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Ethylene oxide

CASRN 75-21-8 | DTXSID0020600

  • Toxicological Review (PDF) (228 pp, 1.84 M)
  • IRIS Executive Summary (PDF) (9 pp, 207 K)
  • Background, History, and Other Supporting Documents (including Appendices)

On this page:

  • Key IRIS
    Values
  • Chemical
    Documents
  • Other EPA
    Information

Noncancer Assessment

Reference Dose for Oral Exposure (RfD) (PDF) (9 pp, 207 K) Last Updated:

Not assessed under the IRIS Program.


Reference Concentration for Inhalation Exposure (RfC) (PDF) (9 pp, 207 K)

Not assessed under the IRIS Program.

Cancer Assessment

Weight of Evidence for Cancer (PDF) (9 pp, 207 K) Last Updated: 12/16/2016

WOE Characterization Framework for WOE Characterization
Carcinogenic to humans (Inhalation route) Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005)
Basis:
  • Under the Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005), ethylene oxide is "carcinogenic to humans" by the inhalation route of exposure, based on (1) strong, but less than conclusive on its own, epidemiological evidence of lymphohematopoietic cancers and breast cancer in EtO exposed workers, (2) extensive evidence of carcinogenicity in laboratory animals, including lymphohematopoietic cancers in rats and mice and mammary carcinomas in mice following inhalation exposure, (3) clear evidence that EtO is genotoxic and sufficient weight of evidence to support a mutagenic mode of action for EtO carcinogenicity, and (4) strong evidence that the key precursor events are anticipated to occur in humans and progress to tumors, including evidence of chromosome damage in humans exposed to EtO.
  • This may be a synopsis of the full weight-of-evidence narrative.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure (PDF) (9 pp, 207 K)

Not Assessed under the IRIS Program.


Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure (PDF) (9 pp, 207 K)

Inhalation Unit Risk: 5 x 10-3 per µg/m3
Extrapolation Method: Linear extrapolation. Two-piece linear spline model with knot at 1,600 ppm × days for lymphoid cancer. Two-piece linear spline model with knot at 5,750 ppm × days for breast cancer incidence in females. POD of 1% extra risk was used for both cancer types, includes application of age-dependent adjustment factors (ADAFs).
Tumor site(s): Immune, Reproductive
Tumor type(s): Lymphoid cancer, (female) breast cancer (Steenland et al., 2003, 2004)
Note: EPA has concluded that ethylene oxide is carcinogenic by a mutagenic mode of action. Thus, based on the EPA cancer guidelines (2005), the inhalation unit risk (IUR) addressing lifetime exposure includes application of ADAFs. The IUR is recommended for lifetime exposures. EPA has also provided an adult-based cancer unit risk of 3 x 10-3 per µg/m3. This adult-based cancer unit risk can be used instead of the IUR when assessing cancer risk associated with exposure scenarios that don’t include early life (< 16 years of age) or when other calculations by the user are necessary (e.g., when applying ADAFs to age-specific exposure estimates).

Chemical Documents

Dec 2016: Evaluation of the Inhalation Carcinogenicity of Ethylene Oxide (Final Report) (Report)

Oct 2016: Evaluation of the Inhalation Carcinogenicity of Ethylene Oxide (2016 Interagency Science Discussion Draft) (Report)

Aug 2014: Evaluation of the Inhalation Carcinogenicity of Ethylene Oxide (Revised August 2014 External Review Draft) (SAB Review Draft) (Report)

Jul 2013: Evaluation of the Inhalation Carcinogenicity of Ethylene Oxide (Revised July 2013 External Review Draft) (Public Comment Draft) (Report)

Jul 2011: Evaluation of the Inhalation Carcinogenicity of Ethylene Oxide (2011 Interagency Science Discussion Draft) (Report)

Sep 2006: Evaluation of the Carcinogenicity of Ethylene Oxide (2006 External Review Draft) (Report)

Jun 1985: Health Assessment Document for Ethylene Oxide (Report)

Apr 1984: Health Assessment Document for Ethylene Oxide (External Review Draft) (Report)

Other EPA Information

Additional EPA toxicity information may be available by visiting the following sites:
  • Human Health Benchmarks for Pesticides (HHBP). This database provides human health benchmarks for pesticides that may be present in drinking water.
  • Office of Pesticide Programs Pesticide Chemical Search. This database provides links to health effects information and registration status for pesticides.
  • Chemistry Dashboard. This database provides information on chemical structures, experimental and predicted physicochemical, and toxicity data.

Related Links

  • EPA Chemicals Dashboard - Ethylene oxide
  • eChemPortal - Ethylene oxide

Tumor Sites

Immune
Immune

Reproductive
Reproductive

Chemical Structure

Ethylene oxide

Synonyms

  • AETHYLENOXID (GERMAN)
  • AI3-26263
  • ALPHA,BETA-OXIDOETHANE
  • ANPROLENE
  • Amprolene
  • Anproline
  • Caswell no 443
  • DIHYDROOXIRENE
  • DIMETHYLENE OXIDE
  • E O
  • ENT-26263
  • EPA pesticide chemical code 042301
  • ETO
  • ETYLENU TLENEK (POLISH)
  • Epoxyethane
  • Ethene oxide
  • Ethox
  • Ethylene Oxide
  • Fema no 2433
  • NCI-C50088
  • OXACYCLOPROPANE
  • OXANE
  • OXIDOETHANE
  • OXIRAAN (DUTCH)
  • OXIRAN
  • OXIRANE
  • OXIRENE, DIHYDRO-
  • OXYFUME
  • OXYFUME 12
  • T-GAS
  • USEPA/OPP Pesticide Code: 042301
  • 1,2-EPOXYETHANE
  • 75-21-8
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