Environmental and Biological Monitoring of Workers Exposed to Low Levels of Toluene

Abstract

The aim of the study was to assess the validity of proposed biological tests for monitoring of workers at low levels of toluene exposure. Measurements of environmental concentrations and biological tests for toluene exposure were performed for five consecutive days with six subjects, exposed to this solvent only in a printing industry. The toluene environmental concentrations, measured for each worker for the whole workshift by personal sampling pumps, ranged from 42 to 253 mg/m³. At the beginning of the working day (6:30 a.m.), hippuric acid was determined in exposed workers and in a control group; the comparison was not significant. The urine samples from exposed workers were collected at the end of the workshift and were analyzed for hippuric acid and o-cresol contents. The values were corrected for grams of creatinine. Using all available data (30 observations), a significant correlation was found between the TWA and both metabolites at the end of the workshift and between the two metabolites. The toluene TWA also was determined using passive dosimeters (24 observations); the data correlated with both urinary metabolites. Toluenemia, measured at the end of the workshift in the second and fourth day (12 observations) significantly correlated with toluene TWA concentrations obtained with the two sampling methods (r = 0.96 for charcoal tubes and 0.92 for passive dosimeters). In our opinion, the better correlation of environmental concentrations of toluene with hippuricuria than with o-cresoluria suggests that hippuric acid is a more valid biological test of occupational exposure to toluene. The good correlation with toluene TWA concentrations suggests that also toluenemia is a reliable test for biological monitoring. De Rosa, E.; Bertolucci, G.B.; Sigon, M.; Chiesura Corona, P.; Perbellini, L; Brugnone, F.: Environmental and biological monitoring of workers exposed to low levels of tolune.