Biomarkers of aromatic isocyanates in exposed workers

Sammanfattning: The aromatic isocyanates, toluene diisocyanate (TDI) and methylenediphenyl diisocyanate (MDI), are used in the production of polyurethane (PUR) foams, paints, elastomers and glues. The use of isocyanates is increasing, and exposure to isocyanates is the most common cause of occupational asthma. Biomarkers of TDI and MDI were determined as the corresponding amines, toluenediamine (TDA) and methylenedianiline (MDA), in hydrolysed urine, plasma and erythrocytes from exposed workers. The amines were determined, after derivatisation with pentafluoropropionic anhydride, using gas chromatography-mass spectrometry with chemical ionisation, monitorinh negative ions. The levels of TDA and MDA in urine varied considerably during and between work days, while only limited variations were seen in plasma. At least two urinary elimination phases were observed. A relation was found between the concentrations of TDA and MDA in plasma and the urinary elimination rates of TDA and MDA after the cessation of work. A significant correlation was also found between the concentrations of TDA in plasma and the TDI air levels. TDI was found to be covalently bound to albumin in plasma and most likely to haemoglobin in erythrocytes. In urine, different TDI-modified biomolecules were observed. The use of biomarkers has made it possible to discover new groups of exposed workers, and to make preventive measures to reduce/eliminate exposure and avoid illness.