Tungsten Demystified

What is tungsten? Tungsten occurs naturally in the environment, in minerals, but not as the pure metal. As an element, tungsten can be neither created nor destroyed chemically, although tungsten can change forms in the environment. What happens to tungsten when it enters the environment? Tungsten is released into air as fine dust-like particles by weathering. Emissions from hard metal industries also increase tungsten levels in air. The amount of tungsten that has been measured in the ambient air is, in general, less than 10 billionths of a gram per cubic meter (or parts per billion ). Very small dust particles of tungsten in the air fall out onto surface water, plant surfaces, and soil either by themselves or when rain or snow falls. These tungsten particles eventually recycle back in the soil or in the bottoms of lakes, rivers, and ponds, where they stay and mix with tungsten that is already there. Tungsten in water originates mainly from dissolution of tungsten from rocks and soil that water runs over and through. Tungsten has not been detected in the vast majority of surface water and groundwaters of the United States. Some exceptions include areas near mines and natural deposits, and also in Churchill County (City of Fallon), in Nevada, where tungsten has been detected in municipal water and groundwater. Only a very small fraction of tungsten in water originates from the settling of dust out of the air. Most tungsten products of human-origin that enter waterways originate from industry discharges of waste water. Tungsten in water may be in either soluble or insoluble forms. Insoluble tungsten in water can settle to the bottom where it enters sediment. Some insoluble tungsten compounds, however, can remain suspended in ocean water for many years, requiring as long as 1,000 years to settle to the bottom. Tungsten occurs naturally in soil as a mineral, or component of soil. It occurs in amounts that vary over a wide range from less than 1 to as high as 83 thousandths of a gram per kilogram of soil. Another way to say this is that the tungsten concentration ranges from 1 to 83 parts per million (ppm) in soil by weight. Disposal of coal ash, incinerator ash, and industrial wastes may increase the amount of tungsten in soil. A portion of tungsten in soil does not dissolve in water, but remains bound and is not likely to move deeper into the ground and enter groundwater. The remaining soluble portion may move deeper into the ground and enter groundwater if the pH is greater than 7. In the environment, chemical reactions can change the water-soluble tungsten compounds into insoluble forms. In some cases, water-insoluble tungsten compounds can change to soluble forms. In general, exposure to water-soluble tungsten compounds in the environment will pose a greater threat to human health than water-insoluble forms. How can tungsten affect my health? 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. You are not likely to experience any health effects that would be related to exposure to tungsten or tungsten compounds. Tungsten compounds have caused breathing problems and changed behavior in some animals given very large amounts of tungsten compounds, but you are not likely to be exposed to amounts of tungsten in the air you breathe or the food or water you take into your body that would be large enough to cause similar effects. If you are a worker who has inhaled tungsten heavy metal dust, your exposure would help determine if health effects similar to those seen in animals might occur. How can tungsten enter and leave my body? Tungsten can enter your body from the food you eat or the water you drink, from the air you breathe, or from contact with the skin. When you eat, drink, breathe, or touch things containing tungsten compounds that can easily be dissolved in water, tungsten enters your blood and is carried to all parts of your body. Most of the tungsten that enters your blood is rapidly released from your body in the urine. When you eat or drink things containing tungsten, much of the tungsten passes through your digestive system and is released from your body in the feces. When you breathe air that contains tungsten, some of the tungsten moves quickly to your bloodstream from the lungs, and some of the tungsten is cleared from your lungs in mucus that is either swallowed or spit out. When you swallow tungsten that was first in your lungs, it passes through your digestive system as if you had eaten it. Some enters your blood from your digestive system and some passes out with the feces. A small portion of the tungsten that enters your blood may spend some time in bone, fingernails, or hair. Some of this tungsten is slowly eliminated from your body through the urine and feces. How can tungsten affect children? (This section discusses potential health effects in humans from exposures during the period from conception to maturity at 18 years of age.) Children could be affected in the same ways as adults. In adult animals, very large amounts of tungsten compounds have been shown to cause breathing problems and changes in behavior. However, it is not likely that children would be exposed to amounts of tungsten in the air they breathe or the food or water they consume that would be large enough to cause effects similar to those that were seen in the animals. Animal studies have shown that tungsten in the blood of a pregnant mother can enter the blood of a fetus in the womb. Studies in dairy cows have shown that tungsten may also enter the milk. There is no information to suggest that the effects seen in animals could not occur in humans. We do not know whether unborn babies, babies, and children might differ from adults in their susceptibility to health effects from exposure to tungsten or tungsten compounds. Article Sourced From: Toxicological Profile For Tungsten US Department of Health and Human Services, Public Health Service Agency for Toxic Substances and Disease Registry

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