Dimethylethylamine and dimethylbenzylamine in foundries and the epoxy industry : Analysis, metabolism, biological monitoring, toxicological effects and occupational exposure

Sammanfattning: Dimethylethylamine (DMEA) and dimethylbenzylamine (DMBA) are tertiary aliphatic amines, used as catalysts e.g., in mould core manufacturing and heat cured epoxy systems. Health effects such as visual disturbances and respiratory irritation occur among workers handling DMEA and airway symptoms are recorded by many workers exposed to DMBA. In this thesis, gas chromatographic methods for the determination of DMEA and DMBA in air and DMEA, dimethylethylamine- N-oxide (DMEAO), DMBA and dimethylbenzylaminc-N-oxide (DMBAO) in urine have been developed in order to monitor the air concentration of the amines, to investigate the metabolism and to establish methods useful for biological monitoring. Studies have been performed on volunteers in experimental exposures and on workers in the industrial setting. Dose-effect and dose-response relations were investigated for both DMEA and DMBA. An exposurechamber was developed, using a permeation technique, for the generation of low air levels of DMBA.DMEA and DMBA were rapidly absorbed through the respiratory tract and quickly distributed in the body. DMEA was to a large extent (90 %) metabolised into DMEAO and DMEA and DMEAO (SumDMEA) were excreted into the urine following a biphasic pattern. DMBA was metabolised to nearly 100 % and eliminated into the urine with a half-life of 4.3 h. More than 50 % was eliminated within 2 hours after the exposure. There was a significant correlation between the time-weighted average exposure level (TWA) of the two amines and the concentration of the amines and their metabolites (SumDMEA, SumDMBA) in the post-shift urine, in both the experimental and industrial study. Thus, both U-SumDMEA and U-SumDMBA may become important biomarkers in order to monitor industrial exposures of the corresponding amine.DMEA exposure to a constant air level of 40-50 mg/m3 during eight hours caused epithelial corneal oedema with visual disturbances and respiratory irritalion. A 15 min exposure at 80 mg/m 3 caused eye irritation but no visual disturbances and 8 h exposure at 20 mg/m3 did not cause visual disturbances or eye irritation.Low air concentrations (20-120 )Jg/m3 ) of DMBA increased the number of metachromatic cells and eosinophils in a dose-response related manner in the nasal mucosa in healthy vountecrs, without causing significant clinical symptoms.Industrial exposure levels of DMEA in mould core manufacturing workers were determined. The mean TWA of DMEA was 3.7 mg/m3 (range 0.5-14). The determination of DMBA in epoxy workers showed a mean TW A air concentration of 18 pg/m3 (range 3-48), with a 2 h peak exposure of 91 µ/m3.This thesis will facilitate the evaluation and assessment of risk and threshold limit values of DMEA, DMBA, and other related compounds.