Guidelines for recognition of occupational cancers in Korea: the results of scientific review by Korean Society of Occupational and Environmental Medicine (2013–2016)

This thematic collection includes the articles to review eleven occupational cancer related risks or working conditions and to propose the guidelines of S. Korea.

Levels of blood lead and urinary cadmium in industrial complex residents in Ulsan

BACKGROUND: Populations neighboring industrial complexes are at an increased health risk, due to constant exposure to various potentially hazardous compounds released during industrial production activity. Although there are many previous studies that focus on occupational exposure to heavy metals, studies that focused on environmental exposure to lead and cadmium are relatively rare. The purpose of this study is to evaluate the extent of the environmental exposure of heavy metals in residents of industrial area. METHODS: Four areas in close proximity to the Ulsan petrochemical industrial complex and the Onsan national industrial complex were selected to be included in the exposure group, and an area remotely located from these industrial complexes was selected as the non-exposure group. Among the residents of our study areas, a total of 1573 subjects aged 20 years and older were selected and all study subjects completed a written questionnaire. Blood and urine samples were obtained from about one third of the subjects (465 subjects) who provided informed consent for biological sample collection. Total 429 subjects (320 subjects from exposure area, 109 subjects from non-exposure area) were included in final analysis. RESULTS: The geometric mean blood lead level among the subjects in the exposed group was 2.449 μg/dL, which was significantly higher than the non-exposure group's level of 2.172 μg/dL. Similarly, the geometric mean urine cadmium levels between the two groups differed significantly, at 1.077 μg/g Cr. for the exposed group, and 0.709 μg/g Cr. for the non-exposure group. In a multiple linear regression analysis to determine the relationship between blood lead level and related factors, the results showed that blood lead level had a significant positive correlation with age, the male, exposure area, and non-drinkers. In the same way, urine cadmium level was positively correlated with age, the female, exposure area, and smokers. CONCLUSIONS: This study found that blood lead levels and urine cadmium levels were significantly higher among the residents of industrial areas than among the non-exposure area residents, which is thought to be due to the difference in environmental exposure of lead and cadmium. Furthermore, it was clear that at a low level of exposure, differences in blood lead or urine cadmium levels based on age, gender, and smoking status were greater than the differences based on area of residence. Therefore, when evaluating heavy metal levels in the body at a low level of exposure, age, gender, and smoking status must be adjusted, as they are significant confounding factors.

Detection of Helicobacter pylori in Gastric Aspirates Using a Monoclonal Antibody-Based Test

BACKGROUND/AIMS: The objective of this study was to evaluate a monoclonal antibody-based test to detect Helicobacter pylori-specific antigen in gastric aspirates from humans. METHODS: Sixty-one volunteers were enrolled in the study. All of the subjects underwent a 13C-urea breath test (UBT) before esophagogastroduodenoscopy. Gastric aspirates were analyzed for pH and ammonia and used for polymerase chain reaction (PCR), culture, and monoclonal antibody-based detection of H. pylori. Multiple biopsies of the gastric antrum and body were obtained for a rapid urease test (RUT) and histological evaluation. RESULTS: Thirty-six subjects were H. pylori-positive and 25 were H. pylori-negative according to the UBT results. Compared with the H. pylori-negative subjects, H. pylori-positive subjects had a higher pH (4.77+/-1.77 vs 3.49+/-1.30, p<0.05) and ammonia level (1,130.9+/-767.4 vs 184.2+/-126.3, p<0.0001). The sensitivities and specificities of the PCR test, RUT, culture test, and monoclonal antibody-based test were 100% and 72%, 89% and 100%, 47% and 100%, and 78% and 100%, respectively. CONCLUSIONS: The monoclonal antibody-based test for diagnosing H. pylori infection in gastric aspirates has increased sensitivity compared with the culture test and specificity as high as that of the RUT. The test may be useful as an additive test for examining gastric aspirates.

Sensitization rates of airborne pollen and mold in children / 소아과

PURPOSE: Aeroallergens are important causative factors of allergic diseases. Previous studies on aeroallergen sensitization rates investigated patients groups that had visited pediatric allergy clinics. In contrast, we investigated sensitization rates in a general population group of elementary school to teenage students in Incheon, Jeju, and Ulsan. METHODS: After obtaining parental consent, skin-prick tests were performed on 5,094 students between March and June 2010. Elementary school students were tested for 18 common aeroallergens, whereas middle and high school students were tested for 25 allergens. The 25 allergens included Dermatophagoides pteronyssinus, Dermatophagoides farinae, pollen (birch, alder, oak, Japanese cedar, pine, willow, elm, maple, Bermuda grass, timothy grass, rye grass, orchard grass, meadow grass, vernal grass, mugwort, Japanese hop, fat hen, ragweed, and plantain), and mold (Penicillatum, Aspergillus, Cladosporium, and Alternaria). RESULTS: The sensitization rates in descending order were 25.79% (D. pteronyssinus), 18.66% (D. farinae), 6.20% (mugwort), and 4.07% (willow) in Incheon; 33.35% (D. pteronyssinus), 24.78% (D. farinae), 15.36% (Japanese cedar), and 7.33% (Alternaria) in Jeju; and 32.79% (D. pteronyssinus), 30.27% (D. farinae), 10.13% (alder), and 8.68% (birch) in Ulsan. The dust mite allergen showed the highest sensitization rate among the 3 regions. The sensitization rate of tree pollen was the highest in Ulsan, whereas that of Alternaria was the highest in Jeju. The ragweed sensitization rates were 0.99% in Incheon, 1.07% in Jeju, and 0.81% in Ulsan. CONCLUSION: The differences in sensitization rates were because of different regional environmental conditions and distinct surrounding biological species. Hence, subsequent nationwide studies are required.

Two Case of Erythroleukemia and Myelodysplastic Syndrome in a Non-Destructive Inspector / 대한산업의학회지

BACKGROUND: Ionizing radiation is a group 1 carcinogen according to the IARC(International Agency for Research on Cancer) classification. With the development of the radiation related industry, the number of radiation exposed workers has been increasing. There have been several reports on AML(Acute Myeloid Leukemia) on exposure to ionizing radiation; however, there are no reports of occupational malignant lymphohematopoietic disease related to non-destructive inspection. CASE REPORT 1: A 35-years-old male, who had worked for 10 years in non-destructive inspection, was diagnosed with myelodysplastic syndrome. He worked 8 hours a day, for three weeks per months, where he was exposed to 192Ir and 60Co radiation sources. Because he had not worn a film badge for monitoring his radiation exposure dose, the accurate exposure dose was not reported. The estimate exposure dose calculated via a chromosomal study was 1.20 Gy, which exceed the dose limits of Korean radiation dose standards, which are 50 and 100 mSv annually and quinquennially respectively. CASE REPORT 2: A 26-years-old male, who had worked for 2.5 years in the same company was also diagnosed with myelodysplastic syndrome. CONCLUSION: Non-destructive inspection is the main source of ionizing radiation in the workplace, which could be the cause of malignant lymphohematopoietic diseases. Therefore, more practical plans and guidelines are needed to prevent non-destructive inspectors from workplace radiation exposure.

A Case of Appendicular and Rectal Metastasis from Gastric Cancer Detected by Endoscopic Resection / 대한소화기내시경학회지

A hematogenous or lymphogenous metastasis and a direct or disseminated invasion can occur in cases of a gastrointestinal metastasis. Moreover, a hepatic or peritoneal metastasis is common in advanced gastric cancer. However, a colonic metastasis, particularly an appendicular metastasis, is quite rare. Recently, we experienced a case with an appendicular submucosal tumor-like elevated lesion and multiple rectal elevated lesions during a colonoscopy in an advanced gastric cancer patient. The appendicular lesion was resected endoscopically and a biopsy of the rectal lesions was performed. The pathologic diagnosis was an appendicular and rectal metastasis of a signet ring cell carcinoma. We describe a case of appendicular and rectal metastasis from gastric cancer. The results highlight the importance of considering a metastatic carcinoma when an appendicular or rectal mass is found incidentally in a malignant neoplasm patient.

Conservative Treatment of Colonoscopic Perforations / 대한소화기내시경학회지

BACKGROUND/AIMS: Colonoscopic perforation can be treated by both operative or non-operative methods. Non-operative management, and especially conservative management, may be appropriate for selected individuals. We wanted to verify the usefulness of performing conservative management for treating colonoscopic perforations. METHODS: We reviewed the medical records of the colonoscopic perforation cases that occurred in the recent 5 yrs. 11 cases of perforation occurred from among 8,536 colonoscopic procedures. RESULTS: Ten cases occurred from a therapeutic procedure (five from polypectomy and another five occurred from an endoscopic (submucosal dissection) and one case occurred from a diagnostic procedure. The perforation sites were the ascending colon (three cases), transverse colon (two cases), descending colon (one case), sigmoid colon (two cases), and rectum (three cases). There were five intraperitoneal perforations and five retroperitoneal perforations. All the cases were detected within 12 hours and all the cases had received good bowel preparation. 10 cases were managed conservatively (nothing by mouth, broad spectrum antibiotics and, Levin tube suction). One case was managed by an operative procedure due to the large size of the defect and the patient's wish. All the patients recovered without complications. The mean hospital stay was 9.5 days. CONCLUSIONS: Colonoscopic perforation can managed conservatively in selected cases, such as for those cases that will undergo post-therapeutic colonoscopy and those cases that have undergone good bowel preparation.

A Case of Mesenteroaxial Gastric Volvulus Diagnosed Using Endoscopic Procedure / 대한소화기내시경학회지

Gastric volvulus is characterized by an abnormal rotation of the stomach typically 180degrees left to right around a line joining the relatively fixed pylorus and the esophagus. Gastric volvulus can be classified anatomically as organoaxial, mesenteroaxial or combined, and symptomatically as acute or chronic. Acute gastric volvulus is an extremely rare emergency surgical condition. The classical triad of gastric volvulus are severe nausea with a paradoxical inability to vomit, localized epigastric pain and an inability to pass a nasogastric tube. Gastric volvulus may be suspected on a plain radiological examination of the abdomen as well as by its symptoms. It is confirmed by the specific findings on the esophagogastroduodenoscopy. We report a case of acute mesenteroaxial gastric volvulus, that was treated using laparoscopic reduction and anterior gastropexy.

Two Cases of Juvenile Retention Polyp of Right Colon in Adult / 대한소화기내시경학회지

Colorectal polyps are classified histologically as either neoplastic or nonneoplastic polyps. A juvenile polyp, which is sometimes referred to as a retention polyp, is a type of nonneoplastic polyp. Juvenile polyps are found most commonly in children less than 10 years of age. However, they are also encountered, albeit rarely, in adolescents or adults of all ages. The most common clinical problem is painless rectal bleeding. Most juvenile polyps are found in the rectosigmoid colon, and more than 90% are detected within 20 cm from the anal verge. In Korea, there are some reports of juvenile polyps located in the rectosigmoid colon in adults. We report two cases of juvenile colon polyps in adult that presented as a hematochezia, which were located at the hepatic flexure and ascending colon.

Two Cases of Successful Clipping Closure of Iatrogenic Duodenal Perforation Occurred during Endoscopic Procedure / 대한소화기내시경학회지

The risk of complications associated with endoscopic procedures, including bleeding and perforation, tends to increase due to the magnification of the therapeutic endoscopic spectrum. In cases of duodenal perforation, surgical closure is the treatment of choice; however, there have been some cases in which the nonsurgical treatment of an iatrogenic duodenal perforation during an endoscopic procedure was effected via endoscopic clipping closure. Here, we report two cases of successful endoscopic clipping closure of an iatrogenic duodenal perforation occur ring during a duodenoscopy insertion for ERCP and endoscopic mucosal resection for the treatment of duodenal adenoma.

A Case of Serrated Adenoma Presenting as Colon Cancer / 대한소화기내시경학회지

Serrated adenoma (SA) is a distinct form of colorectal neoplasia and it is defined as a neoplastic lesion composed of a monotonous cell population with atypical nuclei proliferating in serrated glandular architectures. Hyperplastic polyp is considered a benign lesion with no malignant potential. However, SA progressed into frank carcinoma has been demonstrated in an individual case, and 'serrated neoplasia pathway' is suggested by some authors as an alternative to classical adenoma-carcinoma sequence. Distinguishing between hyperplastic polyp and SA is important because of the different management implications and the increased potential for neoplastic progression in the latter, but sometimes it is very difficult. SA is usually small and sessile polypoid lesion. We report a case of SA presenting as large fungating mass similar to colon cancer, diagnosed as hyperplastic polyp initially by colonoscopic biopsy and confirmed as after SA the surgery.

The Influence of Fusional Vergence on the Postoperative Ocular Alignment in Intermittent Exotropia

The purpose of this study was to evaluate the influence of fusional vergence on the ocular alignment after surgery in intermittent exotropia. We evaluated fusional convergence and divergence with rotary prism. We examined 44 patients with intermittent exotropia who were followed up postoperatively for at least 6 months from January 1995 to June 1998. The angle of deviation was measured preoperatively, 1 week after surgery and on the last follow-up day. We evaluated the break and recovery point of fusional convergence and divergence at near and far at each measurement of angle of deviation. The subjects were divided into two groups according to the deviation at the last visit : Orthophoria group and Undercorrection group. Orthophoria group was defined as having the deviation equal to or less than 15 delta of exodeviation, and undercorrection group was defined as having the deviation more than 15 delta of exodeviation. In Orthophoria group, break point and recovery point of convergence were 28.07 delta and 26.34 delta at near, 25.52 delta and 22.55 delta at far. The break point and recovery point of divergence were 18.21 delta and 12.38 delta at near, 12.70 delta and 7.73 delta at far. In Undercorrection group, break point and recovery point of convergence were 25.86 delta and 24.71 delta at near, 25.20 delta and 25.80 delta at far. The break point and recovery point of divergence were 18.86 delta and 13.29 delta at near, 17.90 delta and 15.40 delta at far. There was no significant difference between two groups. According to the change from deviation at postoperative 1 week to final deviation, the subjects were divided into four groups. We evaluated the difference of fusional convergence and divergence, according to the change of angle of deviation between postoperative 1 week and the last follow-up day, but there was no significant difference. In conclusion, we can not find any significant influence of fusional vergence on the ocular alignment after surgery in intermittent exotropia.

Neuropsychiatric Symptoms of Workers Exposed to 2-Bromopropane / 대한산업의학회지

To investigate the impact of 2-bromopropane on neuropsychiatric symptoms, 33 exposed workers and 77 non-exposes workers in electronic company were recruited. Neuropsychiatric symptoms were assessed using self-administered questionnaire. Memory disturbance, concentration disturbance, sleep disturbance, understanding disturbance and acute irritation symptom were more frequent in workers exposed to 2-bromopropane. To investigate the association between 2-bromopropane exposure and neuropsychiatric symptoms, total symptom scores of exposed workers were compared with those of non-exposed workers. Mean value in the exposed workers was significantly higher than that of non-exposed comparisons. The mean value of total symptom score of smokers in exposed workers was significantly higher than that of smokers in non-exposed workers. In multivariate regression analysis, exposure status was significant predictor for total symptom score after controlling the effects of age, sex, education, smoking status and alcohol intake. Above findings suggest that 2-bromopropane was significantly associated with neuropsychiatric symptoms. Therefore, it is recommended that further research with objective assessments and long follow-up should be done to confirm the results of this study.

Mental Disorders and Fitness for Work in Korea / 대한산업의학회지

OBJECTIVES: This study investigated the actual state of people with mental disorders in Korea, in order to present an alternative proposal for their work fitness and vocational rehabilitation. METHODS: The authors conducted this study through a review of statistics on the prevalence of mental disorder, labor laws, and the literatures related with work fitness and vocational rehabilitation of people with mental disorders. RESULTS: According to recent surveys, about 3 million people in Korea are likely to have mental disorders which could lead to discrimination in social life and dishonor in occupational career, either in the present or near future. Therefore, evaluation of work fitness and vocational rehabilitation for persons with mental disorders are important. At present, work fitness for psychiatric patients is evaluated without suitable guidelines regarding the kinds and severity of mental disorders that impede work capacity. Furthermore, mental disorder-specific fitness for work is not under consideration. CONCLUSION: It is true that most psychiatric patients have some limitation in performing their job. However, judging from the results of some research, proper displacement, apprehension of co-workers, and adjusted workplace could help them complete their tasks properly despite their troublesome psychiatric symptomatology. The government must help all citizens to do their best in their social life, and show a deep interest in the employment of all disabled people including those with psychiatric disorders. Above all we have to change our attitudes and preconceptions against people with mental disorders. Some labor laws, which presently impede employment of people with psychiatric disorders, need to be revised in their favor. Future work capacity evaluation should be done on the basis of ability to function in the workplace rather than symptomatology.

Change on Lens Accomodation and Pupil Light Reflex in VDT works / 예방의학회지

We studied on change of lens accommodation and pupil light reflex caused by VDT work in six women and compared them with those of other office works. The results were as follows. 1. In VDT work group, the accommodation contraction velocity decreased during the first 2-hr VDT task, then recovered markedly by the end of the one-hour lunch break, and then decreased again by the end of the 2nd 2-hr VDT task. Changes of relaxation velocity showed similar pattern although it was less typical than that of contraction velocity. 2. There was no marked change in accommodation contraction velocity and amplitude of accommodation in general office work group and near-distance office work group, and in the near-distance office work accommodation relaxation velocity decreased according to work load without recovery after lunch break. 3. Initial pupil diameter, initial pupil area of light reflex decreased significantly during VDT task only in VDT work group, and didn't recover after lunch break. These results suggest possibility that changes of accommodation contraction velocity, accommodation relaxation velocity, near point distance, and pupil diameter and area are useful in evaluating characteristics of VDT work. For this, more research adjusted individual differences, circadian rhythm, emotional stress needs.

Prevalence and Risk Factors of Occupational Low Back Pain among the Production Workers in a Steel and a Welding Material Manufacturing Factories / 대한산업의학회지

A cross-sectional study was conducted for detecting the risk factors and to propose an effective control program for occupational low back pain. The subjects were 1,665 male production workers employed at a steel factory and a welding material manufacturing factory. The data were collected by a self-reported questionnaire and a medical examination with a rehabilitation specialist for ten days in September, 1997. The contents of the questionnaire were as follows: general characteristics, physical characteristics, employment status, type of work, working environment and the experience of low back pain. The number of cases with symptoms of occupational low back pain were 321, so the point prevalence was 19.3 persons/100 persons. The number of cases with a history of occupational low back pain for one year were 554, so the one year period prevalence was 33.3 persons/100 persons. The point and one year period prevalences of occupational low back pain showed no significant differences in age, marital status, educational level and body mass index. The point and one year period prevalences of occupational low back pain showed no significant differences in alcohol drinking, smoking, stretching exercise and regular exercise. The point and one year period prevalences of occupational low back pain were significantly higher in the unsatisfied group than the satisfied group(p < 0.01), However, no significant differences were found among tenures and shift work. The point and one year period prevalences of occupational low back pain were significantly higher in the lifting of heavy materials group than the nonlifting group(p < 0.01). However, no significant differences were found among posture of the waist and the working posture. Through the multivariate logistic regression, significantly associated factors with occupational low back pain were found to be dissatisfaction with job(point prevalence: OR=1.78, 95% CI: 1.21-2.61; one year prevalence: OR=1.76, 95% CI: 1.26-2.47), lifting of heavy materials(point prevalence: OR=1.94. 95% CI: 1.44-2.61: one year prevalence: OR=2.17, 95% CI: 1.70-2.77) and tenure(point prevalence: OR=1.03. 95% CI: 1.01-1.06: one year prevalence: OR=1.02, 95% CI: 1.00-1.05).

Hematological Changes and Immunological Function in Children Living Near the Petrochemical Estate in Ulsan / 대한산업의학회지

OBJECTIVES: To evaluate the hematological changes and the immunological function of children living near the petrochemical estate in Ulsan. METHODS: The study subjects comprised of 238 children who consisted of 143 children living near the petrochemical estate and 95 children living in a suburban area. We conducted the hematological examination 3 times, in April, July and October. Also we evaluated the immunological function of some children in July. To confirm differences between schools repeated measures ANOVA of generalized linear model was done controlling age and sex as covariates. RESULTS: The blood cell counts of children showed differences between schools in accordance with the survey month. The total WBC, neutrophil, and lymphocyte counts of children living in a suburban area decreased in July and increased in October again, but those of some children living near the petrochemical estate did not changed distinctly. The RBC counts of children living in a suburban area decreased in July and increased in October again, but those of some children living near the petrochemical estate decreased as time passed. The changes of the amount of hemoglobin of all study subjects were similar with those of RBC. The platelet counts of all study subjects decreased in July and increased in October again. In the generalized linear model, school was a significant independent variable for the total WBC, RBC, and platelet counts, and sex was a significant independent variable for the RBC counts. Age was a significant independent variable for the lymphocyte and platelet counts. P values of all blood cell were statistically significant in interaction variable between the survey month and school, and those of the total WBC, neutrophil, and lymphocyte counts were statistically significant in interaction variable between the survey month and age. The immunological function showed no significant difference between study groups. CONCLUSIONS: The total WBC and RBC counts which would be easily affected by volatile organic compounds(VOCs) in the atmosphere showed differences between schools in accordance with the survey month. This suggests that the amounts of exposure to VOCs are different among each school children in different months. To ascertain the hematological changes by VOCs, an additional study evaluating the concentrations of atmosphere of VOCs and biological monitoring of some VOCs is needed.

Evaluation of Finger Skin Temperature by Cold Provocation Test for Diagnosis of Hand-Arm Vibration Syndrome / 대한산업의학회지

OBJECTIVES: Various objective tests have been widely used worldwide for diagnosing the hand-arm vibration syndrome. Among these, the cold provocation test has been frequently used to confirm the presence of Raynaud's phenomenon. This study was carried out in order to evaluate finger skin temperature by cold provocation test(10 degrees C for 10 minute) for the diagnosis of hand-arm vibration syndrome METHODS: Fifty-eight workers who had been exposed to local vibration were examined. Information concerning age, occupation, types of vibration tools used, presence of subjective symptoms such as vibration induced white finger(VWF), and numbness and tingling were collected. The subjects were classified into three groups according to their symptoms(Vascular, Neural, and No symptom group). In order to examine the applicability of the cold provocation test using water at 10 degrees C for 10 minute, we compared finger skin temperature between the groups. RESULTS: The mean value of the finger skin temperature at 5 minutes and 10 minutes after cold provocation as well as the recovery rate in the vascular group were significantly lower than that seen in the other groups. CONCLUSIONS: The evaluation of finger skin temperature by cold provocation test is very useful method for the diagnosis of hand-arm vibration syndrome. The test results will assist in confirming the diagnosis of the hand-arm vibration syndrome.

Medical Surveillance of Glass Fiber Workers in Korea / 예방의학회지

The industrial use of MMMF(man-made mineral fibers), has been increasing, particularly since the banning of most asbestos products. Fibrous minerals can cause health abnormalities currently associated with occupational exposure to glass fiber. This study was conducted to evaluate health risks of glass fiber manufactory workers within the country. we examined questionaries, physical examination including auscultation, chest x-ray, pulmonary function test for 488 male workers, to go through their dermal itching symptoms and respiratory evaluation. we had the results as follows. 1. In 45% of the workers itching had been expressed at their entrance. At that time we was investigating, 18.5% had itching, and most of them complained it when they fall asleep and night. The frequent itching site is waist and groin, upper and lower extremity in order, and it had been expressed mainly during summer and winter. 2. As the results of ventilatory functions test, 6.0% were obstructive type, 1.0% were restrictive type. so, glass fiber exposures should be controlled or elimination by protective devices in the workplace. 3. The means of FVC, FFV1, FFV1% were in normal range. As the comparison of ventilatory functions by age groups, MMF was decreased significantly for the group, 50 years old and more than other groups. And the comparison by the serving periods at glass fiber producing factory, MMF was decreased for the workers had worked for 11-15 years. Therefore, MMF be more sensitive index in the evaluation of ventilatory impairments caused by glass fiber workers.

Impact of Solvent Exposure on the Occupational Hearing Loss / 대한산업의학회지

OBJECTIVES: This study was to evaluate the impacts of simultaneous exposure to noise and mixed solvents on workers'hearing threshold level (HTL) over five-year period. METHODS: The study was conducted by interview and annual audiometric test on workers in ship building industry from 1994 to 1998. The cases(workers who exposed to noise and mixed solvent simultaneously) were 43 male workers and controls (workers who exposed to nolle) were selected by matching method with regard to age, sex, carrier, and noise exposure level. To assess the impacts of solvent exposure on hearing threshold level, with considering other factors, general liner model was used. RESULTS: 1. The audiogram of all subjects showed typical sensorineural hearing loss pattern. The mean HTLe were increased at high frequency (4000HB and 8000Hz) for study period. 2. The HTLs of cases were more increased than those of controls at high frequencies (4000Hz and 8000Hz), but there was not statlstical significance. 3. The impact of age on the HTL was statistically significant at 250Hz and 500Hz (p(0.05), and the impact of noise on the HTL was statistically significant at 250Hz, 2000Hz and 4000Hz (p(0.05), but the impact solvent exposure on the HTL was not significant. 4. The changes in HTLs of cases were higher than those of controls at high frequency, there were not statistical significance at 4000Hz, but only at 8000Hz (p=0.087). 5. Statistical analysis of the general linear model implicated that the changes in HTL was impacted by noise exposure bevel significantly (p=0.031) and Impacted by solvent exposure weakly (p=0.087) at 8000Hz. CONCLUSIONS: The results of this study suggest that workers who simultaneously exposed to noise and mixed solvent were at risk for more affected HTL than those exposed to noise exposure only, but we could not find definitive evidence. Further detailed studies must be made in large number of workers.