Urinary Hippuric Acid Concentration Research Articles

Analyzing urinary hippuric acid as a metabolic health biomarker through a supramolecular architecture

The prevalence of metabolic disorders has been found to increase concomitantly with alternations in habitual diet and lifestyle, indicating the importance of metabolic health monitoring for early warning of high-risk status and suggesting effective intervention strategies. Hippuric acid (HA), as one of the most abundant metabolites from the gut microbiota, holds potential as a regulator of metabolic health. Accordingly, it is imperative to establish an efficient, sensitive, and affordable method for large-scale population monitoring, revealing the association between HA level and metabolic disorders. Upon systematic screening of macrocycle•dye reporter pair, a supramolecular architecture (guanidinomethyl-modified calix[5]arene, GMC5A) was employed to sense urinary HA by employing fluorescein (Fl), whose complexation behavior was demonstrated by theoretical calculations, accomplishing quantification of HA in urine from 249 volunteers in the range of 0.10 mM and 10.93 mM. Excitedly, by restricted cubic spline, urinary HA concentration was found to have a significantly negative correlation with the risk of metabolic disorders when it exceeded 0.76 mM, suggesting the importance of dietary habits, especially the consumption of fruits, coffee, and tea, which was unveiled from a simple questionnaire survey. In this study, we accomplished a high throughput and sensitive detection of urinary HA based on supramolecular sensing with the GMC5A•Fl reporter pair, which sheds light on the rapid quantification of urinary HA as an indicator of metabolic health status and early intervention by balancing the daily diet.

Benzoic acid supplementation improves the growth performance, nutrient digestibility and nitrogen metabolism of weaned lambs.

Nitrogen is one of the essential components of proteins and nucleic acids and plays a crucial role in the growth and development of ruminants. However, the nitrogen utilization rate of ruminants is lower than that of monogastric animals, which not only reduces protein conversion and utilization, but also increases manure nitrogen discharge as well as causing environmental pollution. The lamb stage is an important period in the life of sheep, which can affect the production performance and meat quality of fattening sheep. The purpose of this experiment was to explore effects of benzoic acid supplementation on growth performance, nutrient digestibility, nitrogen metabolism and plasma parameters of weaned lambs. A total of 40 weaned male Hu sheep lambs with similar body weight were randomly divided into 4 groups: control with no benzoic acid (0 BA) and the lambs in other 3 groups were fed 0.5, 1, and 1.5% benzoic acid on the basis of experimental diet (0.5, 1, and 1.5 BA, respectively). The experiment lasted for 60 days. Results showed that the average daily gain of 1 BA group was significantly increased (p < 0.05) when compared to 0 and 1.5 BA groups, while an opposite tendency of dry matter intake to average daily gain ratio was observed. The dry matter, organic matter, neutral detergent fiber and acid detergent fiber digestibility of 1 BA group was significantly increased (p < 0.05) as compared with 0 and 1.5 BA groups as well as plasma albumin content. Also, the urinary hippuric acid and hippurate nitrogen concentrations in 1 and 1.5 BA groups were higher (p < 0.05) than those in 0 and 0.5 BA groups. Additionally, the nitrogen intake in 0.5 and 1 BA groups was significantly increased (p < 0.05) when compared to other groups. At 1 h after morning feeding, the plasma benzoic acid concentration of 1 BA group reached up to maximum value and was higher (p < 0.05) than other groups, and then began to decrease. Similarly, the hippuric acid concentration in plasma of 1 and 1.5 BA groups was higher (p < 0.05) than that of 0 BA group from 1 to 4 h post morning feeding. At 3 h after feeding, the urea nitrogen concentration in plasma of 0 BA group was higher (p < 0.05) than that of 1.5 BA group. Overall, the appropriate supplementation of benzoic acid (1%) in the diet can improve growth performance and nitrogen metabolism of weaned lambs.

Assessment of The Impact of Toluene Exposure on Urinary Hippuric Acid Concentration of Batik Workers in Special Region of Yogyakarta, Indonesia

Assessment of The Impact of Toluene Exposure on Urinary Hippuric Acid Concentration of Batik Workers in Special Region of Yogyakarta, Indonesia

The Effects of Fasting on Toluene Metabolite (Hippuric Acid) Excretion in Urine (A Case Study of Shoe-Makers in Tambak Oso Wilangun Village-Surabaya)

Background: An increase in toluene metabolite (hippuric acid) excretion in urine can be stimulated by such factors as fasting, smoking and coffee consumption. This research aimed at studying the effects of fasting on urinary toluene excretion of shoemakers in Tambak Oso Wilangun-Surabaya. Method: This controlled case-study was conducted to 20 workers with purposive sampling method from the population. The independent variables of the study include toluene concentration, fasting or not fasting condition, smoking, and coffee consumption. The dependent variable was urinary hippuric acid concentration. Pearson Correlation test was conducted to identify the correlation between toluene concentration and hippuric acid concentration. Paired-t-test was used to compare hippuric acid concentration in fasting and non-fasting condition. The correlations between coffee consumption and smoking and hippuric acid concentration were analyzed by using chi-square test (I±=0,05). Risk assessment was used to identify the health risk from occupational toluene exposure. Result: The research showed that most of the respondents (65) were at risk to health problems related to toluene exposure (RQ>1). The statistical tests showed no significant correlation between toluene concentration and hippuric acid concentration; there was a significant difference between hippuric acid concentration before and after fasting (p=0,016; p<I±); there was a significant correlation between hippuric acid concentration (non fasting) with smoking habit (p=0,022), coffee consuming habit (p=0,025); and between hippuric acid concentration (in fasting condition) with coffee consuming (p=0,039). Conclusion: Fasting, coffee consuming and smoking habit can increase urinary hippuric acid excretion. It is recommended for future researcher to control both coffee consumption and smoking when investigating the effects of fasting to urinary hippuric acid excretion to avoid biased results. Respondents are suggested to improve ventilation system in their workshops and use chemical cartridge respirator, apron and gloves while working. © 2019, Indian Journal of Forensic Medicine and Toxicology. All rights reserved.

34 - Evaluation of oxidative stress and toluene exposure among adolescent inhalant users at a tertiary care centre of North India

Background Inhalants are linked with numerous adverse health effects. Production of reactive oxygen species (ROS) could be one of the contributing factors. Literature suggests that intentional toluene inhalation causes a decrease in antioxidants and formation of ROS inducing oxidative stress. The present study evaluated the effect of oxidative stress among adolescent inhalant users seeking treatment at a tertiary care centre of India. Methods The study included individuals exposed to toluene (Group I) and healthy individuals with no history of drug use (Group II). Five ml of blood and thirty ml of urine was collected from each patient, meeting the inclusion criteria. Urinary Hippuric acid and serum concentrations of Malondialdehyde (MDA), Protein Carbonyls (PC), 8-hydroxydeoxyguanine (8-OHdG) Glutathione peroxidase (GPx) activity, Superoxide Dismutase (SOD) activity and Total Antioxidant capacity (TAC) were measured using Gas liquid chromatography, spectrophotometry and ELISA techniques. Statistical analysis was done using SPSS 22.0. Results A total of 134 male subjects (toluene exposed, n = 67 and unexposed, n = 67) were included. Mean Age for Group I and Group II were 14.8±2.12 and 14.7±2.02 years respectively. Mean hippuric acid concentration (mg/ml) in group I and II was found to be 1.6±1.8 and 0.3±0.3 (p Conclusion This indicates that toluene abuse is linked to oxidative stress. There is a need to create awareness among adolescent inhalant users about the adverse health effects of toluene use. Further studies with larger sample size are needed to clarify the biological significance of oxidative stress among inhalant users. Supported by National Drug Dependence Treatment Centre, AIIMS, New Delhi and University Grants Commission, Government of India.

Urinary trans-trans muconic acid (exposure biomarker to benzene) and hippuric acid (exposure biomarker to toluene) concentrations in Mexican women living in high-risk scenarios of air pollution

ABSTRACTThis study aimed to determine t,t-muconic acid (t,t-MA; exposure biomarker for benzene) and hippuric acid (HA; exposure biomarker for toluene) concentrations in the urine of women living in Mexico. In a cross-sectional study, apparently healthy women (n = 104) were voluntarily recruited from localities with a high risk of air pollution; t,t-MA and HA in urine were quantified using a high-performance liquid chromatography (HPLC) technique. Mean urinary levels of t,t-MA ranged from 680 to 1,310 μg/g creatinine. Mean values of HA ranged from 0.38 to 0.87 g/g creatinine. In conclusion, compared to data recently reported in literature, we found high urinary levels of t,t-MA and HA in assessed women participating in this study. We therefore deem the implementation of a strategy aimed at the reduction of exposure as a necessary measure for the evaluated communities.

The New Danger of Thirdhand Smoke: Why Passive Smoking Does Not Stop at Secondhand Smoke

Passive smoking exposure is a topic of great concern for public health because of its well-known adverse effects on human health (International Agency for Research on Cancer 2004). Two news articles on this topic were published in the February 2011 issue of Environmental Health Perspectives (Burton 2011; Lubick 2011). Lubick (2011) discussed the global health burden of secondhand smoke, and Burton (2011) emphasized a new and alarming consequence of smoking in indoor environments—“thirdhand smoke”—a term first coined in 2006 (Szabo 2006). Secondhand smoke is defined as “the combination of smoke emitted from the burning end of a cigarette or other tobacco products and smoke exhaled by the smoker” (World Health Organization 2007). Thus, secondhand smoke exposure consists of an unintentional inhalation of smoke that occurs close to people smoking and/or in indoor environments where tobacco was recently used. Thirdhand smoke is a complex phenomenon resulting from residual tobacco smoke pollutants that adhere to the clothing and hair of smokers and to surfaces, furnishings, and dust in indoor environments. These pollutants persist long after the clearing of secondhand smoke. They are reemitted into the gas phase or react with oxidants or other compounds present in the environment to form secondary contaminants, some of which are carcinogenic or otherwise toxic for human health (Matt et al. 2011). Thus, thirdhand smoke exposure consists of unintentional intake (mainly through inhalation but also via ingestion and dermal routes) of tobacco smoke and other related chemicals that occurs in the absence of concurrent smoking. Exposure can even take place long after smoking has ceased, through close contact with smokers and in indoor environments in which tobacco is regularly smoked. Lubick (2011) considers secondhand smoke synonymous with passive smoking, as do the majority of the authors publishing on this topic. However, in light of new evidence about thirdhand smoke (Matt et al. 2011), it is no longer appropriate to use the term “secondhand smoke” as a synonym for passive smoking or environmental tobacco smoke, because it represents a pars pro toto. In other words, using the term “secondhand smoke” mistakes one part of the problem for the whole. Instead, we propose that “passive smoking” or “environmental tobacco smoke” be used as a more inclusive term to describe any tobacco smoke exposure outside of active smoking. This question of terminology is of particular concern for researchers evaluating passive smoking exposure in indoor settings, especially in domestic environments. Since numerous countries have introduced smoking bans in enclosed public places, domestic environments have become the main sources of passive smoking exposure (World Health Organization 2007). We believe researchers should determine the independent contributions of secondhand and thirdhand smoke when they assess the magnitude of pollutant intake due to passive smoking exposure.

SMOKING AND SECONDHAND SMOKE: Global Estimate of SHS Burden

SMOKING AND SECONDHAND SMOKE: Global Estimate of SHS Burden

Influence of Coffee Intake on Urinary Hippuric Acid Concentration

Intake of foods and drinks containing benzoic acid influences the urinary hippuric acid (HA) concentration, which is used to monitor toluene exposure in Japan. Therefore, it is necessary to control the intake of benzoic acid before urine collection. Recently, some reports have suggested that components of coffee, such as chlorogenic, caffeic, and quinic acids are metabolized to HA. In this study, we evaluated the influence of coffee intake on the urinary HA concentration in toluene-nonexposed workers who had controlled their benzoic acid intake, and investigated which components of coffee influenced the urinary HA concentration. We collected urine from 15 healthy men who did not handle toluene during working hours, after they had consumed coffee, and we measured their urinary HA concentrations; the benzoic acid intake was controlled in these participants during the study period. The levels of chlorogenic, caffeic, and quinic acids in coffee were analyzed by LC-MS/MS. Urinary HA concentration increased significantly with increasing coffee consumption. Spectrophotometric LC-MS/MS analysis of coffee indicated that it contained chlorogenic and quinic acids at relatively high concentrations but did not contain benzoic acid. Our findings suggest that toluene exposure in coffee-consuming workers may be overestimated.

Follow-up Study on Occupational Exposure to Organic Solvents and Neurobehavioral Performances of Automotive Painters

Background/Aims: This study assessed occupational exposure to organic solvents and neurobehavioral performance of exposed automotive painters. The mean personal air toluene concentration (PATC), urinary hippuric acid concentration, and standard score (SS) of the modified WHO Neurobehavioral Core Test Battery (NCTB) of exposed workers in 2008 were compared with those obtained in 2004. Methods: The study subjects consisted of 48 automotive painters who had participated in the 2004 study. They were re-examined in 2008 using PATC, urinary hippuric acid concentration, and 7 test items of the NCTB. A questionnaire was used to obtain sociodemographic information. Results: The mean PATC in 2008 was 0.403 ppm, which was significantly lower (P < 0.001). The mean SS for the Digit Span Test, Benton Visual Retention Test, Pursuit Aiming Test, and Total NCTB were significantly higher in 2008 compared to those in 2004 with the exception of the Santa Ana Manual Dexterity Test that showed significantly lower mean SS in 2008 compared to those in 2004. Conclusion: The lower concentration of solvents in the workplace and a shorter duration of exposure have contributed toward an improvement in the neurobehavioral performance of automotive painters in 2008 as compared to those in 2004 with the exception of manual dexterity.

Modification of the Relationship Between Urinary 8-OHdG and Hippuric Acid Concentration by GSTM1, Gstt1, and Aldh2 Genotypes

Modification of the Relationship Between Urinary 8-OHdG and Hippuric Acid Concentration by GSTM1, Gstt1, and Aldh2 Genotypes

Modification of the relationship between urinary 8-OHdG and hippuric acid concentration by GSTM1, GSTT1, and ALDH2 genotypes

Urinary hippuric acid (HA) has been widely used as a biological marker of occupational exposure to toluene, although it is no longer valid for low levels of toluene exposure. Toluene exposure is known to induce oxidative DNA damage and the metabolism is affected by genetic polymorphisms of some metabolizing enzymes. Therefore, genetic polymorphisms of these metabolizing enzymes must be considered in the evaluation of oxidative stress caused by toluene exposure. We evaluated the relationship between urinary 8-hydroxydeoxyguanosine (8-OHdG), a marker of oxidative DNA damage, and urinary HA in individuals without occupational exposure to toluene and characterized the possible roles of GSTM1, GSTT1, and aldehyde dehydrogenase 2 (ALDH2) genotypes in the relationships between these markers. In this study, we enrolled 92 healthy Koreans. Urinary HA and 8-OHdG levels were measured and the correlations between them were statistically tested according to the GSTM1, GSTT1, and ALDH2 genotypes. HA did not significantly correlate with urinary 8-OHdG in overall subjects. However, the correlation between them showed a statistical significance in individuals with GSTM1-null, GSTT1-null, and ALDH2 *2/*2 genotypes (r = 0.766, p < 0.01). This study shows that the relationship between urinary HA and 8-OHdG concentration is modified by genetic polymorphisms of some metabolizing enzymes such as GSTM1, GSTT1, and ALDH2.

Influence of tea and coffee on biomonitoring of toluene exposure

The intake of some benzoic acid-containing foods or drinks such as green tea and coffee is known to increase urinary hippuric acid (HA) concentrations, and, unless this can be accounted for, may result in false-positive findings during the biological monitoring of toluene exposure. To investigate the influence of green tea and coffee ingestion on urinary HA concentrations. Time-weighted average exposures to toluene were monitored by measuring urinary HA in 245 car painters in 2005 and again in 2006. Samples of both urine and blood were collected during work hours. All the participants were also asked about their alcohol intake, smoking and dietary and beverage habits, especially green tea and coffee. To clarify the relationship between green tea and coffee ingestion, workers were prohibited from consuming green tea and coffee for 1 day before the health check-up in 2006. The frequency of positive urinary HA concentrations (>1.0 g/l) in heavy consumers of green tea and/or coffee was significantly higher than that of the non-consumer or light consumers (OR 2.34, 95% CI 1.15-4.74). Prohibiting green tea and coffee ingestion was effective in decreasing the frequency of falsely elevated urinary HA concentrations (P < 0.01). The consumption of green tea and/or coffee can result in an overestimation of urinary HA concentrations and cause false-positive results during the biological monitoring of workers exposed to low doses of toluene.

Effects of the Exposure to Polycyclic Aromatic Hydrocarbons or Toluene on Thiobarbituric Acid Reactive Substance Level in Elementary School Children and the Elderly in a Rural Area

Polycyclic aromatic hydrocarbons (PAH) and toluene have been reported to induce reactive oxygen species and oxidative stress. This study was performed to investigate the effects of low level exposure to PAHs or toluene on the lipid peroxidation level in elementary school children and the elderly in a rural area. Forty seven elementary school children and 40 elderly people who were living in a rural area and not occupationally exposed to PAH or toluene were the subjects of this study. Information about active or passive smoking and diet was obtained using a self-administered questionnaire. The urinary 1-hydroxypyrene (1-OHP), 2-naphthol, hippuric acid and thiobarbituric acid reactive substance (TBARS) concentrations were measured, and these values were corrected with the urinary creatinine concentration. In school children, the geometric means of the urinary 1-OHP, 2-naphthol, hippuric acid and TBARS levels were 0.02 micromol/mol creatinine, 0.47 micromol/mol creatinine, 0.14 g/g creatinine and 0.95 micromol/g creatinine, respectively. Those values for the elderly were 0.07 micromol/mol creatinine, 1.87 micromol/mol creatinine, 0.11 g/g creatinine and 1.18 micro mol/g creatinine, respectively. The mean levels of urinary 1-OHP, 2-naphthol and TBARS were significantly higher in the elderly subjects than in the children. The urinary TBARS level was not correlated with the urinary 1-OHP, 2-naphthol and hippuric acid, but they were correlated with the age of the subjects. These results suggest that low level inhalation exposure to PAH or toluene does not markedly increase lipid peroxidation, and age is a significant determinant of lipid peroxidation.

Delayed and Competitively Inhibited Excretion of Urinary Hippuric Acid in Field Workers Coexposed to Toluene, Ethyl Benzene, and Xylene

The purpose of this study was to investigate whether the metabolic suppression of hippuric acid (HA) occurs in field workers coexposed to toluene, xylene and ethyl benzene. Eleven male spray painters were recruited into this study and monitored for 2 weeks using a repeated-measures study design. The sampling was conducted for 3 consecutive working days each week. Toluene, ethyl benzene, and xylene in the air were collected using 3M 3500 organic vapor monitors. Urine samples were collected before and after work shift, and urinary HA, methyl hippuric acid, mandelic acid, and phenylgloxylic acid concentrations were determined. In the first week, toluene concentrations were 2.66 +/- 0.95 (mean +/- SE) ppm, whereas ethyl benzene and xylene concentrations were 27.84 +/- 3.61 and 72.63 +/- 13.37 ppm, respectively, for all subjects. Pre-work shift HA concentrations were 230.23 +/- 37.31 mg/g creatinine, whereas pre-work shift HA concentrations were 137.81 +/- 14.15 mg/g creatinine. Mean urinary HA concentration was significantly greater in the pre-work shift samples than in the pre-work shift samples (p = 0.043). In the second week, toluene concentrations were much lower (0.28 ppm), whereas ethyl benzene and xylene were 47.12 +/- 8.98 and 23.88 +/- 4.09 ppm, respectively, for all subjects. Pre-work shift HA concentrations were 351.98 +/- 116.23 mg/g creatinine, whereas pre-work shift HA concentrations were 951.82 +/- 116.23 mg/g creatinine. Mean urinary HA concentration was significantly greater in the pre-work shift samples than in the pre-work shift samples (p <0.01); a significant correlation (r = 0.565; p = 0.002) was found between pre-work shift urinary HA levels and ethyl benzene exposure. This study showed that urinary HA peak was delayed to next morning for workers coexposed to toluene, ethyl benzene, and xylene; xylene and ethyl benzene probably played competitive inhibitors for metabolism of toluene. The study also presumed that urinary HA became the major metabolite of ethyl benzene at the end of work shift, when the exposure concentrations of ethyl benzene were 2.0 times those of xylene.

Laboratory diagnosis of toluene-based inhalants abuse

Toluene is the main substance contained in products used as inhalants. The frequent abuse of toluene-based inhalants requires the definition of a simple laboratory parameter that allows acute exposure assessment. This study aimed at defining urinary hippuric acid (UHA) levels related to intentional exposure to toluene, and to correlate them to blood toluene concentration (BT). Methods. BT and UHA levels were measured in 65 homeless adolescents of Porto Alegre, Brazil. Results. Toluene was detected in 91.9% of the investigated population, who presented BT levels from 0.5 to 83.7 μg/mL. There was good correlation between UHA and BT concentrations (r = 0.78), and in homeless adolescents, UHA levels higher than 3.0 g/g creatinine indicate intentional exposure to toluene. Conclusions. The determination of UHA concentrations can be used as a screening method for the detection of intentional exposure to toluene, but its diagnosis must include BT toluene dosage, as well as circumstantial and clinical evidence.

A Monoclonal Antibody to Hippuric Acid: An Improved Enzyme‐Linked Immunosorbent Assay for Biological Monitoring of Toluene Exposure

A novel monoclonal antibody (MAb) to hippuric acid (HA) was prepared using an HA analog, N‐α‐benzoyl‐lysine, as an immunogen. An enzyme‐linked immunosorbent assay (ELISA) for HA was established using the anti‐HA MAb named HA01BL. When the specificity of the MAb was analyzed by the ELISA system, the MAb was revealed to be less reactive to methylhippuric acids and to be more specific to HA than previously reported polyclonal antibodies. The detection limit of HA by the ELISA was approximately 1 µg/mL. The urinary HA concentration determined by the ELISA system correlated well with that obtained by high performance liquid chromatography.

Occupational Toluene Exposure Induces Cytochrome P450 2E1 mRNA Expression in Peripheral Lymphocytes

Print workers are exposed to organic solvents, of which the systemic toxicant toluene is a main component. Toluene induces expression of cytochrome P450 2E1 (CYP2E1), an enzyme involved in its own metabolism and that of other protoxicants, including some procarcinogens. Therefore, we investigated the association between toluene exposure and the CYP2E1 response, as assessed by mRNA content in peripheral lymphocytes or the 6-hydroxychlorzoxazone (6OH-CHZ)/chlorzoxazone (CHZ) quotient (known as CHZ metabolic ratio) in plasma, and the role of genotype (5′-flanking region RsaI/PstI polymorphic sites) in 97 male print workers. The geometric mean (GM) of toluene concentration in the air was 52.80 ppm (10–760 ppm); 54% of the study participants were exposed to toluene concentrations that exceeded the maximum permissible exposure level (MPEL). The GM of urinary hippuric acid at the end of a work shift (0.041 g/g creatinine) was elevated relative to that before the shift (0.027 g/g creatinine; p < 0.05). The GM of the CHZ metabolic ratio was 0.33 (0–9.3), with 40% of the subjects having ratios below the GM. However, the average CYP2E1 mRNA level in peripheral lymphocytes was 1.07 (0.30–3.08), and CYP2E1 mRNA levels within subjects correlated with the toluene exposure ratio (environmental toluene concentration:urinary hippuric acid concentration) (p = 0.014). Genotype did not alter the association between the toluene exposure ratio and mRNA content. In summary, with further validation, CYP2E1 mRNA content in peripheral lymphocytes could be a sensitive and noninvasive biomarker for the continuous monitoring of toluene effects in exposed persons.

THE EXPOSURE OF TOLUENE AND RESPIRATORY PROBLEMS AMONG AUTOMOTIVE INDUSTRY WORKERS IN SELANGOR

ISEE-439 Aim: A cross sectional study was carried to determine the association between toluene in air and urinary hippuric acid (toluene metabolite), and pulmonary functions and respiratory symptoms among exposed workers in an automotive industry in Selangor. Methods: Workers in the paint shop were selected as the exposed group (N = 66) and a group of administrative workers (N = 42) was the control group. Respiratory symptoms were determined using a modified American Thoracic Society's questionnaire. Individual workers' breathing zones were sampled for toluene at the beginning and before the end of the work shift. Toluene was analyzed using gas chromatography. Measurements of pulmonary function were carried out with a spirometer. Urine samples were collected at the end of the work shift. Urine hippuric acid levels were analyzed by high performance liquid chromatography. Results: Respiratory symptoms most commonly experienced by the respondents were cough with phlegm (70.97 %); the least common symptom was shortness of breath (12.90 %). The prevalence of respiratory symptoms was significantly higher among the exposed group [cough (p< 0.001); cough with phlegm (p<0.001); chest tightness (p=0.003)]. The mean air toluene concentration was 1.44 ppm (SD = 4.47). A significant association was found between air toluene levels and chest tightness (χ2 =4.364, p=“0.037”). The exposed group had a significantly higher prevalence of abnormal FEV1% predicted, FVC% predicted and FEV1/FVC% predicted, than the comparative group. There were significant differences in the FVC% predicted (p=0.015), FEV1% predicted (p<0.001) and FEV1/FVC% predicted (p<0.001), between the two groups. ANCOVA analysis showed a significant difference in FEV1 (p<0.001), FEV1% predicted (p<0.001) and FEV1/FVC% predicted (p<0.001) between the two study groups, after adjusting for age, work duration, body mass index and smoking habits. The mean urinary hippuric acid concentration was 0.24 μg/g creatinine (SD = 1.40 μg/g creatinine). There was no significant correlation between urinary hippuric acid and any of the respiratory symptoms, lung function outcomes, or the air toluene levels. Multiple linear regression analysis showed that no variable significantly influenced the lung function tests and urinary hippuric acid concentrations. Conclusion: Exposure to organic solvents has significant chronic health effects, as indicated by the higher prevalence of respiratory symptoms and the reduction in lung functions, among the exposed group. The air toluene and urinary hippuric acid levels were not associated with the lung function results. Therefore, chemical compounds in the solvents, which have not been identified in this study, may have been associated with the respiratory problems.

톨루엔 폭로근로자의 요중 마뇨산 농도 및 건강장해

The relationships between subjective symptoms of toluene exposed workers and concentration of their urinary excretion of hippuric acid were investigated. The exposed groups of 146 workers exposed to toluene and the control groups of 47 workers have never been exposed to toluene in Ulsan area were selected and studied. Hippuric acid was measured by HPLC, and counts of blood cells and liver function test were also performed. The mean value of urinary hippuric acid concentration of the control group was 0.322(<TEX>$\pm$</TEX>0.267) g/L, while that of the exposed group was 1.260(<TEX>$\pm$</TEX>0.395) g/L. As the concentration of hippuric acid had statistical proximity in <TEX>$0.1\%$</TEX> level, WBC, GOT, and GPT didn't have any proximity(P>0.05). The exposed group showed lower level of leucocyte counts 6522.40(1710.3) than the control group 6891.50(1483.7). The exposed group showed higher level of GOT(25.75), GPT(27.09) than GOT(23.75), GPT(25.21) of the control group. Dried skin was the highest complained symptom of toluene exposed workers, the second strained eye, the third poor auditory function, and the fourth was headache.