CAS 75-56-9 · TSCA · United States of America

Propylene oxide (1,2-epoxypropane) under TSCA

C3H6O · 环氧丙烷

Status: Listed. Propylene oxide is on the TSCA Inventory as a grandfathered pre-1979 substance and is currently listed as TSCA Active. **OSHA PEL 100 ppm 8-hr TWA** at 29 CFR 1910.1000 Table Z-1 (verify against https://www.osha.gov/annotated-pels); note: lighter than EO batch 28 1 ppm. **California Proposition 65 listed as carcinogen since 1 July 1988** (verify exact listing date against OEHHA https://oehha.ca.gov/proposition-65/proposition-65-list before invoicing California-distributed product). **TRI Section 313 listed**: Form R annual reporting required. **EPA RMP threshold 10,000 lb** for regulated flammable substance (verify current threshold against 40 CFR 68 Appendix A at https://www.ecfr.gov/current/title-40/part-68). NOT on DEA scheduling. NO active US AD/CVD case on Chinese-origin PO currently (verify against https://access.trade.gov/ before invoicing). Section 301 List 3 25% additional duty applies on Chinese-origin PO (HS 291020). NOT under active TSCA Section 6 risk evaluation (verify against https://www.epa.gov/assessing-and-managing-chemicals-under-tsca).

The US PO lane has **moderate regulatory profile** (lighter than EO batch 28): Cal Prop 65 "WARNING" labelling (since 1988) + EPA RMP 10,000 lb threshold + TRI Form R + OSHA PEL 100 ppm 8-hr TWA. NO active US AD/CVD case. Section 301 List 3 25% additional duty applies. NOT under active TSCA Section 6 risk evaluation. Major US producers: Dow Chemical (Plaquemine Louisiana; styrene monoxide co-process), LyondellBasell (Bayport Texas + Channelview Texas; PO/SM co-process), Indorama Ventures (Port Neches Texas + Conroe Texas; chlorohydrin + cumene hydroperoxide). US is comparatively self-sufficient. **PO distinguishing pattern in US lane**: lighter regulatory stack than EO batch 28 but heavier than xylene batch 21 / ethyl acetate batch 23 (Cal Prop 65 + EPA RMP + TRI all apply).

Listing and threshold

Substance Propylene oxide (1,2-epoxypropane) (CAS 75-56-9), C3H6O
Regime US Toxic Substances Control Act (TSCA), administered by EPA
Jurisdiction United States of America
Status Listed
Tonnage threshold CDR (Chemical Data Reporting) threshold: 25,000 lb (11,340 kg) manufactured or imported per site per year

Classifications under this regime

  • OSHA Hazard Communication Standard (HCS): GHS H224 / H301 / H311 / H315 / H319 / H331 / H335 / H340 / H350
  • OSHA PEL 29 CFR 1910.1000 Table Z-1: 100 ppm 8-hr TWA (per https://www.osha.gov/annotated-pels)
  • NIOSH REL: 2 ppm 8-hr TWA (occupational carcinogen, 0.2 ppm REL preferred; verify against https://www.cdc.gov/niosh/npg/npgd0530.html)
  • NOT subject to TSCA Section 6 Risk Evaluation currently
  • **EPA RMP threshold 10,000 lb**
  • NOT on TSCA Section 5(a)(2) Significant New Use Rule list
  • NOT on DEA List I or List II
  • **California Proposition 65 listed as carcinogen since 1 July 1988** (verify exact listing date against OEHHA https://oehha.ca.gov/proposition-65/proposition-65-list)
  • **TRI Section 313 listed**: Form R annual reporting required
  • DOT hazardous materials regulation (49 CFR 172.101): UN 1280, Class 3, PG I
  • **IARC: Group 2B (possibly carcinogenic to humans)**

Restrictions and conditions of use

  • No TSCA Section 6 use restrictions currently
  • OSHA-compliant SDS and workplace HazCom training required
  • **Cal Prop 65 listing requires "WARNING"** on consumer products containing PO above No-Significant-Risk-Level
  • **EPA RMP threshold 10,000 lb**: Risk Management Plan filing required for above-threshold facilities
  • NO active US AD/CVD case on Chinese-origin PO currently
  • Section 301 List 3 25% additional duty applies on Chinese-origin PO (HS 291020)
  • NFPA 30 Flammable and Combustible Liquids Code applies for storage (Flam. Liq. 1 PG I drives strict requirements)
  • TRI Form R annual reporting

Importer obligations

TSCA is a self-certification regime: importers attest at customs entry that the substance is on the TSCA Inventory. The dominant practitioner-facing layer for PO is **Cal Prop 65 "WARNING" labelling + EPA RMP 10,000 lb threshold + TRI Form R annual reporting**. NO active AD/CVD case. Section 301 List 3 25% additional duty applies. Major US domestic producers: Dow Chemical (Plaquemine Louisiana; styrene monoxide co-process), LyondellBasell (Bayport Texas + Channelview Texas; PO/SM co-process), Indorama Ventures (formerly Huntsman; Port Neches Texas + Conroe Texas; chlorohydrin + cumene hydroperoxide).

Required documents

  • TSCA Section 13 Import Certification statement on customs entry
  • OSHA-compliant SDS reflecting H224 / H301 / H311 / H315 / H319 / H331 / H335 / H340 / H350 classification
  • Customs entry CBP Form 7501 with HS code 291020 (propylene oxide) and Section 301 List 3 25% duty applied
  • **EPA RMP filing** (where site exceeds 10,000 lb threshold)
  • Cal Prop 65 "WARNING" label compliance documentation for consumer-product downstream applications
  • TRI Form R annual report
  • CDR filing every 4 years if site exceeds 25,000 lb/yr threshold
  • NFPA 30-compliant storage tank engineering documentation for bulk receipt

Common compliance traps

The pitfalls that have bitten importers on this lane in the past. None of these is theoretical.

  • **OSHA PEL 100 ppm 8-hr TWA** is moderate (lighter than EO batch 28 1 ppm)
  • **Cal Prop 65 listing applies to all finished-product distribution to California**
  • **EPA RMP threshold 10,000 lb**: Risk Management Plan filing required
  • **TRI Form R annual reporting**
  • Flam. Liq. 1 PG I drives strict NFPA 30 storage requirements
  • NO active US AD/CVD case on Chinese PO currently
  • Section 301 List 3 25% additional duty applies; structurally lighter than caprolactam batch 14 + acetic acid batch 19 lanes
  • Major US domestic producers: Dow Chemical (Plaquemine Louisiana; styrene monoxide co-process), LyondellBasell (Bayport Texas + Channelview Texas; PO/SM co-process), Indorama Ventures (Port Neches Texas + Conroe Texas; chlorohydrin + cumene hydroperoxide)
  • US is comparatively self-sufficient in PO through domestic supply

Where to read next

For substance-level identifiers (formula, molecular weight, SMILES, InChIKey), GHS hazard profile, IMDG transport class, and full sourcing reference for propylene oxide (1,2-epoxypropane), see the CAS 75-56-9 sourcing reference.

For grade-by-grade buying notes, freight maths, supplier-tier pricing, and a worked landed-cost example, the propylene oxide (1,2-epoxypropane) cornerstone hub covers the full sourcing chain.

For the structure and history of TSCA, see the TSCA glossary entry.

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Cross-jurisdiction profile and sourcing references

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