Urinary Hippuric Acid Levels Research Articles

A fast and accurate colorimetric assay for quantifying hippuric acid in human urine

Hippuric acid is an abundant metabolite in human urine. Urinary hippuric acid levels change with toxic exposure to aromatic compounds, consumption of fruits and vegetables, cancers, chronic kidney disease, schizophrenia and Crohn's disease. While urinary hippuric acid can be detected and quantified via mass spectrometry or nuclear magnetic resonance spectroscopy, a colorimetric assay would be preferable for a low-cost, point-of care clinical assay. Two colorimetric methods, that use p-dimethylaminobenzaldehyde (DMAB) or benzenesulfonyl chloride (PhSO2Cl), respectively, have been previously developed to detect hippuric acid but these assays have many limitations. We replaced PhSO2Cl with p-toluenesulfonyl chloride (p-TsCl), to create a simpler, faster and more accurate method that works with human urine. This modified colorimetric assay detects from 60 μM to 1000 μM hippuric acid in urine in 2 min. We also corrected for the effects of interfering compounds present in urine such that the assay works across many urine backgrounds. We validated this improved assay on multiple hippurate-spiked urine samples, observing an excellent correlation (R2 > 0.94) between observed and known hippurate concentrations. These data suggest that this colorimetric assay is accurate and should greatly facilitate the measurement of hippuric acid in urine to detect a variety of human conditions.

Complex poisoning mainly with benzyl alcohol complicated by paralytic ileus: a case report

BackgroundBenzyl alcohol is used as stripping agent in paints and other applications, and benzyl alcohol poisoning is indicated by symptoms, such as impaired consciousness, respiratory depression, hypotension, metabolic acidosis, and renal dysfunction.Case presentationA 27-year-old Asian man was transported to a hospital for severe disturbance of consciousness following exposure to a paint stripper containing benzyl alcohol, ethylene glycol, and hydrogen peroxide, which he was using to repaint a bridge. The patient was treated under sedation for benzyl alcohol poisoning. On day 3 of hospitalization, his abdominal computed tomography scan revealed a paralytic ileus, so he was transferred to our hospital. The combined toxicity from multiple substances, mainly benzyl alcohol, was thought to be a contributing factor for the paralytic ileus. Upon arrival, the patient also had chemical burns, hypernatremia, and elevated myogenic enzyme levels. His urinary hippuric acid level was high (14.9 g/L) upon admission to the previous hospital. We treated the patient with artificial respiration management, while avoiding high-density oxygen, and with gastrointestinal decompression by gastric tube implantation; laxatives were also administered. The paralytic ileus improved on the 4th day, the tube was removed on the 6th day, and the patient was discharged on the 11th day of hospitalization. No apparent complications were observed at discharge.ConclusionsTo the best of our knowledge, this is the first case report of paralytic ileus caused by benzyl alcohol, although multiple factors may have influenced the symptoms. After exposure to benzyl alcohol by inhalation and dermal absorption, the patient developed impaired consciousness, metabolic acidosis, and paralytic ileus, and the presence of elevated urinary hippuric acid led to a definitive diagnosis.

Urinary hippuric acid level as a biological indicator of toluene exposure on batik workers

Urinary hippuric acid (uHA) is one of the biomonitoring parameters of toxic organic exposure, such as toluene. Repeated exposure to a low concentration of toluene may lead to chronic effects such as central nervous system damage. In the preliminary study, toluene was found in the batik industry's working area in Yogyakarta, Indonesia. This study aims to assess the health condition of batik workers to toluene exposure based on the concentration of uHA. There were 52 respondents divided into 2 groups: the batik workers as the exposed group (30 respondents) and the non-batik workers as the control group (22 respondents). The urine sample was taken from batik workers at the end of the shift, and uHA was measured using spectrophotometry. The uHA value was corrected with urinary creatinine. The results showed that the average uHA concentration of batik workers was higher than that of the control group. The result also showed that workers with more than 2 years working period, writing workers, and stamping workers give an Odds Ratio (OR) of 6.43, 6.75, and 9.00 respectively on having a higher concentration of uHA. Workers with toluene exposure symptoms were also having a higher concentration of uHA than workers without any symptoms.

Rheumatoid arthritis in low-level toluene-exposed workers based on nationwide medical surveillance data in Korea.

There is growing evidence that exposure to organic solvents can play a role in the etiology of rheumatoid arthritis (RA). This prospective cohort study aimed to investigate the association between RA and toluene exposure. The study cohort consisted of Korea Occupational Safety and Health Agency data from male workers exposed to toluene who had undergone a toluene-associated special medical examination at least once between January 1, 2000 and December 31, 2004 (n = 148,870). The morbidity from RA based on hospital admission records was estimated from 2000 to 2005 using National Health Insurance Claim Data. The standardized admission ratio (SAR) for RA was calculated with reference to the general population. Levels of urinary hippuric acid (HA), a metabolite of toluene, were measured and used for exposure assessment. Toluene-exposed workers were at an elevated risk of seropositive rheumatoid arthritis (ICD-10 code M05) with an SAR of 2.38 (95% confidence interval [CI]: 1.14-4.37) and other rheumatoid arthritis (M06) with an SAR of 1.22 (95% CI: 0.91-1.59). When data were stratified according to the duration of toluene exposure and by tertiles of urinary HA level, no significant difference was apparent. SARs of the toluene-exposed workers are higher than that of the general reference population, indicating that exposure to toluene may contribute to an increased risk of RA. Further studies of toluene-exposed workers with longer follow-up are needed.

塗膜剥離剤の吸入により急性ベンジルアルコール中毒を来した1例(A case of benzyl alcohol poisoning by inhalation of paint stripper)

要旨症例は45歳の男性で，バイオハクリX–WB®（ベンジルアルコール34.8%含有）を用いた，塗膜剥離作業中に意識障害を来し，救急搬送された。来院時のバイタルサインはGCS E1V1M1，呼吸数24/min，血圧114/82mmHg，脈拍 104/min，SpO2 98%であった。気管挿管し人工呼吸管理を開始した。血圧低下，進行性の代謝性アシドーシスと尿細管障害による多尿を認めたが，対症療法で対応した。第2病日には意識レベル改善，血圧低下や代謝性アシドーシスも自然軽快し，抜管した。身体症状は順調に改善したが，高次機能障害は遷延した。第24病日に独歩退院した。臨床症状と尿中馬尿酸が高値であったことから，吸入曝露によるベンジルアルコール中毒と診断した。後日，ベンジルアルコールの血中濃度を解析し，診断を確定した。ベンジルアルコール中毒は成人での報告は稀である。意識障害，低血圧，代謝性アシドーシス，腎障害などの重篤な症状を来すが，特異的な治療法はなく，集中治療室で対症的に全身管理を行う必要がある。

Toluene abuse markers in marginalized populations.

Toluene abuse is one of the most common addictions among marginalized Roma. The aim of the study was the comparison of urinary toluene metabolite levels in marginalized population of Eastern Slovakia as compared to the majority population, and to verify the validity of the answers, given in the questionnaires, regarding toluene abuse. The study was carried out as part of the HEPA-META project aiming to map the prevalence of health problems in marginalized Roma. The majority of people living outside the area of the segregated Roma communities comprised the control group. The total number of study participants was 770. Statistically significant differences in the levels of hippuric acid and o-cresol were found between Roma and the majority population. Variations in urinary hippuric acid levels in addition to toluene abuse can be caused also by dietary factors, medical treatment as well as alcohol consumption, which is frequent (not only) in marginalized communities.

A Clinic-Based Study in Treatment-Seeking Adolescent Inhalant Users in India: Implications for Management

ABSTRACTAn exploratory study was conducted on 23 consecutive treatment-seeking adolescent inhalant users at a tertiary drug dependence treatment center in India. Sociodemographic, clinical parameters and neuropsychological functioning were assessed using semi-structured interview, Composite International Diagnostic Interview (CIDI 3.0) for diagnosis, checklist for health damage and withdrawal symptoms, Malin's Intelligence Scale for Indian Children (MISIC), Memory for Design test and Stroop test. Routine biochemical testing and urinary hippuric acid level for recent inhalant use, measured using Gas Liquid Chromatography with Nitrogen Phosphorous Detector (GLC-NPD) was conducted. All participants were urban males (mean age 16 [SD = 1.8] years), who used either ink eraser fluid (87%) or glue (13%). Most participants experienced inhalant withdrawal (80%) and revealed high prevalence of psychiatric co-morbidity (52%), behavioral problems (43.5%), and neuropsychological deficits. Biochemical analysis validated recent (1–3 days) toluene exposure in 69.6% of participants, consistent with self-report. Management plans should take these issues into consideration.

Visual functions of workers exposed to organic solvents in petrochemical industries.

Aim:The purpose of this study was to evaluate the visual functions of workers exposed to organic solvents in petrochemical industries.Materials and Methods:Thirty workers from the petroleum refinery and 30 age-matched controls (mean age) were recruited. Visual functions and occupational exposure levels were assessed among both the groups. Visual acuity, contrast sensitivity, color vision, and visual fields were evaluated at the workplace. The biological samples, namely blood and urine, were collected at the workplace and transported to the laboratory for analysis. The urinary excretion of hippuric and methylhippuric acid as well as creatinine was measured by high performance liquid chromatography.Results:The mean age of the workers and controls were 39.7 ± 7.6 years and 38.6 ± 8.1, years respectively. The mean years of experience of the workers were 15.6 ± 6.8 years. Visual acuity was >0.01 LogMAR among both the control and case groups. The contrast sensitivity was reduced at 12cpd among workers. Comparison between groups was done using independent sample t-test. The mean difference in color confusion index was 0.11 ± 0.05 (P = 0.037*). The mean difference in visual fields was −0.31 ± 0.36 dB (P = 0.933). The mean difference in urinary hippuric acid level (urinary metabolite of toluene) between the groups was 0.19 ± 0.96 g/g creatinine (P = 0.049FNx01). The mean difference in the excretion of methylhippuric acid (urinary metabolite of xylene) was 0.06 ± 0.04g/g creatinine (P = 0.154). We also found that exposure was a significant risk factor for color vision defect with an odds ratio of 4.43 (95% CI: 1.36–14.4); P = 0.013.Conclusion:The study results showed that contrast sensitivity and color vision were affected among workers in petrochemical industry.

Abstract C13: Use of air monitoring and urine biomarker assays to measure geographic disparities in exposure to VOCs in Washington, DC

Abstract The District of Columbia has one of the highest cancer incidence and mortality rates in the nation in conjunction with significant cancer-related geographic and racial disparities. Increased exposure to environmental carcinogens, such as benzene, in high risk areas of DC is of public health importance and may play a role in these disparities in cancer incidences and mortality rates. Volatile Organic Compounds (VOC), such as toluene and benzene, are absorbed by the body and undergo metabolism to produce bio-activated (can lead to cancer and other serious health effects) metabolites that are excreted from the body via the urine and/or feces. Air monitoring and urinary biomarker assays are accepted methods for exposure assessment of VOCs but little is known regarding the correlation between the two. In this study we compared the urinary concentrations of hippuric acid and t,t-muconic acid (two known benzene and toluene metabolites, respectively) with indoor and outdoor exposure levels of toluene and benzene in high risk (<1 mile from highway/freeway) and low risk urban areas (>3 miles from the highway/freeway) in Washington, DC. First morning void urine samples were collected from 16 adult residents in high risk areas and 14 adult residents in low risk areas after 72 hours of air monitoring. Urine samples were sent to NMS laboratory and metabolite levels were measured using liquid chromatography/ mass spectrometry. Indoor and outdoor benzene and toluene levels were measured in the same homes over 72 hours using a 3M Organic Vapor Monitor and analyzed using gas chromatograph mass spectrometer (GC/MS). t,t-muconic acid urinary concentration levels in normal non-exposed individuals has been previously reported at .0001g/l and hippuric acid levels have been reported at <1.4 g/l. In our study participants, mean levels of urinary t,t-muconic and hippuric acid were .0003g/l and .35 g/l, respectively. Toluene levels, as measured by air monitoring, indoors (-0.34, p=0.08) and outdoors (-0.004, p=0.98) were both negatively correlated with urinary hippuric acid levels. A negative correlation was also observed between outdoor benzene levels and t,t-muconic acid (-0.23, p =0.11), however indoor levels showed a positive correlation with the urinary biomarker (0.13, p =0.52). We also observed higher levels of t,t-muconic acid in the high risk residents (87.17g/gCR) compared to low risk residents (59.54 g/gCR; p =0 .56). The positive correlation between indoor benzene levels and urinary t,t-muconic acid levels suggest the presence of additional sources of benzene inside the homes. Though air levels of VOCs are a good indicator of exposure, urinary metabolites may give a more measure of VOC exposure. Although not statistically significant, we observed a disparity in exposure to VOCs in “high risk” versus “low risk” areas in Washington, DC. Citation Format: Ashley Corrin Huderson, Chiranjeev Dash, Lucile Adams-Campbell. Use of air monitoring and urine biomarker assays to measure geographic disparities in exposure to VOCs in Washington, DC. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr C13. doi:10.1158/1538-7755.DISP13-C13

Hippuric Acid Levels in Paint Workers at Steel Furniture Manufacturers in Thailand

BackgroundThe aims of this study were to determine hippuric acid levels in urine samples, airborne toluene levels, acute and chronic neurological symptoms, and to describe any correlation between urinary hippuric acid and airborne toluene.MethodsThe hippuric acid concentration in the urine of 87 paint workers exposed to toluene at work (exposed group), and 87 nonexposed people (control group) was studied. Study participants were selected from similar factories in the same region. Urine samples were collected at the end of a shift and analyzed for hippuric acid by high performance liquid chromatography. Air samples for the estimation of toluene exposure were collected with diffusive personal samplers and the toluene quantified using gas–liquid chromatography. The two groups were also interviewed and observed about their work practices and health.ResultsThe median of the 87 airborne toluene levels was 55 ppm (range, 12–198 ppm). The median urinary hippuric acid level was 800 mg/g creatinine (range, 90–2547 mg/g creatinine). A statistically significant positive correlation was found between airborne toluene exposure and urine hippuric acid levels (r = 0.548, p < 0.01). Workers with acute symptoms had significantly higher hippuric acid levels than those who did not (p < 0.05). It was concluded that there was a significant correlation between toluene exposure, hippuric acid levels, and health (p < 0.001).ConclusionThere appears to be a significant correlation between workers exposure to toluene at work, their urine hippuric acid levels, and resulting symptoms of poor health. Improvements in working conditions and occupational health education are required at these workplaces. There was good correlation between urinary hippuric acid and airborne toluene levels.

Evaluation of Toluene Exposure in Workers at Industrial Area of Sidoarjo, Indonesia by Measurement of Urinary Hippuric Acid

Background: Toluene is a harmful substance still being used as a solvent and catalyst in many industries that can increase the level of urinary hippuric acid (UHA). This study was designed to examine the level of toluene and UHA among workers of industrial site in seven companies in Sidoarjo, Indonesia and to analyze the risk factors for abnormal UHA. Methods: This study was an analytical cross-sectional study conducted during August to September 2008. The locations were selected based on the fact that toluene was utilized in the production process of these companies. Urinary hippuric acid was analyzed with screen spectrophotometer 3000 on obtained urine samples from workers. Urinary hippuric acid of higher than 1.6 g/g creatinine was considered as abnormal. Workers' characteristics were collected via questionnaires completed by the workers. Toluene in workplace air was obtained with the reagent tube and the samples were analyzed using gas chromatography. Results: In total, 96 subjects were studied. Workers examined in this study suffered from watery eyes, shortness of breath, cough, runny nose, fatigue, and skin irritation. Urinary hippuric acid level was normal in 91 workers (95%). Five subjects had abnormal levels of urinary hippuric acid. Levels of toluene in workplace air at all companies were below the ratified governmental regulatory threshold value (< 50 ppm) with the maximum level of 28.1 ppm. Abnormal HPA was higher in workers with older ages, lower educational attainments and not using the personal protective equipment (PPE). Conclusion: Toluene concentration in the air of the ink, paint and printing companies in Sidoarjo, Indonesia was within ratified limit. Workers with older ages, lower educational attainment and not using the PPEs are probably more vulnerable to toluene toxicity.

Subclinical abnormalities in workers with continuous low-level toluene exposure

Short-term exposure to a high concentration (TWA > 100 ppm) of toluene can cause hepatotocixity and neurotoxicity in humans. Data on the effects of exposure to low levels of toluene, however, are controversial. In addition, few studies on the effects of toluene exposure on the autonomic nervous system have been conducted. Urine samples from 34 male factory workers in Taiwan who were exposed to low levels of toluene either intermittently (n = 13) or continuously (n = 21) were taken on a Monday morning after a 2-day hiatus and at the end of the workweek on Friday evening. Urinary hippuric acid levels were measured using high-performance liquid chromatography (HPLC). A complete blood work-up was also performed for each subject. The prevalence and severity of neurotoxic symptoms were investigated by a self-reported questionnaire, a neuropsychiatric battery, and sympathetic and peripheral nerve function tests. The mean value of urinary hippuric acid corrected for creatinine (Cr) was 0.34 ± 0.18 g/g Cr on Monday morning and 0.43 ± 0.26 g/g Cr on Friday evening. The difference in the mean value of urinary hippuric acid between the two periods (p < 0.01) and the odds ratio of impairment of sympathetic (OR = 4.13, p = 0.11) and peripheral nerves (OR = 6.94, p = 0.074) were higher in workers continuously exposed to toluene. In addition, workers who were continuously exposed to toluene had a lower mean platelet count (216 ± 41 × 10(6) /µL) than workers who were intermittently exposed (252 ± 40 × 10(6)/µL), (p = 0.018). Furthermore, there was a positive relationship between neurological abnormalities and a self-reported neuropsychiatric measurement (r = 0.35-0.66, p < 0.05) in all workers. These data suggest that continuous exposure to low levels of toluene may be associated with sympathetic and peripheral nerve dysfunction and sub-clinical hematological damage. Further research needs to be carried out regarding how chronic exposure to low-levels of toluene affects workers.

Estudo retrospectivo dos níveis de ácido hipúrico urinário em exames de toxicologia ocupacional

Hippuric acid is the primary metabolite of toluene, a solvent widely used in industrial processes with considerable toxic effects, a fact which justifies regularly monitoring individuals with occupational exposure to this solvent. This work aims at evaluating urinary hippuric acid levels found in workers subject to biological monitoring. A retrospective study was carried out with data referring from 2002 to 2005, in which exams results and employment status were analyzed (periodic, post-employment, and pre-employment exams). Results indicate a significant reduction in hippuric acid levels for 2005. Periodic exams presented higher results than pre-employment and post-employment exams. No significant difference was found in individuals grouped according to their status in each of the established intervals, their reference numbers, and maximum biological levels allowed. Hippuric acid levels detected indicate low risk of toluene exposure for the population under evaluation, probably due to a growing concern with the deployment of measures regarding occupational hygiene.

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.

Health Consequences of Catabolic Synthesis of Hippuric Acid in Humans

Hippuric acid has been a major human metabolite for years. However, there is no well-known documented health benefit associated with it except for excretion of environmental-toxic exposures of aromatic compounds such as toluene, or from dietary protein degradation and re-synthesis by intestinal microflora metabolism of quinic acid via the shikimate pathway. Thus hippuric acid can appear in humans as an excretory product from natural or unnatural sources. It has been believed over the years that the major source of urinary hippuric acid levels in humans has come from environmental toxic solvent exposures. However, more recently it was been shown that approximately 1-2 mM hippuric acid is excreted daily in the urine, even in the absence of organic solvent exposure, signalling abundant metabolic dietary sources of hippuric acid are also apparent. One of these has been dietary proteins. The other is from the well-documented presence of quinic acid in healthy colored foodstuffs. Quinic acid is a key metabolite associated with the shikimate pathway existing only in plants, and it is responsible for essential amino acid biosynthesis such as tryptophan, phenylalanine and tyrosine. Here we review the evidence that the human gastrointestinal tract microflora are responsible for quinic acid metabolism not only to hippuric acid, but more importantly to efficacious antioxidant amino acids and vitamins.

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.

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.

Measuring Inhalant Abuse Among Homeless Youth in Southern Brazil

In order to measure urinary level of hippuric acid among Brazilian homeless youth suspected of having inhaled toluene in previous hours, urine samples were voluntarily collected from the youth around two hours after they arrived at an “open-school” in Porto Alegre, Brazil. Hippuric acid levels were determined by gas chromatography in urine specimens of 50 homeless children and adolescents. In 86% of the urine specimens, hippuric acid levels were within the range of 3.6 g/g creatinine and 46.1 g/g creatinine. Very high urinary hippuric acid level may indicate voluntary toluene abuse. A cut-off urinary hippuric acid level value needs to be established for toluene self-exposure diagnosis.

Assessment of Neurobehavioral Performance Among Rotogravure Printing Workers Exposed to Toluene

1 ) O b j e c t i v e s : The aims of this study were to investigate the occupational exposure level to toluene among rotogravure printers and neurobehavioral effects among them. M e t h o d s : Fifty rotogravure printers and 147 controls participated in this study. Environmental and biological monitoring was performed for the investigation of toluene expo - sure level, and neurobehavioral performance test were performed by using the Behavioral Assessment and Research System with Korean language instructions(BARS-K). Results: The major results were as follows; 1. Geometric mean toluene concentrations in the ambient air of 5 rotogravure printing work - places were 10.5 (GSD 5.9)∼181.9 (GSD 17.7), with a grand total of 56.7 (GSD60.9) ppm. 2. The geometric mean urinary hippuric acid level for rotogravure printers of 5 workplaces were 0.31 (GSD 0.11)∼5.14 (GSD 0.55), with the grand total of 1.87 (GSD 2.06) g/g creati - nine. 3. There was a linear correlation between hippuric acid levels in urine and the exposed toluene in air: urine hippuric acid (g/g creatinine)=0.03 toluene (ppm) + 0.15 (r=0.899, p<0.01, n=50). 4. After adjustment for confounders, significant associations were found between toluene exposure and Digit span forwards, Digit span backwards, Tapping preferred hand, Symbol digit and Selective attention trials. Conclusions: 1. Rotogravure printers were occupationally exposed to relatively high concen - tration to toluene, and their neurobehavioral performances were decreased. 2. The BARS neurobehavioral testing program, which minimizes the use of text in the instructions, was very effective in overcoming the cultural barriers in neurobehavioral testing.