Arsenic poses a serious threat to the health of the drought-affected people as tube-well waters in the region, particularly in seven upazilas of Rajshahi and Chapainawabganj districts have become vulnerable to arsenic contamination, reports BSS. The people of Godagari and Tanore upazilas of Rajshahi and Volahat upazila of Chapainwabganj are the worst sufferers. However, arsenicosis could be prevented coupled with reducing its fatal consequences if the patients are ensured with safe drinking water and proper healthcare management at preliminary stage. The observation came at a symposium styled ‘Health Effects of Chronic Exposure to Arsenic’ at Deans Conference hall of Faculty of Science in Rajshahi University (RU) here on Thursday. The Department of Molecular Nutrition and Toxicology of University of Burney in Japan and Department of Biochemistry and Microbiology of RU jointly organised the symposium to mark the 10th anniversary of their joint research on the issue (The Independent, February 3, 2017).
Arsenicosis:About 30 million people are being exposed to arsenic contaminated water. Patients are graduallyincreasing and recent knowledge of health threats posed by arsenic indicates that it gives rise to cancer, diabetesmellitus and cardiovascular disease. At present, Directorate General of Health Services (DGHS) is conducting awareness programs, training of healthcare service providers and patient screening programs. Directorate of Public Health Engineering (DPHE) conducts water screening for arsenic. Thecollaboration between DGHS and DPHE at field level may help make their interventions more effective.DGHS, in the next sector program, will run training programs, arsenicosis mitigation programs and help DPHEto strengthen water screening at the community level.
Arsenic is a naturally occurring substance that can be found in air, water, and soil. It can also be released into the environment by certain agricultural and industrial processes, such as mining and metal smelting. Arsenic comes in two forms (organic and inorganic); the inorganic form is more toxic than the organic form.Inorganic arsenic is naturally present at high levels in the groundwater of certain countries, including Bangladesh. Arsenic is a naturally occurring element that is widely distributed in the Earth’s crust. Arsenic is classified chemically as a metalloid, having both properties of a metal and a nonmetal; however, it is frequently referred to as a metal. Elemental arsenic (sometimes referred to as metallic arsenic) is a steel grey solid material. However, arsenic is usually found in the environment combined with other elements such as oxygen, chlorine, and sulfur. Arsenic combined with these elements is called inorganic arsenic. Arsenic combined with carbon and hydrogen is referred to as organic arsenic.
Most inorganic and organic arsenic compounds are white or colorless powders that do not evaporate. They have no smell, and most have no special taste. Thus, you usually cannot tell if arsenic is present in your food, water, or air.Inorganic arsenic occurs naturally in soil and in many kinds of rock, especially in minerals and ores that contain copper or lead. When these ores are heated in smelters, most of the arsenic goes up the stack and enters the air as a fine dust. Smelters may collect this dust and take out the arsenic as a compound called arsenic trioxide (As2O3). However, arsenic is no longer produced in Bangladesh; all of the arsenic used in Bangladesh is imported.
Prolonged ingestion of arsenic-containing drinking water is associated with an increased risk of bladder cancer. In addition, cancers of the skin, lung, digestive tract, liver, kidney, and lymphatic and hematopoietic systems have been linked to arsenic exposure.
Access to a safe water supply for drinking, food preparation, and irrigation of food crops is the most important way to prevent exposures to arsenic.Arsenic cannot be destroyed in the environment. It can only change its form, or become attached to or separated from particles. It may change its form by reacting with oxygen or other molecules present in air, water, or soil, or by the action of bacteria that live in soil or sediment. Arsenic released from power plants and other combustion processes is usually attached to very small particles. Arsenic contained in wind-borne soil is generally found in larger particles. These particles settle to the ground or are washed out of the air by rain. Arsenic that is attached to very small particles may stay in the air for many days and travel long distances. Many common arsenic compounds can dissolve in water. Thus, arsenic can get into lakes, rivers, or underground water by dissolving in rain or snow or through the discharge of industrial wastes. Some of the arsenic will stick to particles in the water or sediment on the bottom of lakes or rivers, and some will be carried along by the water. Ultimately, most arsenic ends up in the soil or sediment. Although some fish and shellfish take in arsenic, which may build up in tissues, most of this arsenic is in an organic form called arsenobetaine (commonly called "fish arsenic") that is much less harmful.
Since arsenic is found naturally in the environment, we will be exposed to some arsenic by eating food, drinking water, or breathing air. Children may also be exposed to arsenic by eating soil. Analytical methods used by scientists to determine the levels of arsenic in the environment generally do not determine the specific form of arsenic present. Therefore, we do not always know the form of arsenic a person may be exposed to. Similarly, we often do not know what forms of arsenic are present at hazardous waste sites. Some forms of arsenic may be so tightly attached to particles or embedded in minerals that they are not taken up by plants and animals.
We normally take in small amounts of arsenic in the air you breathe, the water we drink, and the food we eat. Of these, food is usually the largest source of arsenic. The predominant dietary source of arsenic is seafood, followed by rice/rice cereal, mushrooms, and poultry. While seafood contains the greatest amounts of arsenic, for fish and shellfish, this is mostly in an organic form of arsenic called arsenobetaine that is much less harmful. Some seaweed may contain arsenic in inorganic forms that may be more harmful. Children are likely to eat small amounts of dust or soil each day, so this is another way they may be exposed to arsenic. The total amount of arsenic we take in from these sources is generally about 50 micrograms (1 microgram equals one-millionth of a gram) each day. The level of inorganic arsenic (the form of most concern) we take in from these sources is generally about 3.5 microgram/day.
If we swallow arsenic in water, soil, or food, most of the arsenic may quickly enter into our body. The amount that enters our body will depend on how much we swallow and the kind of arsenic that we swallow. This is the most likely way for us to be exposed near a waste site. If we breathe air that contains arsenic dusts, many of the dust particles settle onto the lining of the lungs. Most of the arsenic in these particles is then taken up from the lungs into the body. We might be exposed in this way near waste sites where arsenic-contaminated soils are allowed to blow into the air, or if we work with arsenic-containing soil or products. If we get arsenic-contaminated soil or water on our skin, only a small amount will go through our skin into our body, so this is usually not of concern.
Both inorganic and organic forms leave your body in your urine. Most of the inorganic arsenic will be gone within several days, although some will remain in our body for several months or even longer. If we are exposed to organic arsenic, most of it will leave our body within several days.
Scientists use many tests to protect the public from harmful effects of toxic chemicals and to find ways for treating persons who have been harmed.
One way to learn whether a chemical will harm people is to determine how the body absorbs, uses, and releases the chemical. For some chemicals, animal testing may be necessary. Animal testing may also help identify health effects such as cancer or birth defects. Without laboratory animals, scientists would lose a basic method for getting information needed to make wise decisions that protect public health. Scientists have the responsibility to treat research animals with care and compassion. Scientists must comply with strict animal care guidelines because laws today protect the welfare of research animals.
Perhaps the single-most characteristic effect of long-term oral exposure to inorganic arsenic is a pattern of skin changes. These include patches of darkened skin and the appearance of small "corns" or "warts" on the palms, soles, and torso, and are often associated with changes in the blood vessels of the skin. Skin cancer may also develop. Swallowing arsenic has also been reported to increase the risk of cancer in the liver, bladder, and lungs
Almost no information is available on the effects of organic arsenic compounds in humans. Studies in animals show that most simple organic arsenic compounds (such as methyl and dimethyl compounds) are less toxic than the inorganic forms. In animals, ingestion of methyl compounds can result in diarrhea, and lifetime exposure can damage the kidneys. Lifetime exposure to dimethyl compounds can damage the urinary bladder and the kidneys.
Children who are exposed to inorganic arsenic may have many of the same effects as adults, including irritation of the stomach and intestines, blood vessel damage, skin changes, and reduced nerve function. Thus, all health effects observed in adults are of potential concern in children. There is also some evidence that suggests that long-term exposure to inorganic arsenic in children may result in lower IQ scores. We do not know if absorption of inorganic arsenic from the gut in children differs from adults.
There is some evidence that exposure to arsenic in early life (including gestation and early childhood) may increase mortality in young adults. There is some evidence that inhaled or ingested inorganic arsenic can injure pregnant women or their unborn babies, although the studies are not definitive. Studies in animals show those large doses of inorganic arsenic that cause illness in pregnant females can also cause low birth weight, fetal malformations, and even fetal death. Arsenic can cross the placenta and has been found in fetal tissues. Arsenic is found at low levels in breast milk. Regulations and recommendations can be expressed as “not-to-exceed” levels, that is, levels of a toxic substance in air, water, soil, or food that do not exceed a critical value that is usually based on levels that affect animals; they are then adjusted to levels that will help protect humans.
Sometimes these not-to-exceed levels differ. Recommendations and regulations should be updated periodically as more information becomes available.
The writer is former Head, Department of Medical Sociology
Institute of Epidemiology, Disease Control & Research (IEDCR)
Dhaka, Bangladesh
E-mail: [email protected]