N-Methylpyrrolidone (a.k.a. 1-methyl-2-pyrrolidone or NMP) is a solvent used in a variety of industries and applications, such as paint and coating removal, petrochemical processing, engineering plastics coatings, agricultural chemicals, electronic cleaning and industrial/domestic cleaning.
22 facilities reported manufacturing or importing 184.7 million pounds of NMP in the U.S. in 2011, according to Chemical Data Reporting by the chemical industry. The manufacturers with public names were: Toray Holding (USA) Inc. in Washington, OM Group Inc. in Minnesota, BASF Corp. in Louisiana, and Ashland Inc., Nova Molecular Technologies Inc., and Lyondell Chemical Company all in Texas. Three entities claimed their names as confidential business information.
Animal studies reviewed by EPA show NMP poses a risk of developmental toxicity, and may pose a risk of reproductive toxicity.
A number of other adverse effects were observed in different studies, including effects on body weight, liver, kidney, spleen, thymus, and brain.
NMP is listed under California’s Prop 65 as a developmental toxin.
EPA estimates high releases to the environment. NMP is found in drinking water and indoor environments. Based on available data, EPA concluded that NMP has low acute and chronic toxicity to aquatic organisms and birds.
385 facilities, combined, reported that they disposed of or otherwise released around 8.1 million pounds of NMP in 2015, according to EPA’s Toxics Release Inventory.
According to EPA’s risk assessment related to paint stripping uses published on March 23, 2015, the populations most vulnerable are:
- Pregnant women and the developing fetus, as well as women of childbearing age who may become pregnant, with high exposure to NMP through paint strippers
For paint stripping uses of NMP, benzyl alcohol is an effective and safer alternative (although it does exhibit the central nervous system toxicity of all organic solvents).
Note: EPA states that using NMP-resistant gloves may reduce risks when the exposure to the chemical is for less than four hours per day.
EPA has proposed a rule to regulate the use of NMP in paint and coating under Section 6 of the newly reformed TSCA.
Under the European Union’s REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulation, NMP is classified as a “substance of very high concern” and included in the candidate list for authorization because of its toxicity for reproduction.
The Netherlands has proposed a restriction on manufacturing, and all industrial and professional uses of the substance, where workers’ exposure exceeds a level specified in the restriction. A decision adopting this restriction (with modifications) is pending.
For more information:
- EPA, Fact Sheet: N-Methylpyrridoline, NMP
- EPA, 2015 final risk assessment for NMP
- EPA, TRI Explorer (2015 National Analysis dataset, released October 2016, accessed January 2017)
- European Chemicals Agency, Substance Information: 1-methyl-2-pyrrolidone
- California Office of Environmental Health Hazard Assessment, n-Methylpyrrolidone
- Institute for Research & Technical Assistance, 2006 report to California Department of Health Services and US EPA
- EPA Safer Chemical Ingredient List