Under the International Fire Code (IFC), N-Methyl-2-pyrrolidone (NMP) is not classified as a “Toxic” or “Highly Toxic” material. While NMP is legally classified as a toxic substance under environmental and labor laws (such as the EPA’s TSCA and OSHA’s Hazard Communication Standard) due to its health effects, the IFC uses a very specific, narrow definition of toxicity based on acute (short-term) lethal exposure.
The IFC (specifically Section 202) defines “Toxic” and “Highly Toxic” based on LD50 (lethal dose) and LC50 (lethal concentration) values for acute exposure.
Oral: LD50 between 50 mg/kg and 500 mg/kg.
Dermal: LD50 between 200 mg/kg and 1,000 mg/kg.
Inhalation: LC50 between 200 ppm and 2,000 ppm.NMP’s actual acute toxicity values far exceed these thresholds (meaning it is much less acutely lethal):
Oral LD50: ~3,914 mg/kg (Rat)
Dermal LD50: ~8,000 mg/kg (Rabbit)
Inhalation LC50: > 5.1 mg/L (Rat, 4 hours)Because NMP does not meet these “lethal” thresholds, it does not trigger the stringent IFC requirements for Toxic Materials (such as specialized exhaust ventilation, gas detection, or treatment systems) that apply to materials like chlorine or ammonia.
Although it isn’t “Toxic” by IFC code definition, it is still regulated as a Health Hazard.
Feature NMP Classification IFC / NFPA 704 Rating
Acute Toxicity Low Health: 2 (Intense/Continued exposure could cause temporary incapacitation)
Flammability Combustible (Class IIIA) Fire: 2 (Flash point ~196°F – 204°F)
Instability Stable Reactivity: 0