Vinyl chloride [factsheet]

VINYL CHLORIDE

Please Note: The main sources of information for this fact sheet are the Agency for Toxic Substances and Disease Registry's (ATSDR's) Toxicological Profile for Vinyl Chloride and Case Studies in Environmental Medicine. Vinyl Chloride Toxicity. Other secondary sources include the Hazardous Substances Data Bank (HSDB), a database of summaries of peer-reviewed literature, and the Registry of Toxic Effects of Chemical Substances (RTECS), a database of toxic effects that are not peer reviewed.

Environmental/Occupational Exposure

* Ambient air concentrations of vinyl chloride are generally quite low, with exposure occurring from the discharge of exhaust gases from factories that manufacture or process vinyl chloride, or evaporation from areas where chemical wastes are stored. (1,2)

* Air inside new cars may contain vinyl chloride at higher levels than detected in ambient air because vinyl chloride may outgas into the air from the new plastic parts. (1,2)

* Drinking water may contain vinyl chloride released from seepage into water in areas where chemical wastes are stored or from contact with polyvinyl pipes. (1,2)

* Occupational exposure to vinyl chloride may occur in those workers concerned with the production, use, transport, storage, and disposal of the chemical. (1,2)

* Vinyl chloride is a microbial degradation product of trichloroethylene in groundwater; 100 percent transformation to trichloroethylene was obtained after 10 days under anaerobic conditions. (3)

Assessing Personal Exposure

* Vinyl chloride can be detected in urine and body tissues, but the tests are not reliable indicators of total exposure. (1,2)

Health Hazard Information

Acute Effects:

* Acute (short-term) exposure to high levels of vinyl chloride via inhalation in humans has resulted in effects on the CNS, such as dizziness, headaches, and giddiness. (1,2,4)

* Vinyl chloride is reported to be slightly irritating to the eyes and respiratory tract in humans. (1,2)

* Tests involving acute exposure of animals, such as the LC₅₀ test in mice, have shown vinyl chloride to have high acute toxicity from inhalation exposure. (5)

Chronic Effects (Noncancer):

* Liver damage may result from chronic (long-term) exposure to vinyl chloride in humans, through both inhalation and oral exposure. (1,2,4)

* Individuals occupationally exposed to vinyl chloride through inhalation have developed a set of symptoms termed "vinyl chloride disease," which is characterized by liver damage, effects on the lung, poor circulation in the fingers, changes in the bones at the end of the fingers, thickening of the skin, and changes in the blood. (1,2)

* Animal studies have reported effects on the liver, kidney, and CNS from chronic exposure to vinyl chloride. (1,6,7)

* EPA has not established an RfC or an RfD for vinyl chloride. (8)

Reproductive/Developmental Effects:

* Human studies have suggested an association between men occupationally exposed to vinyl chloride and miscarriages in their wives' pregnancies although other studies have not supported these findings. (1,2)

* Several human studies have reported an association between vinyl chloride exposure in pregnant women and an increased incidence of birth defects, while other studies have not supported these findings. (1,2,4)

* Several case reports suggest that male sexual performance may be affected by vinyl chloride. However, these studies are limited by lack of quantitative exposure information and possible concomitant exposure to other chemicals. (1)

* Animal studies have reported decreased fetal weight and birth defects at levels that are also toxic to maternal animals in the offspring of rats exposed to vinyl chloride through inhalation. (1)

* Testicular damage to rats exposed for up to 12 months has been reported at levels as low as 10 ppm. (8,9)

* It would be prudent to consider vinyl chloride as posing both reproductive and developmental hazards. (1)

Cancer Risk:

* Inhaled vinyl chloride in humans has been shown to increase the risk of a rare form of liver cancer (angiosarcoma of the liver). (1,2,4,6)

* Vinyl chloride exposure, through inhalation, has also been associated with cancer of the brain, lung, and digestive tract in humans. (1,2,4)

* Animal studies have shown that vinyl chloride, via inhalation, increases the incidence of angiosarcoma of the liver and cancer of the liver and brain. (1,2,6)

* Several rat studies show a pronounced early-life susceptibility to the carcinogenic effect of vinyl chloride, i.e., early exposures are associated with higher cancer incidence than much longer exposures that occur after maturity. (10)

* EPA has classified vinyl chloride as a Group A, human carcinogen. (11)

* The cancer potency value for vinyl chloride is under review by EPA. However, EPA has previously calculated an inhalation unit risk of 8.4 H 10^-5 Fg/m³ and an oral unit risk of 5.4 H 10^-5 Fg/L for vinyl chloride. (11)

* EPA's Office of Air Quality Planning and Standards, for a hazard ranking under Section 112(g) of the Clean Air Act Amendments, has ranked vinyl chloride in the nonthreshold category. The 1/ED₁₀ value is 1.6 per (mg/kg)/d and this would place it in the medium category under Superfund's ranking for carcinogenic hazard. ( )

Physical Properties

* Vinyl chloride is a colorless gas with a mild, sweet odor. (1)

* The odor threshold for vinyl chloride is 3,000 ppm. (13)

* Vinyl chloride is slightly soluble in water and is quite flammable. (1)

* The chemical formula for vinyl chloride is C₂H₃Cl and the molecular weight is 62.5 g/mol. (1)

* The vapor pressure for vinyl chloride is 2,660 mm Hg at 25 EC, and it has a log octanol/water partition coefficient of 1.36. (1)

Uses

* Most of the vinyl chloride produced in the United States is used to make polyvinyl chloride, a material used to manufacture a variety of plastic and vinyl products. (1)

* Smaller amounts of vinyl chloride are used as a refrigerant gas and in the manufacture of other chemicals. (1)

Health Data from Inhalation Exposure

Concentration (mg/m³)	Health numbers^a	Regulatory, advisory numbers^b	Reference
1,000,000.0
_ _ _ _ 100,000.0
_ _ _ _ 10,000.0
_ _ _ _ 1,000.0
_ _ _ _ 100.0	* LC₅₀ (rabbits) (588 mg/m³) * LC₅₀ (mice) (299 mg/m³)		4 4
_ _ _ _ 10.0		* ACGIH STEL (25.6 mg/m³) * ACGIH TLV and OSHA (15 min) (12.8 mg/m³)	3 3
_ _ _ _ 1.0		* OSHA (8 h) (2.6 mg/m³)	3

ACGIH STELCAmerican Conference of Governmental and Industrial Hygienists' short-term exposure limit; 15-min time-weighted-average exposure that should not be exceeded at any time during a workday even if the 8-h time-weighted-average is within the threshold limit value.

ACGIH TLVCAmerican Conference of Governmental and Industrial Hygienists' threshold limit value expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effects.

LC₅₀ (Lethal Concentration₅₀)CA calculated concentration of a chemical in air to which exposure for a specific length of time is expected to cause death in 50% of a defined experimental animal population.

OSHACOccupational Safety and Health Administration's limit.

^a Health numbers are toxicological numbers from animal testing or risk assessment values developed by EPA.

^b Regulatory numbers are values that have been incorporated in Government regulations, while advisory numbers are nonregulatory values provided by the Government or other groups as advice.

References

1. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Vinyl Chloride. U.S. Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 1993.

2. Agency for Toxic Substances and Disease Registry (ATSDR). Case Studies in Environmental Medicine. Vinyl Chloride Toxicity. U.S. Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 1990.

3. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Trichloroethylene. U.S. Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 1992.

4. E.J. Calabrese and E.M. Kenyon. Air Toxics and Risk Assessment. Lewis Publishers, Chelsea, MI. 1991.

5. U.S. Department of Health and Human Services. Registry of Toxic Effects of Chemical Substances (RTECS, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.

6. U.S. Department of Health and Human Services. Hazardous Substances Data Bank (HSDB, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.

7. Sokol et al. Experimental studies on the chronic toxic effects of vinyl chloride in rats. J. Hyg. Epidem. Microbiol. Immunol., 24(3):285-294. 1980.

8. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on Vinyl Chloride. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1993.

9. Bi et al. Effect of vinyl chloride on testis in rats. Ecotoxicol. Environ. Safety, 10(3):281-289. 1985.

10. V.J. Cogliano and J.C. Parker. Some implications of toxicology and pharmacokinetics for exposure assessment. J. Expo. An. Environ. Epid. Suppl, 1:187-207. 1992.

11. U.S. Environmental Protection Agency. Health Effects Assessment Summary Tables. Annual Update. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1993.

12. U.S. Environmental Protection Agency. Technical Background Document to Support Rulemaking Pursuant to the Clean Air ActCSection 112(g). Ranking of Pollutants with Respect to Hazard to Human Health. EPAB450/3-92-010. Emissions Standards Division, Office of Air Quality Planning and Standards, Research Triangle Park, NC. 1994.

13. J.E. Amoore and E. Hautala. Odor as an aid to chemical safety: Odor thresholds compared with threshold limit values and volatilities for 214 industrial chemicals in air and water dilution. Journal of Applied Toxicology, 3(6):272-290. 1983.