Dermal absorption and urinary elimination of N-methyl-2-pyrrolidone

Objectives: The dermal absorption of the solvent N-methyl-2-pyrrolidone (NMP) and its elimination in urine was investigated in an experimental study. Methods: Seven volunteers were exposed to 1045 mg of liquid NMP under occlusive conditions for 2 h. Urine was collected before, during and up to 72 h after the exposure and analysed for NMP by GC/MS after liquid-liquid extraction. Additionally, the remaining NMP in the pads was determined to estimate the total dermal uptake. Results: The concentration of NMP in urine increased rapidly after beginning of the exposure up to 1 h after the exposure was completed. A peak concentration of 1,836 +/- 863 mu g/l was observed, the half-life in urine was 3.2 h. About 0.5% of the absorbed dose was excreted metabolically unchanged. An average dermal absorption of 5.5 mg cm(-2) h(-1) was calculated. Conclusions: The results of this study show that the percutaneous absorption of NMP may contribute significantly to the overall uptake of the solvent, e.g. in the workplace. Therefore, a biological monitoring of NMP exposed workers is essential for occupational-medical surveillance.