CAS 75-21-8 · TSCA · United States of America

Ethylene oxide (oxirane) under TSCA

C2H4O · 环氧乙烷

Status: Restricted. Ethylene oxide is on the TSCA Inventory and carries among the heaviest ongoing US regulatory activity of any dataset substance. **EPA TSCA Section 6 Final Risk Evaluation (2020)** found unreasonable risk to human health for multiple conditions of use (verify the published date and findings against https://www.epa.gov/assessing-and-managing-chemicals-under-tsca; some references cite 2020 publication, some 2021). **EPA TSCA Section 6(a) Risk Management Rule** for ethylene oxide is in late-stage rulemaking (verify the current Subpart citation, finalisation status, and effective date against https://www.epa.gov/assessing-and-managing-chemicals-under-tsca and https://www.federalregister.gov/ before relying; some prior dataset references cited 40 CFR Part 751 Subpart D FINALISED 2024). **EPA NESHAP** for hospital plus commercial ethylene oxide sterilizers issued 2024 dramatically tightened EO emission limits for medical-device sterilisation (verify the applicable Subpart letter at https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-63 before relying on a specific subpart citation). **Active OSHA Ethylene Oxide Standard 29 CFR 1910.1047** (specific carcinogen standard with PEL 1 ppm 8-hr TWA, STEL 5 ppm, Action Level 0.5 ppm; verify against https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1047). **California Proposition 65 listed as carcinogen since 1 July 1987 plus as developmental and female plus male reproductive toxicant on subsequent dates** (verify the exact listing dates for each toxicology endpoint against OEHHA https://oehha.ca.gov/proposition-65/proposition-65-list before invoicing California-distributed product). **TRI Section 313 listed**. **EPA RMP threshold 10,000 lb** (verify current threshold against 40 CFR 68 Appendix A at https://www.ecfr.gov/current/title-40/part-68). NO active US AD/CVD case on Chinese-origin EO currently (verify against https://access.trade.gov/ before invoicing). Section 301 List 3 25% additional duty applies on Chinese-origin EO (HS 291010).

The US EO lane carries the **heaviest ongoing regulatory activity of any dataset substance**: TSCA Section 6 Risk Management Rule (40 CFR Part 751 Subpart D) FINALISED 2024 + EPA NESHAP Hospital Ethylene Oxide Sterilizers Rule (2023) + EPA NESHAP Commercial Ethylene Oxide Sterilizers Rule (2024) + OSHA EO-specific 29 CFR 1910.1047 PEL + Cal Prop 65 + EPA RMP 10,000 lb threshold + TRI Form R. EPA 2014 IRIS update found EO ~30x more carcinogenic than previously thought; this drove cascade of regulatory tightening 2021-2024. **EO is structurally NOT internationally traded as bulk**; intra-complex captive consumption dominates. NO active US AD/CVD case. Section 301 List 3 25% additional duty applies. Major US producers: Dow Chemical, Shell Chemicals, LyondellBasell, MEGlobal, Indorama Ventures, Saudi Aramco / Motiva. End-use: MEG batch 8 chain ~75%, surfactants + ethoxylates ~10%, polyether polyols ~5%, ethanolamines ~5%. **EO distinguishing pattern in US lane**: most-regulated substance in dataset by ongoing regulatory activity; medical-device sterilisation cascade (Hospital + Commercial Sterilizer NESHAP Rules) is industry-defining compliance retrofit 2024-2027.