Arsenic Contamination: An Overview

Md. Arafat Rahman                                                                                                                                                                                                                           

Water is another name of life. Today, life-saving water is being poisoned by arsenic. Arsenic-contaminated water poses a serious threat to public health. People are slowly dying by drinking arsenic-contaminated water. Even 30 years ago, the country’s shallow tube well water was pure, but gradually it was contaminated with arsenic. According to experts, there is no cure for arsenic poisoning.

Arsenic is a toxic mineral element. It has no taste or smell. Arsenic is used to make semiconductors and alloys. As a basic substance, it does not dissolve in water and is not toxic. But when oxides are formed in the air, it becomes toxic. Arsenic is a semi-metal or by-metal of brittle nature with a grayish white color. Nature’s arsenic is not harmful to public health in most cases. However, in recent times, man-made activities have increased the concentration of arsenic in the environment and the air, soil and water in different parts of the world have become contaminated with arsenic, causing a variety of serious health problems. Arsenic and arsenic compounds are being used in various ways for human welfare, but in excess of certain amounts it can be fatal. Naturally arsenic is present in very small amounts in nature but the intensity of arsenic may increase, such as the emission of metal extraction reactors. The arsenic concentration in river water is lower than normal, but there are exceptions in areas where geothermal water or mines are extracted.

A small amount of arsenic can be found in the human body, soil and sea water. More arsenic is observed inside the soil than on the surface. There is a layer of rock beneath the soil that contains a compound called pyrites. Arsenic exists in this compound. However, the most arsenic is found in the crust of the rock. Arsenic sulfide, oxide and arsenide are considered to be the main sources of arsenic. The main source of arsenic in our country is tube well water. Arsenic pollution in Bangladesh has reached at an alarming proportion. Arsenic is stored in a special layer under the soil and is pumped out through tube well water.

Over the past few decades, the use of chemical fertilizers and pesticides in agricultural production has increased dramatically, polluting rivers, canals, and seawater. This excessive use of chemical fertilizers and pesticides is one of the causes of arsenic contamination. The special layer of soil that contains a substance called arsenopyrite is being mixed with water due to the extraction of excess water from the ground. The billions of liters of water we pump out for daily use, starting with agriculture, create a temporary vacuum in the groundwater that mixes arsenic with water mixed with air and oxygen. The cause is arsenic pollution.

Arsenic pollution is a global problem. High levels of arsenic have been detected in groundwater in about 50 countries on all continents. Since the first detection in Taiwan, arsenic contamination has been gradually identified in many countries around the world. The most polluted areas are Latin America (Argentina, Chile, Mexico, Nicobagua and other countries); Southeast Asia (Vietnam, Cambodia, Thailand, Laos, Myanmar) and South Asia (Bangladesh, India, Nepal, Pakistan). In addition, the United States, Canada, Spain, Italy, Germany, the United Kingdom, China, Brazil, Australia, New Zealand, etc. countries have different levels of arsenic pollution. Bangladesh is considered to be the most polluted country in terms of the affected or at-risk population.

The first report of arsenic contamination was found in India in 1986. In some parts of the northern and southern parganas of India, the effects of arsenic on the human body are noticeable. It was later identified in different countries of the world. Symptoms of arsenic in the human body do not appear immediately. In many cases the symptoms appear after 6 months or more. Its toxicity is based on the amount of arsenic in the water. If anyone drinks the high amount of arsenic mixed water for a long time, its symptoms appear quickly. At first, brown spots are seen on the body or palms of the hands. Later on, the fingers start to rot. Many times the reaction to arsenic causes the skin on the soles of the feet to thicken and the toes to bend.

People with arsenic can get cancer. Redness is seen on the tongue, gums and lips of arsenic infected patients. Feeling anorexia, lossing of appetite and nausea also seen. Gradually the heart becomes inactive. The amount of white and red blood cells in human blood decreases. Many times the blood vessels are damaged and there is severe damage to the fetus in pregnant women. Arsenic contamination in Bangladesh has made people think. The level of arsenic contamination has increased drastically. The presence of arsenic in the groundwater of Baragharia Union of Chapainawabganj district was first discovered in 1993 in our country.

The ‘Bangladesh Arsenic Mitigation Water Supply Project’ (BAMWSP) was launched with the responsibility of implementing data collection, analysis, storage and pollution mitigation strategies on arsenic centrally. The most comprehensive and systematic survey on arsenic contamination in Bangladesh so far was conducted in 1998-99 by the British Department of Public Health and Engineering in collaboration with the British Geological Survey and Mott MacDonald Limited.

Two different methods are usually used in Bangladesh for testing arsenic levels in groundwater. The first one is called ‘Field Kit Method’. It is a method of qualitative to semi-quantitative type. Tested water in this method is classified into two types – safe and unsafe. The second method of arsenic testing is laboratory analysis. It is completely quantitative and contains the exact amount of arsenic in groundwater. Since 1993, extensive groundwater samples have been tested using both field kits and laboratory methods.

Under the BAMWSP project, about 5 million tube wells have been tested in 260 upazilas of the country out of which arsenic has been detected in 26% of the tube wells above the Bangladesh standard. Besides, the Department of Public Health Engineering has surveyed other areas of the country in about 190 upazilas. At present arsenic contamination maps have been made across the country to show that the presence of arsenic is much higher in the southern part of the country. However, analysis of village, union and upazila based results shows that in some areas tube wells are 100% free from arsenic contamination and in some areas 100% free from pollution.

Then in 2001, the British Geological Survey tested tube well water in 61 districts of Bangladesh and found that 42% of tube well water contained levels of arsenic higher than the World Health Organization standard. According to a 2008-09 survey by the Bangladesh Department of Health, the number of arsenic infected patients was 19,165 in Chittagong Division, 8,315 in Khulna Division, 5,552 in Dhaka Division, 4267 in Rajshahi and Rangpur Division, 788 in Barisal Division and 233 in Sylhet Division. The level of arsenic contamination in Bangladesh is higher than other neighboring countries. The most polluted districts in Bangladesh are Chandpur, Munshiganj, Gepalganj, Madaripur, Noakhali, Satkhira, Comilla and Bagerhat. The least polluted districts are Thakurgaon, Panchagarh, Natore and Nilphamari.

Prevention is currently the most effective way to get rid of arsenic poisoning. Scientists have not yet discovered the treatment of arsenic-infected patients. The World Health Organization (WHO) report said that 0.05 mg of arsenic is tolerable for the human body, but the current report says that if the level is more than 0.01 mg for Bangladesh, it will be harmful to health. Therefore, more importance should be given to prevention and remedy. Studies have shown that arsenic levels are higher in shallow tube well water. Especially at a depth of 100-200 meters the presence of arsenic is low.

The following steps can be taken to prevent and remedy arsenic contamination-.

· Deep tube well water should be used for food and cooking.

· Rainwater does not contain arsenic. So rain water should be stored and used.

· Awareness of arsenic through radio, television and rural rituals.

· There is no arsenic in the water of ponds and canals. In this case, the water of ponds, canals or beels should be filtered and boiled for 20 minutes.

· Water should be provided by digging new ponds in arsenic affected villages.

· Establishment of arsenic treatment plant through government assistance.

· Tube well water should be tested from time to time through various government and non-government organizations.

· Purification of water with buckets, pitchers and fly ash invented by SOES, CSIR through filters.

· Arsenic-containing tube wells should be marked with red color to stop drinking water from them.

· Arsenic is not a contagious or contagious disease, so without panic consulting a doctor.

At present, various organizations are working on arsenic in Bangladesh. In November 1996, representatives of the Dhaka Community Hospital visited several districts of the country and went to Calcutta for sample testing. Later in 1997,

Rajshahi University conducted another survey in 15 districts. At that time, the Department of Geology and Mining of the University collected water samples from 600 places in the border districts of West Bengal in Bangladesh and sent them to Jadavpur University. Finally, the School of Environment, University of Jadappur, India and NIPSOM, Bangladesh jointly conducted experiments in 17 districts of Bangladesh to find the level of arsenic contamination.

A 2010 report by the Bangdesh government and UNICEF on 54 districts found that 233 upazilas, 2,000 unions and 31,497 villages in 47 districts were affected by arsenic. According to the Asia Arsenic Network Jessore, the number of people infected with arsenic in Jessore district alone is about 3,000. In some villages of the upazilas of Jessore district 60% of the people are affected.

Since arsenic is not a contagious disease, we need to consult a doctor without panic. We need to raise awareness among the people. Steps must be taken to stay free from arsenic at the personal, family, social and village levels. Public and private support needs to be increased. Arsenic enters the human body through drinking water, so it is needed to drink arsenic-free pure water. Steps should be taken to eradicate this disease like tuberculosis, cholera, smallpox etc. People need to be aware and the government needs to make arrangements to provide safe clean water in arsenic affected areas.

Arsenic contamination in groundwater is not a new health problem for mankind. However, the problem is new in Bangladesh and the high level of pollution is an exception. Being a densely populated country, the problem has become more pronounced. As the most conservative, it is seen that about 30 million people in Bangladesh today are in the grip of arsenic disaster. It is difficult to solve this problem and provide alternative safe drinking water for this huge population. Which areas need to be considered on an emergency basis and which areas can be excluded is clear from the arsenic contamination map.

Several alternative methods of arsenic removal are described above, such as domestic filters, community-based arsenic treatment plants, deeper tube wells, surface water use, and rainwater harvesting. No one particular method is applicable for the whole country, but different strategies can be applied for different regions to ensure safe drinking water supply. Despite various measures, arsenic problem remains a major public health problem in Bangladesh. A significant number of people are still at risk of arsenic exposure.

Author is a Columnist & Asst. Officer of Career & Professional Development Services Department  at Southeast University, Dhaka, Bangladesh


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