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ABSTRACT: The present study was initiated to examine whether urinary benzylmercapturic acid (or N-acetyl-S-benzyl cysteine, BMA), a mercapturate metabolite of toluene, increases in relation to the intensity of toluene exposure, and whether this metabolite is a better marker of occupational exposure to toluene than two traditional markers, hippuric acid and o-cresol. Accordingly, end-of-shift urine samples were collected from 122 printers and 30 office clerks (all men) in the second half of a working week. Solvent (toluene) exposure of the day (8 h) was monitored by means of diffusive sampling. Quantitative relation with toluene showed that BMA had a greater correlation coefficient with toluene (r = 0.7) than hippuric acid (r = 0.6) or o-cresol (r = 0.6). The levels in the urine of the non-exposed control subjects were below the detection limit of 0.2 microg/l for BMA, whereas it was at substantial levels for hippuric acid and o-cresol (239 mg/l and 32 microg/l as a geometric mean, respectively). Thus, BMA, hippuric acid and o-cresol could separate the exposed from the non-exposed when toluene was at < 1, 50 and 3 ppm, respectively. Overall, therefore, it appeared reasonable to conclude that BMA is superior to hippuric acid and o-cresol as a marker of occupational exposure to toluene.
Toxicology Letters 04/2004; 147(2):177-86. · 3.23 Impact Factor
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ABSTRACT: A hand-saving HPLC method to measure urinary phenylmercapturic acid (PMA) was developed which allows about 35 PMA determinations per day. The method involves conversion of pre-PMA to PMA by the addition of sulfuric acid to a urine sample, extraction into an ether-methanol mixture followed by condensation under a nitrogen stream. The condensate was introduced to a ODS-3 column in a HPLC system, and PMA in the column was eluted into a mobile phase of acetonitrile: methanol: perchloric acid: water. The elution of PMA was monitored at 205 nm. One determination will be completed in 40 min. The method was applied to analysis of end-of-shift urine samples from 152 workers exposed up to 210 ppm benzene, 66 workers exposed to a mixture of benzene (up to 116 ppm) and toluene + xylenes (up to 118 ppm), and 131 non-exposed controls of both sexes. A linear regression was established between time-weighted average intensity of exposure to benzene and urinary PMA. From the regression, it was calculated that urinary PMA level will be about 6.4 mg/l after 8-hour exposure to benzene at 100 ppm, and that PMA in urine accounted for about 0.1% of benzene absorbed. No effects of sex, age, and smoking habit of individuals were detected, and the effect of co-exposure to toluene + xylenes at the levels comparable to that of benzene was essentially nil, which indicates an advantage of PMA as a benzene exposure marker over monoto tri-phenolic metabolites or t,t-muconic acid.
Industrial Health 05/2000; 38(2):195-204. · 0.94 Impact Factor
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ABSTRACT: To establish a convenient method by high-pressure liquid chromatography (HPLC) to measure toluene in urine as a marker of occupational exposure to toluene.
As soon after sampling as possible, 1 ml of urine was mixed with an equal volume of acetonitrile in a 2.2-ml HPLC glass bottle, and the bottle was tightly sealed and stored at 4 degrees C. Immediately before HPLC determination, 100 microl methanol was added to the mixture to prevent confounding effects of glycosuria, and the bottle was spun to remove any suspended matter. An aliquot of the supernate was introduced into the HPLC system and analyzed on a PRODIGY column, with an acetonitrile - perchloric acid phosphoric acid - water mixture serving as the mobile phase. The effluent was monitored at 191 nm.
The method can measure toluene in urine every 20 min, the detection limit was 2 microg/l, the coefficient of variation was less than 5%, and the recovery rate was 100%. No significant reduction in toluene concentration was observed for 1 week after storage at 4 degrees C. When the method was applied to end-of-shift urine samples from 13 male workers exposed to toluene at 18-140 ppm and also to urine samples from 10 nonexposed male controls, toluene in urine was linearly related to toluene exposure concentration, with a regression line passing close to the origin. The correlation coefficient was as high as 0.97 (n=23). No toluene was detected in control urine samples. Calculations suggest that urinary toluene accounts for as little as less than 0.01% of the toluene absorbed via inhalation and that the absorbed toluene is converted almost quantitatively to hippuric acid and, by less than 0.1%, to o-cresol.
Archiv für Gewerbepathologie und Gewerbehygiene 08/1998; 71(5):302-8. · 1.89 Impact Factor
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ABSTRACT: The relationship between the time-weighted average intensity of exposure to toluene and o-cresol concentration in shift-end urine was investigated in nearly 500 factory workers of both sexes in China, together with a similar number of nonexposed control subjects. Toluene concentration (25 ppm as geometric mean and 550 ppm as the maximum) was monitored by diffusive sampling using carbon cloth as adsorbent followed by gas chromatographic (GC) analysis. o-Cresol (up to 7 mg/l) was measured by GC after acid hydrolysis of samples. Urinary o-cresol levels correlated significantly (r = 0.69-0.77; p < 0.01) with toluene exposure in men, women and the two sexes in combination, regardless of correction for urine density. When compared with hippuric acid, however, o-cresol was less sensitive as an indicator of exposure to toluene and is not a suitable biological marker for detecting low level toluene exposure. Since urinary o-cresol level was significantly reduced by smoking, drinking, and the two habits combined, it cannot be considered reliable as an indicator of exposure to toluene.
American Journal of Industrial Medicine 06/1994; 25(5):697-708. · 1.63 Impact Factor
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ABSTRACT: The urinary excretion of hippuric acid and methylhippuric acid was studied in workers (233 subjects; 122 men and 111 women) exposed to toluene and xylenes in combination and in non-exposed controls (281 subjects; 141 men and 140 women) recruited from the same factories or factories of the same regions. Smoking and drinking habits of the subjects were obtained by medical interviews. From each worker, one urine sample was collected at the end of a shift and analysed for hippuric and methylhippuric acids by high performance liquid chromatography. Air samples for the estimation of toluene and xylenes were collected with diffusive personal samplers. There was a linear correlation between the time weighted average exposure either to toluene or xylene isomers and the concentrations of hippuric acid or methylhippuric acid isomers in urine. Essentially no difference was found in the correlation between quantitative exposure and excretion in the three xylene isomers. Comparison of the slopes of regression lines indicated the absence of metabolic interaction between toluene and xylenes at the measured concentrations. The metabolism of toluene and xylenes was significantly reduced among smokers or drinkers compared with non-smokers and non-drinkers.
Occupational and Environmental Medicine 02/1994; 51(1):42-6. · 3.02 Impact Factor
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ABSTRACT: Chromosome aberration rates and sister chromatid exchange frequency were examined in the peripheral lymphocytes of 38 male workers who were engaged in organic glass production and exposed to methyl methacrylate (MMA) vapors at the concentrations of 0.9 ppm to 71.9 ppm. The results were compared with the findings in the concurrent nonexposed male subjects. Comparison of the exposed group with the nonexposed controls showed that there were no exposure-related changes in chromosome aberration rate. SCE frequency was higher in the exposed group than in the controls, but this was considered to be due to higher ages of the former group than that of the latter. In fact, selection of nonsmokers and further classification of the exposed nonsmokers into two groups of those with exposure below and above a median MMA concentration (ca. 4 ppm) failed to show any difference among the three nonsmoking groups in cytogenetic parameters, or any dose-dependency. The present results, although in a limited number of subjects, indicate that occupational methyl methacrylate exposure under the conditions studied is not associated with mutagenicity. This conclusion confirms the absence of mutagenicity of methyl methacrylate in humans, and is in general agreement with a majority of the results of studies on mutagenicity in vitro, animal carcinogenicity and occupational cancer epidemiology of methyl methacrylate.
Industrial Health 02/1994; 32(2):97-105. · 0.94 Impact Factor
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ABSTRACT: The correlation between exposure to three xylene isomers and resulting urinary excretion of corresponding methylhippuric acid (MHA) isomers was studied among 175 Chinese workers of both sexes who had been predominantly exposed to xylenes (exposure to xylenes accounting for 70% or more of the total exposure on a ppm basis). Nonexposed controls (281 men and women) were also studied to define the background level of MHAs in urine. The solvent exposure of xylene-exposed workers during their workshift was monitored by diffusive sampling of breathing zone air, and MHAs in shift-end urine were determined by high-performance liquid chromatography. Regression analysis showed that the concentration of each MHA isomer correlated significantly with the time-weighted average intensity of exposure to the corresponding xylene isomer, and therefore the correlation between the sum of three xylene isomers in air and that of three MHA isomers in urine was also significant; the slope of the regression line was essentially the same among the three isomers. The calculated regression line suggested that the urinary MHA level after hypothetical exposure to xylenes at 100 ppm will be somewhat less than the proposed biological exposure index and biological tolerance value. Two social habits of smoking and drinking in combination suppressed the conversion of xylenes to MHAs in male workers.
Archiv für Gewerbepathologie und Gewerbehygiene 02/1993; 64(7):533-9. · 1.89 Impact Factor
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ABSTRACT: A factory survey was conducted in three provinces in China from 1985 to 1989. The time-weighted average toluene concentrations in breathing zone air were monitored by diffusive sampling, whereas hippuric acid (HA) concentrations in shift-end urine samples were measured by high performance liquid chromatography (HPLC). Exposed workers (456 men and women) were those for whom toluene (up to 548 ppm toluene) accounted for greater than or equal to 90% of total exposure (by vapor concentration in ppm), whereas 517 nonexposed controls were recruited from the same factories or from factories of the same region. There was a linear correlation between the intensity of toluene exposure and HA concentration in the shift-end urine. Comparison of the results with findings in the literature shows that the toluene-induced increase in urinary HA concentration among workers in China is significantly smaller than the published values, whereas HA concentrations in urine samples from nonexposed controls are comparable to the levels previously reported.
American Journal of Industrial Medicine 02/1992; 22(3):313-23. · 1.63 Impact Factor
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ABSTRACT: The effects of occupational exposure to N,N-dimethylformamide (DMF) on sister chromatid exchange (SCE) rates were studied in peripheral lymphocytes from 22 DMF-exposed women (aged 22-52 years) in comparison with 22 sex-, age-, and residence-matched controls. All subjects were nonsmokers and nondrinkers as confirmed by medical interview. The 22 pairs were divided by the intensity of exposure to DMF into 3 subgroups of high-exposed (8 pairs with mean DMF exposure at 5.8 ppm), middle-exposed (5 pairs with DMF at 0.7 ppm in combination with toluene at 0.9 ppm), and low-exposed (9 pairs with DMF at 0.3 ppm). The SCE rates were significantly higher in the high (P less than 0.005) and middle (P less than 0.01) exposed than in their matched pairs, and the increase was related to the intensity of DMF exposure.
Archiv für Gewerbepathologie und Gewerbehygiene 02/1992; 64(1):65-7. · 1.89 Impact Factor
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ABSTRACT: Nearly 1,000 serum samples were obtained from apparently healthy workers of both sexes in various factories in Beijing during 1988-1989 and were examined for hepatitis B virus infection markers by radioimmunoassay. The overall prevalence (all ages and both sexes combined) of cases positive for HBsAg, anti-HBs and anti-HBc were 3.7%, 36.6% and 37.7%, respectively and the rate of those negative to any of the three markers studied was 56.1%. The infection rate was lower than the values reported early in the 1980s for Beijing populations or the values for populations in other parts of China.
Asia-Pacific Journal of Public Health 02/1991; 5(4):345-9. · 1.06 Impact Factor
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ABSTRACT: Subjective symptoms, hematology, serum biochemistry and other clinical signs were investigated in 56 dry-cleaning workers exposed to tetrachloroethylene at 20 ppm (as a geometric mean of 8-hr time-weighted average), and the results were compared with the findings in 69 non-exposed controls from the same factories. There were exposure-related increases in the prevalence of subjective symptoms during the work as well as in the past 3 month period, whereas there was no significant changes in hematology. Effects of the exposure on liver and kidney functions were also negative as judged by emission enzyme activities, BUN and creatinine in the serum.
Industrial Health 02/1991; 29(3):111-21. · 0.94 Impact Factor
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ABSTRACT: The prevalence of HBV infection was investigated by radioimmunoassay for HBsAg, anti-HBs and anti-HBc in over 1000 workers in large scale factories located in four industrial cities (Jinxi, Shanghai, Wuxi and Xian) in 1987 to 1990. The age dependency of the prevalence was not evident. The overall prevalence rate of those positive for any of the three markers was 62.6%. The rate was significantly (p < 0.01) higher than the rates found in Beijing in a previous study but lower than the values observed in earlier studies.
Asia-Pacific Journal of Public Health 01/1991; 5(4):350-8. · 1.06 Impact Factor
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ABSTRACT: Urine samples were collected from 152 workers (64 men, 88 women) who had been exposed to benzene, 53 workers (men only) exposed to a mixture of benzene and toluene, and 213 non-exposed controls (113 men, 100 women). The samples were analysed for 1,2,4-benzentriol (a minor metabolite of benzene) by high performance liquid chromatography. The time weighted average solvent exposure of each worker was monitored by diffusive sampling technique. The urinary concentration of 1,2,4-benzentriol related linearly to the intensity of exposure to benzene both in men and women among workers exposed to benzene, and was suppressed by toluene co-exposure among male workers exposed to a mixture of benzene and toluene. A cross sectional balance study in men at the end of the shift of a workday showed that only 0.47% of benzene absorbed will be excreted into urine as 1,2,4-benzenetriol, in close agreement with previous results in rabbits fed benzene. The concentration of 1,2,4-benzenetriol in urine was more closely related to the concentration of quinol than that of catechol. The fact that phenol and quinol, but not catechol, are precursors of 1,2,4-benzentriol in urine was further confirmed by the intraperitoneal injection of the three phenolic compounds to rats followed by urine analysis for 1,2,4-benzenetriol.
British journal of industrial medicine 09/1989; 46(8):559-65.
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Bulletin of Environmental Contamination and Toxicology 09/1989; 43(2):220-4. · 1.02 Impact Factor
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ABSTRACT: Blood samples were collected from male and female factory workers aged greater than or equal to 16 years (with no occupational exposure to metals including cadmium) in the 3 cities of Hefei (323 subjects), Shenyang (78 subjects), and Jinxi (137 subjects) in China from 1985 to 1987. The samples were analyzed for cadmium in a single laboratory by automated flameless atomic absorption spectrophotometry under strict quality control. The effect of smoking was evident in Hefei, Shenyang and Jinxi, while the effect of aging was not apparent. There were no sex or regional differences in blood cadmium levels in non-smokers in the 3 cities (e.g., 1.2, 1.3 and 1.4 micrograms/l as geometric means in non-smoking women in Hefei, Shenyang and Jinxi, respectively). There was general agreement in blood cadmium levels between the present results and the values reported in the literature, although the latter values were generally based on small study populations.
Toxicology Letters 06/1989; 47(2):145-53. · 3.23 Impact Factor
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ABSTRACT: A method for rapidly determining t,t-muconic acid (MA) by high performance liquid chromatography was developed and successfully applied to urine samples from 152 workers exposed to benzene (64 men, 88 women) and 213 non-exposed controls (113 men, 100 women). The MA concentrations in urine correlated linearly with time weighted average benzene concentrations in the breath zone air of workers. A cross sectional balance study showed that about 2% of benzene inhaled is excreted into the urine as MA. The MA concentrations in the urine of the non-exposed was below the detection limit (less than 0.1 mg/l) in most cases, and the 95% lower confidence limit of MA for those exposed to benzene at 5 ppm (5.0 mg/l as a non-corrected value) was higher than the 97.5%-tile values for the non-exposed (1.4 mg/l). In practice, it was possible to separate those exposed to 6-7 ppm benzene from the non-exposed by means of urine analysis for MA. The urinary MA concentration was suppressed by coexposure to toluene.
British journal of industrial medicine 03/1989; 46(2):122-7.
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ABSTRACT: One hundred and sixty five Korean women in a shoe factory in Masan, Korea were evaluated on hepatitis B virus infection by solid-phase radioimmunoassay in 1986. The participants were women of child-bearing ages, mostly in 20's and 30's. About two thirds (105/165) of the subjects had serological evidence of past or present hepatitis B virus infection, and 17% (28/165) were HBsAg-positive. In view of possible risk of vertical transmission of hepatitis B virus, further epidemiological study was considered necessary to establish preventive measures.
Asia-Pacific Journal of Public Health 02/1989; 3(2):145-9. · 1.06 Impact Factor
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ABSTRACT: Personal monitoring of 8-hour time-weighted average intensity of exposure with diffuse samplers and analysis of shift-end urine for total trichloro-compounds (TTC) and other metabolites were conducted in two groups of workers in China, one (121 subjects) exposed to tetrachloroethylene (TETRA) alone, and the other (38 subjects) exposed to a mixture of TETRA and trichloroethylene (TRI). Urinalysis was also performed on samples from 103 non-exposed controls. A linear exposure-excretion relationship could be observed in both groups of workers. Comparison of these results with those of Japanese TETRA-workers suggested the presence of ethnic difference in TETRA metabolism. Urinary metabolite levels were markedly lower in the mixed (TETRA + TRI) exposure group as compared to previous findings in a group exposed to TRI alone. The observation indicates that metabolism of TRI is suppressed by the co-exposure to TETRA in humans.
American Journal of Industrial Medicine 02/1989; 16(6):675-84. · 1.63 Impact Factor
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ABSTRACT: The exposure-excretion relationship was investigated in 140 trichloroethylene (TRI)-exposed workers and 114 nonexposed controls. The time-weighted average intensity of exposure to TRI during the shift as measured by the diffusive sampling method was compared with metabolite levels in the urine collected at the end of the shift in the second half of a working week, when the urinary metabolite levels are expected to reach a maximum. The TRI levels in breathing zone air of the exposed workers were mostly below 50 ppm. The urinary metabolite levels (i.e., total trichloro-compounds, trichloroethanol, and trichloroacetic acid) increased as a linear function of the TRI exposure. The relationship between the two exposure indicators was statistically significant in men, women, and both combined. The cross-sectional balance study at the end of the shift revealed that about 4% of TRI absorbed will be excreted at the end of the shift, in agreement with the long biological half-life of this chlorinated hydrocarbon solvent. A possible ethnic difference in the metabolism of TRI is discussed.
American Journal of Industrial Medicine 02/1989; 15(1):103-10. · 1.63 Impact Factor
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ABSTRACT: Blood samples were obtained from 537 adults (age greater than or equal to 16 years) living in three cities in China; in Hefei in 1985, and in Shenyang and Jinxi in 1987. The samples were subjected to blood lead (Pb-B) analyses. The subjects were factory workers either in solvent-synthesizing or solvent application plants with no known exposure to metals (including lead). Their smoking and drinking habits were confirmed in medical interviews. Blood lead was significantly higher in smokers than in non-smokers, although no dose-dependency was observed. The Pb-B values in non-smokers were log-normally distributed. The Pb-B among non-smokers was significantly higher in men [104.0 micrograms l-1 (1.428) 87] [geometric mean (geometric standard deviation) number of determinations] than in women [75.5 micrograms l-1 (1.358) 225] when the data from the three cities were combined. There was a significant difference in the Pb-B levels of non-smoking men in the three cities studied, suggesting that regional food habits should be considered as a possible contributory factor of a non-occupational nature. The present findings are compared with observations from Korea and Japan from the viewpoint of environmental health.
Science of The Total Environment 12/1988; 77(1):35-44. · 3.29 Impact Factor
