CAS 78-93-3 · TSCA · United States of America

Methyl ethyl ketone (MEK, butan-2-one) under TSCA

C4H8O · 丁酮 / 甲乙酮

Status: Listed. MEK is on the TSCA Inventory as a grandfathered pre-1979 substance and is currently listed as TSCA Active. **OSHA PEL 200 ppm 8-hr TWA** at 29 CFR 1910.1000 Table Z-1 (verify against https://www.osha.gov/annotated-pels). NOT on EPA RMP threshold list. **DEA List II controlled chemical** under 21 CFR 1310 plus CMEA 2005 (Combat Methamphetamine Epidemic Act) retail restrictions; methamphetamine precursor concern (verify the current 21 CFR 1310.02 substance list at https://www.ecfr.gov/current/title-21/chapter-II/part-1310/section-1310.02 before relying). NOT on California Proposition 65 (verify against OEHHA https://oehha.ca.gov/proposition-65/proposition-65-list before relying on negative listing). **TRI Section 313**: MEK was DELISTED from TRI in 2005 (verify current TRI listing status against https://www.epa.gov/toxics-release-inventory-tri-program before relying). NO active US AD/CVD case on Chinese-origin MEK currently (verify against https://access.trade.gov/ before invoicing). Section 301 List 3 25% additional duty applies on Chinese-origin MEK (HS 291412). Major US domestic producers (verify each company-site pair against the producer's public website before relying): ExxonMobil Baton Rouge Louisiana, Sasol Lake Charles Louisiana, Shell Chemicals Deer Park Texas.

The US MEK lane is dominated by **DEA List II CMEA 2005 retail restrictions plus OSHA PEL 200 ppm plus Section 301 List 3 25% additional duty**. NOT on Cal Prop 65. TRI delisted 2005. NO active US AD/CVD case. Major US producers: ExxonMobil Baton Rouge Louisiana, Sasol Lake Charles Louisiana, Shell Chemicals Deer Park Texas. US is comparatively self-sufficient. **MEK distinguishing pattern in US lane**: DEA List II CMEA-precursor scheduling parallel to acetone batch 15 pattern, TRI-delisted (lighter than benzene batch 22 or formaldehyde batch 18) plus solvent end-use dominance.

Listing and threshold

Substance Methyl ethyl ketone (MEK, butan-2-one) (CAS 78-93-3), C4H8O
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 H225 / H319 / H336
  • OSHA PEL 29 CFR 1910.1000 Table Z-1: 200 ppm 8-hr TWA (per https://www.osha.gov/annotated-pels)
  • NIOSH REL: 200 ppm 8-hr TWA, 300 ppm STEL (verify against https://www.cdc.gov/niosh/npg/)
  • NOT subject to TSCA Section 6 Risk Evaluation currently (verify against https://www.epa.gov/assessing-and-managing-chemicals-under-tsca)
  • NOT on TSCA Section 5(a)(2) Significant New Use Rule list
  • NOT on EPA RMP threshold list
  • **DEA List II controlled chemical** under 21 CFR 1310 (CMEA 2005 retail restrictions)
  • NOT on California Proposition 65 list (verify against OEHHA https://oehha.ca.gov/proposition-65/proposition-65-list before relying on negative listing)
  • TRI Section 313: DELISTED 2005 (verify current TRI listing status against https://www.epa.gov/toxics-release-inventory-tri-program before relying)
  • DOT hazardous materials regulation (49 CFR 172.101): UN 1193, Class 3, PG II
  • IARC: Group 3 (not classifiable as to its carcinogenicity to humans), evaluated in Monograph Volume 71 (1999) (verify the current classification and Monograph volume against https://monographs.iarc.who.int/list-of-classifications before invoicing)

Restrictions and conditions of use

  • OSHA-compliant SDS and workplace HazCom training required
  • **DEA List II CMEA 2005 retail restrictions**: retail sale tracking, customer ID, transaction logs (similar to acetone batch 15 pattern)
  • NO active US AD/CVD case on Chinese-origin MEK currently
  • Section 301 List 3 25% additional duty applies on Chinese-origin MEK (HS 291412)
  • NFPA 30 Flammable and Combustible Liquids Code applies for storage
  • TRI: delisted 2005; verify current status before assuming Form R reporting waiver

Importer obligations

TSCA is a self-certification regime. The dominant practitioner-facing layer is **DEA List II CMEA 2005 retail restrictions plus Section 301 List 3 25% additional duty plus OSHA PEL 200 ppm plus NFPA storage compliance**. NO active AD/CVD case. Major US domestic producers: ExxonMobil Baton Rouge Louisiana, Sasol Lake Charles Louisiana, Shell Chemicals Deer Park Texas. US is comparatively self-sufficient for MEK through domestic supply.

Required documents

  • TSCA Section 13 Import Certification statement on customs entry
  • OSHA-compliant SDS reflecting H225 / H319 / H336 classification
  • Customs entry CBP Form 7501 with HS code 291412 (MEK) and Section 301 List 3 25% duty applied
  • **DEA List II CMEA documentation** for retail-sale chain (where applicable to downstream distribution)
  • 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.

  • **DEA List II CMEA 2005 retail restrictions** drives downstream retail-distribution overhead (similar to acetone batch 15 pattern)
  • OSHA PEL 200 ppm 8-hr TWA workplace exposure-control overhead
  • NOT on Cal Prop 65 (verify against OEHHA before relying on negative listing)
  • TRI: delisted 2005; verify current status
  • NO active US AD/CVD case on Chinese MEK currently
  • Section 301 List 3 25% additional duty applies; structurally lighter than caprolactam batch 14 plus acetic acid batch 19 lanes
  • Major US producers: ExxonMobil Baton Rouge Louisiana, Sasol Lake Charles Louisiana, Shell Chemicals Deer Park Texas

Where to read next

For substance-level identifiers (formula, molecular weight, SMILES, InChIKey), GHS hazard profile, IMDG transport class, and full sourcing reference for methyl ethyl ketone (mek, butan-2-one), see the CAS 78-93-3 sourcing reference.

For grade-by-grade buying notes, freight maths, supplier-tier pricing, and a worked landed-cost example, the methyl ethyl ketone (mek, butan-2-one) cornerstone hub covers the full sourcing chain.

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

Need cross-jurisdiction compliance support on this substance? Run it through the REACH / TSCA / IECSC / AICIS / K-REACH checker, or send us the substance and the destination and we will quote FOB China and CIF / DDP landed including the regulatory work on the destination side.

Read next

Cross-jurisdiction profile and sourcing references

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