Benzyl alcohol as a marker of occupational exposure to toluene

Benzyl alcohol (BeOH) is a urinary metabolite of toluene, which has been seldom evaluated for biological monitoring of exposure to this popular solvent. The present study was initiated to develop a practical method for determination of BeOH in urine and to examine if this metabolite can be applied as a marker of occupational exposure to toluene. A practical gas-liquid chromatographic method was successfully developed in the present study with sensitivity low enough for the application (the limit of detection; 5 microg BeOH /l urine with CV=2.7%). Linearity was confirmed up to 10 mg BeOH/l, the highest concentration tested, and the reproducibility was also satisfactory with a coefficient of variation of 2.7% (n=10). A tentative application of the method in a small scale study with 45 male workers [exposed to toluene up to 130 ppm as an 8-h time-weighted average (8-h TWA)] showed that BeOH in the end-of-shift urine samples was proportional to the intensity of exposure to toluene. The calculated regression equation was Y=50+1.7X (r=0.80, p<0.01), where X was toluene in air (in ppm as 8-h TWA) and Y was BeOH in urine (in microg/l of end-of-shift urine). The levels of BeOH in the urine of the non-exposed was about 50 microg/l, and ingestion of benzoate as a preservative in soft drinks did not affect the BeOH level in urine. The findings as a whole suggest that BeOH is a promising candidate for biological monitoring of occupational exposure to toluene.