Silvia Fustinoni1, Rosa Mercadante, Laura Campo. 1. Department of Occupational and Environmental Medicine, University of Milano, Milan, Italy. silvia.fustinoni@unimi.it
Abstract
PURPOSE: To study the excretion kinetics of urinary toluene, TOL-U, and o-cresol, o-C, following occupational exposure to toluene in order to define the best time for sample collection, to apply a non-invasive approach based on self-collected urine sampling. METHODS: Five rotogravure printing workers exposed to uncontrolled levels of toluene collected spot urine samples over three consecutive working days and the following day of rest. In each sample TOL-U and o-C were measured and kinetics of excretion evaluated. RESULTS: Toluene exposure ranged from 48.3 to 75.3 mg/m(3); TOL-U and o-C ranged from 1.4 to 34.6 microg/L and from 0.013 to 1.012 mg/L. A time course trend was obtained: TOL-U and o-C increased during the shift and peaked at the end of exposure and up to 2 h later, respectively; afterwards they rapidly decreased following apparent first order kinetics. Considering TOL-U, the elimination half-life for the first fast phase was 79 (+/-35 standard error) min, and for the second slow phase was 1,320 (+/-1,162) min. For o-C the elimination half-life for the first fast phase was 231 (+/-48) min. Considering a toluene uptake of 86%, TOL-U and o-C excreted in urine were about 0.0067 and 0.18% of the up taken. CONCLUSION: Our results support the use of end shift TOL-U as a short term biomarker of occupational exposure to toluene and show the feasibility of self-collected urine sampling to investigate the elimination kinetics of industrial toxics in humans.
PURPOSE: To study the excretion kinetics of urinary toluene, TOL-U, and o-cresol, o-C, following occupational exposure to toluene in order to define the best time for sample collection, to apply a non-invasive approach based on self-collected urine sampling. METHODS: Five rotogravure printing workers exposed to uncontrolled levels of toluene collected spot urine samples over three consecutive working days and the following day of rest. In each sample TOL-U and o-C were measured and kinetics of excretion evaluated. RESULTS:Toluene exposure ranged from 48.3 to 75.3 mg/m(3); TOL-U and o-C ranged from 1.4 to 34.6 microg/L and from 0.013 to 1.012 mg/L. A time course trend was obtained: TOL-U and o-C increased during the shift and peaked at the end of exposure and up to 2 h later, respectively; afterwards they rapidly decreased following apparent first order kinetics. Considering TOL-U, the elimination half-life for the first fast phase was 79 (+/-35 standard error) min, and for the second slow phase was 1,320 (+/-1,162) min. For o-C the elimination half-life for the first fast phase was 231 (+/-48) min. Considering a toluene uptake of 86%, TOL-U and o-C excreted in urine were about 0.0067 and 0.18% of the up taken. CONCLUSION: Our results support the use of end shift TOL-U as a short term biomarker of occupational exposure to toluene and show the feasibility of self-collected urine sampling to investigate the elimination kinetics of industrial toxics in humans.