Vinyl chloride

Overview

EPA is announcing the release of the final report, Toxicological Review of Vinyl Chloride: in support of the Integrated Risk Information System (IRIS). The updated Summary for Vinyl Chloride and accompanying Quickview have also been added to the IRIS Database.

Background

Common synonyms of vinyl chloride (VC) include chloroethene, chloroethylene, ethylene monochloride, and monochloroethene. VC is a synthetic chemical used as a chemical intermediate in the polymerization of polyvinyl chloride. At room temperature and pressure, it is a colorless gas with a mild, sweet odor. As the data shown above indicate, VC is poorly soluble in water. Structurally, VC is a haloalkene and is related to vinylidene chloride and trichloroethylene. The Draft Toxicological Review was developed to evaluate both the cancer and non cancer human health risks from environmental exposure to vinyl chloride. A reference concentration (RfC), and a reference dose (RfD) were developed based upon induction of liver cell polymorphism in a chronic dietary study utilizing Wistar rats. An RfC of 1E-1 mg/m³ and an RfD of 5E-3 mg/kg-d are recommended. On the basis of sufficient evidence for carcinogenicity in human epidemiology studies vinyl chloride is reaffirmed to be a known human carcinogen. Cancer potencies were derived for oral and inhalation exposure. An oral slope factor of 1.3 per (mg/kg-day) for continuous exposure during adulthood and 2.5 per (mg/kg-day) for continuous lifetime exposure from birth, based upon a chronic dietary study in female Wistar rats is recommended; an inhalation unit risk of 4.3 E-6 per (55g/m³) for continuous exposure during adulthood and 8.7 E-6 per (55g/m³) for continuous lifetime exposure from birth is also recommended, based upon exposure of male and female Sprague Dawley rats and Swiss mice, via inhalation, for a lifetime. A PBPK model was used in the derivation of the RfC, RfD, and cancer potency estimates. Its use is based on the assumption that equal tissue concentrations of reactive metabolite, chlorethylene oxide or chloracetaldehyde, at the critical target site will result in equivalent toxicity between species.

History/Chronology

Date	Description
May 1999	EPA released the draft report for external peer review.
May 2000	EPA released the final tox report and summary document and posted these to the IRIS database.

This document has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

• IRIS Toxicological Review and Summary Documents for Vinyl Chloride (2000 Final) (PDF)  (197  pp, 4.3 MB, about PDF)
• IRIS Summary of Vinyl Chloride (PDF)  (64  pp, 333.0 KB, about PDF)

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Document Related Link(s)

• IRIS Toxicological Review and Summary Documents for Vinyl Chloride (External Review Draft)