Vinyl chloride Quickview (CASRN 75-01-4)

Status of Data for Vinyl chloride

File First On-Line: 08/07/2000; Last Significant Revision: 08/07/2000

Category (section)	Status	Last Revised
Oral RfD Assessment	On-line	08/07/2000
Inhalation RfC Assessment	On-line	08/07/2000
Carcinogenicity Assessment	On-line	08/07/2000

Synonyms

Vinyl chloride Vinyl chloride monomer Chloroethylene Chloroethene

VC VCM 75-01-4

Chronic Health Hazard Assessments for Noncarcinogenic Effects

Reference Dose for Chronic Oral Exposure (RfD)

Critical Effect	Point of Departure*	UF	RfD
Liver cell polymorphism	NOAEL (HED): 9 x10-2 mg/kg-day	30	3 x10-3 mg/kg-day

* The Point of Departure listed serves as a basis from which the Oral RfD was derived. See Discussion of Conversion Factors and Assumptions for more details.

• Principal and Supporting Studies (Oral RfD)
  • Rat chronic feeding study, Til et al., 1983, 1991
• Confidence in the Oral RfD
  • Study -- High
  • Database -- Medium/High
  • RfD -- Medium

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Reference Concentration for Chronic Inhalation Exposure (RfC)

Critical Effect	Point of Departure*	UF	RfC
Liver cell polymorphism	NOAEL (HEC): 2.5 mg/m3	30	1x10-1 mg/m3

* The Point of Departure listed serves as a basis from which the Inhalation RfC was derived. See Discussion of Conversion Factors and Assumptions for more details.

• Principal and Supporting Studies (Inhalation RfC)
  • Rat chronic feeding study, Til et al., 1983, 1991
• Confidence in the Inhalation RfC
  • Study -- High
  • Database -- Medium/High
  • RfC -- Medium

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Carcinogenicity Assessment for Lifetime Exposure

• Weight-of-Evidence Characterization
  • A (Human carcinogen)
  • Known/likely human carcinogen
• Weight-of-Evidence Narrative:
  • 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 (U.S. EPA, 1986). Under the Proposed Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1996), it is concluded that VC is a known human carcinogen by the inhalation route of exposure, based on human epidemiological data, and by analogy the oral route because of positive animal bioassay data as well as pharmacokinetic data allowing dose extrapolation across routes. VC is also considered highly likely to be carcinogenic by the dermal route because it is well absorbed and acts systemically.
  • This may be a synopsis of the full weight-of-evidence narrative. See IRIS Summary.

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Quantitative Estimate of Carcinogenic Risk from Oral Exposure

Oral Slope Factor(s)	Extrapolation Method
7.2 x10-1 per mg/kg-day 1 (Continuous lifetime exposure during adulthood)	LMS method
1.5 per mg/kg-day 1 (Continuous lifetime exposure from birth)	LED 10/ linear method

¹ This represents the lowest/highest of multiple discrete oral slope factors for this substance. See IRIS Summary.

Drinking Water Unit Risks
2.1 x10-5 per µg/L 2 (Continuous lifetime exposure during adulthood)
4.2 x10-5 per µg/L 2 (Continuous lifetime exposure from birth)

² This represents the lowest/highest of drinking water unit risks for this substance. See IRIS Summary.

Risk Level	Concentration
E-4 (1 in 10,000)	2.4 µg/L(Continuous lifetime exposure from birth)
E-5 (1 in 100,000)	2.4x10-1 µg/L(Continuous lifetime exposure from birth)
E-6 (1 in 1,000,000)	2.4x10-2 µg/L(Continuous lifetime exposure from birth)
E-4 (1 in 10,000)	4.8 µg/L(Continuous lifetime exposure during adulthood)
E-5 (1 in 100,000)	4.8x10-1 µg/L(Continuous lifetime exposure during adulthood)
E-6 (1 in 1,000,000)	4.8x10-2 µg/L(Continuous lifetime exposure during adulthood)

• Dose-Response Data (Carcinogenicity, Oral Exposure)
  • Tumor Type: Total of liver angiosarcoma, hepatocellular carcinoma, and neoplastic nodules
  • Test Species: Female Wistar rats
  • Route: Oral, Diet
  • Reference: Feron et al., 1981

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Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

Inhalation Unit Risk(s)	Extrapolation Method
4.4 x10-6 per µg/m3 4 (Continuous lifetime exposure during adulthood)	LMS method
4.4 x10-6 per µg/m3 (Continuous lifetime exposure during adulthood)	LED 10/ linear method
8.8 x10-6 per µg/m3 (Continuous lifetime exposure from birth)	LMS method
8.8 x10-6 per µg/m3 4 (Continuous lifetime exposure from birth)	LED 10/ linear method

⁴ This represents the lowest/highest of multiple discrete inhalation unit risks for this substance. See IRIS Summary.

Inhalation Concentrations at Specified Risk Levels

Risk Level	Concentration
E-4 (1 in 10,000)	2.3x101 µg/m3(Continuous lifetime exposure during adulthood)
E-5 (1 in 100,000)	2.3 µg/m3(Continuous lifetime exposure during adulthood)
E-6 (1 in 1,000,000)	2.3x10-1 µg/m3(Continuous lifetime exposure during adulthood)

• Dose-Response Data (Carcinogenicity, Inhalation Exposure)
  • Tumor Type: Liver angiosarcomas, angiomas, hepatomas, and neoplastic nodules
  • Test Species: Female Sprague-Dawley rats
  • Route: Inhalation
  • Reference: Maltoni et al. (1981, 1984)