Chloroethane


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Introduction

Chloroethane, which is also called ethyl chloride, is a colorless gas (vapor) at room temperature and pressure, with a characteristic sharp odor. In containers under pressure chloroethane is a liquid, but the liquid evaporates quickly when exposed to room air. It catches fire easily. The largest single use for chloroethane is to make tetraethyl lead, which is a gasoline additive, but as new stricter government regulations reduce the amount of lead additives allowed in gasoline, the production of chloroethane has decreased dramatically in recent years. Other uses include the production of ethyl cellulose, dyes, medicinal drugs, and other commercial chemicals, and use in the foaming of plastics, as a solvent, and as a refrigerant. It is also used to numb skin before medical procedures such as ear piercing and skin biopsy and to treat sports injuries.

Structural diagram: National Institutes of Health


Fate & Transport

Chloroethane is a man-made compound, and human activity is responsible for almost all the chloroethane released to the environment. Most chloroethane released to the environment ends up as a gas in the atmosphere, but small amounts may enter groundwater as a result of filtration through soil. Once in the atmosphere, chloroethane breaks down fairly quickly by reacting with substances in the air. It takes about 40 days for half of any given amount of chloroethane released to the atmosphere to disappear. In groundwater, chloroethane appears to change eventually to a simpler form, possibly by reacting with water, but not enough is known to be sure this occurs or to determine how long this substance persists in groundwater.

Exposure Pathways

Humans can be exposed to chloroethane from environmental, occupational, and consumer sources. During the mid-to-late 1970s and the early 1980s, chloroethane was found in samples of outdoor air. Air samples collected in city and suburban areas contained an average level of 41 to 140 parts of chloroethane per trillion parts of air (ppt), and rural air samples contained less than 5 ppt. Current atmospheric levels of chloroethane are expected to be even lower than these low levels found in the past because of the sharp decrease in chloroethane production in the United States over the past few years and the decrease in emissions that followed. The presence of chloroethane in air can be linked to release from factories that manufacture or use chloroethane, evaporation from some landfills, solvents, refrigerants, and anesthetics, release in fumes from the burning of plastics and other materials found in trash, and spills from shipping accidents. The limited amount of information available about chloroethane in drinking water suggests that extremely low levels of chloroethane may be expected in some drinking water supplies because of formation during chlorination, contamination of rivers and lakes used as drinking water supplies, or seepage into groundwater following storage of chemical wastes or disposal at waste sites; however, not enough information is available to show what levels of chloroethane occur in drinking water under these circumstances. At this time, chloroethane has been found at at least 40 of 1177 National Priorities List (NPL) hazardous waste sites in the United States. No information is available to show that chloroethane is found in food.

Exposure may also result from contact with various consumer products including some solvents, paints, foamed plastics, and refrigerants. People may be exposed to chloroethane through skin contact when it is used as an agent to numb skin before ear piercing and skin biopsy, to treat sports injuries, and for other medical reasons. Occupational exposure may result from inhaling chloroethane and skin contact with it. Workers who may be exposed to chloroethane include registered nurses, automobile mechanics, physicians, medical workers, athletes, sports trainers, coaches, office machine mechanics and repairmen, household appliance and accessory installers, assemblers, professional painters, heavy equipment mechanics, diesel mechanics, plumbers, and pipe fitters. According to a National Institute for Occupational Safety and Health (NIOSH) survey conducted between 1981 and 1983, an estimated 47,230 workers in the United States were exposed to chloroethane in the workplace.

Metabolism

Chloroethane can enter the body when a person breathes air containing chloroethane vapor. Most chloroethane vapor inhaled this way will be removed quickly by the lungs. Chloroethane may also enter the body through the skin, although most of it quickly leaves the skin surface by evaporation. When a person drinks water containing chloroethane, it enters the body through the digestive tract. It is not known how chloroethane leaves the body, or how quickly, when it enters through the skin or digestive tract.

Chloroethane will most often enter the body by being inhaled if persons near hazardous waste sites are exposed to it, although it may also enter in contaminated drinking water.

Health Effects

Short-term exposure to very high levels of chloroethane vapor can produce temporary feelings of drunkenness, and still higher levels cause lack of muscle coordination and unconsciousness. Accidental death has resulted from its former medical use as an anesthetic during major surgery. It is not known whether chloroethane produces cancer in humans, but long-term exposure to high levels of chloroethane vapor has been shown to produce cancer in some laboratory animals. It is not yet known whether lower levels produce cancer in animals. Chloroethane spray produces a freezing, numbing sensation on the skin and can result in frostbite if the exposure lasts beyond the recommended time.

Information excerpted from:

Toxicological Profile for Chloroethane December 1989

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