Ethylene oxide is primarily produced in Texas and Louisiana with sites in Texas accounting for nearly half of all emitted ethylene oxide in the United States. Because ethylene oxide is emitted in Texas and has been determined by other agencies to be a carcinogen, the Texas Commission on Environmental Quality (TCEQ) undertook a carcinogenic dose-response assessment for use in TCEQ's remediation and air permitting programs. The TCEQ assessed the carcinogenic hazards of ethylene oxide and derived a chronic inhalation unit risk factor (URF) in its 2020 Ethylene Oxide Carcinogenic Dose-Response Assessment Development Support Document (TCEQ DSD).

As requested by TCEQ, the National Academies of Sciences, Engineering, and Medicine assembled an ad hoc committee to review the methods, results, and conclusions of the TCEQ DSD. The committee considered whether the conclusions are clearly presented, scientifically supported, and based on the best available scientific information. The report finds that the lack of application of systematic review methods, the exclusion of critical epidemiological data, the limitations in the modeling approach and use of unpublished validation data all contribute to a lack of confidence in TCEQ's risk assessment of ethylene oxide.

Contents

• The National Academies of SCIENCES • ENGINEERING • MEDICINE
• COMMITTEE TO REVIEW TEXAS COMMISSION ON ENVIRONMENTAL QUALITY'S ETHYLENE OXIDE DEVELOPMENT SUPPORT DOCUMENT
• BOARD ON ENVIRONMENTAL STUDIES AND TOXICOLOGY
• Reviewers
• Acknowledgments
• Acronyms and Abbreviations
• Summary
  • THE COMMITTEE'S TASK AND APPROACH
  • SUMMARY OF THE COMMITTEE'S FINDINGS AND RECOMMENDATIONS
  • NEXT STEPS
• 1. Introduction
  • ETHYLENE OXIDE
  • PRIOR CANCER ASSESSMENTS
  • DEVELOPMENT OF TOXICITY VALUES
  • THE COMMITTEE'S TASK
  • THE COMMITTEE'S APPROACH TO THE TASK
  • ORGANIZATION OF THE REPORT
• 2. Hazard Identification
  • PREVIOUS CANCER ASSESSMENTS
  • SYSTEMATIC REVIEW PROCESS AND CONSIDERATIONS
  • EPIDEMIOLOGICAL EVIDENCE FOR BREAST CANCER
  • EXPERIMENTAL ANIMAL DATA TO INFORM HAZARD ASSESSMENT
  • MOA CONSIDERATIONS
  • FINDINGS AND RECOMMENDATIONS
• 3. Dose-Response
  • CONSIDERATION OF MORTALITY AND INCIDENCE DATA
  • TCEQ'S DOSE-RESPONSE ASSESSMENT FOR LYMPHOID CANCERS
  • NIOSH
  • UCC
  • AGE-DEPENDENT ADJUSTMENT FACTORS
  • INFLUENCE OF MOA ON MODEL SELECTION
  • DOSE-RESPONSE MODEL SELECTION
  • TCEQ'S SYSTEMATIC REVIEW FOR DOSE-RESPONSE
  • OTHER CONSIDERATIONS: ENDOGENOUS ETHYLENE OXIDE
  • FINDINGS AND RECOMMENDATIONS
• References
• Appendix A. Committee Biographies
• Appendix B. Public Meeting Agenda

Suggested citation:

National Academies of Sciences, Engineering, and Medicine. 2025. Review of Texas Commission on Environmental Quality's Ethylene Oxide Development Support Document. Washington, DC: National Academies Press. https://doi.org/10.17226/28592.

Digital Object Identifier: https://doi.org/10.17226/28592

This publication is available from the National Academies Press, 500 Fifth Street, NW, Keck 360, Washington, DC 20001; (800) 624-6242; https://nap.nationalacademies.org.

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