The effect of diabetes on 4-year changes of hearing thresholds in male workers exposed to noise in a single company: a longitudinal study

BACKGROUND: Recently, several studies have assessed the association between diabetes and hearing impairment. However, the effect of diabetes on hearing impairment is not well known in diabetic patients exposed to noise, a typical cause of hearing impairment. The aim of this study is to longitudinally analyze the effect of diabetes on hearing impairment in workers exposed to similar noise levels from 2013 to 2017 who had experienced little change in their working conditions. METHODS: The study subjects included 2,087 male workers exposed to noise in a single company and who underwent health examinations at the same hospital in Ulsan city in 2013 and 2017. Hearing impairment was defined that a pure-tone average of pure-tone audiometry (PTA) thresholds at 1,000, 2,000, 3,000, and 4,000 Hz was 25 dB and over in both ears. Statistical analyses were conducted using χ2 tests, ANOVA, and Cox proportional hazard models. We analyzed covariates that might affect hearing impairment, including age; working period; levels of total cholesterol, triglyceride, and serum creatinine; smoking and alcohol history; and noise level. RESULTS: The average PTA thresholds and their average changes between 2013 and 2017 were significant in the diabetes mellitus (DM) group than those in the normal and impaired fasting glucose group. Among the subjects with the same status of fasting glucose group in 2013 and 2017, the adjusted hazard ratios for incident hearing impairment among those in the DM group compared to normal group were 3.35 (95% confidence interval [CI], 1.54–7.29) in the left ear and 5.66 (95% CI, 2.01–15.98) in the right ear. CONCLUSIONS: This study suggested that the risk of hearing impairment in the DM group was significantly higher than that in the normal group in both ears, even when exposed to similar noise levels.

Relationship of cigarette smoking and hearing loss in workers exposed to occupational noise

OBJECTIVES: To investigate the effects of smoking on hearing loss among workers exposed to occupational noise. METHODS: From the results of a special workers health examination performed in 2011, we enrolled 8,543 subjects exposed to occupational noise and reviewed the findings. Using self-reported questionnaires and health examination results, we collected data on age, smoking status, disease status, height, weight, and biochemistry and pure tone audiometry findings. We divided the workers into 3 groups according to smoking status (non-smoker, ex-smoker, current smoker). Current smokers (n = 3,593) were divided into 4 groups according to smoking amount (0.05-9.9, 10-19.9, 20-29.9, > or =30 pack-years). We analyzed the data to compare hearing thresholds between smoking statuses using analysis of covariance (ANCOVA) after controlling for confounder effects. RESULTS: According to ANCOVA, the hearing thresholds of current smokers at 2 k, 3 k, and 4 kHz were significantly higher than that of the other groups. Multiple logistic regression for smoking status (reference: non-smokers) showed that the adjusted odds ratios of current smokers were 1.291 (95% confidence interval [CI]: 1.055-1.580), 1.180 (95% CI: 1.007-1.383), 1.295 (95% CI: 1.125-1.491), and 1.321 (95% CI: 1.157-1.507) at 1 k, 2 k, 3 k, and 4 kHz, respectively. Based on smoking amount, the adjusted odds ratios were 1.562 (95% CI: 1.013-2.408) and 1.643 (95% CI: 1.023-2.640) for the 10-19.9 and > or =30 pack-years group, respectively, at 1 kHz (reference: 0.05-9.9 pack-years). At 2 kHz, the adjusted odds ratios were increased statistically significantly with smoking amount for all groups. At all frequencies tested, the hearing thresholds of noise-exposed workers were significantly influenced by current smoking, in particular, the increase of hearing loss at low frequencies according to smoking amount was more prevalent. CONCLUSIONS: Current smoking significantly influenced hearing loss at all frequencies in workers exposed to occupational noise, and heavier smoking influenced low-frequency hearing loss more greatly. There was a dose-response relationship between smoking amount and low-frequency hearing thresholds; however, this was not observed for high-frequency hearing thresholds. Therefore, well-designed prospective studies are needed to clarify the effects of smoking on the degree of hearing loss.

The General Characteristics and Results of the Cold Provocation Test in the Risk Group of HAVS / 대한산업의학회지

OBJECTIVES: The cold provocation test for diagnosing the vascular component in hand-arm vibration syndrome (HAVS) is likely to be accepted as an objective test, and a few studies have been performed. However, controversy has continued regarding the diagnostic performance of this method. Although objective methods such as plethysmography and laser doppler flowmetry have been studied, they have not received as much attention as other diagnostic methods. Therefore, our study aim was to spread the awareness of HAVS by reporting the results of the cold provocation test in a hand-transmitted vibration exposure group. METHODS: The study subjects were 549 workers who had been exposed to hand-transmitted vibrations and reported symptoms in their hands. While the subject immersed both their hands in 10degrees C water for 10 minutes, the skin temperature of 10 fingers was recorded from pre-immersion time to 20 minute postimmersion including 10 minutes immersion time. The recovery rates were calculated from the recorded skin temperatures. The 'decreased recovery rate' criteria were less than 30% at 5 minutes post-immersion and 60% at 10 minute post-immersion. RESULTS: Of the subjects, 69.1% and 30.9% had more severe symptoms in the right and left hands, respectively. The mean finger skin temperature of the right hand after cold-water immersion for 10 minutes was approximately 10degrees C, which increased gradually with time, but they did not reach the baseline temperature at 20 minutes post-immersion. The deviations of the skin temperature in the subjects were higher in the recovery phase than in the baseline and cold immersion phase. The 3rd finger of both hands showed the lowest 5-minute recovery rate among the fingers examined, and the left 4th finger and right 3rd finger showed the lowest 10-minute recovery rate. Of the subjects, 37.6% and 10.4% of subjects showed a lower recovery rate at 5 and 10 minutes in at least one finger, respectively, while 10.2% showed a lower recovery rate at both 5 and 10 minutes simultaneously in at least one finger. CONCLUSIONS: The larger deviations in the recovery phase than in the other phases indicated that interindividual differences are more prominent in the recovery phase. There might be no benefit in observing the finger skin temperature for an additional 10 minutes after 10 minutes post-immersion. Overall, approximately 10% of the subjects in the HAVS risk group had HAVS.

The Characteristics of Tinnitus and Hearing Threshold: In Workers with Noise Induced Hearing Loss from a Hospital Setting / 대한산업의학회지

OBJECTIVES: This study was carried out to define the relationship between the characteristics of tinnitus and hearing threshold (puretone and speech) in workers with noise induced hearing loss (NIHL). METHODS: A total of 189 cases(378 ears) from workers with compensation claims for NIHL during 2004-2009 were investigated. Various factors, including age, work carriers, body mass index (BMI), blood pressure, noise exposure level of worksite hearing threshold, speech discrimination score, pitch match, and loudness of tinnitus were analyzed. RESULTS: The average hearing threshold of all subject was 44.2 dBHL, puretone audiometry thresholds in subjects with tinnitus were lower than the non-tinnitus group (except at 8000 Hz). Using speech audiometry, the tinnitus group showed a lower speech recognition threshold and speech discrimination score. The tinnitus group also had an average tinnitus frequency of 4195.2 Hz, loudness of 73.6 dB, and tinnitus sensation average of 6.0 dBSL. These frequencies of tinnitus were in the lowest puretone audiometry frequencies. Tinnitus loudness had a strong relationship with puretone and speech audiometry thresholds. CONCLUSIONS: In cases beyond moderate hearing loss, the tinnitus group had a better puretone (except 8000 Hz) and speech hearing status, and most comfortable loudness (MCL) level. In addition, puretone and speech audiometry thresholds increase with tinnitus loudness.

AnAnalysis of the Length of Admission for Some Musculoskeletal Disordersamong the National Health Insurance Corporation Data / 대한정형외과학회잡지

PURPOSE :The goals of this study were to investigate the medical care utilization and statistics of lengths of admissions such as the means, modes, medians, maximums, and minimums for patients with some musculoskeletal diseases among the National Health Insurance Corporation data. We provided basic recommendations for the proper lengths of admissions of occupationally injured workers with these diseases in Korea. METERIALS AND METHODS: The study subjects were 20 to 59 year-old patients who were admitted from January 1, 2000 to June 30, 2001, over 4-day lengths of admission for the management of 20 different musculoskeletal disorders. We calculated means, standard deviations, modes, medians, maximums, minimums, and points of inflection for the lengths of admission of patients with these disorders. RESULTS: The mean length of admission for carpal tunnel syndrome was 8.0+/-6.2 days, that of Raynaud's syndrome was 10.5+/-7.7 days, that of internal derangements of the knee was 12.9+/-11.8 days, that of unspecified internal derangements of the knee was 13.3+/-13.0 days, that of cervical disc disorder with radiculopathy was 16.8+/-19.0 days, that of other cervical disc displacements was 15.9+/-15.9 days, that of lumbar and other intervertebral disc disorders with radiculopathy was 14.9 +/-13.8 days, that of unspecified intervertebral disc displacements was 14.9+/-13.9 days, that of unspecified synovitis and tenosynovitis was 12.5+/-9.9 days, that of ganglions was 7.5+/-7.3 days, that of fasciitis, NEC, was 19.8+/-24.7 days, that of adhesive capsulitis of the shoulder was 15.2+/-15.5 days, that of impingement syndrome of the shoulder was 11.4+/-12.0 days, that of medial epicondylitis was 11.2+/-7.3 days, that of lateral epicondylitis was 12.1+/-11.5 days, that of myalgias was 12.4+/-19.5 days, that of sprain and strain of the cervical spine was 12.4+/-10.2 days, that of sprain and strain of the lumbar spine was 12.3+/-10.9 days, that of a current tear of the meniscus was 13.3+/-13.2 days, and that of sprain and strain involving the cruciate ligaments of the knee was 18.2+/-17.0 days. Every point of inflection was the 80th percentile or the 90th percentile of the lengths of admission of the subjects. CONCLUSION: This study has significant weaknesses, such as limitations of applicable ranges and errors in the National Health Insurance Corporation data, among others. However, the authors present various statistics and points of inflection of lengths of admissions for patients suffering from 20 work-related musculoskeletal disorders in the general population. Those cases in which the lengths of admissions of patients with the above-mentioned musculoskeletal disorders that are greater than the points of inflection, need to be evaluated carefully.

Disability Duration in Musculoskeletal Injured Patients due to Automobile Accidents

OBJECTIVE: The aims of this study were to refer descriptive statistics of the disability duration in musculoskeletal injured patients in the automobile accidents. METHOD: The authors chose 469,319 injured patients in traffic accidents as subjects that met inclusion criteria with 8 representative Abbreviated Injury Scale (AIS) comparable with 4th edition of Korean standard classification of diseases. Mean, standard deviation, mode, median, maximum and minimum of 8 representative AIS code were calculated. RESULTS: Mean disability duration for minor cervical sprain was 18.8 days, that of moderate cervical disc herniation was 56.2 days, that of serious cervical disc herniation was 141.5 days, that of minor lumbar sprain was 21.2 days, that of moderate lumbar disc herniation was 53.5 days, that of serious lumbar disc herniation was 128.1 days, that of sprain of 3 major joint in lower limb without desmorrhexis was 24.0 days, and that of dislocation or desmorrhexis of 3 major joint in lower limb was 101.2 days. CONCLUSION: Disability duration of the representative musculoskeletal diseases comparable to AIS code in 4th edition of Korean standard classification of diseases was presented and this study can be utilized as a basic recommended disability duration of automobile injured persons.

Characteristics of Disability Recuperation Musculoskeletal Diseases at a Ship-Yard

OBJECTIVE: This study was performed to analyze the length of work-related musculoskeletal disability and to identify the various related factors of disability duration. METHOD: Approved cases work-related musculoskeletal disease between Jan 1, 2000 and Jan 6, 2004 were collected by using the workers' compensation company's database and questionnaire. The cases were comprised of 16 more frequent musculoskeletal diseases. 551 approved musculoskeletal disease cases were composed of 295 recuperated cases and 256 recuperating cases. RESULTS: The average length of work-related musculoskele- tal disability were 420.3+/-246.2 day in the recuperated group and 428.0+/-328.9 day in the recuperating group. The mean disability length of musculoskeletal diseases were over one year with similar distribution except for ganglion. The length of disability were not affected by age, employment duration, type and number of co-mobidity, time from claim receipt to allowance, type of treatment. But, operation history and accident type were affected to the length of disability. CONCLUSION: The results suggest that the length of work- related musculoskeletal disability was not determined by biomedical disease related factors, however, it determined by social and social insurance systemic factors.

Comparison of the Standard Threshold Shift Criteria for Evaluating Hearing Conservation Programs / 대한산업의학회지

OBJECTIVES: Workers from a factory was selected to compare 8 standard threshold shift criteria with the Korean diagnostic criteria of noise-induced hearing loss for this cohort study. METHODS: From 1990 to 1999, 491 workers at a manufacturing company with complete record of the hearing test covering the range of 0.5~6 kHz for 10 consecutive years were finally selected. Eight standard threshold shift criteria (15 dB once, NIOSH (1972), 10 dB average 3~4 kHz, OSHA STS, AAOHNS, 15 dB twice, 15 dB 1~4 kHz, OSHA STS twice) along with the Korean standard for diagnosing the noise-induced hearing loss (the average hearing threshold at 0.5, 1 and 2 kHz) were compared to calculate the degree of the threshold shift and the minimum time required to detect the change. RESULTS: Those workers showing at least one positive shift in the 'once'criteria of NIOSH (1972) were 92.5%; the 'average'criteria of 10 dB average 3~4 kHz were 35.8%; 'twice'criteria of 15 dB twice were 44.4%. The duration from the baseline to the year showing the first positive shift was from 3.2 +/- 3.1 years (NIOSH, 1972) to 6.0 +/- 2.1 years (OSHA STS twice). The percentage of true positive shift ranging from 20.4% (AAO-HNS) to 69.8% (NIOSH, 1972). There were 10 (2%) which met the Korean diagnostic criteria of noise-induced hearing loss. CONCLUSIONS: Currently the concept of hearing threshold shift in diagnosing the hearing loss was adopted in Korea thus in this study we determined the validity and the effect of the various hearing threshold shift criteria and showed that NIOSH (1972) criteria was the best of all. In the future, hearing data from various manufacturing workers should be compared to thoroughly evaluate the threshold shift criteria and to establish adequate standard for Korean workers.

Evaluation of Ototoxicity by Mixed Organic Solvents Using the Upper Limit of Hearing / 대한산업의학회지

OBJECTIVES: This study evaluated the ototoxicity by mixed organic solvents on workers'hearing using the upper limit of hearing(ULH). METHODS: Seven hundred ninety-seven male workers in the ship building industry who were evaluated by interview with an upper limit of hearing from August 2000 to July 2002 were enrolled in the study. The subjects were divided into 3 groups according to exposure profile and job: officers, field supporters, and painters. To assess the ototoxicity of mixed organic solvent exposure on hearing, with regard to confounders, the general liner model was used. RESULTS: After controlling for the possible confounders, such as age, career, noise exposure level, tinnitus, alcohol intake, and smoking, the estimated mean for ULH of the painter group was higher than that of the officer and the field supporter groups. These differences of mean ULH were at the borderline of statistically significance(p=0.069). CONCLUSIONS: The results of this study suggest that a relatively lower level of mixed organic solvent chronically affected the hearing organ or auditory pathway. ULH seems to be a useful method for early detection of the ototoxicity of organic solvents.

Relationship of Biological Indices of Manganese with Pallidal Index on MRI in Liver Cirrhotics / 대한산업의학회지

OBJECTIVES: The objectives of this study were to clarify which biological manganese exposure indices reflect the pallidal signal intensities in magnetic resonance imaging (MRI) in liver cirrhotics. METHODS: We examined whole blood, plasma, RBC and urinary manganese concentrations, as well as, brain MRI in 22 cirrhotic patients and 10 healthy controls. From MRI scans we calculated the signal intensity of the globus pallidus using the pallidal index (PI), the ratio of the globus pallidus to subcortical frontal white-matter signal intensity in axial T1-weighted MRI planes multiplied by 100. In addition, we studied the relationships between PI and other measurements. RESULTS: The high signal intensity in the globus pallidus on T1-weighted MRI was observed in 18 (81.8%) patients. There was a significant correlation between whole blood and RBC manganese concentration, and PI on MRI. According to multiple linear regression, whole blood and RBC manganese concentration reflected PI on MRI better the other indices did. CONCLUSIONS: Whole blood and RBC manganese concentrations could be useful as biological manganese exposure indices that reflect PI on MRI.

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.

Epidemiologic Characteristics of Hand-Arm Vibration Syndrome through Occupational Disease Surveillance System in Busan, Ulsan, Kyungnam Province / 대한산업의학회지

OBJECTIVES: The objectives of this study were to estimate the epidemiologic characteristics of hand-arm vibration syndrome (HAVS) due to occupational exposure of hand transmitted vibration and to identify the occupations and industries where such exposures arises, and the main sources of exposure. METHODS: In April 2001 the Busan, Ulsan, and Kyung-Nam Province occupational disease surveillance system was established to measure the incidence and prevalence of work-related HAVS and other occupational diseases in these Korean provinces. Occupational physicians of nine hospitals in Busan, Ulsan, and Kyung-nam Province were involved in this project between April 2001 and November 2002. Physicians collected information through questionnaires and interviews. Information gathered included age, occupation, types of vibration tools used and presence of subjective symptoms such as vibration-induced white finger (VWF), numbness and tingling. RESULTS: A total 192 cases were reported with 188 males and 4 females. The shipbuilding industry was the most common type of industry and grinders were the most common source of exposure. Symptoms of neurological disorder were more common than those of vascular disorder. CONCLUSIONS: The authors concluded that exposure to hand transmitted vibration is common and that HAVS is one of the most common occupational diseases in Korea. However, the range and extent of hand transmitted vibration and the overall prevalence of HAVS in Korea is still unknown. More extensive research on this syndrome in order to priorite necessary preventive measures is required.

Cohort Study for the Effect of Chronic Noise Exposure on Blood Pressure among Male Workers / 예방의학회지

OBJECTIVE: Whether exposure to chronic noise induces an increase in blood pressure, or the development of hypertension, has not been established. A cohort study was performed to identify the effects of chronic noise exposure on blood pressure. METHODS: 530 males working at a metal manufacturing factory in Busan, Korea were enrolled for the study. They were monitored for 9 consecutive years, from 1991 to 1999, with an annual health check-up. The subjects were divided into 4 groups, which were determines by noise level categories(NLC) according to noise intensity ; NLC-I: office workers, exposed to noise a level below 60dB(A); NLC-II: field technical supporters or supervisors, frequently exposed to workplace noise, wearing no hearing protection device; NLC-III: workers, exposed to workplace noise below 85 dB(A), wearing ear plugs or muffs; NLC-IV: workers, exposed to workplace noise over 85 dB(A), wearing both ear plugs and muffs. RESULTS: After controlling possible confoundens, such as baseline age, smoking, alcohol intake, exercise, family history of hypertension, systolic(SBP) or diastolic blood pressure(DBP) and changes in BMI (body mass index), the pooled mean for the systolic blood pressures, over the duration of the study period, were 3.8mmHg, 2.0mmHg and 1.7mmHg higher in NLC-IV, NLC-III NLC-II groups, respectively, than in the NLC-I group. There were no significant differences in the diastolic blood pressures between the groups. CONCLUSION: This study suggests that chronic noise exposure increases systolic blood pressure independently, among male workers.

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.

Prevalence and Risk Factors of Tinea Pedis in Workers of Shipbuilding Industry / 대한산업의학회지

OBJECTIVES: Recently,tinea pedis has been reported to be a type of occupational dermatoses because of its high prevalence in specific working conditions.Although there is no doubt that the environment surrounding work places, the usual habits of workers etc are intimately related to this skin conditions, there is some controversy as to whether or not this condition is a real occupational illness and what is the exact cause of the high prevalence of this illness is. In this study, the prevalence of tinea pedis in workers from the shipbuilding industry was investigated andthe risk factors of this disease were evaluated. This study also aimed to verify whether or not tinea pedis is one of the occupational diseases. METHODS: The results of interviews, questionnaires and clinical findings from 1,419 workers who visited the occupational health center for an annual routine check for their health state were analyzed. RESULTS: Among the 1,419 workers, 778 workers (54.8%)had tinea pedis. By simple logistic regression analysis,the prevalence of tinea pedis was found to be affected by some variables, including the job category, the types of work,the kinds of footwear, whether or not they were using communal baths in the work places, and a family history of tinea pedis.In contrast, by multiple logistic regression analysis,only utilization of the communal baths in the work places and a family history of tinea pedis turned out to be statistically significant risk factors. CONCLUSIONS: In this study, the major factors contributing to the high prevalence of tinea pedis are the use of communal baths in the workplace and a positive family history. However, the wearing of safety shoes was not statistically significant. Therefore, tinea pedis could not be confirmed to be an occupational disease. On the basis of these results, a solution to the environmental hygiene of communal baths and the personal hygiene of individuals needs to be improved in order to prevent tinea pedis.

Trend of the Changes in the Level of Blood Lead, Urinary Arsenic and Urinary Cadmium of Children in Ulsan: 3-year Follow-up Study / 예방의학회지

OBJECTIVES: To obtain basic data on blood lead level and urinary level of arsenic and cadmium of children living near a petrochemical estate and a suburban area in Ulsan, Korea and to observe the trend of the changes in the level of these metals in these children. METHODS: The study subjects comprised 626 children living near a petrochemical estate and 299 children living in a suburban area of Ulsan. We analyzed the level of lead, arsenic and cadmium using atomic absorption spectrometer. RESULTS: The mean levels of blood lead in children living near the petrochemical estate were 5.25 microgram/dl, 5.24 microgram/dl, and 7.24 microgram/dl in the years 1997, 1999, and 2000, respectively, whereas those of children living in the suburban area were 3.81 microgram/dl, 4.75 microgram/dl, and 7.19 microgram/dl respectively. The mean levels of urinary arsenic in children living near the petrochemical estate were 4.57 microgram/g creatinine, 4.78 microgram/g creatinine, and 6.02 microgram /g creatinine in the year 1997, 1999, and 2000 respectively, whereas those of children living in suburban area were 2.35 microgram/g creatinine, 4.75 microgram/g creatinine, and 7.07 microgram/g creatinine, respectively. The mean levels of urinary cadmium in children living near the petrochemical estate were 1.15 microgram/g creatinine, 1.05 microgram/g creatinine, and 1.71 microgram/g creatinine in the year 1997, 1999, and 2000, respectively, whereas those of the children living in the suburban area were 0.74 microgram/g creatinine, 1.29 microgram/g creatinine, and 1.48 microgram/g creatinine, respectively. There were increasing trends in the level of blood lead, urinary arsenic and cadmium of children in Ulsan, and the differences in the level of these metals were disappearing between the children living in other areas year by year. CONCLUSIONS: These results suggest that the amount of exposure to lead, arsenic, and cadmium is increasing from year to year, and there is a need for periodic biological and atmospheric monitoring of these metals in Ulsan.

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.

Respiratory Health of the Children Living near the Petrochemical Estate in Ulsan / 예방의학회지

OBJECTIVES: To evaluate the effect of low-level exposure of air pollutants on the respiratory tract of the children living near the petrochemical estate in Ulsan. METHODS: The study design was cross-sectional, and the study subjects consisted of 150 children(76 boys, 74 girls) living near the petrochemical estate and 100 children(53 boys, 47 girls) living in a suburban area. We investigated respiratory health using self-administered questionnaires(ATS-DLD-78), radiological examination, and pulmonary function test such as FVC and FEV1. RESULTS: There were higher prevalence rates of respiratory symptoms in the children living near the petrochemical estate than the children living in a suburban area. And the results of FVC and FEV1 of 11-years old children living near the petrochemical estate were lower than those of the children living in a suburban area. CONCLUSIONS: Chronic exposure of low-level air pollutants would affect respiratory health of the children. Therefore, further a longitudinal study of respiratory health will be needed for children living near the petrochemical estate in Ulsan.

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.

Hematological Changes of Welders / 예방의학회지

OBJECTIVES: To ascertain whether some result of hematological examination could be as reference data for health management of welders. METHOD: The authors conducted the hematological examination of 1,018 welders and 531 control workers of a shipbuilding industry in Ulsan using automatic blood analyzer. RESULTS: The WBC count of welders was lower than that of control on controlling the age and the duration of employment, but changes of other blood cells were not observed. CONCLUSION: We could use the results of hematological examination such as WBC counts as an indicator for subtle changes of health status of welders.