Health effects of 1,1,2,2-Tetrachloroethane
Contents
Introduction
1,1,2,2?Tetrachloroethane (Source:alanwood.net) 1,1,2,2?Tetrachloroethane is a synthetic, colorless, dense liquid that does not burn easily. It is volatile and has a penetrating, sweet odor similar to chloroform. Its production has decreased significantly in the United States. In the past, it was used in large amounts to produce other chemicals and as an industrial solvent. 1,1,2,2?Tetrachloroethane was also used to separate fats and oils from other substances, to clean and degrease metals, and in paints and pesticides. Less toxic chemicals are now available to replace this solvent, and large-scale commercial production has stopped, although some production still occurs. Its present use appears to be as a chemical intermediate, and information about this use is limited. (Health effects of 1,1,2,2-Tetrachloroethane)
Pathways in the enviroment
Most 1,1,2,2?tetrachloroethane released into the environment eventually moves into the air or groundwater. If released on the land, it does not tend to attach to soil particles. When released to surface water, much of the chemical will evaporate back to the air, while the remainder may break down due to reactions with water. Similar reactions can take place in soils and sediments. Most of 1,1,2,2-tetrachloroethane is expected to disappear from groundwater and air in about 1 year. 1,1,2,2?Tetrachloroethane degrades by losing chlorine atoms. The resulting chemicals may also pose a health hazard. It has been estimated that 1,1,2,2?tetrachloroethane should not build up significantly in the bodies of fish or other aquatic organisms.
Exposure
In the past, average levels of 1,1,2,2?tetrachloroethane in air have usually been below 10 parts per trillion (ppt) (10 parts in 1,000,000,000,000 parts). However, average concentrations as high as 57 parts per billion (ppb) (57 parts in 1,000,000,000 parts) have been measured in city air. More recent information on the levels of this substance in air is not available. Current levels are expected to be lower since this substance is no longer used commercially. 1,1,2,2-Tetrachloroethane has been found in surface water and groundwater at many locations across the United States; however, the levels of this chemical are too low to be measured at most of these locations (scientists cannot accurately determine how much is present). The average levels of 1,1,2,2?tetrachloroethane are around 0.6 ppb in water samples at locations where it is measurable. Based on available information, 1,1,2,2?tetrachloroethane is not commonly found in drinking water, soil, or food.
Most people are not expected to be exposed very much to 1,1,2,2?tetrachloroethane since the levels of this chemical are usually very low in the environment and it is no longer used by the general public. Higher levels of 1,1,2,2-tetrachloroethane have been found in groundwater at a few locations in the United States. Individuals who use or drink the groundwater from these locations may have higher exposures to 1,1,2,2-tetrachloroethane. People who live near hazardous waste sites and industrial buildings where 1,1,2,2?tetrachloroethane is used may be exposed to this chemical by breathing in contaminated air, by touching contaminated soil, or by drinking contaminated water.
When a chemical such as 1,1,2,2?tetrachloroethane is used in making other chemicals, it is generally contained in closed automatic systems, which are not open to the air. Therefore, workers are not usually exposed to high levels of 1,1,2,2?tetrachloroethane. A national survey conducted in 1981–1983 estimated that 4,143 workers were exposed to 1,1,2,2?tetrachloroethane. However, the use of this chemical has decreased since 1983, so the number of exposed workers may now be much lower. More recent data are not available.
In addition to exposures in air and drinking water, people may be exposed to 1,1,2,2?tetrachloroethane from spills and other accidents or normal operations in workplaces. The compound has been used as a solvent for many operations. If you are exposed to such spills or involved in such work, you are most likely to be exposed by breathing in vapors of the chemical or from skin contact.
Pathways in the enviroment
1,1,2,2?Tetrachloroethane can enter the body when a person breathes air containing the chemical or when the chemical comes into contact with a person's skin. If you accidentally drank water containing it, 1,1,2,2?tetrachloroethane would be absorbed into your body. 1,1,2,2?Tetrachloroethane is converted to more harmful products in animals and probably in humans. Most of it leaves the body within a few days through the breath or through the urine.
Health effects
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.
1,1,2,2?Tetrachloroethane is not life-threatening unless you intentionally or accidentally drink more than a few spoonfuls at one time or spill a large amount so that you breathe it and get it on your skin. Breathing concentrated fumes of 1,1,2,2?tetrachloroethane (enough so that you notice its sickeningly sweet smell) can rapidly cause fatigue, vomiting, dizziness, and possibly unconsciousness. Most people recover from these effects once they are in fresh air. Breathing, drinking, or having 1,1,2,2?tetrachloroethane come into contact with your skin may cause liver damage, stomachaches, or dizziness if you are exposed long enough to high amounts. The health effects on people from long-term exposure to small amounts of 1,1,2,2?tetrachloroethane are not known.
It is not known whether 1,1,2,2?tetrachloroethane causes cancer in people. In a long-term study, 1,1,2,2?tetrachloroethane caused an increase in liver tumors in mice, but not in rats. The International Agency for Research on Cancer (IARC) has determined that 1,1,2,2?tetrachloroethane cannot be classified as to its ability to cause cancer in humans, while the EPA has determined that the chemical is a possible human carcinogen. Not enough information is available to determine whether exposure to the chemical will cause reproduction problems or birth defects in people.
Effect on children
This section discusses potential health effects in humans from exposures during the period from conception to maturity at 18 years of age.
Children exposed to large amounts of 1,1,2,2?tetrachloroethane probably would be affected in the same manner as adults. It is not known whether the health of children may be more strongly affected than that of adults following exposure to 1,1,2,2?tetrachloroethane. It is possible that children are less strongly affected than adults because the ability of their body to convert 1,1,2,2?tetrachloroethane into more harmful products is immature. No information was located regarding the detection of 1,1,2,2?tetrachloroethane in breast milk or in developing fetuses of mothers exposed to the chemical. However, based on similarities to other chlorinated hydrocarbons such as 1,1,1-trichloroethane, it is expected that 1,1,2,2?tetrachloroethane could be transferred across the placenta from an exposed mother to a developing fetus.
Reducing exposure
If your doctor finds that you have been exposed to substantial amounts of 1,1,2,2?tetrachloroethane, ask whether your children might also have been exposed. Your doctor might need to ask your state health department to investigate.
Families are not likely to be exposed to amounts of 1,1,2,2?tetrachloroethane that are high enough to be a health concern because the chemical is no longer used in household products. It is possible that some old household products (such as cleaners, degreasers, and paints) contain small amounts of 1,1,2,2?tetrachloroethane; these products should be kept out of reach from children.
Medical tests
There are no specific medical tests to determine whether you have been exposed to 1,1,2,2?tetrachloroethane. Urine and blood tests are available, but are common to several other types of chemicals and would not specifically indicate exposure to 1,1,2,2?tetrachloroethane. The symptoms of 1,1,2,2?tetrachloroethane poisoning (stomachaches, fatigue, and dizziness) are common to many diseases, and so these symptoms are not very useful in determining whether you were exposed to this particular chemical. 1,1,2,2?Tetrachloroethane can affect the liver and medical tests can determine whether the liver is working properly. However, liver disease may have many causes; therefore, the presence of liver disease is not a reliable indicator for exposure to 1,1,2,2?tetrachloroethane.
Further Reading
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