Saliva as an analytical tool to measure occupational exposure to toluene

OBJECTIVE: To describe a sensitive and rapid method for the determination of toluene in saliva. Biomonitoring of toluene exposure is commonly performed by determination of urinary hippuric acid, o-cresol or toluene itself. The analysis of blood toluene has been verified as another method for biomonitoring. However, drawing blood is invasive and can often not be performed at the workplace for hygienic reasons. Sampling of saliva may be non-invasive, easy to perform and a viable alternative for biomonitoring in the workplace. METHODS: We measured the solvent concentration in saliva specimens of 5 healthy volunteers studied in the laboratory and a group of 36 workers exposed to toluene in the synthetic leather industry. Saliva was collected into Salivette (Sarstedt, Germany) devices by sterile cotton rolls placed in the mouth and then squeezed into pre-weighted vials. Environmental toluene was collected for the duration of a work-shift by Radiello (FSM, Italy) passive samplers. Toluene in urine and saliva (head space analysis) and in environmental samples was measured by GC-MS. RESULTS: Environmental toluene levels ranged from 0.22 to 57.20 mg/m(3), while the concentrations of the solvent in saliva and urine ranged from 0.12 to 18.30 microg/L, and from 0.47 to 26.64 microg/L, respectively. The correlation coefficients (r) between biological and environmental levels of toluene were 0.77 and 0.93, respectively, for saliva and urine samples. CONCLUSION: This preliminary study suggests that saliva may offer many advantages over 'classical' biological fluids such as blood as it is readily accessible and collectible: therefore saliva toluene may be considered as a possible biomarker of exposure to toluene.