1,2-Dichloroethane


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Introduction

1,2-Dichloroethane is a clear, man-made liquid that is not found naturally in the environment. 1,2-Dichloroethane (also known as 1,2-ethylene dichloride, dichloroethylene, or ethylene dichloride) evaporates at room temperature and has a pleasant smell and a sweet taste. 1,2-Dichloroethane burns with a smoky flame. Its most common use today is to make vinyl chloride and several substances that dissolve grease, glue, and dirt. 1,2-Dichloroethane is also added to leaded gasoline to remove lead. In the past, it was found in trace amounts in products that industry used to clean cloth, remove grease from metal, and to break down oils, fats, waxes, resins, and rubber. 1,2-Dichloroethane was formerly a component of products used in the home such as some cleaning solutions and pesticides; some adhesives, such as those used to glue wallpaper or carpeting; and some paint, varnish, and finish removers. Although large amounts of 1,2-dichloroethane are produced today, the vast majority is used to make other chemical products.

Structural diagram: National Institutes of Health


Fate & Transport

1,2-Dichloroethane can enter the environment when it is made, packaged, shipped, or used. Most 1,2-dichloroethane is released to the air, although some is released to rivers or lakes. 1,2-Dichloroethane could also enter soil, water, or air in large amounts in an accidental spill.

1,2-dichloroethane evaporates into the air very rapidly from soil and water. In the air it breaks down by reacting with other compounds formed by the sun. 1,2-Dichloroethane will stay in the air for 47-182 days. It may also be removed from air in rain or snow. Since it stays in air for a while, the wind may transport it over large distances.

1,2-dichloroethane dissolves in water where it breaks down very slowly, most of it evaporating into the air. Only very small amounts are taken up by plants, fish, and birds. We do not know exactly how long 1,2-dichloroethane stays in water, but we do know that it stays longer in lakes than in rivers.

From soil, 1,2-dichloroethane either evaporates into the air or travels down through the soil and enters underground water. Small living organisms in soil and groundwater may transform it into other primarily less harmful compounds, although this happens slowly. If a large amount of 1,2-dichloroethane enters soil from an accident, hazardous waste site, or landfill, it may travel a long way underground and contaminate drinking water wells.

Exposure Pathways

Humans are exposed to 1,2-dichloroethane mainly by breathing it or by drinking water that contains 1,2-dichloroethane. Human exposure has usually occurred when the chemical has been improperly disposed of, or spilled onto the ground. However, 1,2-dichloroethane has also been found in the air near industries where it is made or used in manufacturing. Humans can be exposed to low levels of 1,2-dichloroethane through the skin or air by contact with old products made with 1,2-dichloroethane, such as cleaning agents, pesticides, and glued wallpaper and carpet. Such exposure is probably not enough to cause harmful health effects.

1,2-Dichloroethane has been found in U.S. drinking water at levels ranging from 0.05 to 19 parts of 1,2-dichloroethane per billion (ppb) parts of water. An average amount of 175 ppb has been found in 12% of the surface water and groundwater samples taken at 2,783 hazardous waste sites. 1,2-Dichloroethane has also been found in the air near urban areas at levels of 0.1-1.5 ppb and near hazardous waste sites at levels of 0.01-0.003 ppb. Humans may also be exposed to 1,2-dichloroethane through its use as a gasoline additive to reduce lead content, but these small levels are not expected to affect human health. As the use of leaded gasoline declines, fewer people will be exposed to 1,2-dichloroethane this way.

Besides these environmental exposures, occupational exposures may occur for workers involved in the manufacture or use of chemicals containing 1,2-dichloroethane. Occupational groups with the largest number of workers exposed to 1,2-dichloroethane include automobile mechanics, registered nurses, heavy equipment mechanics, janitors, and machinists.

Metabolism

1,2-Dichloroethane can enter the body when people breathe air or drink water that contains 1,2-dichloroethane. Studies in animals also show that 1,2-dichloroethane can enter the body through the skin. Humans are most likely to be exposed in and outside the workplace by drinking water containing 1,2-dichloroethane or by breathing 1,2-dichloroethane that has escaped from contaminated water and soil into the air.

Experiments in animals show that 1,2-dichloroethane that is breathed in or eaten goes to many organs of the body but usually leaves in the breath within 1 or 2 days. The breakdown products of 1,2-dichloroethane in the body leave quickly in the urine. Soil near hazardous waste sites probably does not have high amounts of 1,2-dichloroethane because it evaporates quickly into the air. So exposure near a hazardous waste site most likely occurs most often by breathing contaminated air than by touching contaminated soil.

Health Effects

People who were accidently exposed to large amounts of 1,2-dichloroethane in air or who accidently or intentionally swallowed 1,2-dichloroethane often developed nervous system disorders and liver and kidney disease. They often died from heart failure. We do not know what levels of 1,2-dichloroethane caused these effects. Studies in experimental animals also found that breathing or swallowing large amounts of 1,2-dichloroethane produced nervous system disorders and kidney disease. Reduced ability to fight infection was also seen in experimental animals who breathed or swallowed 1,2-dichloroethane, but no evidence of this has been reported in humans. Longer-term exposure to lower doses also caused kidney disease in animals. Evidence from animal studies suggests that 1,2-dichloroethane probably does not produce birth defects or affect reproduction.

Exposure to 1,2-dichloroethane has so far not been associated with cancer in humans. One epidemiological study revealed a relationship between cancer incidence and exposure to environmental pollutants in groundwater, including 1,2-dichloroethane; however, subjects were probably exposed to numerous other chemicals at the same time. Cancer was seen in laboratory animals who were fed large doses of the chemical. When 1,2-dichloroethane was put on the skin of laboratory animals, they developed lung tumors. Breathing 1,2-dichloroethane may also cause cancer in animals. In view of the cancer findings in animals, one cannot rule out the possibility of cancer in humans. The Department of Health and Human Services has determined that 1,2-dichloroethane may reasonably be anticipated to be a carcinogen. The International Agency for Research on Cancer has determined that 1,2-dichloroethane is possibly carcinogenic to humans. EPA has determined that 1,2-dichloroethane is a probable human carcinogen.

Information excerpted from:

Toxicological Profile for 1,2-Dichloroethane May 1994

Agency for Toxic Substances and Disease Registry
U.S. Dept. of Health and Human Services