Dr. Nitish Priyadarshi
Fig: 16 years old girl suffering from arsenic toxicity. This girl belongs to Sahebgunj district of Jharkhand. She is not able to walk properly due to pain in her feet. Her parents are worried about her marriage.
Fig: Man showing arsenic affected areas of his body.
- INTRODUCTION AND DISCUSSION:
Arsenic contamination of groundwater has led to a massive epidemic of arsenic poisoning in Bangladesh and West Bengal in India and neighbouring countries. It is estimated that approximately 57 million people are drinking groundwater with arsenic concentrations elevated above the World Health Organization's standard of 10 parts per billion. The arsenic in the groundwater is of natural origin, and is released from the sediment into the groundwater due to the anoxic conditions of the subsurface. This groundwater began to be used after western NGOs instigated a massive tube well drinking-water program in the late twentieth century. This program was designed to prevent drinking of bacterially contaminated surface waters, but failed to test for arsenic in the groundwater. Many other countries and districts in South East Asia, such as Vietnam, Cambodia, and Tibet, China, are thought to have geological environments similarly conducive to generation of high-arsenic groundwaters. Arsenicosis was reported in Nakhon Si Thammarat, Thailand in 1987, and the dissolved arsenic in the Chao Phraya River is suspected of containing high levels of naturally occurring arsenic, but has not been a public health problem due to the use of bottled water.
An environmental health disaster is unfolding in West Bengal and Bangladesh. Tens of millions of persons in many districts are drinking ground water with arsenic concentrations far above acceptable levels. Thousands of people have already been diagnosed with poisoning symptoms, even though much of the at-risk population has not yet been assessed for arsenic-related health problems. Alarming level of arsenic in the groundwater of eight districts of West Bengal and 2 districts of Jharkhand in East India has become a serious health hazard. The number of people suffering from skin lesions, muscular disorder and even cancer, is constantly going up. This is an acute 'environmental health' problem since the rural population in these districts is solely dependent on groundwater for drinking, bathing and cooking.
The source of the problem is geological in origin, which has aggravated due to excessive withdrawal of groundwater for paddy cultivation in the wake of the green revolution of the 1970s.
ARSENIC IN JHARKHAND
A detailed study has been presented on groundwater metal contents of Sahebgunj district in the state of Jharkhand, India with special reference to arsenic. Both tubewell and well waters have been studied separately with greater emphasis on tubewell waters. Groundwaters of all the nine blocks of Sahebgunj district have been surveyed for iron, manganese, calcium, magnesium, copper and zinc in addition to arsenic. Groundwaters of three blocks of Sahebgunj, namely, Sahebgunj, Rajmahal and Udhawa have been found to be alarmingly contaminated with arsenic present at or above 10 ppb.
Rivers flowing through the coal fields of Jharkhand have been reported to carry arsenic responsible for arsenic poisoning in downstream areas of West Bengal. The coal fields of Bachara and Piprawar areas of Jharkhand have contaminated the waters of the Damodar and its tributary, the Safi, causing problems in West Bengal. According to Nitish Priyadarshi, arsenic contamination arises mainly due to the dumping of waste from the coal mines along the river bed. Coals of the area mentioned contains sufficient amount of arsenic as described below.
Distribution of Arsenic in the water and in the Permian coals of North Karanpura Coalfield of Jharkhand State of India:
The North Karanpura coalfield, a western most member in the east-west chain of the Damodar Valley Basin, forms a large expanse of coal bearing sediments spread over Hazaribag, Ranchi and Palamau districts of Jharkhand State. It covers a total area of around 1230sq. Km. For the arsenic study, samples from coal from Badam, Kerendari, KDH, Rohini, Dakra and Karkatta were analysed by the author. Molybdenum-blue Colorimetry was used as the chemical technique for arsenic determination as recommended by the International Standard Organisation. Concentration of arsenic in coal samples range from 0.01 to 0.49ppm with an arithmetic mean of 0.15ppm. (Priyadarshi, 2004). Concentration of arsenic is low compared to most world coals. Average ash% is very high (up to 32.51%).
To understand the environmental impact of arsenic in coals of research area, water and sediments were analysed for arsenic concentration. Concentration were moderately high (2 ppm) in the sediments of local streams flowing through the coal mining area. Average concentration of arsenic in the sediments of mine water was 1.4 ppm. Though the concentration of arsenic is low in the surface water ( 0.001-0.002 ppm) it may still affect the local habitants especially during summer season when the consumption of water increases many folds. People of this area is consuming water from several years. Effects of arsenic will be there if the people of the area consume water containing arsenic for longer periods.
Real truth is that people of the area are ignorant about this toxicity. Few people know about this but due to lack of pure source of water they are helpless and are forced to depend on the contaminated water.
Local communities of the Sahebgunj district in the state of Jharkhand, are already showing sign of arsenic toxicity. Sufferers are complaining about body ache, skin problems, nausea etc.
General Source of arsenic
Arsenic is widely distributed throughout the earth's crust.
Arsenic is introduced into water through the dissolution of minerals and ores, and concentrations in groundwater in some areas are elevated as a result of erosion from local rocks.
Industrial effluents also contribute arsenic to water in some areas.
Arsenic is also used commercially e.g. in alloying agents and wood preservatives.
Combustion of fossil fuels is a source of arsenic in the environment through disperse atmospheric deposition.
Inorganic arsenic can occur in the environment in several forms but in natural waters, and thus in drinking-water, it is mostly found as trivalent arsenite (As(III)) or pentavalent arsenate (As (V)). Organic arsenic species, abundant in seafood, are very much less harmful to health, and are readily eliminated by the body.
Drinking-water poses the greatest threat to public health from arsenic. Exposure at work and mining and industrial emissions may also be significant locally.
Chronic arsenic poisoning, as occurs after long-term exposure through drinking- water is very different to acute poisoning. Immediate symptoms on an acute poisoning typically include vomiting, oesophageal and abdominal pain, and bloody "rice water" diarrhoea. Chelation therapy may be effective in acute poisoning but should not be used against long-term poisoning.
The symptoms and signs that arsenic causes, appear to differ between individuals, population groups and geographic areas. Thus, there is no universal definition of the disease caused by arsenic. This complicates the assessment of the burden on health of arsenic. Similarly, there is no method to identify those cases of internal cancer that were caused by arsenic from cancers induced by other factors.
Long-term exposure to arsenic via drinking-water causes cancer of the skin, lungs, urinary bladder, and kidney, as well as other skin changes such as pigmentation changes and thickening (hyperkeratosis).
Increased risks of lung and bladder cancer and of arsenic-associated skin lesions have been observed at drinking-water arsenic concentrations of less than 0.05 mg/L.
Absorption of arsenic through the skin is minimal and thus hand-washing, bathing, laundry, etc. with water containing arsenic do not pose human health risk.
Following long-term exposure, the first changes are usually observed in the skin: pigmentation changes, and then hyperkeratosis. Cancer is a late phenomenon, and usually takes more than 10 years to develop.
The relationship between arsenic exposure and other health effects is not clear-cut. For example, some studies have reported hypertensive and cardiovascular disease, diabetes and reproductive effects.
Exposure to arsenic via drinking-water has been shown to cause a severe disease of blood vessels leading to gangrene in China (Province of Taiwan), known as 'black foot disease'. This disease has not been observed in other parts of the world, and it is possible that malnutrition contributes to its development. However, studies in several countries have demonstrated that arsenic causes other, less severe forms of peripheral vascular disease.
According to some estimates, arsenic in drinking-water will cause 200,000 -- 270,000 deaths from cancer in Bangladesh alone.
Priyadarshi, N.: Arsenic in Damodar poisoning West Bengal. Indian Express, July 12, 1998.
Priyadarshi, N. 2004. Distribution of arsenic in Permian Coals of North Karanpura coalfield, Jharkhand. Jour. Geol. Soc. India, 63, 533-536.
Dr. Nitish Priyadarshi
Geologist and Lecturer
Department of Environment and Water Management,