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Toxics: Vinyl chloride Disclaimer Vinyl chloride Introduction | Fate and Transport | Exposure Pathways Metabolism | Health Effects Introduction Vinyl chloride is a colorless gas as normal temperatures. It is also known as chloroethene, chloroethylene, ethylene monochloride, or monochloroethylene. It is flammable (easily capable of burning) as a gas and is not stable at high temperatures or pressure. Vinyl chloride will exist in liquid form if it is kept under high pressure. Vinyl chloride has a mild, sweet odor. Most people begin to smell vinyl chloride in the air at 3,000 parts vinyl chloride per million parts (ppm) of air. Most people begin to taste vinyl chloride in water at 3.4 ppm. All vinyl chloride is man-made or results from the breakdown of other manmade substances, such as trichloroethene, trichloroethane, and tetrachloroethene. Production of vinyl chloride in the United States has grown an average of 7 percent from the early 1980s to the early 1990s, with an additional increase of approximately 22 percent between the years of 1992 and 1993. Most of the vinyl chloride produced in the United States is used to make polyvinyl chloride (PVC). PVC is used to make a variety of plastic products including pipes, wire and cable coatings, and packaging materials. Other uses include furniture and automobile upholstery, wall coverings, housewares, and automotive parts. At one time, vinyl chloride was also used as a coolant, as a propellant in spray cans, and in some cosmetics. Since the mid 1970s, it has not been used for these purposes. Fate & Transport Most of the vinyl chloride that enters the environment comes from the plastics industries, which release it into the air or into waste water. EPA limits the amount that industries may release. Vinyl chloride is a breakdown product of other manmade chemicals in the environment. Vinyl chloride has entered the environment at hazardous waste sites as a result of its improper disposal or leakage from storage containers or from spills. Vinyl chloride has been found in tobacco smoke, perhaps as a result of the manufacturing process. Liquid vinyl chloride evaporates easily into the air. Vinyl chloride in water or soil evaporates rapidly if it is near the surface. Vinyl chloride in the air breaks down in a few days. When vinyl chloride breaks down in air, it can form other harmful chemicals. A limited amount of vinyl chloride can dissolve in water. It can enter groundwater and can also be found in groundwater from the breakdown of other chemicals. It is unlikely that vinyl chloride will build up in plants or animals that you might eat. Exposure Pathways Since vinyl chloride commonly exists in a gaseous state, you are most likely to be exposed to it by breathing it in. Vinyl chloride is not normally found in urban, suburban, or rural air in amounts that are detectable by the usual methods of analysis. However, vinyl chloride has been found in the air near plastics industries, hazardous waste sites, and landfills. The amount of vinyl chloride in the air near these places ranges from trace amounts to 0.041 ppm of air, but may exceed 1 ppm. Levels as high as 44 ppm have been found at some landfills. One can also be exposed to vinyl chloride in the air through tobacco smoke from cigarettes or cigars. You may also be exposed to vinyl chloride by drinking water from contaminated wells but how often this occurs is not known. Most drinking water supplies do not contain vinyl chloride. In a 1982 survey, vinyl chloride was found in less than 1 percent of the 945 groundwater supplies tested in the United States. The concentrations found in groundwater were up to 0.008 ppm, with a detection limit of 0.001 ppm. Other studies have reported groundwater vinyl chloride concentrations at or below 0.38 ppm. At one time, the flow of water through PVC pipes added very low amounts of vinyl chloride to water. For example, in one study of newly installed pipes, the drinking water had 0.001 ppm of vinyl chloride. No current information on the amount of vinyl chloride released from PVC pipes into water is available. In the past, vinyl chloride could get into food that was stored in materials that contained PVC. Now the U.S. government regulates the amount of vinyl chloride in food packaging materials. A model of food systems shows that when levels less than 1 ppm of vinyl chloride monomer are used in PVC packaging, "essentially zero" vinyl chloride enters food by contact with these products. Exposure to vinyl chloride can also occur in the workplace by breathing in any vapors in the air or if it comes into contact with your skin or eyes. Almost 80,000 people work with vinyl chloride at their jobs. This number includes workers who make vinyl chloride and PVC and workers who use PVC to make other objects such as pipes. Metabolism If vinyl chloride comes into contact with your skin, negligible amounts may pass through the skin and enter your body. Vinyl chloride is more likely to enter your body when you breathe air or drink water containing it. This could occur near certain factories or hazardous waste sites or in the workplace. Most of the vinyl chloride that you breathe in or swallow enters your blood rapidly. The vinyl chloride in your blood travels through your body. When some portion of it reaches your liver, it is changed into several different substances. Most of these new substances also travel in your blood. Once they reach the kidneys, they leave your body in your urine. Most of the vinyl chloride is gone from your body a day after you breathe it in or swallow it. The liver, however, makes some new substances that do not leave your body as rapidly. A few of these substances are more harmful than vinyl chloride because they react with chemicals inside your body and interfere with the way your body uses or responds to these chemicals. Some of these substances react in the liver and cause damage there. It takes more time for your body to get rid of these changed chemicals, but eventually your body will remove them as well. If you breathe in or swallow more vinyl chloride than your liver can chemically change, you will breathe out excess vinyl chloride. Health Effects If you breathe high levels of vinyl chloride, you will feel dizzy or sleepy. These effects occur within 5 minutes at about 10,000 ppm of vinyl chloride. You can easily smell vinyl chloride at this concentration. If you breathe very high levels, you may pass out. You can rapidly recover from these effects if you breathe fresh air. Some people get a headache when they breathe fresh air immediately after breathing very high levels of vinyl chloride. People may die if they breathe extremely high levels of vinyl chloride. These levels are much higher than the levels that cause you to pass out. Studies in animals show that extremely high levels of vinyl chloride can damage the liver, lungs, and kidneys. These levels can also damage the heart and prevent blood clotting. The effects of drinking high levels of vinyl chloride are unknown. If you spill liquid vinyl chloride on your skin, it will numb the skin and cause redness and blisters. Some people who have breathed vinyl chloride over several years have developed changes in the structure of their livers. People are more likely to develop these changes if they breathe high levels of vinyl chloride. Some people who have worked with vinyl chloride have developed nerve damage, and others have developed an immune reaction. The lowest levels that cause liver changes, nerve damage, and the immune reaction in humans are not known. Certain jobs related to polyvinyl chloride production expose workers to very high levels of vinyl chloride. Some of these workers have problems with the blood flow in their hands. Their fingers turn white and hurt when they go into the cold. It may take a long time to recover when they go into a warm place. In some of these people, changes have appeared on the skin of their hands and forearms. Also, bones at the tips of their fingers have broken down. Studies suggest that some people may be more sensitive to these effects than others. Some men who work with vinyl chloride have complained of a lack of sex drive. Results of studies in animals show that long-term exposure may damage the sperm and testes. Some women who work with vinyl chloride have had irregular menstrual periods. Some have developed high blood pressure during pregnancy. Studies of women who live near vinyl chloride manufacturing plants could not prove that vinyl chloride causes birth defects. Studies using pregnant animals show that breathing vinyl chloride may harm their unborn offspring. Animal studies also show that vinyl chloride may cause increased numbers of miscarriages early in pregnancy. It may also cause decreased weight and delayed skeletal development in fetuses. The same very high levels of vinyl chloride that caused these fetal effects also caused adverse effects in the pregnant animals. Results from several studies suggest that breathing air or drinking water containing low levels of vinyl chloride may increase the risk of getting cancer. Studies of workers who have breathed vinyl chloride over many years showed cancer of the liver. Brain cancer, lung cancer, and some cancers of the blood also may be connected with breathing it daily for several years. Studies of long-term exposure in animals show that increases in cancers of the liver and mammary glands may occur at very low levels of vinyl chloride in the air. Studies show that animals fed low levels of vinyl chloride each day during their lifetime had an increased risk of getting liver cancer. The Department of Health and Human Services has determined that vinyl chloride is a known carcinogen. The International Agency for Research on Cancer has determined that vinyl chloride is carcinogenic to humans, and EPA has determined that vinyl chloride is a human carcinogen. Information excerpted from Toxicological Profile for Vinyl chloride August 1995 Update Agency for Toxic Substances and Disease Registry United States Public Health Service