Role of urinary biomarkers of N,N-dimethylformamide in the early detection of hepatic injury among occupational exposed workers

To determine the sensitive and convenient biomarkers for the early detection of hepatic injury in N,N-dimethylformamide (DMF) exposed workers. Seventy-nine individuals in a synthetic leather factory were investigated with questionnaire survey. The air samples, urine samples, and blood samples were collected at the specific time point. Airborne DMF and the urine metabolites of DMF were measured by gas chromatography (GC), high-performance liquid chromatography (HPLC), and gas chromatography-mass spectrometry (GC-MS). Traditional liver function tests and hepatic fibrosis parameters were performed by auto-chemistry analyzer and ELISA methods. The urine concentration of N-acetyl-S-(N-methylcarbamoyl)-cysteine (AMCC), one of the metabolites of DMF, was positively correlated with activities of liver function enzymes. About 60% subjects with urine AMCC concentration above 40 mg/g creatinine showed raised liver enzymes activities. In terms of hepatic fibrosis parameters, we found 4 of 5 abnormal total serum bile acid (SBA) and 4 of 4 abnormal serum hyaluronidase (HA) among workers with higher amount of urine AMCC. Workers exposed to DMF with higher urine AMCC levels were more likely to develop liver diseases. In addition, SBA and HA have the potential to act as early indicators of toxic hepatic fibrosis activities for occupational health surveillance.