Hippuric acid and ortho‐cresol as biological indicators of occupational exposure to toluene

Abstract

Industrial exposure to toluene was studied in a group of 18 subjects working in a printing plant, exposed only to this solvent. Environmental monitoring was carried out using personal samplers for the whole work-shift. Urine samples were collected for the determination of hippuric acid and ortho(o)-cresol before toluene exposure, at the end of the work-shift, and 5, 9, and 17 h after the end of the work-shift. The values of two metabolites in all the urinary samples were corrected for g creatinine and specific gravity (1.024). Toluene time weighted average (TWA) concentrations ranged from 51 to 221 mg/m3 (7-h samples; two samplings lasting 3.5 h each). Urinary hippuric acid and o-cresol values at the end of the work-shift were significantly higher than the prework-shift values. Both hippuricuria and o-cresoluria end-of-work-shift values, corrected for creatinine and specific gravity, were significantly related to the mean daily environmental concentration of toluene, the correlation being weaker for o-cresol. Correlation coefficients were 0.88 and 0.84 for hippuric acid and 0.63 and 0.62 for o-cresol after correction for creatinine and specific gravity, respectively. No significant relationship was observed between environmental exposure and the values of the two urinary metabolites 5, 9, and 17 h after the end of the work-shift. Extrapolated values from the linear regression analysis at 375 mg/m3 were in good agreement with the biological exposure index (BEI) suggested by ACGIH for hippuric acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Limited Validity of o-Cresol and Benzylmercapturic Acid in Urine as Biomarkers of Occupational Exposure to Toluene at Low Levels

“…For example, De Rosa et al 29) observed a high correlation coefficient of 0.78 for o-CR-U cr among 14 workers exposed to toluene up to 61 ppm. The same group 30) obtained a similarly high coefficient of 0.79 for o-CR-U cr among 18 printers exposed to up to 59 ppm. Nise 23) observed a correlation coefficient of 0.57 for o-CR-U cr in a factory survey in which 58 workers were exposed to toluene at 25.6 ppm as a median and 132 ppm as the maximum.…”

Validation of Urine Density Correction in Cases of Hippuric Acid and Un-metabolized Toluene in Urine of Workers Exposed to Toluene

“…When the CCs were compared among the former 8 reports, it was observed that the CCs for observed values were significantly greater (p=0.022) than the CCs for CR-corrected values although not different from the CCs for SG-corrected values. In case of the remaining 33 cases (excluding incomplete sets of De Rosa et al 51) and Anger and Krämer 50) ), CCs calculated with CR-or SGcorrected values did not differ from the CCs with observed values (p>0.05). The lack of difference was also the case when the evaluation was made with toluene exposure cases only (n=17).…”

“…The available 37 cases (counted by analytes in urine) with CCs under more than two correction conditions are listed in Table 5. Among them, no CC with air-borne toluene was reported for SG-corrected values in case of Anger and Krämer 50) and it was also the case for observed values in De Rosa et al 51) . The types of air-borne solvents were various but the reports were most abundant for toluene.…”

Occupational Exposure to Aromatic Hydrocarbons at a Coke Plant: Part II. Exposure Assessment of Volatile Organic Compounds

“…average intensity of exposure to toluene has been investigated by several authors [18][19][20][21] . In our work no statistically significant association was found between urinary 2-methylphenol and toluene in.…”