The validity of urinary metabolites as indicators of low exposures to toluene.

Exposure to toluene was studied in a group of 14 subjects working in a printing industry, who were exposed to this solvent only. Environmental monitoring was carried out using personal samplers for the whole workshift over three consecutive days. Toluene TWA concentrations ranged from 37 to 229 mg/m3. At the end of the workshift on each day of investigation, urine samples were collected for the determination of hippuric acid and ortho-cresol. Hippuric acid was also determined for urine before the workshift and on the Saturday and Monday mornings after the end of exposure; hippuric acid was also determined in 16 controls over the same five-day period. At the end of the workshift, hippuricuria levels in exposed workers always turned out to be statistically different from pre-workshift levels and those of the controls. The end-of-workshift hippuricuria levels of exposed workers were significantly correlated with the mean daily environmental concentration (TWA): in the three days of comparative study, we found r = 0.63 (P less than 0.05) on Day 1, r = 0.90 (P less than 0.001) on Day 2, and r = 0.87 (P less than 0.001) on Day 3. Ortho-cresol turned out to be correlated with daily exposure less significantly than hippuric acid: r = 0.49 (n.s.) on Day 1; r = 0.78 (P less than 0.001) on Day 2, and r = 0.65 (P less than 0.05) on Day 3. Using all available data (41 observations), a very significant correlation (P less than 0.001) was found between the TWA and both metabolites (r = 0.80 for hippuric acid; r = 0.68 for o-cresol). The values of the two metabolites in the end-of-workshift urine samples (41 observations) also turned out to be well correlated (r = 0.70; P less than 0.001). The authors conclude that hippuric acid is a valid test for evaluating even low exposures to toluene.

Rubber manufacture: sampling and identification of volatile pollutants.

Volatile pollutants produced from several rubber goods manufacturing processes were sampled and analyzed. Samples were collected in the vulcanization areas of a shoe-sole factory, a tire retreading operation, and also in the extrusion areas of the retreading operation and an insulated cable manufacturer. Volatile organics from the vulcanization and extrusion operations were collected on activated charcoal, desorbed with trichlorofluoromethane and analyzed by GC/MS. Approximately 100 different compounds were identified and quantitated; their cumulative concentrations ranged from 25 to 27000 micrograms/cubic meter.

Occupational styrene exposure: environmental and biological monitoring.

Occupational exposure to styrene was studied by environmental and biological monitoring in 22 workers employed in a fiberglass reinforced plastic factory. The mean environmental styrene concentration in individual workplaces ranged from 120 to 684 microliter/l. Blood styrene, which was tested at the end of the work shift, ranged from 450 to 3700 micrograms/l. Urinary mandelic and phenylglyoxylic acid, which were determined at the end of the work shift, ranged from 133 to 2100 and from 107 to 685 mg/l, respectively. Environmental styrene exposure was better correlated with styrenemia than with mandelicuria and phenylglyoxylicuria considered either individually or together. The ratio between environmental and blood styrene showed that styrenemia was, on average, 3.3-4.9 times higher than environmental styrene concentration.

Biomonitoring of occupational toluene exposure.

Toluene exposure was studied in 20 workers employed in painting and hand-finishing in an art furniture factory. Toluene was determined in the environmental air of places of work and in the alveolar air and blood of the workers. Hippuric acid and cresols were also tested in the workers' urine. Blood and urine tests were carried out before the work shift on Monday and Friday morning and at the end of the work shift on Friday afternoon. The other tests were performed on Friday afternoon only. Alveolar toluene concentrations, which were significantly correlated with environmental toluene concentrations (r = 0.6230; P less than 0.01), corresponded to 19.4% of the toluene concentration in the atmosphere. Blood toluene was also found in painters on Monday morning and was significantly correlated with the other parameters. On Friday afternoon it was three times higher than the environmental toluene concentration. Urinary o-Cresol was highly correlated with toluene in the atmosphere, in blood and with hippuric acid in urine. On the basis of the slope of the regression line the ratio between urinary o-Cresol and blood toluene concentration was 0.99. At the end of the work shift urinary hippuric acid concentration was highly correlated with o-Cresoluria and with toluene in blood and in the atmosphere.