Evaluation of current biological exposure index for occupational N,N-dimethylformamide exposure from synthetic leather workers

The aim of this study was (1) to investigate the correlation between external exposure to N,N-dimethylformamide (DAY) and urinary excretion of DMF and N-methylformamide; (2) to assess whether the correspondence between the current occupational exposure limit setting and recommended urinary biological exposure index is substantial; and (3) to evaluate whether coexposure to toluene, methyl ethyl ketone, and ethyl acetate has an effect on urinary excretion of DAY and N-methylformamide (MMF). Urinary DAY and NAY were significantly correlated (P < 0.01) with one another and also significantly correlated with airborne DMF (P < 0.01) over the range of 1.55 to 152.8 mg/m(3). Urinary DAY can be considered a complementary marker for short-term exposure. Urinary concentration of NAY, and DMF, corresponding to the 8-hour exposure to airborne DAY at 30 mg/m(3) was estimated to 38.4 mg/L or 39.4 mg/g creatinine for NW and to 0.92 mg/L or 0.96 mg/g creatinine for DMF.