Abstract
The purpose of this study was to investigate whether the metabolic suppression of hippuric acid (HA) occurs in field workers coexposed to toluene, xylene and ethyl benzene. Eleven male spray painters were recruited into this study and monitored for 2 weeks using a repeated-measures study design. The sampling was conducted for 3 consecutive working days each week. Toluene, ethyl benzene, and xylene in the air were collected using 3M 3500 organic vapor monitors. Urine samples were collected before and after work shift, and urinary HA, methyl hippuric acid, mandelic acid, and phenylgloxylic acid concentrations were determined. In the first week, toluene concentrations were 2.66 ± 0.95 (mean ± SE) ppm, whereas ethyl benzene and xylene concentrations were 27.84 ± 3.61 and 72.63 ± 13.37 ppm, respectively, for all subjects. Pre–work shift HA concentrations were 230.23 ± 37.31 mg/g creatinine, whereas pre–work shift HA concentrations were 137.81 ± 14.15 mg/g creatinine. Mean urinary HA concentration was significantly greater in the pre–work shift samples than in the pre–work shift samples (p = 0.043). In the second week, toluene concentrations were much lower (0.28 ppm), whereas ethyl benzene and xylene were 47.12 ± 8.98 and 23.88 ± 4.09 ppm, respectively, for all subjects. Pre–work shift HA concentrations were 351.98 ± 116.23 mg/g creatinine, whereas pre–work shift HA concentrations were 951.82 ± 116.23 mg/g creatinine. Mean urinary HA concentration was significantly greater in the pre–work shift samples than in the pre–work shift samples (p <0.01); a significant correlation (r = 0.565; p = 0.002) was found between pre–work shift urinary HA levels and ethyl benzene exposure. This study showed that urinary HA peak was delayed to next morning for workers coexposed to toluene, ethyl benzene, and xylene; xylene and ethyl benzene probably played competitive inhibitors for metabolism of toluene. The study also presumed that urinary HA became the major metabolite of ethyl benzene at the end of work shift, when the exposure concentrations of ethyl benzene were 2.0 times those of xylene.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
American Conference of Governmental Industrial Hygienists (2001) Documentation of the threshold LIMIT values and biologic exposure indices, 7th ed. American Conference of Governmental Industrial Hygienist, Cincinnati, OH
Clayton GD, Clayton FE (1993) Patty’s industrial hygiene and toxicology. Volumes 2A, 2B, 2C, 2D, 2E, and 2F: Toxicology. 4th ed. Wiley, New York, NY, p 1343
Engstrom K, Riihimaki V, Laine A (1984) Urinary disposition of ethylbenzene and m-xylene in man following separate and combined exposure. Int Arch Occup Environ Health 54:355–363
Engstrom K, Elovaara E, Aitio A (1985) Metabolism of ethylbenzene in the rat during long-term intermittent inhalation exposure. Xenobiotica 15:281–286
Ikeda M (1995) Exposure to complex mixtures: Implications for biologic monitoring. Toxicol Lett 77:85–91
Jacobson GA, McLean S (2003) Biologic monitoring low level occupational xylene exposure and the role of recent exposure. Ann Occup Hyg 47(4):331–336
Jang JY, Droz PO, Kim S (2001) Biologic monitoring workers exposed to ethylbenzene and coexposed to xylene. Int Arch Occup Environ Health 74:31–37
Lauwerys RR, Hoet P (2001) Industrial chemical exposure: Guidelines for biologic monitoring, 3rd ed. Lewis, Boca Raton, FL, p 220
Mao IF, Chen ML, Lo EW (1996) Simultaneous determination of urinary metabolites of toluene, xylene, styrene and ethyl benzene by solid-phase extraction technique and high-performance liquid chromatographic/photo diode array detection. Int J Environ Anal Chem 64:1–9
National Institute for Occupational Safety and Health (2003) Manual of analytic methods, 4th ed. Issue 3, method 9301: Hippuric and methyl hippuric acids in urine. National Institute for Occupational Safety and Health, Cincinnati, OH
Riihimaki V, Savolainen K, Pfaffli P, et al. (1982) Metabolic interaction between m-xylene and ethanol. Arch Toxicol 49:253–263
Tardif R, Lapare S, Plaa GL, Brodeur J (1991) Effect of simultaneously exposure to toluene and xylene on their respective biologic exposure indices in humans. Int Arch Occup Environ Health 63:279–284
Tardif R, Charest-Tardif G, Brodeur J, Krishnan (1997) Physiologically based pharmacokinetic modeling a ternary mixture of alkyl benzene in rats and humans. Toxicol Appl Pharmacol 144:120–134
Tassanuyakul W, Birkett DJ, Edwards JW, et al. 1996. Human cytochrome P450 isoform specificity in the regioselective metabolism of toluene and o-, m-, and p-xylene. J Pharm Exp Ther 276(1):101–108
Taussky HH (1954) A microcolorimetric determination of creatine in urine by the Jaffet’s reaction. J Biol Chem 208:853–861
Thienes C, Haley TJ (1972) Clinical toxicology, 5th ed. Lea and Febiger, Philadelphia, PA, p 126
Toftgard R, Nilsen OG (1982) Effect of xylene and xylene isomers on cytochrome P-450 and in vitro enzymatic activities in rat liver, kidney and lung. Arch Toxicol 23:197–212
Okayama Igakkai Zasshi 96 Yamasaki Y (1984) The determination of urinary metabolites of ethylbenzene in men by high performance liquid chromatography. Okayama Igakkai Zasshi 96 (5/6):531–535
Acknowledgments
The investigators thank the National Science Council, Taiwan (Contract No. NSC 91-2320-B-010-074) for financially supporting this research. We are also indebted to the spray painters who participated in this study.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Mao, I.F., Chang, F.K. & Chen, M.L. Delayed and Competitively Inhibited Excretion of Urinary Hippuric Acid in Field Workers Coexposed to Toluene, Ethyl Benzene, and Xylene. Arch Environ Contam Toxicol 53, 678–683 (2007). https://doi.org/10.1007/s00244-006-0084-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00244-006-0084-5