ASSESSMENT OF OCCUPATIONAL EXPOSURE TO 4,4'-METHYLENEDIANILINE BY THEANALYSIS OF URINE AND BLOOD-SAMPLES

Seven workers at a work site where methylenedianiline (MDA) was used a s a curing agent for an epoxy resin were studied during 4 workdays and one weekend. Internal exposure was monitored by analysis of 4,4'-MDA in hydrolysed urine and blood. After acidic hydrolysis, MDA was extrac ted, derivatised by use of pentafluoropropionic anhydride, and determi ned by gas chromatography and mass spectrometry, with negative ion che mical ionization. There was wide variation of MDA concentrations in hy drolysed blood between the workers (range 10-60 nmol/l). Also, the uri nary excretion rate varied considerably both between and within the in dividual workers (0-90 mu mol/h). The urinary excretion displayed some variation in relation to exposed periods. The urinary levels were lin early related to the concentrations in blood (r(s) = 0.93, P = 0.02). The present results show the value of excretion of MDA in hydrolysed u rine and concentrations in blood as means for the biological monitorin g of MDA exposure. In this case, the exposure was probably mainly derm al, in spite of extensive protection measures.