Liver function in workers exposed to N,N-dimethylformamide during the production of synthetic textiles

Objective: In a factory producing synthetic fibers the hepatotoxic effects of the solvent N,N-dimethylformamide (DMF) were investigated in 126 male em ployees, especially with regard to the combination effects of DMF exposure and ethyl alcohol consumption. A collective of similar structure from the s ame factory served as a control collective. Methods: Reference is made to t he results of air measurements and biological monitoring presented in a pre vious publication. The DMF concentrations in the air ranged from < 0.1 (det ection limit) to 37.9 ppm (median 1.2 ppm). Concentrations of the DMF metab olite N-methylformamide (NMF) in urine were 0.05-22.0 mg/l (preshift) and 0 .9-100.0 mg/l (postshift), corresponding to 0.02-44.6 mg/g creatinine (pres hift) and 0.4-62.3 mg/g creatinine (postshift). A standardized anamnesis wa s drawn up for relevant previous illnesses and other factors influencing li ver function. The laboratory tests included parameters especially relevant to the liver (e.g., AST, ALT, gamma-GT, hepatitis B and C antibodies, and c arbohydrate-deficient transferrin). Results: The results indicate a statist ically significant toxic influence of DMF on liver function. Alcohol has a synergistic effect. The effects of DMF and those of alcohol are dose-depend ent. Under the existing workplace conditions the hepatotoxic effects of alc ohol are more severe than those of DMF. In the exposed group there was a st atistically significantly greater number of persons who stated that they ha d drunk less since the beginning of exposure (13% versus 0). This correspon ded with the data on symptoms occurring after alcohol consumption (71% vers us 4%). In the work areas with lower-level exposure to DMF there was greate r alcohol consumption. It corresponded to that of the control collective no t exposed to DMF. Conclusion: In this study we tried to differentiate and q uantify the interaction between DMF exposure and alcohol consumption and th e influence of both substances on liver function. The experience gained fro m former occupational health surveillance in DMF-exposed persons and from t he present study show that there are individual differences in tolerance of interactions between DMF and ethyl alcohol. Further studies are necessary for the evaluation of these individual degrees of susceptibilitiy.