. According to a survey conducted by the Central Pollution Control Board, residents of these areas are suffering from diseases like Melanesia, Kurtosis and Gangrene and their normal problems are related to breathing.
Solution of the Arsenic Problem:
Many techniques have been discovered for redemption of the problem of arsenic in India. They are, precipitation with the help of iron and aluminum hydroxide, ion exchange, reverse osmosis and suction of such materials on the surface. Some equipment’s based on such techniques are also working in West Bengal.
According to a report “Arsenic Contamination in Ground Water and its Control” published by Central Pollution Control Board, whichever instruments based on absorption method are installed in West Bengal, they work properly only for some period.
After some time, it is essential to clean the absorption medium, otherwise the instrument does not work properly. In arsenic affected areas of West Bengal, concentration of iron is excessive. Blocks of iron compounds are formed and they collect on the medium. They absorb comparatively more arsenic. Hence, if arsenic containing compounds are not removed from time to time, the medium would not work properly and its capacity will decrease.
A group of engineers under Nick P. Nicholedus of Connecticut University (USA) have prepared such a filter which separates arsenic from water and it can be directly fitted in a tube well. In this filter small pieces of iron and sand are filled and by rusting of iron, all the arsenic is absorbed from water.
Scientists of Canada have also discovered a new technique for removing arsenic which is not only cheaper and effective but can also be shifted from one place to another. Dust of Alumna is used in it. Atoms of arsenic are absorbed in alumna as sponge collects water in it. Thereafter a mixture of alumna and water goes to a micro filter which is based on a membrane.
This water passes through filter whereas, alumna and arsenic come back in the reactor. This method can remove 99.9 per cent arsenic. When arsenic and alumna collect in sufficient quantity, then an acidic solution is mixed in it, which separates alumna from arsenic. This complete equipment is very small and can be taken anywhere. Hence, in view of scientists, it is very useful specially for developing countries.
Many techniques are available for removing arsenic from drinking water but in spite of it, crores of people are suffering from diseases on account of this problem. Hence, it is the responsibility of governments, local bodies and NGOs to make the public aware about the evil effects of arsenic and the available techniques for removing it.