Health effects of 1,1-dichloroethane
1,1-Dichloroethane is a colorless, oily, man-made liquid. It evaporates quickly at room temperature and has an odor like ether. 1,1-Dichloroethane burns easily. When 1,1-dichloroethane is released to the environment, it usually exists as a vapor rather than a liquid. It is used primarily to make 1,1-trichloroethane and a number of other chemicals. It is also used to dissolve such other substances as paint, varnish and finish removers, and to remove grease. 1,1-Dichloroethane was used as a surgical anesthetic, but is no longer.
Almost all of the 1,1-dichloroethane from industrial sources that is released goes into the air. 1,1-Dichloroethane can also be found in the environment as a breakdown product of 1,1,1-trichloroethane in landfills where air comes in contact with 1,1,1-trichloroethane. 1,1-Dichloroethane not dissolve easily in water. The small amounts released to water can evaporate easily into the air. 1,1-Dichloroethane remains as a vapor in the air for about 2 months and dissolved in water for about 5 days. The vapor in air can be washed out by rain or broken down by sunlight. 1,1-Dichloroethane in water will evaporate. Small amounts of 1,1-dichloroethane released to soil can also evaporate into the air or move through the soil to enter groundwater. It is not known how long 1,1-dichloroethane remains in the soil.
Although it does not dissolve easily in water, low levels can be found in water.
Exposure to 1,1-dichloroethane
You can be exposed to 1,1-dichloroethane by breathing air containing its vapors in the outdoor air or in your workplace, or by drinking water contaminated with it. Releases from industrial processes are the main source of this chemical in the air. Some members of the general population may be exposed to low levels of 1,1-dichloroethane from this source (0.08-0.14 parts per billion [1 part 1,1-dichloroethane per 1 billion parts of air, or ppb]).
Levels in this range have been measured around industrial plants in Magna, Utah (0.082 ppb); Iberville, Louisiana (0.12 ppb); Deer Park, Texas (0.14 ppb); and Baton Rouge (0.058 ppb) and Geismary, Louisiana (0.14 ppb). You may be part of a much smaller population of workers who could be exposed to higher levels of 1,1-dichloroethane in your workplace, if you are employed in the chemical, rubber and plastic, electrical, or oil and gas industries. However, since current levels of production and use are not known, it is difficult to predict how often exposure might occur from these sources of 1,1-dichloroethane.
Exposure can also occur near sites where the chemical was improperly disposed of or spilled on the ground. The average concentration of 1,1-dichloroethane in the air across the United States is reported to be 55 parts of 1,1-dichloroethane per one trillion parts of air (ppt). These ambient levels may be from chlorinated water or building materials.
The air levels of 1,1-dichloroethane are usually lower in rural areas and higher in industrialized areas. Higher levels have been found in the air around some small sources of release, such as hazardous waste sites.
1,1-Dichloroethane has been found in drinking water (that is, water that has usually been treated and that comes out of your tap) in the United States at levels that range from trace amounts to 4.8 parts of 1,1-dichloroethane per one billion parts of water (ppb). 1,1-Dichloroethane has not been detected in any surface water samples from rivers, lakes, or ponds. No information is available on background levels of 1,1-dichloroethane in soil or food.
Pathways for 1,1-dichloroethane in the body
1,1-Dichloroethane can enter your body if you breathe contaminated air or drink contaminated water. 1,1-Dichloroethane is believed to rapidly enter your body when it is breathed or swallowed. It is not known what factors affect how quickly 1,1-dichloroethane enters your body. Studies in animals show that it is likely that 1,1-dichloroethane can also enter your body through your skin.
The most common way you could be exposed to 1,1-dichloroethane released from hazardous waste sites would be by breathing contaminated air around the site. Soil and water in and around hazardous waste sites are not likely to contain high concentrations of 1,1-dichloroethane because it escapes quickly into the air. Therefore, though this route of exposure cannot be ruled out, exposure of the skin from soil or water contaminated with 1,1-dichloroethane is much less likely.
Experiments in animals indicate that the 1,1-dichloroethane that is inhaled or swallowed may go to many organs of the body, depending on the amount taken in. However, most of the 1,1-dichloroethane taken in is usually removed unchanged from the body in the breath within 2 days. A small part of the 1,1-dichloroethane taken in is broken down, and these breakdown products are quickly removed in the breath or urine.
Health effects of 1,1-dichloroethane
Reliable information on how 1,1-dichloroethane affects the health of humans is not available. Because brief exposures to 1,1-dichloroethane in the air at very high levels have caused death in animals (16,000 ppm), it is likely that exposure to such high levels of 1,1-dichloroethane in the air can also cause death in humans.
You should know that 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 such health effects 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.
Additionally, there are vigorous national and international efforts to develop alternatives to animal testing. The efforts focus on both in vitro and in silico approaches and methods. For example, theNational Toxicology Program (NTP) at the National Institute of Environmental Health Sciences (NIEHS) created the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) in 1998. The role of NICEATM is to serve the needs of high quality, credible science by facilitating development and validation—and regulatory and public acceptance—of innovative, revised test methods that reduce, refine, and replace the use of animals in testing while strengthening protection of human health, animal health and welfare, and the environment. In Europe, similar efforts at developing alternatives to animal based testing are taking place under the aegis of the European Centre for the Validation of Alternative Methods (ECVAM).
Some studies in animals have shown that 1,1-dichloroethane can cause kidney disease after long-term, high-level exposure in the air. 1,1-Dichloroethane caused cancer in animals given very high doses (over 3,000 mg/kg/day) by mouth for a lifetime. Delayed growth was observed in the offspring of animals who breathed high concentrations of 1,1-dichloroethane during pregnancy.
The severity of these effects may increase when people or animals are exposed to increased levels of 1,1-dichloroethane. Since these effects were seen in animals at high doses, it is also possible that they could occur in humans exposed to high levels of 1,1-dichloroethane. However, we have no information to indicate that these effects do occur in humans.
Harmful levels of exposure to 1,1-dichloroethane
There is no reliable information on what levels of exposure to 1,1-dichloroethane have resulted in harmful health effects in people.
In animals, birth defects were seen in the offspring of rats exposed to high levels (1,750 parts per million [ppm]) in air.
Medical tests for exposure to 1,1-dichloroethane
Tests are available that measure 1,1-dichloroethane in urine, blood, breath and body tissues. Because urine, blood, and breath samples are easily obtained, these samples are examined to determine if a person has been exposed to 1,1-dichloroethane. These tests are not routinely available at a doctor's office and would require special equipment for sampling and detection of the compound. Since most of the 1,1-dichloroethane that is taken into the body leaves within two days, these tests must be done soon after exposure occurs.
Although these tests can confirm that a person has been exposed to 1,1-dichloroethane, it is not yet possible to use the test results to predict the type or severity of any health effects that might occur or the level of exposure that may have occurred. Because exposure to 1,1-dichloroethane at hazardous waste sites is likely to include exposure to other similar chemicals at the same time, levels of 1,1-dichloroethane measured through these types of medical tests may not reflect exposure to 1,1-dichloroethane alone.
- The Agency for Toxic Substances and Disease Registry
- Interagency Coordinating Committee on the Validation of Alternative Methods
- European Centre for the Validation of Alternative Methods
- Institute for Laboratory Animal Research
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