BIOLOGICAL MONITORING OF WORKERS EXPOSED TO N-N-DIMETHYLFORMAMIDE .2.DIMETHYLFORMAMIDE AND ITS METABOLITES IN URINE OF EXPOSED WORKERS

N,N-Dimethylformamide (DMF) exposure was monitored in a synthetic leat her factory; at the same time, urinary dimethylformamide and its metab olites were measured in urine samples collected before and at the end of workshifts. The study was run during two different periods. During the first phase ten workers were observed for 3 days (Monday, Tuesday and Wednesday) in the same week. In the second phase 16 workers were i nvolved in the study on a Friday and on the following Monday. Urinary DMF, as well as hydroxymethyl-N-methylformamide and hydroxymethylforma mide [measured as N-methylformamide (NMF) and formamide, respectively] , were measured in all urine samples. Formamide was also measured as a ''physiological'' product in subjects not exposed to dimethylformamid e. Environmental exposure to DMF ranged between about 10 and 25 mg/m(3 ). The unmodified solvent found in urine collected at the end of the e xposure was significantly related to the environmental concentrations of DMF; its urinary concentrations were found to range between 0.1 and 1 mg/l. Higher concentrations of NMF (mean 23.3 mg/l) and formamide ( 24.7 mg/l) were measured in urine samples collected at the end of work shifts. The same concentrations were related to individual exposures t o DMF. N-Acetyl-S-(N-methylcarbamoyl)cysteine in the urine of workers exposed to DMF showed a mean concentration of 40.4 mg/l on Friday (bef ore and after the workshift) and a mean concentration of 10.3 mg/l on Monday. Its slow kinetic profile favours its body accumulation during the working week. N,N-dimethylformamide and N-methylformamide in urine collected at the end of the workshift are good markers of current occ upational exposure to dimethylformamide, while N-acetyl-S-(N-methylcar bamoyl)cysteine seems a useful biological marker for monitoring repeat ed exposure to the solvent.