Job Stress, Heart Rate Variability and Metabolic Syndrome / 대한산업의학회지

OBJECTIVE: A growing body of literature has documented that job stress is associated with the development of cardiovascular disease. Nevertheless, the pathophysiological mechanism of this association remains unclear. Therefore, we tried to elucidate the relationship between job stress, heart rate variability and metabolic syndrome. METHOD: The study design was cross-sectional, and 169 industrial workers were recruited. A structured-questionnaire was used to assess the general characteristics and job characteristics (work demand, decision latitude). Heart rate variability (HRV) was recorded using SA-2000 (medi-core). HRV was assessed by time-domain and by frequency-domain analyses. Time domain analysis was performed for SDNN (Standard Deviation of NN interval), and spectral analysis for low-frequency (LF), high-frequency (HF) and total frequency power. Metabolic syndrome was defined on the basis of clustering of risk factors, when three or more of the following cardiovascular risk factors were included in the fifth quintile: glucose, systolic blood pressure, HDL-cholesterol (bottom quintile), triglyceride and waist-hip ratio. RESULTS: The results showed that job characteristics were not associated with cardiovascular risk factors. The high strain group had a less favorable cardiovascular risk profile with higher levels of blood pressure, glucose, homocysteine, and clotting factor than the lower strain group (low strain+passive+active group), but the difference was not statistically significant. The SDNN of HRV was significantly lower in the high strain group than in the low strain group. The prevalence of metabolic syndrome in the low strain, passive, active and high strain groups was 9.7%, 13.9%, 14.9% and 23.8%, respectively. In the high strain group, the metabolic syndrome was significantly related to a decreased SDNN. However, we could not find a significant association in LF/HF ratio. CONCLUSION: This result suggests that decreased HRV does not play a role in the development of disease; however, it can induce cardiovascular abnormalities or dysfunctions related to the onset of heart disease among high risk groups.

Occupational disease surveillance system in Busan, Ulsan, Kyung-Nam area / 대한산업의학회지

OBJECTIVE: Occupational medicine specialists in the Busan, Ulsan and Kyung-Nam areas established an area-based occupational disease surveillance system and used this system to collected case information for the purpose of preventing occupational diseases METHODS: 11 hospitals participated in this system. The authors selected five main diseases, which were hand-arm vibration syndrome (HAVS), work-related musculoskeletal disorder (WRMSD), occupational asthma, occupational skin disease and occupational lung cancer and established their case definitions. All cases were reported on the web, and real time analysis was conducted. RESULTS: Between Apri1 2001 and April 2003, 192 cases of HAVS, 118 cases of WRMSD, 33 cases of occupational asthma, 17 cases of occupational skin disease and 17 cases of occupational lung cancer (for a total of 377 cases of these five main diseases) were reported. Most of the HAVS cases came from shipbuilding, and 172 of them (92.7 %) were associated with grinding. Of the four main types of WRMSD, carpal tunnel syndrome (CTS) was the most prevalent with 46 cases and shipbuilding was also the main industry involved (83.9 %). The ergonomic risk factors involved mainly associated with the hand. In 19 (57.6 %) and 4 (12.1 %) cases of occupational asthma, the agents included isocyanate and welding fume, respectively. 64.7 % of the cases of occupational skin diseases were contact dermatitis, and organic solvents and welding fume were the main agents involved. The causative agents of occupational lung cancer included Cr, welding fume, PAH, Ni, etc. 10 (58.8 %) of the cases were diagnosed as squamous cell carcinoma and 5 (29.4 %) as adenoma. CONCLUSION: This result showed that an area-based occupational disease surveillance system might provide an effective method of evaluating the prevalence of such diseases, however the Busan, Ulsan and Kyung-Nam provinces are too large to be treated as individual areas. Therefore, the authors suggest that each province should establish its own surveillance system.

Relationship between Job Stress and Pulse Wave Velocity as a Cardiovascular Risk Factor / 대한산업의학회지

OBJECTIVE: The objective of this study was to elucidate the relationship between job stress and pulse wave velocity (PWV) as a cardiovascular risk factor. METHOD: The study design was cross-sectional, and a total of 234 industrial workers were recruited. A structured-questionnaire was used to assess the general characteristics and job characteristics (work demand, decision latitude) using a modified Karasek model. Cuffs were applied to the extremities and a microphone for phonocardiography was placed at the second intercostal space at the margin of the sternum. The subjects rested in a supine position for 5 min, and PWV was measured using a VP-1000(Colin Waveform analyzer). RESULTS: There were significant correlations between blood pressure, glucose, total cholesterol, coagulation factor and PWV. The group with low decision latitude and high decision latitude showed higher levels of PWV, but the differences were not significan. The PWV (left) was significantly higher in the high strain group than in the lower strain group. After adjustment for age and cardiovascular risk factors, job strain was still associated with PWV. CONCLUSION: These result suggest that the high strain group among workers is related to an increased risk of PWV as a marker of atherosclerosis.

Job instability of Labor Market and Preplacement Health Examination: the Case of Hearing Loss / 대한산업의학회지

OBJECTIVES: This study examines the problem of the preplacement health examination in terms of hearing loss case, where workers have been experiencing job instability in the labor market. METHODS: In order to measure the 2-year job retention rate of employees in 79 shipbuilding subcontracted companies in Kyongnam province, we utilized the same methods as those used by Neumark et al(1999), and Bernhardt et al(1999). We surveyed 79 heath and safety personnel from the companies with a questionnaire to evaluate the present status of the preplacement health examination. We reviewed the preplacement health certificates(result of audiometric hearing thresholds) of 1,818 recruits issued by Daewoo hospital from January 1 to June 30, 2001. RESULTS: The job retention rate was 40.3 %(male 38.53 %, female 52.01 %). Of the 79 health and safety personnel of companies, 44(55.7 %) perceived the preplacement health examination as a tool for the selection of recruits, 3(3.8 %) as a procedure for job fitting and 31(39.2 %) as both. Most of them were against the acceptance of recruits with hearing loss, spinal disease and hepatitis. Among the 1,818 workers who underwent the preplacement health examination, 530(29.1 %) were examined after employment, but 1,096(60.3 %) were examined before employment. The number with previous job experience was 1,591(87.5 %). In the audiometric hearing threshold results, the prevalence of hearing loss was positively correlated with age. There was a significant difference in the prevalence of hearing loss depending on previous job and number of quitting at 4,000 Hz. CONCLUSIONS: The comparison of 2-year job retention rates before and after the Korean economic crisis of 1997 suggests that job stability has been aggravated especially for cohorts of long tenure, irregular job, and old age. This evidence shows that previous job and age play a role in determining worker employment based on perceived results from the preplacement health examination. This result suggests that a pre-employment health examination be substituted for the preplacement health examination based on the essential job functions and reasonable accommodation. Because it has little relevance in a wide range of employment and minor health problems, the results of this examination should not debar applicants from employment.

A Meta-analysis of the Association between Blood Lead and Blood Pressure / 예방의학회지

OBJECTIVES: To integrate the results of studies which assess an association between blood lead and blood pressure. METHODS: We surveyed the existing literature using a MEDLINE search with blood lead and blood pressure as key words, including reports published from January 1980 to December 2000. The criteria for quality evaluation were as follows: 1) the study subjects must have been workers exposed to lead, and 2) both blood pressure and blood lead must have been measured and presented with sufficient details so as to estimate or calculate the size of the association as a continuous variable. Among the 129 articles retrieved, 13 studies were selected for quantitative meta-analysis. Before the integration of each regression coefficient for the association between blood pressure and blood lead, a homogeneity test was conducted. RESULTS: As the homogeneity of studies was rejected in a fixed effect model, we used the results in a random effect model. Our quantitative meta-analysis yielded weighted regression coefficients of blood lead associated with systolic blood pressure and diastolic blood pressure results of 0.0047 (95% confidence interval [CI]: -0.0061, 0.0155) and 0.0004 (95% CI: -0.0031, 0.0039), respectively. CONCLUSIONS: The published evidence suggested that there may be a weak positive association between blood lead and blood pressure, but the association is not significant.

The Association of Workplace Cumulative Noise Exposure and Blood Pressure / 대한산업의학회지

OBJECTIVES: The association of workplace cumulative noise exposure and blood pressure was investigated in this study using cross-sectional design. METHODS: The study population comprised 852 manufacturing male workers of whom occupational health examination data, questionnaire and personnel records were available. Workplace ambient noise monitoring data was used for calculating individual cumulative noise exposure level. Mean of each systolic and diastolic blood pressure of occupational health examination data was used for individual systolic and diastolic blood pressure level. Possible confounding variables including family history of hypertension, smoking habit, alcohol drinking habit were collected by questionnaire. On the basis of job location and duration of work at the location, a cumulative time-weighted average noise level was calculated for each workers. According to this cumulative noise exposure level, each study subject was categorized as low noise exposure group, moderate noise exposure group, high noise exposure group, very high noise exposure group. Among noise exposure groups, mean of systolic and diastolic blood pressure was compared after adjusting possible confounding variables such as age, body mass index, serum cholesterol level, family history of hypertension, smoking history, alcohol drinking habit. RESULTS: After adjusting possible confounding variables, noise exposure group was significant explanatory variables for both systolic and diastolic blood pressure, and mean of both systolic and diastolic blood pressure of very high exposure group was higher than that of low exposure group. CONCLUSIONS: These findings suggested that the high cumulative noise exposure might elevate the blood pressure.

The Health Status Assessment of Subcontracted Workers / 대한산업의학회지

OBJECTIVES: The strategy for the labor flexibility through subcontracted labor have brought a negative effect on the lives of the workers, such as the increase of the unstable employment. This study was conducted to analyze the relationship between the employment of subcontracted firms and the health status of them, and to find out some problems which have been caused in the process of health evaluation and the characteristics of social exclusion. METHODS: We reviewed the periodical health examination and preemployment health examination in order to compare health status of the subcontracted workers with those of the parent firm workers. The SF-36 questionnaire was administered to assess the self-perceived health status. RESULTS: The result shows that compared to the working duration of the parent firm workers, those of the subcontracted workers were shorter, and the job transfer rate was higher. In the periodical health examination, the prevalence of occupational and general disease was higher in the parent firm(10%) than in the subcontracted firms(6%). Preemployment health examination plays an important role in worker's health management. Among 6,260 workers who received preemployment health examination, the prevalence of disease was 37.9%. Mean scores of health status measured by SF-36 were lower in the subcontracted firm than in the parent firm. CONCLUSIONS: Due to social exclusion of the subcontracted workers from the periodical health examination, there is a possibility that the periodical health examination have the healthy worker effect. These results suggests that the preemployment health examination could be a more appropriate indicator which is able to assess the health status of the subcontracted workers than the periodical health examination.

The Similar Exposure Group and Exposure Variation in Ship-Building Painters: Focused on Xylene Exposure / 대한산업의학회지

OBJECTIVES: This study was conducted to assess the concentration of xylene exposure and exposure variability of a similar exposure group(SEG) in accordance with job title and confined space. METHOD: The study subjects included 28 workers working in the painting process in the ship-building industry. Measurement of subjects were repeated three times. Within and between-worker exposure variance components were estimated from log-transformed exposure concentrations employing a one-way nested random effects analysis of variance model. A uniformly exposed group was defined as one where the between-worker variance(sigmaB2) was less than or equal to 0.031 or bwR95 or=0.031) and the ratios of the 97.5th and 2.5th percentile workers of the log normally distributed exposures of each group of workers was more than 2. However dividing job title into confined space(in-block, out-block, in/out-block) decreased the between-worker exposure variability. CONCLUSION: This study focused on the quantitative aspects of exposure in painters in the ship-building industry. We cannot accept the assumption that SEG are uniformly exposed, as a major component of variation in exposure relates to differences in tasks or other factors. Therefore, the observational schemes can be improved by investigating jobspecific task and practice.

A Meta-analysis on the Association between Chronic Noise Exposure and Blood Pressure / 예방의학회지

OBJECTIVES: This study was conducted to integrate the results of studies assessing the association between chronic noise exposure and blood pressure. METHODS: Using a MEDLINE search with noise exposure, blood pressure and hypertension as key words, we retrieved articles from the literature that were published from 1980 to December 1999. The criteria for quality evaluation were as follows: 1) the study subjects must have been workers employed at a high noise level area 2) The paper should use average and cumulative noise exposure as method for exposure evaluation. 3) Blood pressure in each article should be reported in a continuous scale Among the 77 retrieved articles, six studies were selected for quantitative meta-analysis. Before the integration of the regression coefficients for the association between blood pressure and noise level, homogeneity tests were conducted. RESULTS: All studies were a cross-sectional design and the study subjects were industrial workers. Five papers used a time-weighted average for noise exposure and only one paper calculated the cumulative noise exposure level. The measurement of blood pressure in the majority of studies were accomplished in a resting state, and used an average of two or more readings. The homogeneity of studies was rejected in a fixed effect model, so we used the results in a random effect model. The results of the quantitative meta-analysis, the weighted regression coefficient of noise associated with systolic blood pressure and diastolic blood pressure were 0.05 (95% confidence interval [CI]: -0.03, 0.13) and 0.06 (95% CI: -0.01, 0.13), respectively. CONCLUSIONS: Our results suggested that chronic exposure to industrial noise does not cause elevated blood pressure.

Incidence and Risk Factors for Occupational Low Back Pain Among Shipyard Workers / 대한산업의학회지

OBJECTIVES: This study was conducted to estimate the incidence rate, and to identify the risk factors for the occupational low back pain among shipyard workers. METHODS: The study subjects consisted of 9,784 workers who were employed in a ship-building industry(excluded workers who had a history of low pack pain before 1995 or did not take periodic health examination in 1995). The cases were 220 people who experienced back pain from January 1, 1996 to December 31, 1998. To assess risk factors for occupational low back pain, Cox propotional hazard model was used. RESULTS: During the recent three years from 1996 to 1998, the incidence rate per 1,000 persons was 7. 8 in 1996, 8. 8 in 1997, and 3. 1 in 1998. The main causes of work-related low back pain were sprain, strain and disc herniation. Lifting was the most common cause of back pain(35. 3%), and carrying(10.2%) and pulling(8.0%) were followed. In Cox proportional harzard model, independent risk factors for back pain were body mass index(R.R.; 1.54, 959o C.I.: 1.06-2.25), shift work(R.R.; 1.65, 95% C.I.: 1.19-2.28), and lifting heavy material(R.R. ; 3.95, 95% C.I: 2.29-6.82). CONCLUSIONS: This study suggests that the risk factors of back pain in shipyard workers were body mass index, shift work and lifting.

Effects of Job Strains on Absenteeism from Work / 예방의학회지

OBJECTIVES: The purpose of this study was to assess the relationship between job strains and absenteeism from work. METHODS: The study design was cross-sectional, and the study subjects consisted of 1,166 workers who were employed in the small-sized industries. A self administered questionnaire was used to measure the general characteristics, job characteristics(job demand, job control), and social support(coworker support, supervisor support) at work. The Job Content Questionnaire(JCQ) was used to assess job demand(2 items) and decision lattitude(10 items). Social support at work (10 items) was measured using JCQ. Sick absence was collected using self-report and were rechecked by the attendance record of their company. Odds ratios and 95% confidence intervals for the association between job strain and sick absence were estimated. The modifying effect of social support was evaluated by stratification. Logistic regression was used to estimate the relationship between job strain and sick absence. RESULTS: In the bivariate analysis, the variables related to sick absence were age, marital status, occupation, job demand. Four distinctly different kinds of level of job strain were generated by the combination of job demand and job control: low strain group, high strain group, active group, and passive group. The crude odds ratio of high job strain was 1.78(95% CI: 1.26-2.53), and those of active group and passive group were 1.33(95% CI: 1.07-1.66) and 1.13 (95% CI: 0.88-1.47), respectively. The odds ratio of high job strain after adjusting for age and occupation were still significant. The odds ratio of high job strain in low social support was 5.96(95% CI: 2.45-14.51), but that in high social support was 0.73(95% CI: 0.26-2.01). CONCLUSIONS: Job strain was associated with increased risk of absenteeism from work, and social support at work modified the association between job strain and sick absence.

Study on Perceived Occupational Psychosocial Stress and Work-related Musculoskeletal Disorders among VDT Works / 대한산업의학회지

It has been hypothesized that jobs that have both high psychological demands and low decision latitude ('job strain") can lead to musculoskeletal disorder. The objective of this study was to test whether job strain was correlated with the presence of work-related musculoskeletal disorder, especially myofascial pain syndrome (MPS). Information on demographic factors, confounders such as household load and taking care of children or not, and scores for decision latitude, job demand, and social support was obtained by self-administered questionnaire, which had been developed in Korean language, by adopting NIOSH instrument and Extended Karasek Model (16 items). All subjects were also examined by rehabilitation medicine specialists for musculoskeletal disorders. Subjects (n=370) could be categorized into 4 groups, these were, housewives(n=89), shipyard CAD workers(n=89), general female workers(n=79; nurses, insurance counselors, public officials, clerks, etc), and telephone directory assistance operators(n=113). Results from univariate analyses indicated that all demographic factors, all confounders, scores for decision latitude and social support were not associated with the risk of musculoskeletal disorder. However, score for job demand was higher in musculoskeletal disorder cases than others. In subgroup analysis, this association was convinced again, in telephone directory assistance operators. Job strain model showed that the group of telephone directory assistance operators was high-strain group, and OR of musculoskeletal disorder was 2.446 (95% C.I. : 1.174, 5.096), when comparing this with the low strain group. In conclusion, job strain is a risk factor for work-related musculoskeletal disorder.

Evaluation of Health Exams on Local Vibration Illness among Shipyard Workers / 대한산업의학회지

A hand-arm vibration syndrome, local vibration illness, occurs in some workers who use hand held vibration tools. It consists of white fingers, diffusely distributed finger neuropathy, pain in the hand and arm, and a small excess risk of osteoarthritis. This study is aimed to identify effective methods to confirm local vibration illness among various health exams, which are mentioned in worker's special health exam regulation. In addition, this study is aimed to quantitatively assess the daily vibration exposure level as a major determinant of vibration illness. The subjects, 46 vibration workers, were selected according to the results of the first special health exam about vibration hazards at shipbuilding industry in 1997. They all had experiences of work related blanching of fingers. Fifteen controls, who had no vibration exposure at all, were also recruited to compare their test results with the results of vibration workers. We adopted 1 subjective and 6 objective tests to evaluate the effectiveness and feasibility for confirming local vibration illness. These tests were history taking of subjective symptoms according to the Stockholm classification, checking blood pressure of finger, checking grasp power, checking finger skin temperature, nail-bed pressing test, vibration perceptional threshold test, and skin prick test for pain perception. Among these, checking skin temperature, nail-bed pressing test, and vibration perception test included cold water provocations. We also estimated some vibration exposure levels of hand held vibration tools by using previously published data from one automobile company. In conclusion, history taking of subjective symptoms according to the Stockholm classification, nail-bed pressing test, and vibration perceptional threshold test were discovered to be effective to diagnose local vibration illness. Furthermore, vibration perceptional threshold on right fingers showed a dose-response relationship to daily vibration exposure levels. The parameter beta was 0.0005(+/-0.0002), and statistically significant by REM (random effects model).

Comparison of Renal Function in Spinal cord Injury Patient with and without Reflux / 대한비뇨기과학회지

The serum creatinine level, excretory urogram, endogenous creatinine clearance value, urine culture and method of drainage of urine of 116 patients with spinal cord injury were examined and compared. The serum creatinine value was found to be poor indicators of renal deterioration in these patients. Combination of bilateral reflux and suprapubic drainage resulted in a greater degree of renal damage, but no reflux with intermittent catheterization group had a good result.

One Case of Xanthogranulomatous Pyelonephritis / 대한비뇨기과학회지

Xanthogranulnmatous pyelonephritis is an unusual chronic renal infection associated with renal calculi, urinary tract infection or obstruction in many cases. It is characterized by orange-yellow nodules of inflamed parenchymal tissue macroscopically and foamy lipid-laden histiocyte microscopically. We report a case of Xanthogranulomatous pyelonephritis in a 74 years old male.