Toxicity Profiles

RAGs A Format for Vinyl Chloride - CAS Number 83329

Vinyl chloride (VC), also known as chloroethene, is a halogenated aliphatic hydrocarbon. It is a colorless gas with a mild sweetish odor that is slightly soluble in water and soluble in hydrocarbons, oil, alcohol, chlorinated solvents, and most common organic liquids. VC is produced by thermal cracking of ethylene chloride and does not occur naturally. It is used primarily as an intermediate in the manufacture of polyvinyl chloride (PVC); limited quantities are used as a refrigerant and as an intermediate in the production of chlorinated compounds. It is a biodegradation product of trichloroethylene, tetrachloroethylene, and 1,1,1-trichloroethane. VC may leach into groundwater from spills, landfills, and industrial sources.

VC is rapidly absorbed from the digestive tract and lungs. Breathing high levels of VC can cause dizziness or sleepiness. Breathing very high levels can cause passing out, and breathing extremely high levels can cause death. Humans exposed to VC in air for long periods of time can develop changes to the structure of their livers. Workers exposed to VC have developed nerve damage and immune reactions. Other workers have developed problems with the blood flow in their hands: the tips of their fingers turn white and hurt when they are in cold temperatures. Sometimes, the bones in the tips of their fingers have broken down. The effects of drinking high levels of VC are unknown. If VC is spilled on skin, numbness, redness, and blisters may occur. Animal studies have shown that long-term (365 days or longer) exposure to VC can damage the sperm and testes. It has not been proven that VC causes birth defects in humans, but animal studies have shown that breathing VC can harm unborn offspring and may also cause increases in early miscarriages.

Studies show that VC causes liver cancer in humans. On the basis of sufficient evidence for carcinogenicity in human epidemiology studies, VC is considered to best fit the weight-of-evidence Category "A," according to current EPA Risk Assessment Guidelines. Agents classified into this category are considered known human carcinogens. This classification is supported by positive evidence for carcinogenicity in animal bioassays including several species and strains, and strong evidence for genotoxicity.

The following is a presentation of the toxicity information associated with Vinyl Chloride.

• The Oral Chronic Reference Dose is 3.00E-03 (mg/kg-day).
• The Oral Chronic Reference Dose has a modifying factor of 1.
• The Oral Chronic Reference Dose has an uncertainty factor of 30.
• The Oral Chronic Reference Dose is based on the Til et al. study from 1991.
• The Oral Chronic Reference Dose study target organ is liver.
• The Oral Chronic Reference Dose study critical effect is cell polymorphism.
• The overall confidence in the Oral Chronic Reference Dose is medium.

• The Inhalation Chronic Reference Concentration is 1.00E-01 (mg/m³).
• The Inhalation Chronic Reference Concentration has a modifying factor of 1.
• The Inhalation Chronic Reference Concentration has an uncertainty factor of 30.
• The Inhalation Chronic Reference Concentration is based on the Til et al. study from 1991.
• The Inhalation Chronic Reference Concentration study target organ is liver.
• The Inhalation Chronic Reference Concentration study critical effect is cell polymorphism.
• The overall confidence in the Inhalation Chronic Reference Concentration is medium.

• The Dermal Chronic Reference Dose is 3.00E-03 (mg/kg-day).
• The Dermal Chronic Reference Dose is based on a gastrointestinal absorption factor of 1.0000.

• The Oral Slope Factor is 1.40E+00 (mg/kg-day)^-1.
• The Oral Slope Factor study target organ is liver.
• The Oral Slope Factor study cancer type is tumors.
• The Oral Slope Factor is based on the Feron et al. study from 1981.

• The Inhalation Unit Risk is 8.8E-03 (mg/m³)^-1.
• The Inhalation Unit Risk study target organ is liver.
• The Inhalation Unit Risk study cancer type is tumors.
• The Inhalation Unit Risk is based on the Maltoni et al. study from 1984.

• The Dermal Slope Factor is 1.40E+00 (mg/kg-day)^-1.
• The Dermal Slope Factor is based on a gastrointestinal absorption factor of 1.0000.