Monomethylformamide levels in human urine after repetitive exposure to dimethylformamide vapor.

Eight healthy male subjects were exposed to DMF vapor at a concentration of 8.79 +/- 0.33 ppm for six hours daily for five consecutive days. All urine voided by the subjects was collected from the beginning of the first exposure to 24 hours past the end of the last exposure and each sample was analyzed for monomethylformamide (MMF). MMF was rapidly eliminated from the body with urine values peaking within a few hours following the end of each exposure period. Very little was found in the 24-hour postexposure sample and none was found in a 48-hour postexposure sample. There was no increased excretion of MMF in the urine following repetitive exposure. The mean for the seven-hour (end of exposure) sample was 4.74 microgram/ml or 736.8 microgram. Lower and upper one-sided 95% tolerance limits for 95% of the population were 1.2 microgram/ml (367 microgram) and 13.9 microgram/ml (1625 microgram). The coefficient of variation (CV) for microgram MMF/ml was approximately 25 times more variable than the CV for total microgram.