NMP is safe to use only when direct skin contact is engineered out. N-methyl-2-pyrrolidone (CAS 872-50-4) is a combustible liquid with a 204 °F flash point and low volatility, so vapor risk is modest at room temperature. The serious hazard is dermal: EPA’s risk evaluation ties NMP to reproductive harm and organ damage, primarily through direct skin exposure.
What is NMP and what is it used for?
N-methyl-2-pyrrolidone — also written 1-methyl-2-pyrrolidone, and sold as NMP or M-Pyrol — is a high-boiling polar aprotic solvent. It dissolves an unusually wide range of polymers, resins, and organics, and it does so without evaporating quickly. That combination is why it became the default solvent in applications where a fast-flashing solvent would be useless.
- Lithium-ion battery electrode manufacturing (PVDF binder slurries)
- Semiconductor and electronics photoresist stripping and surface cleaning
- Petrochemical extraction, including butadiene and aromatics recovery
- Engineering polymer production — polyimides, polyamides, polysulfones
- Paint, coating, and adhesive stripping in commercial settings
- Agricultural and pharmaceutical formulation as a carrier solvent
NMP is part of the wider industrial solvent portfolio RightPath Industries distributes, alongside acetone, acetonitrile, toluene, and the glycol ethers.
What are the physical properties of NMP?
The numbers below come from the NOAA CAMEO Chemicals datasheet for N-methyl-2-pyrrolidone and drive nearly every handling decision on this page.
| Property | Value |
|---|---|
| CAS number | 872-50-4 |
| Chemical formula | C5H9NO |
| Molecular weight | 99.13 |
| Boiling point | 396 °F (202 °C) at 760 mmHg |
| Melting point | −9 °F (−23 °C) |
| Flash point | 204 °F (96 °C) |
| Specific gravity | 1.03 at 77 °F — denser than water |
| Vapor density (air = 1) | 3.4 — heavier than air |
| Water solubility | ≥ 100 mg/mL at 68 °F |
| NFPA 704 rating | Health 2, Flammability 2, Instability 0 |
| UN/NA number | UN1993, Combustible Liquid (ERG Guide 128) |
| DOE PAC-1 / PAC-2 / PAC-3 | 30 ppm / 32 ppm / 190 ppm |
Two of these values matter more than the rest. The 204 °F flash point makes NMP a combustible liquid, not a flammable one — it will not ignite at ambient temperature the way acetonitrile or acetone will. And a vapor density of 3.4 means any vapor that does form settles into pits, sumps, and low spots rather than dispersing upward.
Why is skin contact the main NMP hazard?
NMP absorbs readily through intact skin. Because it barely evaporates, a splash stays on the skin and keeps absorbing instead of flashing off. EPA’s December 2020 TSCA risk evaluation, as amended by its December 2022 final revised risk determination, concluded that NMP presents an unreasonable risk of injury to human health — citing miscarriage and reduced fertility, plus liver, kidney, immune system, and nervous system damage, driven primarily by direct dermal contact.
Inhalation is the secondary route. Hot vapors irritate the nose and throat, and spray application raises the inhalation contribution sharply. Ingestion irritates the mouth and stomach. In a fire, NMP can form toxic oxides of nitrogen.
Does NMP have an OSHA exposure limit?
No. NMP has no OSHA permissible exposure limit and no NIOSH recommended exposure limit — it does not appear in the NIOSH Pocket Guide to Chemical Hazards. The absence of a PEL is not evidence of safety; it reflects the fact that the hazard is dermal rather than airborne, and OSHA’s air contaminant table was never built for that. Employers still owe a hazard assessment and controls under the general duty clause and the hazard communication standard.
Where an airborne benchmark is needed for emergency planning, the Department of Energy Protective Action Criteria above are the usual reference. NMP is also reportable under EPCRA section 313 (the Toxics Release Inventory).
What PPE and engineering controls does NMP require?
Design the job so liquid NMP never touches skin. Enclose transfers, use closed-loop pumping instead of open pouring, and provide local exhaust wherever the material is heated, sprayed, or agitated.
Glove and suit selection matters because barrier materials vary widely. DuPont’s ASTM F739 permeation testing for NMP shows the spread:
| Barrier fabric | Normalized breakthrough time |
|---|---|
| Tychem 4000 | 101 minutes |
| Tychem 6000 | > 480 minutes |
| Tychem 6000 FR | > 480 minutes |
| Tychem RESPONDER CSM | > 480 minutes |
| Tychem 10000 | > 480 minutes |
Baseline PPE per the CAMEO response recommendations is goggles or a face shield plus chemical-resistant gloves. Verify your specific glove model against its manufacturer’s NMP permeation data — thin nitrile disposables are not adequate for immersion or extended contact. Stage eyewash and quick-drench facilities in every transfer area, and train handlers on the product SDS before first use.
How is NMP regulated by the EPA?
In June 2024, EPA proposed a risk management rule for NMP under TSCA section 6. As of EPA’s most recent update to its NMP risk management page, the rule remains proposed rather than final. The proposal, if finalized, would:
- Establish an NMP Workplace Chemical Protection Program (WCPP) covering nearly all industrial and commercial uses
- Require controls preventing direct dermal contact, effective one year after the rule is finalized
- Limit NMP in consumer glues and adhesives to no more than 45%, with container-size and labeling limits on other consumer products
- Ban commercial use in automotive care, cleaning and degreasing, metal products, and furniture care products
- Ban use in antifreeze, de-icing products, and lubricants, which EPA believes have already ceased
EPA specifically noted that semiconductor and lithium-ion battery manufacturers largely already run the enclosed, automated, cleanroom controls the rule would require. Buyers in paints, adhesives, inks, coatings, and soldering face the larger compliance lift. Track docket EPA-HQ-OPPT-2020-0744 for the final rule.
How should NMP be stored, shipped, and spill-controlled?
- Storage: cool, ventilated, away from sparks and open flame. Keep containers closed — NMP is hygroscopic and picks up water that shifts its performance.
- Incompatibilities: NMP is a weak base in the amides and imides reactive group. Keep it away from isocyanates, halogenated organics, peroxides, acidic phenols, epoxides, anhydrides, and acid halides. Strong reducing agents such as hydrides can liberate hydrogen.
- Transport: UN1993, Combustible Liquid, ERG Guide 128. See our guide to DOT hazmat classes for solvents for how that flows through to shipping papers and placarding.
- Spills: eliminate ignition sources, dike to contain, absorb, and bag contaminated absorbent and clothing for disposal. Keep NMP out of sewers and waterways. Do not re-enter until the area is verified clean.
- Labeling: every drum carries a GHS label — here is how to read one.
The same discipline that applies to storing acetone safely applies here, with one inversion: acetone’s danger is its vapor, NMP’s danger is the liquid on your hands.
What grades and sizes of NMP does RightPath stock?
RightPath Industries supplies N-methyl-2-pyrrolidone (NMP) in the standard industrial formats: 55-gallon drums, IBC totes, and bulk tank truck quantities. Commercial NMP is specified in two broad tiers — technical or industrial grade for extraction, stripping, and general formulation, and high-purity or electronic grade where trace metals and water content are controlled for semiconductor and battery use. Tell us the application and we will quote to the specification that fits it.
Every lot ships with a Safety Data Sheet and a Certificate of Analysis. If you are deciding between drums and totes, our breakdown of drum vs. IBC tote vs. bulk covers the handling and cost trade-offs.
How do you order NMP from RightPath Industries?
RightPath Industries is a Pittsburgh-headquartered chemical distributor carrying more than 8,000 chemicals, shipping nationwide from drums to tank trucks. Send the grade, the volume, the package format, and the delivery ZIP, and you get a same-day, all-in delivered quote — freight and fees included, not bolted on later.
Frequently asked questions about NMP safety
Is NMP banned in the United States?
No. NMP is not banned in the United States. EPA proposed a TSCA risk management rule in June 2024 that would ban several specific commercial uses — automotive care, cleaning and degreasing, metal products, furniture care, antifreeze, de-icing, and lubricants — but the rule has not been finalized, and industrial uses such as battery and semiconductor manufacturing would continue under a workplace protection program.
Is NMP flammable?
NMP is combustible, not flammable. Its flash point is 204 °F (96 °C), well above ambient temperature, and it ships as UN1993 Combustible Liquid. It still burns once heated above its flash point, and combustion can produce toxic nitrogen oxides.
What is the OSHA exposure limit for NMP?
There is no OSHA permissible exposure limit for NMP and no NIOSH recommended exposure limit. NMP has no NIOSH Pocket Guide entry. Employers should base controls on dermal exposure prevention rather than air sampling alone.
Can NMP be absorbed through the skin?
Yes. Dermal absorption is the primary exposure route of concern for NMP and the basis for EPA’s unreasonable-risk determination. Because NMP evaporates slowly, splashed liquid remains on skin and continues absorbing until it is washed off.
What is NMP used for in lithium-ion batteries?
NMP dissolves polyvinylidene fluoride (PVDF) binder to form the cathode slurry that is coated onto electrode foil. The solvent is then evaporated and, in most modern plants, recovered and recycled in a closed system.
Authoritative references: the NOAA CAMEO Chemicals datasheet for N-methyl-2-pyrrolidone for physical and reactivity data, EPA’s Risk Management for n-Methylpyrrolidone (NMP) page for regulatory status, and the ILO International Chemical Safety Card 0513. Always work from the current SDS for the specific product you have on site.