• Journal of the Korean Electrochemical Society
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• v.17 no.3
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• pp.172-178
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• 2014

In this work, we describe an electrochemical immunosensor for simple, fast and quantitative detection of a urinary hippuric acid (HA). Urinary HA, of molecular weight 180 DA, is one of the major metabolites and biological indicators in toluene-exposed humans. Simple and ubiquitous monitoring of exposure to toluene is very important in occupational health care. We propose the electrochemical immunoassay based on the dopamine-antigen conjugate for detecting hippuric acid. Our electrochemical immunoassay system employs a conjugate of dopamine (DA) as an electrochemical active molecule and hippuric acid (HA) as an antigen. As an electrochemical aspect, dopamine (DA) containing two hydroxyl group can show excellent redox signal. Also, dopamine-tethered hippuric acid (DA-HA) shows the reversible redox signal in the immunoassay. The competition between HA and DA-HA generated electric signals proportional to HA concentration. The electrochemical immunoassay was performed with DA-HA on the screen printed carbon electrodes (SPCEs), and then applies the mixture antigen (HA) and HA-antibody. The electrical signals were proportional to HA in the range of 0.010~2.500 mg/mL which is enough range to be used for the point-of-care.

• Journal of Environmental Impact Assessment
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• v.24 no.2
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• pp.154-162
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• 2015

Correlation between occupational exposure levels to toluene and urinary hippuric acid (HA) concentrations were studied for 124 workers at 54 work places. The highest indoor toluene concentration measured at printing process was 81.116 ppm, and their geometric average concentration was as high as 12.304 ppm. The geometric average concentration of hippuric acid in urine samples from workers who are exposed to toluene was 0.714 g/g creatinine. This is almost five times higher than the average HA concentration from non-exposure workers. Printing workers showed the average HA concentration of 1.145 g/g creatinine from their urine samples. It is the highest concentration among the workers exposed to toluene. The correlation coefficient between HA concentrations in urine and indoor toluene concentration at work places was relatively high as r=0.624 (P<0.01). But the correlations of HA with sex, smoking, drinking, age and employment history was relatively low. We can express the regression equation for the urinary HA concentration which is Y = 0.037X + 0.562 as exposure toluene concentration is X. The urinary HA concentrations showed significantly increase depend on indoor toluene concentration at work place.

• Journal of Environmental Health Sciences
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• v.43 no.4
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• pp.324-333
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• 2017

Objectives: The purpose of this study was to assess the correlation relationship between personal exposure and urinary hippuric acid in biological monitoring for airborne toluene in an industrial complex and in general environments. Methods: Personal exposure to toluene and its metabolite, hippuric acid, in urine were simultaneously measured in occupational environments area near an industrial complex and in general environments. The study subjects were divided into three types: 137 workers who use organic solvents in the workplace, 210 residents living near a dyeing industrial complex, and 379 residents living in general environments. The toluene exposures of workers and residents were measured by a passive sampler for four days. The urine of participants was sampled when the passive samplers of personal exposure were collected. Results: The toluene and hippuric acid concentrations of workers were the highest, followed by the concentrations of residents living near a dyeing industrial complex and residents living in general environments. The coefficient of correlation between the concentrations of toluene and hippuric acid among workers was 0.749 (p<0.01) in the workplace. On the contrary, correlations between the concentrations of toluene and hippuric acid among residents living near a dyeing industrial complex and residents living in general environments were all not significant. The relationship between the concentrations of hippuric acid and toluene in three types could be described by the exponential growth model. Conclusions: This study analyzed the relationships between toluene exposure and the concentrations of hippuric acid in urine in high, middle, and low exposure environments, and could be described by the exponential growth model.

• Biomedical Science Letters
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• v.18 no.1
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• pp.42-48
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• 2012

This study was performed to investigate the urinary methyl hippuric acid (UMHA) excretion among aircraft maintenance workers exposed to xylene by examination of blood test, urine test and biochemical tests. Study subjects (301) were divided into 2 groups; non-exposed group (n=123, who were not exposed to xylene), and exposed group (n=178, who were exposed to xylene). The average of blood level and MHA level was normal. The ${\gamma}$-GTP level was 35.5 IU/L (45.7%) in the exposed group and 27.9 IU/L (44.7%) in the non-exposed (control) group. The proportion of total cholesterol (TG) level higher than 150 mg/dl were 34.3% in the exposed group and 21.1% in the non-exposed group. These results were showed statistically significant difference (${\chi}^2$ = 6.10, P<0.05). Other items showed no statistically significant differences. The results of urine tests were no statistically significant differences in protein, occult blood and glucose level.

• 대한예방의학회:학술대회논문집
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• 1995.10a
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• pp.259-260
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• 1995

• 대한예방의학회:학술대회논문집
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• 1995.10a
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• pp.365-366
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• 1995

• 대한예방의학회:학술대회논문집
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• 1996.10a
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• pp.419-420
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• 1996

• Journal of Preventive Medicine and Public Health
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• v.19 no.2 s.20
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• pp.177-183
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• 1986

Subjective symptoms, counts of blood cells and liver function test were conducted on 198 male workers who were exposed to toluene in Kyungin area from September to November, 1986. According to the level of urinary hippuric acid concentration, the total sample was classified into the high exposure group ($concentration{\geqq}3g/1$) and the low exposure group(concentration<3g/1). The following findings were obtained by comparing the two group: 1) Contrary to the previous findings. the urinary hippuric acid concentration of toluene exposed workers showed bimodal distribution. It meant that the toluene exposed workers were mixed with the non-exposed or minimal exposed workers. 2) The high exposure group showed a lower level of leucocytes counts ($6,630{\pm}1,860{\mu}l$) than the low exposure group ($6,340{\pm}1,960/{\mu}l$). 3) The high exposure group showed a higher level of SGOT, SGPT and r-GTP than the low exposure group (p<0.05). 4) The high exposure group complained much more subjective symptoms (e. g. skin rash, loss of appetite, palpitation) than the low exposure group.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.1
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• pp.48-58
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• 1995

This study was performed to find out the exposure level of mixed organic solvents, excretion of urinary hippuricacid and subjective symptoms according to the exposure of organic solvents of female workers who works on 5 shoes manufacturing industries in Taejon City from 24, september to 20, october 1993. The studied groups were divided into 3 groups that were consist of direct exposure group(48 workers), indirect exposure group(49 workers) and non-exposure group(68 workers) to the organic solvents. The exposure levels of toluene of direct exposure group which $89.86{\pm}56.20ppm$ had higher than that of indirect exposure group which had $40.23{\pm}47.21ppm$. In the exposure level of mixed organic solvent(R-value), direct exposure group was $2.84{\pm}1.53$ and exceeded approximatly 3 times the R-value. Whereas, indirect exposure group was not exceeded the R-value as $0.80{\pm}0.61$. In the excretion level of urinary hippuric acid, direct exposure group was $1.78{\pm}1.25g/l$, indirect exposure group was $1.22{\pm}0.93g/l$ and non-exposure group was $0.51{\pm}0.18g/l$ respectively. Therefore both direct exposure group and indirect exposure group were significantly higher than non-exposure group(P<0.01). In the correlation between toluene levels and urinary hippuric acid level, the direct exposure group had positive correlation(R=0.8309, P<0.01), also indirect exposure group had positive correlation(R=0.5859, P<0.05) and also in the correlation between the R value of mixed organic solvents and the urinary hippuric acid levels, the direct exposure group had positive correlation(R=0.4492, P<0.05), and indirect exposure group had ositive correlation(R=0.7911, P<0.01). In the complain rates of the worker's subjective symptoms at work, both direct exposure group and indirect exposure group were higher than non-exposure group(P<0.05, P<0.01). But the sujective symptoms of "floating sensation" of direct exposure group had significantly higher than indirect exposure group. In the percent of subjective symptoms complaints during the worker's daily life, both direct exposure group and indirect exposure group had generally more statistical significance than nonexposure group(P<0.01), direct exposure group had not statistical significant difference from indirect exposure group. As the results mentioned above, it has been analysed that the indirect at the adjacent manufaturing process are exposed to the considerable amount of solvent. Therefore, I think that there should be the betterment of surrounding through the complete working environment management to the occurrence source of the organic solvent, the changes of health management system to the indirect-exposed workers, and the systematic management of the special medical examination and the like.

• Journal of Life Science
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• v.9 no.2
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• pp.136-145
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• 1999

The purpose of this study was to evaluate the effect of organic slovents and noise on hearing loss. We selected organic solvents exposed group of 32 cases, noise exposed group of 31 cases, both noise and solvent exposed group of 31 cases, and control group of 53 cases and studied the relation between exposure level of noise and organic solvents and degree of hearing loss. The results were as follows. The subjects under investigation were exposed to noise and organic solvents under threshold limit values and the amount of urinary hippuric acid excretion were also under biological exposure indices. In case of noise, both noise and organic solvents exposed group and noise exposed group were more exposed than organic solvents exposed group(p<0.05). When urinary hippuric acid excretion were concerned, both noise iud organic solvents exposed group and organic solvents exposed group showed higher values than noise exposed group(p<0.05). In comparison of mean auditory threshold values by frequency, on the air conduction test, both noise and organic solvents exposed group showed significantly higher hearing loss than noise exposed group in 500Hz of right ear, 500 and 2000Hz of left ear(p<0.05). Forty-three cases among 147 subjects were regarded as hearing loss group and average age(42.6years) of hearing loss group was higher than normal groups average age of 38.0 years. Urinary hippuric acid excretions of hearing loss group were significantly higher than normal group(p<0.05). Thirty-eight percent(12cases) of noise exposed group, 40.6 $\%$(13cases) of organic solvents exposed group, 51.6 $\%$(16cases) of both noise and organic solvents exposed group, and 3.8 $\%$(2cases) of unexposed group were regarded as hearing losers. Exposed groups showed higher incidence of hearing loss than unexposed group but there were no significant differences among the exposed groups. The variables showing significant correlation with hearing loss were age and the amount of hippuric acid in urinary excretion. When age were adjusted for the purpose of seeing the effects of hearing losses due to organic solvent, urinary excretion of hippuric acids was the only variable with significant correlation with hearing loss (p<0.05). When odds ratio to hearing loss between control and exposed groups was considered, noise exposed group showed 6.1 times (95 $\%$ CI: 3.3-8.7), organic solvents exposed group showed 7.4 times (95 $\%$ CI: 3.5-14.6) and both noise and organic solvents exposed group showed 17.2 times(95% CI: 5.6-31.8) higher values than unexposed group(p<0.01). Above results suggest that health screening test of hearing loss is also needed in organic solvents exposed workers.