Biological monitoring of trace chemicals in residential environments

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objective : Sick house syndrome, the diverse health effects encountered by people dwelling or working in the new construction, is becoming a noticeable problem in Japan. This study was attempted to make a contribution toward prediction of the adverse health effects of chemicals in residential environments and planning preventive measures. This year we focused on developing a method for quantitative determination of trace level metabolites in urine of individuals exposed to aromatic volatile organic compounds (VOCs) such as toluene, xylene, and styrene by gas chromatography coupled with mass spectrometry (GC-MS).Methods : We targeted of the urinary hippuric acid (HA), o-, m-, and p-methyl hippuric acids (o-, m-, p-MHA), and mandalic acid (MA) and phenylglyoxalic acid (PGA), metabolites of toluene, xylene, and styrene, respectively. Study samples were prepared by adding benzoylleucine as the internal standard (LS.), extracting with ethyl acetate under acid condition. The derivative compo … More unds were then reconstituted in ethyl acetate and identified by GC-MS equipped with DB-1 capillary column. Elution was carried out at initial column temperature 150℃ with an increment at a rate of 10℃/min up to 250℃. The quantitative analysis was operated in SIM mode, selecting the ion m/z 105 for HA, m/z 119 for MHA, m/z 107 for MA, and m/z 105 for PGA. In order to examine the corresponding concentrations of VOCs in ambient air, active sampling by charcoal tubes was used for VOCs collection. After elution with carbon disulfide, the samples were analyzed with GC-MS.Results and discussion : Six urinary metabolites and I.S. were separated and eluted with a good peak by GC-MS. The limits of detection were 40-450 pg by SIM mode and the calibration curves of these compounds were fairly linear. Hippuric acid, MHA, MA, and PGA were all detected from urine of workers working in the new buildings in which higher levels of VOCs (toluene, xylene, and styrene) were found. Since HA of dietary sources could also affect its background level in urine, it cannot become a urinary marker of exposure to trace toluene. However, MHA, MA, and PGA can be used to evaluate low-level exposure to xylene and styrene.Conclusions : This newly developed GC-MS method showed high sensitivity for determination of urinary metabolites of individuals exposed to trace level VOCs. The present results support its usefulness in biological monitoring of indoor VOCs for animals and humans. Less