Toluene metabolites as biological indicators of exposure.
The measurement of exhaled and excreted xenobiotics and their metabolites can provide accurate, non-invasive, and time-flexible measurements of internal dose. We analyzed rates of exhaled (2)H(8)-toluene and excreted urinary metabolites from 33 exposures of men to 50 ppm of (2)H(8)-toluene for 2 h at rest. The total dose was distributed as follows: exhaled (2)H(8)-toluene, 13 +/- 6.2%; (2)H(5)-hippuric acid, 75 +/- 6.4%; (2)H(7)-o-cresol, 0.31 +/- 0.22%; (2)H(7)-m-cresol, 0.53 +/- 0.44%; and (2)H(7)-p-cresol, 11 +/- 3.8%. Interindividual variability was assessed using the coefficients of variation for peak exhalation or excretion rates, and fractions of dose excreted: (2)H(8)-toluene, c.v.=60, 47%; (2)H(5)-hippuric acid, 29, 8.6%; (2)H(7)-o-cresol, 80, 73%; (2)H(7)-m-cresol, 37, 83%; and (2)H(7)-p-cresol, 38, 34%. Excretion rates of the cresols were stable over the first 5 h post-exposure, and o-cresol was determined to be the best urinary indicator of exposure, given the lower background levels of this isomer. The hippuric acid/cresol rate ratios for the first 5 h post-exposure could be described by single exponential terms, and thus provided a means for estimating time since exposure for any finite toluene duration/exposure combination.
Pierce
Crispin H
CH
Department of Environmental Health, University of Washington, P.O. Box 357234, Seattle, WA 98195-7234, USA. crispo@u.washington.edu
Chen
Yili
Y
Dills
Russell L
RL
Kalman
David A
DA
Morgan
Michael S
MS
D000328:Adult; D003408:Cresols / Q000378:metabolism; D004784:Environmental Monitoring; D005260:Female; D006626:Hippurates / Q000378:metabolism; D006801:Humans; D008875:Middle Aged; D014050:Toluene / Q000378:metabolism*
D003408:Cresols; D006626:Hippurates; D014050:Toluene; C077977:cresol; C030514:hippuric acid