Biomarkers in Hydrolysed Urine, Plasma and Erythrocytes Among Workers Exposed to Thermal Degradation Products From Toluene Diisocyanate Foam

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Blood and urine samples were collected from six workers and two volunteers exposed to thermal degradation products from toluene diisocyanate (TDI)-based polyurethane (PUR) before and during the summer vacation. Air samples were collected on filters impregnated with 9-(N-methylaminomethyl)anthracene. The concentrations of the amines corresponding to 2,4- and 2,6-TDI, i.e., 2,4- and 2,6-toluenediamine (TDA), were determined in urine (U-TDA), plasma (P-TDA) and erythrocytes (E-TDA) after acid hydrolysis as pentafluoropropionic anhydride derivatives by GC-MS. Among the workers urinary elimination phases were seen. The estimated medians of the urinary half-lives were for the slow phase 18 d for 2,4-TDA and 19 d for 2,6-TDA. P-2,4-TDA ranged between 2.5 and 19 ng ml-1 and P-2,6-TDA between 4.4 and 30 ng ml-1. The estimated median of the half-lives in plasma were 7.8 d for 2,4-TDA and 9.6 d for 2,6-TDA. E-2,4-TDA ranged between 0.5 and 6.6 ng g-1 and E-2,6-TDA between 1.2 and 14 ng g-1. A significant linear relationship was found between the mean P-TDA and the mean E-TDA. Linear relationships were observed between the mean daily U-TDA and P-TDA and E-TDA. Virtually linear relationships were obtained for P-TDA and E-TDA and the TDI air levels. Proteins from lysed erythrocytes were separated and fractionated by gel filtration. 'TDI'-modified proteins were found in six out of a total of 80 fractions (fractions 51-56). These co-eluted completely with the haemoglobin (UV, 415 nm). Fractions 51-56 contained 89% of the applied amounts of 2,4-TDA and 81% of 2,6-TDA.