Metabolism and Biological Monitoring of Organic Acid Anhydrides

Sammanfattning: The aim of this thesis was to describe the metabolism and to develope methods for biological monitoring for two organic acid anhydrides (OAAs), namely hexahydrophthalic anhydride (HHPA) and methylhexa-hydrophthalic anhydride (MHHPA). The OAAs are reactive, low molecular weight chemicals used in vast quantities in the industry. Many OAAs, including HHPA and MHHPA, are potent IgE sensitisers inducing asthma, rhinitis, and conjunctivitis. Analytical methods for analyses of hexahydrophthalic acid (HHP acid) and methylhexahydrophthalic (MHHP acid; metabolites of HHPA and MHHPA) in plasma and urine and the hemoglobin (Hb) adducts of HHPA and MHHPA in erythrocytes were developed using pentaflourobenzyl bromide derivatisation and gas chromatography mass spectrometry (GC-MS). The kinetics of MHHP acid and protein adducts were investigated and the Hb adducts briefly characterised by means of gel filtration, reversed-phase liquid chromatography, and GC-MS. The levels of the acids in plasma and urine and of the Hb adducts from workers were correlated to their exposure of HHPA and MHHPA. Further, the distribution of tritium-labelled HHPA was investigated in an animals study using autoradiography and gel filtration/ scintillation. The analyses of HHP and MHHP acid in urine and plasma had high precision and accuracy. The analysis of HHPA and MHHPA adducts had a good precision. All methods had a detection limit sufficiently low for application in exposed workers. The major adduct-forming protein in human erythrocytes seemed to be Hb and the major HHPA-binding amino acid was lysine. Strong correlations were found between MHHP acid levels in plasma and urine and MHHPA in air and between levels of Hb-adducts of HHPA and MHHPA and long term or short term exposure, as determined by biomonitoring using HHP or MHHP acid in urine or plasma. Thus, the methods are applicable for biological monitoring of exposure. A fast elimination of MHHP acid in urine show that MHHP acid in plasma and urine reflect one day of exposure. The Hb adducts seemed to be stable in vivo and thus reflecting the exposure during months. In the animal study, tissue-bound HHPA/metabolites mainly occurred in the upper respiratory airways, alimentary tract, whereas no bound radioactivity was observed in the lung. A low selective binding was also observed in kidney of rats. The presented methods and results can be used for exposure assessment of OAAs and for studies of mechanisms behind allegies.