Takeo Tabuchi

Evaluation of hippuric, phenylglyoxylic and mandelic acids in urine as indices of styrene exposure

SummaryIn addition to those of phenylglyoxylic and mandelic acids, a distinct increase in hippuric acid level was observed in the urine of factory workers who were exposed to styrene at 50 to 200 ppm for 160 min. Comparison of the postexposure levels with respective non-exposure levels and supplements with rat exposure experiments revealed hippuric acid to be a poor indicator of styrene exposure at a “moderate degree”, while the other two acids are much more adequate indices. At a higher dose of styrene (e.g., 500 mg/kg i.p. or 100 ppm for 8 hrs for rats), however, the urinary levels of phenylglyoxylic and mandelic acids reach plateaus, while hippuric acid level remained proportional to the amount of styrene given.The biological half-life of styrene in human subjects is approximately 8 hrs as measured by the disappearance of phenylglyoxylic and mandelic acids from urine.

Correlation between lead in plasma and other indicators of lead exposure among lead-exposed workers.

In order to clarify the bioavailability of lead in plasma (PbP), we performed a study on five workers in a Japanese factory manufacturing lead glass-based paints. Blood and urine samples were obtained over a period of 15 months, during which time the workers took it in turns to perform sifting work (with the highest level of lead exposure) for 1-month periods. A total of 75 sets of blood and urine samples were thus obtained. We determined whole blood lead (PbB), PbP, Urinary coproporphyrin (CPU), urinary δ-aminolevulinic acid (ALAU), urinary lead (PbU) and ALA in plasma (ALAP). In the 15 sets of samples obtained at the end of the period with a high level of lead exposure, PbP correlated significantly with ALAU, CPU, PbU and ALAP, but PbB correlated significantly only with PbU. In the 60 sets of samples obtained following a low level of lead exposure, correlation coefficients between the concentrations of PbP and of ALAU, CPU and PbU exceeded those between the concentrations of PbB and of ALAU, CPU and PbU. These findings indicate that PbP is a better dose indicator of lead biochemically available for heme synthesis and that PbU has a closer correlation with PbP than with PbB.

Identification of urinary metabolites in rats treated withp-chloronitrobenzene

Urinary metabolites in rats treated withp-chloronitrobenzene were identified by gas chromatography-mass spectrometry. A single dose of 100 mg/kg body wtp-chloronitrobenzene was administered intraperitoneally to male Sprague-Dawley rats and urine samples were collected from the 8th to 24th hour after the administration. Urinary metabolites were extracted with diethylether at pH 1.0 and pH 10.0 from urine samples hydrolyzed with acid and base and from intact urine samples. Aliquots of the ethereal extracts were injected into a gas chromatograph-mass spectrometer. Nine substances were identified:p-chloroaniline, 2,4-dichloroaniline,p-nitrothiophenol, 2-chloro-5-nitrophenol, 2-amino-5-chlorophenol,p-chloroformanilide, 4-chloro-2-hydroxyacetanilide, a small amount ofp-chloroacetanilide and traces of unchangedp-chloronitrobenzene.

Load on the low back of teachers in nursery schools

In order to evaluate the load on the low back of teachers in nursery schools, basic activity, working posture, child-lifting, and desk-lifting were analyzed for eight nursery teachers using video recording. The trunk inclination angle (TIA) was also measured continuously during full workshifts for 20 nursery teachers using an inclination monitor. The nursery teachers in the 0–1 (year) age class more often adopted low working postures, “sitting on the floor” and “kneeling,” while teachers in the 4–5 age class more frequently adopted high working postures, “standing” and “sitting on a chair.” The mean of TIA among all subjects was 20°. The time spent at a TIA of more than 20° represented 43% of the workshift. The mean and time distribution of TIA did not differ between the age classes. The frequency of trunk-lifting from severe bending forward (TIA > 45°) was 86 times/hour on average. The frequency of trunk-lifting was highest in the 0–1 age class. The number of times of child-lifting was 46 in the 0–1 age class, while it was 1 in the 4–5 age class.

A new HPLC fluorimetric method to monitor urinary delta-aminolevulinic acid (ALA-U) levels in workers exposed to lead

SummaryA new sensitive HPLC method for the determination of urinary delta-aminolevulinic acid (ALA-U) was used to evaluate the relationship between blood-lead (Pb-B) and ALA-U levels in male workers exposed to lead. The differences between the ALA-U levels determined by this method (ALAU-HP) and by a colorimetric method (ALA-U-CL) are discussed. The HPLC method gave values similar to the ALA-U-CL values at high ALA-U level. However, at low blood-lead levels (58 ± 22 μg/l, n = 23), the mean ALA-U-HP level corrected by urinary creatinine level was one-third of the corrected ALA-UCL level (0.83 ± 0.14 and 2.4 ± 0.5 mg/g creatinine, respectively). A significant increase of the mean corrected ALA-U-HP level was observed at 162 ± 22 μg/l Pb-B (P < 0.05, n = 26), while that of ALA-UCL was observed at 245 ± 30 μg/l Pb-B (P < 0.01, n = 37). The regression equation based on the logistic model fitted well to the relationship data between the Pb-B level and the percentage of the subjects with corrected ALA-U-HP above the cut-off point (1.12 mg/g creatinine) and the expected Pb-B level for 50% response was 270 μg/l Pb-B, while it did not fit well to the relationship data between Pb-B level and the percentage of the subjects with corrected ALAU-CL above the cut-off point (3.5 mg/g creatinine). The maximum responses for the two sets of corrected ALA-U levels were both observed at 625 ± 25 μg/l. The corrected ALA-U level by HPLC method seems to be a useful indicator for biological monitoring of exposure to lead at low levels (< 400 μg/l Pb-B = health-based biological limit, WHO) as well as high ones.

A field survey on the health status of workers in dye-producing factories

SummaryHealth status of the workers in dye-producing plants were examined repeatedly in winter and in summer. The items studied cover 1) diazo-positive metabolites in urine 2) methemoglobinaemia, Heinz bodies, methemoglobin reductases and anaemia, and 3) liver function. The urinary diazo-positive metabolite level in the exposed was higher than that in the non-exposed and marked a conspicuous increase in summer as compared in winter, indicating significant intake of the aromatic nitro-amino compounds, while no significant methemoglobinaemia, Heinz bodies, anaemia nor disturbed liver function was observed in any group of the examinees. The results were discussed in connection with the dose-effect relationship, and compared with the experiences in the past.

Effects of Variation in Exposure to Airborne Acetone and Difference in Work Load on Acetone Concentrations in Blood, Urine, and Exhaled Air

Using a physiologically based pharmacokinetic (PBPK) model, the effects of variation of exposure concentration of acetone on three biological indicators--acetone concentrations in blood, urine, and exhaled air--were investigated. The effect of the difference in work load was also examined. It was confirmed that the model could be used to estimate acetone concentrations during fluctuating exposure by comparing simulated acetone concentrations with the corresponding values observed in field surveys. By inputting the exposure situations into the PBPK model, the variabilities of the biological indicators were simulated. The variation of acetone exposure was expressed by seven 1-hour time-weighted averages (CEXPs). The arithmetic means of the CEXPS were 200 and 750 ppm. The geometric standard deviations (GSDs) were 1.5, 2.0, and 3.0, representing low, moderate, and high variations, respectively. Work loads were set at 15 and 50 W. Consequently, there were 12 exposure situations. The acetone concentrations in venous blood (CB) and exhaled alveolar air (CA) at 1 minute after the end of the work shift were selected as biological indicators of exposure because they were predicted to decrease rapidly at the end of exposure and become relatively stable after 1 minute. The acetone concentration in urine excreted during the last 2 hours of the work shift (CU) was also used as a biological indicator. Simulation was repeated 100 times with randomly permuting CEXPs for each situation. The mean values of CB, CU, and CA showed almost no variation regardless of the difference in the GSD of CEXPs. The coefficients of variation increased with the GSD of CEXPs but were less than 0.2. Consequently, these variables were acceptable as biological indicators of daily average exposure for the same work load. However, the difference in work load greatly changed the mean values of CB, CU, and CA, thus making it difficult to use these variables as indicators of daily average exposure for different work loads.

Effects of Dioxin on Metabolism of Estrogens in Waste Incinerator Workers

The authors measured the concentrations of serum dioxins and urinary estrogen metabolites in 57 male waste incinerator workers to determine whether dioxin influenced the metabolism of estrogens. Concentrations of serum dioxin levels and urinary estrogen metabolites, such as estrone, 17α-estradiol, 2-hydroxyestrone, 2-methoxyestrone, 2-hydroxyestradiol, 2-methoxyestradiol, 4-hydroxyestrone, 4-hydroxyestradiol, 4-methoxyestradiol, 16-hydroxyestrone, and estriol from the workers were measured. An analysis of covariance showed that mean estriol concentrations, adjusted for confounding factors among 3 serum dioxin levels, indicated a progressive increase with increasing serum dioxin level: 1.30, 1.41, and 2.02 nmol/mol creatinine at <30.3, 30.3-39.7, and >39.7 pg toxicity equivalent quantity/g lipid, respectively (F = 3.56, p = .036). This study showed that dioxin acts to metabolize estrogens to 16-hydroxyestrogens rather than to 2-or 4-hydroxyestrogens.