Objective To examine the correlation between occupational N, N-dimethylacetamide (DMAC) exposures and urinary N-methylacetamide (NMAC).
Methods A total of 201 workers of 6 work types exposed to DMAC in 3 spandex factories were recruited. Air samples were collected from each work type site, post-shift urine samples at the end of workweek were collected from all studied workers and also from 20 spinning workers at each end of workday for 5 consecutive days. NMAC in urine and DMAC in air were determined by gas chromatography.
Results The time-weighted average (TWA) air levels of DMAC were highest in module washing and spinning sites (P<0.003 3), medians being 32.10 and 22.02 mg/m3 respectively. The urinary NMAC concentrations in module washing workers and spinning workers were significantly higher than workers of other work types, medians being 30.09 and 22.72 mg/gCr respectively. A linear correlation was found between the TWA air levels of DMAC and the creatinineadjusted NMAC levels in urine collected by the end of workweek (r=0.698, P= 0.001). The linear equation was log(U-NMAC)= 0.685+0.455& #215;log(A-DMAC). After 2 consecutive days of exposure, the urinary NMAC was at a higher level in chronically exposed workers (P<0.003 3). A negative linear correlation was found between the DMAC levels in air and the relative internal exposure (RIE) (rs=-0.781, P= 0.001).
Conclusion Air DMAC contents are significantly correlated with urinary NMAC concentrations after logarithmic transformation.
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