Arsenic pollution: An overview
Water is another name of life. Today, this 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. Arsenic is a toxic mineral element. It has no taste or smell. The chemical signal of arsenic is "As".
Arsenic is used to make semiconductor 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. Nature's arsenic is not harmful to public health in most cases. However, in recent times, human activities have increased the concentration of arsenic in environment and air. Soil and water in different parts of the world have become contaminated with arsenic, causing a variety of serious health threats.
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 the substance 'arsenopyrite' is being mixed with water due to extraction of excess water from the ground. Billions of liters of water we pump out for daily use, starting with agriculture create a temporary vacuum in the groundwater and mixes arsenic with air and oxygen mixed water.
Arsenic pollution is a global problem. High levels of arsenic have been detected in groundwater in about 50 countries of all continents. Bangladesh is considered to be the most polluted country in terms of arsenic contamination. 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 water. If one drinks highly arsenic contaminated 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. Sometimes, with the reaction of arsenic, skin of the feet gets thicken. The level of arsenic contamination has increased drastically. In our country the presence of arsenic was first discovered in 1993 in the groundwater of Baragharia Union of Chapainawabganj district.
The 'Bangladesh Arsenic Mitigation Water Supply Project' (BAMWSP) was launched with the responsibility of data collection, analysis, storage and pollution mitigation strategies on arsenic. 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. Testing 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 across 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 which shows 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 pollution.
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 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 or canals 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.
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 diseases 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.
The writer is a columnist & asst officer, Career & Professional Development Services Department, Southeast University