Excretion of unchanged volatile organic compounds (toluene, ethylbenzene, xylene and mesitylene) in urine as result of experimental human volunteer exposure.

To investigate elimination of unchanged volatile organic compounds (VOC's) through urine and the use of respective data for occupational exposure assessment, six volunteers were exposed under controlled conditions to toluene (TOL), ethylbenzene (EB), xylene (XYL) and mesitylene (MES) at concentrations ranging from 20 to 200 mg/m(3). The study was to elicit the toxicokinetic data and compare the precision of VOC's exposure assessment based on determining unchanged compounds in blood, urine and their metabolites in urine. During and after exposure blood and urine samples were analysed by gas chromatography using the headspace and SPME headspace technique The kinetics of VOC's elimination in urine complied with an open two-compartment model. The (half-time) T (1/2 )values varied from 0.45 to 0.88 h for phase I and from 6.7 to 19.2 h for phase II. The precision of the method for unchanged VOC's was similar to that based on unchanged compounds in blood and better than their main metabolites in urine. The obtained result indicate that determining unchanged VOC's in urine can be used as an exposure test even in the ranges of VOC's in the air that are much lower than the current TWA for occupational exposure.