Vinyl chloride is a man-made organic compound, formed when other substances such as trichloroethane, trichloroethylene, and tetrachloroethylene are broken down. In its monomer form it is acutely hazardous, thus it is primarily used for the production of polymers. At room temperature it is a flammable, colorless gas with a sweet odor, but it is easily condensed and usually stored as a liquid. It is one ingredient of cigarette.(2)
belongs to the class of organic compounds known as vinyl chlorides. These are vinyl halides in which a chlorine atom is bonded to an sp2-hybridised carbon atom.
Vinyl chloride poisoning exhibits many of the characteristics of autoimmune diseases. This is believed to be the result of a reactive vinyl chloride intermediate metabolite binding to an immunoglobulin, altering the protein and initiating an immune response. The metabolites of vinyl chloride, especially choloroethylene oxide, are mutagenic and act by covalently binding to DNA. This produces cyclic etheno-adducts, which cause base-pair transitions during transcription and DNA crosslinks. Metabolites also may cause oxidative stress and affecting tumor supressor genes, as vinyl chloride has been known to produce specific mutations in the p53 and Ki-ras genes. Vinyl chloride metabolites are also believed to exert toxic effects in the liver by covalently binding to liver proteins, resulting in cellular toxicity. (2, 1)
Metabolism
Vinyl chloride absorbed primarily via inhalation or ingestion is rapidly distributed throughout the body. It is metabolized mainly in the liver by cytochrome P-450 monooxygenases, first into chloroethylene oxide, then into chloroacetaldehyde, which are the main toxic metabolites. Chloroacetaldehyde is further converted into chloroethanol and monochloroacetic acid. Detoxification occurs in conjunction with glutathione, producing mainly thiodiglycolic acid, which is excreted in the urine. At high doses vinyl chloride may also be excreted by exhalation. (2, 5)
Vinyl chloride is used primarily to make polyvinyl chloride (PVC). PVC is used in a variety of plastic products, such as pipes, wire and cable coatings, and packaging materials. Small amounts of vinyl chloride is sometimes used in furniture and automobile upholstery, wall coverings, housewares, and automotive parts. (2)
Exposure to vinyl chloride results in liver damage, nerve damage, and immune reactions, as well as depression of the central nervous system and cardiac arrhythmias. Long term exposure may result in damage to the sperm and testes of males. Vinyl chloride is also a known carcinogen. (2)
Symptoms
Symptoms of acute vinyl chloride exposure include headache, nausea, dizziness, and drowsiness, possibly resulting in loss of conciousness, coma or cardiac arrhythmias at higher levels. Chronic exposure can lead to lung and kidney irritation, inhibition of bloodclotting, numbness and pain in the fingers, memory loss, and sleep disurbances. (2)
Treatment
Vinyl chloride has no tested antidote. Poisoning is usually handled by preventing further exposure and treating the observed symptoms. (2)
