Factors influencing urinary metabolites among factory employees exposed to toluene and xylene in Thailand

Abstract

ABSTRACT          The aim of this study was to determine factors influencing urinary matabolites among factory employees exposed to toluene and xylene. Data were collected from 118 employees exposed to mixed solvents in 4 factories, and 100 non-exposed employees in a frozen-food factory. Demographic information was obtained by interview. Exposure was determined by personal air samplers and urinary metabolite levels. The average age of the study group was 32.8 (7.3) years. The mean concentration of toluene was 7.50 (9.92) ppm, and xylene was 2.17 (2.30) ppm, respectively. The t-test found significant differences between the exposed and control groups for concentrations of toluene and xylene (p < 0.001). Significant positive associations were found between concentration of toluene and urinary hippuric acid among exposed male and female employees (95% CI = 8.24, 32.21 and 95% CI = 5.61, 80.14). Xylene was associated with urinary concentration of methyl hippuric acid among the whole subject group and the exposed male employees (95% CI = 11.13, 22.29, and 95% CI = -7.37, 133.30), respectively. The results suggested that urinary hippuric acid remained a useful biomarker of toluene exposure among the employees exposed to mixed solvents, and methyl hippuric acid to xylene exposure.