Serum activities of liver enzymes in workers exposed to sub-TLV levels of dimethylformamide

The aim of this study has been to investigate serum activities of liver enzymes in workers exposed to sub-TLV levels of dimethylformamide (DMF). Seventy-two workers and 72 healthy controls participated in the study. All subjects underwent complete physical examinations and abdominal ultrasound examination. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and c-glutamyl transpeptidase (c-GT) were determined by an auto-chemistry analyzer. The data of airborne concentrations of DMF was obtained from the local Center of Disease Control and Prevention. The level of urine N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) was measured by means of high-performance liquid chromatography. Time weighted average (TWA) concentration of the DMF in workplace was 18.6 (range: 9.8-36.2) mg/m . The concentration of the AMCC in workers' urine was 28.32 (range: 1.8-58.6) mg/l and 9 workers' AMCC exceeded the biological exposure index (40 mg/l). Thirty-one workers reported gastrointestinal symptoms (abdominal pain, nausea, anorexia) and 10 workers reported headache, dizziness and/or palpitation in the exposed group. Serum analysis revealed that both the mean of serum activities of liver enzymes (ALT, AST and c-GT) and the percentage of workers with abnormal liver function were significantly higher in the exposed group as compared to the controls. Dimethylformamide can cause liver damage even if air concentration is in the sub-threshold limit value (sub-TLV) level. The protection of skin contact against the exposure to the DMF might be a critical issue as far as the occupational health is concerned.