Estimating amounts of toluene inhaled by workers with protective mask using biological indicators of toluene.

Personal air samplers were attached to workers wearing protective masks to determine the levels of toluene vapor in the breathing zone. Concentrations of toluene in exhaled air, blood and urine; and hippuric acid and o-cresol concentrations in the urine of the workers were determined. Subsequently, toluene concentrations in the air inhaled by workers with and without gas masks were estimated by single and multiple regression equations. Analysis of single regression equations revealed that, compared with toluene concentrations in air, masks decreased the concentrations of the four biological exposure indicators: toluene in exhaled air, urinary toluene, urinary hippuric acid and urinary o-cresol by about 29% in average. Analysis by multiple regression equations showed a decrease of 38% in four biological indicators. Since average exposure to toluene in the shop was relatively low, the workers wore the masks only during high concentrations of toluene; they were, however, exposed to direct inhalation when the masks were removed in lower concentrations.

Large-scale biological monitoring in Japan.

Data from the large-scale biological monitoring program in Japan were assembled and analyzed and the following results were obtained. All workers handling lead and eight kinds of major organic solvents received physical examinations and biological monitoring at the same time. Therefore, the number of workers handling industrial chemicals and that received physical examinations and the number of workers been examined by biological monitorings were similar to each other. The total number of cases examined from 1989 to 1994 was about 661,000 for lead in the blood and about 4,173,000 for the urinary metabolites of eight organic solvents. The results were classified into three categories and category 3 consists of workers having exposure concentrations above the 1988-1989 biological exposure indices of the ACGIH with the exception of lead concentration in the blood where the limit in Japan was set at 40 micrograms/100 ml. The percentage of exposed workers in category 3 was 1.4% for blood lead and 0.2-2.4% for the urinary metabolites of the eight organic solvents. The percentage of exposed workers in category 3 for blood lead, delta-aminolevulinic acid, urinary mandelic acid, N-methylformamide and 2,5-hexanedione in the urine has decreased with time. In ambient monitoring, the percentage of workplaces in classification 3 for lead and styrene also has decreased with time.

[Determination of acetone, methanol, and methyl ethyl ketone in urine using head-space gas chromatography (HS.GC)].

Using HS.GC, We have succeeded in simultaneous determination of Ac, MeOH and MEK in urine without any complicated pretreatment or correction by internal standard. Moreover, in order to lower the detection limits of these materials, study was made on the salting out effect using 14 kinds of salts. As pretreatment, 2.0 ml of urine, 3.0 g of sodium sulfate and small sized magnetic stirrer are put into vial, which is sealed by septum. This is then heated for 10 min in warm bath of 50 degrees C. In order to dissolve the added salts as much as possible, the specimen is stirred by the stirrer. After cooling the liquid to room temperature, the specimen is analysed by HS.GC. The results showed that sodium sulfate was excellent synthetically. 1) Using the urine of workers not exposed to organic solvents three kinds of urine having specific gravity of 1.010, 1.024 and 1.034 were prepared and mixed standard organic solvents (Ac, MeOH and MEK) were added. Recovery percentages and coefficients of variation were calculated. The results showed that recovery percentages ranged from 92.0 to 101.7% and coefficients of variation from 0.2 to 4.6%. 2) The regression equations of standard curves were satisfactory with y = 9053x - 200(r = 0.999, n = 12) for Ac, y = 801x - 400 (r = 0.999, n = 12) for MeOH, and y = 15488x - 277 (r = 0.999, n = 12) for MEK. 3) The detection limits calculated by IUPAC formula were 0.0092 mg/l for Ac, 0.11 mg/l for MeOH and 0.0063 mg/l for MEK. These results indicated that this method is superior to other methods because the pretreatment is very simple, specificity is excellent, analysis by standard curves is possible, and this method is not affected by specific gravity of the urine.

[Determination of trichloroacetic acid and trichloroethanol by head-space gas chromatography (HS.GC)].

Simultaneous determination of trichloroacetic acid (TCA) and trichloroethanol (TCE) in urine was made using head-space gas chromatography (HSGC). TCA was analyzed after methyl esterification by methanol, and TCE was measured with decomposition of conjugation adding sulfuric acid. (1) As preliminary treatment, 0.1 ml of urine and 0.6 ml of esterizer (pure water: sulfuric acid: methanol = 6:5:1, V/V/V) were mixed in a sample vial, which was sealed a septum. This was analyzed in HSGC. (2) By this method, the recovery, standard deviation and coefficient of variation of TCA were 95.7-104.3%, 0.001-0.783 mg/l and 0.8-4.0%, respectively, while those of TCE were 98.6-102.5%, 0.024-1.603 mg/l and 0.8-4.0%, respectively. (3) Calibration curves were linear up to 30 mg/l for TCA (y = 1.838x + 0.023, r = 0.999, n = 8) and 60 mg/l for TCE (y = 0.963x + 0.072, r = 0.999, n = 8). (4) A high correlation between HSGC and alkaline pyridine spectrophotometry was found for both TTC (TCA + TCE = TTC), (y = 0.917x - 3.08, r = 0.980, n = 100, p less than 0.001) and TCA (y = 0.891x - 2.36, r = 0.928, n = 100, p less than 0.001). The values for TCA and TCE obtained with HSGC were lower than those obtained with spectrophotometry. (5) The limits of the detection obtained with this method were 0.002 mg/l for TCA and 0.005 mg/l for TCE according to the formula recommended by International Union of Pure and Applied Chemistry (IUPAC). These results indicate that this simple method is accurate and useful in simultaneous detection of TCA and TCE.