The Relationship of Physical and Psychosocial Risk Factors to Work-related Musculoskeletal Upper Extremity Symptoms amongst Male Automobile Manufacturing Workers / 대한산업의학회지

OBJECTIVES: The objective of this study was to determine the relationship of physical and psychosocial risk factors to work-related musculoskeletal upper extremity symptoms amongst automobile manufacturing workers. METHODS: The cross-sectional study was conducted using male automobile manufacturing workers in order to examine the relationship of physical and psychosocial risk factors to work-related musculoskeletal upper extremity symptoms. A total of 1,793 male workers were asked to complete a self-administered questionnaire. The questionnaire consisted of questions regarding general characteristics, health related behaviors, work-related characteristics, job stress, ergonomic risk factors, and the presence of musculoskeletal symptoms (neck, shoulder, arm, and hand). Work-related musculoskeletal symptoms were evaluated using the National Institute of Occupational Safety and Health (NIOSH) surveillance criteria. In order to measure the physical risk factors, the American National Standard Institute (ANSI) Z-365 Quick checklist was incorporated into the questionnaire. Job stressors were measured using the Korean Occupational Stress Scale (KOSS). A binary logistic regression analysis was performed that examined the relationship of physical and psychosocial risk factors to musculoskeletal symptoms. RESULTS: The result showed that the physical and psychosocial risk factors were associated with musculoskeletal upper extremity symptoms. The workers with high physical risk factors reported more musculoskeletal symptoms than those having low physical risk factors (OR: 2.37, 95% CI: 1.56~3.62). The workers with high job stress were more likely to have an increased risk of musculoskeletal upper extremity symptom compared to those with normal job stress (OR: 2.65, 95% CI: 2.03~3.47). A significant relationship between the combined effects of physical and psychosocial risk factors on musculoskeletal upper extremity symptoms was also found. The workers exposed to high physical risk factors, high job stress, and long working hours were more likely to report musculoskeletal symptoms than those having low physical risk factors, normal job stress and moderate working hours(OR: 2.37, 95% CI: 1.56~3.62). CONCLUSIONS: The results suggest that some physical and psychosocial risk factors increase the risk of work-related musculoskeletal upper extremity symptoms amongst automobile manufacturing workers. In order to prevent or reduce musculoskeletal disorders amongst automobile manufacturing workers, it is strongly recommended to manage the physical psychosocial risks occurring in the workplace.

Job Stress and Self-perceived Fatigue in Korean Farmers / 대한산업의학회지

OBJECTIVES: A growing body of research has documented that job stress has a pivotal role in developing adverse health outcomes. However, little is known about the relationship between farmers' job stress and health outcomes. This study was undertaken to identify the relationship between job stress and self-perceived fatigue in Korean farmers. METHODS: A total of 526 Korean farmers were asked to participate in this study. A self-administered questionnaire was used to assess the participants' general characteristics, job stress and self-perceived fatigue. Job stress was measured using a forty-eight item Farm Stressor Inventory (FSI), and the self-perceived fatigue was estimated by Multidimensional Fatigue Scale (MFS). Binary logistic regression analysis was conducted to examine the relationship between job stress and self-perceived fatigue. RESULTS: The result showed that job stress was associated with self-perceived fatigue. For the farmers with high job stress, the risk of self-perceived fatigue was more likely to increase compared to those with low job stress. For males, labor intensity (OR, 3.88; 95% CI, 1.91~7.89), job environment (OR, 2.45; 95% CI, 1.22~4.93), social support (OR, 2.10; 95% CI, 1.07~4.13), social isolation (OR, 2.45; 95% CI, 1.15~5.60), financial problems (OR, 3.25; 95% CI, 1.53~6.91), uncertainty (OR, 2.48; 95% CI, 1.30~4.75) and health problems (OR, 5.77; 95% CI, 2.46~13.53) were associated with self-perceived fatigue. For females, job environment (OR, 2.23; 95% CI, 1.22~4.08), social isolation (OR, 2.08; 95% CI, 1.05-4.15), physical environment & weather condition (OR, 2.61; 95% CI, 1.33~5.12), financial problems (OR, 2.87; 95% CI, 1.55~5.32), uncertainty (OR, 3.65; 95% CI, 1.95~6.83) and health problems (OR, 3.38; 95% CI, 1.57~7.27) were associated with self-perceived fatigue. CONCLUSIONS: This result suggests that farmers' job stress plays a role in the development of fatigue, and job stressors related to fatigue are slightly different according to gender.

The Relationship between Hospital Departments and Risk of Developing Tuberculosis among Nurses Working at a University Hospitalin Korea: Retrospective Cohort Study / 대한산업의학회지

OBJECTIVES: To investigate the occurring characteristics of pulmonary tuberculosis (TB) among nurses working at a university hospital in Korea. METHODS: A retrospective cohort study was conducted using medical records from a university hospital. A total of 351 nurses without any pulmonary disease were enrolled during 2000~2007, and were followed up until October 2010. To compare with the incidence of TB between occupational subgroups, workplaces were divided into high and low TB-exposure risk departments. For statistical analysis, the relative risks for TB incidences between departments were estimated using Cox proportional hazards models and mean incidences were estimated with person-time years. RESULTS: Seven cases of TB were observed during 2001 person-years. Five and two cases were observed in the high and low TB-exposure risk departments, respectively. The relative risk of TB infection in the high TB-exposure risk departments were 6.52 (95% CI, 1.26~33.60) compared to that in the low TB-exposure risk department. The mean incidence of TB in the total nurses was 0.350% per person-year. CONCLUSIONS: According to the concept of occupational and environmental medicine, high TB-exposure risk departments were more likely to be at increased risk of tuberculosis.

Suicide Trend of Standardized Mortality Ratio and Age Standardized Proportion Mortality Ratio According to Occupational Groups in Korea: 1993-2007 / 대한산업의학회지

OBJECTIVES: A number of studies on the trends of socioeconomic differences in suicide mortality have indicated that these inequality gaps have widened over time and highlight that certain occupations have more suicide risk than others. However suicide rates according to occupation based socioeconomic position have not been frequently studied in Korea. The purpose of this study is to report trends and inequality of suicide according to occupation based social class during 1993-2007 in Korea and to identify occupations with significantly high standardized mortality ratios (SMRs) and proportional mortality ratios (PMRs) for both men and women. METHODS: Korean census records for the years 1995, 2000, and 2005 were linked with the cause of death records from Korean National Statistical Office (KNSO) for the periods 1993-1997, 1998-2003, and 2004-2007 respectively. This data was used to calculate age adjusted proportional mortality ratios (PMRs) and standardized mortality ratios (SMRs) for both men and women aged 25~54 years according to five occupation based socioeconomic positions. RESULTS: Among men, the agricultural-fishery-forestry group had the greatest suicide rate (SMR: 341) with a high PMR (113) and the manual labor group showed the highest PMR (118), while the managers-professional occupation group showed the lowest sPMR (78) and SMR (21). Among women, the agricultural-fishery group had the highest score in SMR (316) and PMR (130), and the technical-artificer group showed the lowest sPMR (71) and SMR (27). The inequality gaps in the suicide mortality rate according to occupation had widened during 1998-2002, but showed a recovery trend plot after 2003. CONCLUSIONS: Although the occupation based socioeconomic inequalities show a recovery trend after 2003, the excess inequality from suicide remains as high as it was prior to the 2002 year in some occupational groups. The results of the current study indicate that the manual and agricultural-fishery-forestry groups were high risk groups of suicide.

The Effect of a Stretching Exercise on Myofascial Pain Syndrome Patients in Small and Medium Sized Industries / 대한산업의학회지

OBJECTIVES: This study was conducted to identify the effect of a stretching exercise on myofascial pain syndrome patients that work in small and medium-sized industry. METHODS: Questionnaires surveys including general characteristics, work-related characteristics, and musculoskeletal symptoms on neck and shoulder area was administered to 393 subjects who worked in small and medium sized industries. Symptomatic workers were examined to identify whether they had myofascial pain syndrome (MPS). Of the 393 subjects, 108 MPS patients performed 6 weeks stretching exercise program. Intensity of pain was estimated with visual analogue scales (VAS). All patients were interviewed to estimate their compliance to stretching exercise program. RESULTS: Of the 393 workers, 119 workers were diagnosed with MPS of the neck and shoulder. Post-exercise VAS was significantly reduced compared to pre-exercise VAS (p<0.05). High compliance patients to stretching exercise were more effective to exercise therapy (OR 2.89, 95% CI 1.19~7.04), and overtime workers were less effective to exercise therapy (OR 0.41, 95% CI 0.17~0.95). CONCLUSION: The Stretching exercise program was identified to be effective in MPS patients in small and medium-sized industries. It is recommended that workers with MPS in small and medium-sized industries practice a well-designed stretching exercise program, and avoid overtime work.

The Association among Exposure of Bisphenol A, Genetic Polymorphism of Metabolic Enzyme and Urinary Metabolite / 대한산업의학회지

OBJECTIVES: To examine bisphenol A (BPA) exposure with subjects in the manufacturing industry and to determine its correlation with metabolites according to genetic polymorphism of metabolic enzymes. METHODS: The study subjects comprised 104 workers in the manufacturing industry, 64 and 40 in the exposed and control groups, respectively. The questionnaire variablesincluded age, use of protective equipment, smoking habit and alcohol intake. Their urine samples were collected in the afternoon and urinary BPA concentration was measured by revising with the urinary creatinine concentration. The genetic polymorphism of the metabolic enzymes was examined by using restriction fragment length polymorphism (RFLP) after extracting DNA from leucocytes. RESULTS: The minimum and maximum BPA level of the exposed group during working time was 34.22 and 221.20 ng/mg, respectively. The urinary BPA concentration was significantly higher in the exposed groups than in the control group. There was no significant difference in the urinary BPA level according to genetic polymorphism of CYP1A1 and CYP2E1, but UGT1A6 showed a significant difference. In multiple regression analysis on the urinary and airborne BPA levels, UGT1A6, use of protective equipments and workplaces were significant variables. CONCLUSIONS: The urinary BPA concentration was affected by the levels to which workers were exposed during their working time and was considered to be metabolized by UGT1A6.

The Association of Occupational Stress with Self-perceived Fatigue in White Collar Employees / 대한산업의학회지

BACKGROUND & OBJECTIVES: A growing body of research has documented that occupational stress is closely associated with increased risk of fatigue. This study was conducted in an effort to assess the relationship of occupational stress to self-perceived fatigue among Korean white collar employees. METHODS: Data were obtained from the National Study for Development and Standardization of Occupational Stress (NSDSOS Project, 2002-2004). Among them, a total of 4,502 white collar employees were recruited. A structured questionnaire was employed to evaluate the participants' sociodemographics, job-related factors, health-related behaviors, occupational stress, and self-perceived fatigue. Occupational stress and self-perceived fatigue were assessed using the Korean Occupational Stress Scale-Short form (KOSS-SF) and the Multidimensional Fatigue Scale (MFS), respectively. RESULTS: In logistic regression analyses, occupational stress was associated with an increased risk of fatigue, and some domains of occupational stress had different effects on fatigue by gender (job demand, job insecurity, and lack of reward for men, job demand, lack of reward, and discomfort in occupational climate for women), which indicates that occupational stress may perform a slightly different role in increasing the risk of fatigue by gender. CONCLUSION: The results of this study suggest that occupational stress is a determinant predictor of selfperceived fatigue. Thus, a stress management program for the reduction of occupational stress, and the promotion of white collar worker's health and quality of life is strongly recommended. Some limitations of this study and considerations for future studies were also discussed.

Occupational Stress in Relation to Cerebrovascular and Cardiovascular Disease: Longitudinal Analysis from the NSDSOS Project / 대한산업의학회지

OBJECTIVES: This prospective study was performed to investigate the association between occupational stress and the development of cerebrovascular and cardiovascular diseases. METHODS: A total of 8,429 employees were selected from a nationwide sample, proportional to both the Korean Standard Industrial Classification and the Korean Standard Occupational Classification. A structured self-reported questionnaire was used to access the demographic and socioeconomic characteristics, health behavior and work related characteristics. 43-items of the full version of Korean Occupational Stress Scale (KOSS) were used to access the participants occupational stress. New cases of hospitalization due to cerebrovascular and cardiovascular diseases were evaluated using medical utilization files received from the National Health Insurance Corporation for the period of March 2004 to December 2005. A logistic regression analysis was performed to investigate the association between occupational stress and cerebrovascular and cardiovascular diseases. RESULTS: 43 new cases of hospitalization due to cerebrovascular and cardiovascular diseases were found. According to the results of the logistic regression analysis, job stressors were related with circulatory diseases after adjustment for gender, age, number of workers, employment type, shift work, smoking, alcohol intake, and regular exercise. Of the 8 subscales, insufficient job control (Adj. RR 2.802; 95% CI 1.038-7.564) and occupational climate (Adj. RR 2.365; 95% CI 1.087~5.143) were significantly associated with cerebrovascular and cardiovascular diseases. However, no significant relationships were found between the 6 KOSS subscales and cerebrovascular and cardiovascular diseases. CONCLUSIONS: Despite the short-term follow-up of about two years, the KOSS subscales of insufficient job control and occupational climate were significantly associated with cerebrovascular and cardiovascular diseases.

Urinary Excretion of Thiodiglycolic Acid According to Sampling Time in Workers Exposed to Vinyl Chloride Monomer / 대한산업의학회지

OBJECTIVES: The study was performed to investigate the changes of urinary thiodiglycolic acid (TDGA) concentration in workers exposed to vinyl chloride monomer (VCM) according to the time of sampling urine. METHODS: The personal exposure to airborne VCM was assessed and urinary TDGA concentration was sampled in 31 workers employed in a VCM and polyvinyl chloride (PVC) manufacturing factory. Urinary TDGA was sampled three times: before the start of the shift after 3 days off (TDGA1), after the end of the first-day shift (TDGA2) and before starting the following day shift after completing the oneday shift (TDGA3). Urinary TDGA in 30 workers who had not been exposed to airborne VCM was sampled after the end of the shift. A gas chromatography/pulsed flame photometric detector (GC/PFPD) was utilized to analyze TDGA concentration in urine after the urine was methylated with trimethylsilyldiazomethane(2.0M in diethyl ether). RESULTS: The creatinine level was 0.179+/-0.271 mg/g in the control workers and 0.218+/-0.443 mg/g in the workers before the start of the shift after 3 days off (TDGA1), showing no significant difference (p=0.7035). Urine samples were compared according to sampling time in order to investigate the change of urinary TDGA concentration in the case of continuous exposure to airborne VCM. In VCM-exposed workers, urinary creatinine concentration was 0.434+/-0.623 mg/g in TDGA2 and 0.767+/-1.056 mg/g in TDGA3, which indicated a gradual but significant increase (p=0.024). In terms of the statistical correlation between airborne VCM and urinary TDGA to evaluate exposure dose per day, of the three urinary TDGA concentrations, TDGA3 showed the highest degree of regression (R(2)=0.4215) with 8h-TWA airborne VCM concentration. CONCLUSION: Based on this result, the excretion half-life of urinary TDGA was assumed to be less than 3 days, because the concentration of urinary TDGA at 3 days after exposure to airborne VCM was decreased to the level of urinary TDGA concentration in the control workers. The concentration of urinary TDGA increased in the case of continuous shift, due to the accumulation of residual metabolites of TDGA. It was considered that TDGA3 can be applied as a useful biological index to evaluate the exposure dose of airborne VCM during one day because TDGA3 showed the highest correlation with the exposure dose of airborne VCM in the previous shift day.

Occupational Stress and Risk Factors for Cardiovascular Diseases / 대한산업의학회지

OBJECTIVES: The aim of this study was to elucidate the relationship between occupational stress and risk factors for cardiovascular diseases. METHOD: The study subjects were 169 male workers aged over 40 who were employed in the shipbuilding industry. A self-reported questionnaire was used to assess the respondents' sociodemographics and occupational stress. Eight domains of occupational stress according to the Korean Occupational Stress Scale (KOSS) were used. We included blood pressure, lipid level (total cholesterol, triglyceride, HDL cholesterol), coagulation factors, pulse wave velocity and heart rate variability as possible cardiovascular risk factors. RESULT: In multiple regression analyses, job demand was associated with triglyceride level, pulse wave velocity and heart rate variability. Interpersonal conflict was related to total cholesterol. Job insecurity was related to heart rate variability. Organizational system was associated with blood pressure, total cholesterol, pulse wave velocity and heart rate variability. Lack of rewards was related to systolic blood pressure and pulse wave velocity. CONCLUSIONS: These results indicate that occupational stress is associated with cardiovascular risk factors.

Fatigue as a Predictor of Medical Utilization, Occupational Accident and Sickness Absence / 대한산업의학회지

OBJECTIVES: This study examined the relationship of fatigue to medical utilization, occupational accident and sickness absence. Subjects and METHODS: Data were obtained from the National Study for Development and Standardization of Occupational Stress (NSDSOS Project, 2002~2004). A total of 30,146 employees categorized within the Korean Standard Industrial Classification and the Korean Standard Occupational Classification were recruited. A structured-questionnaire was used to assess the participants' sociodemographics, job-related factors, health-related behaviors, personality trait, self-perceived fatigue (MFS) and the frequency of medical utilization, occupational accident and sickness absence. Data on medical utilization and occupational accident were confirmed from company health records. Chi-square test and logistic regression analysis were used to elucidate the relationship of self-perceived fatigue to medical utilization, occupational accident and sickness absence. RESULTS: In logistic regression analyses, self-perceived fatigue was associated with medical utilization (outpatient), occupational accident and sickness absence although the strength of the associations was higher in the blue collar workers except for medical utilization. For medical utilization, the white collar workers' adjusted odds ratios of outpatient utilization for workers scoring in the third quartile and the highest quartile, compared to workers scoring in the lowest quartile were 1.50 (95% CI: 1.20-1.87) and 2.16 (95% CI: 1.69-2.75), respectively. The blue collar workers' adjusted odds ratios of outpatient utilization for workers scoring in the second (OR: 1.23, 95% CI: 1.06-1.43), third (OR: 1.42, 95% CI: 1.22- 1.66) and highest quartile (OR: 1.83, 95% CI: 1.55-2.17), respectively, compared to workers scoring in the lowest quartile were statistically significant. However, no associations were found between fatigue and inpatient utilization for either the white or blue collar workers. The blue collar workers' adjusted odds ratios of being injured for workers scoring in the second, third and highest quartile were 1.41 (95% CI: 1.00-2.00), 1.57 (95% CI: 1.10-2.22) and 2.41 (95% CI: 1.69-3.44), respectively, compared to those scoring in the lowest quartile, but, those of the white collar workers were not significant. There was more likely to an increased risk of sickness absence in workers scoring in the second, third and highest quartile compared to those scoring in the lowest quartile in both white and blue collar workers, but the magnitudes of risk were higher in the blue collar workers than the white collars workers. CONCLUSION: This result suggests that fatigue is a determinant predictor of medical utilization, occupational accident and sickness absence, and that the pattern of risks for the three outcomes differs according to the occupational type. Some limitations of this study and considerations for future study were also discussed.

Association between Job Stress on Heart Rate Variability and Metabolic Syndrome in Shipyard Male Workers

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. The purpose of this study is to elucidate the relationship between job stress, heart rate variability, and metabolic syndrome. The study design was cross-sectional, and a total of 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), and was assessed by time-domain and by frequency-domain analyses. Time domain analysis was performed using SDNN (Standard Deviation of normal to normal interval), and spectral analysis using low-frequency (LF), high-frequency (HF), and total frequency power. Metabolic syndrome was defined on the basis of risk factors being clustered when three or more of the following cardiovascular risk factors were included in the fifth quintile: glucose, systolic blood pressure, high-density lipoprotein cholesterol (bottom quintile), triglyceride, and waist-hip ratio. The results showed that job characteristics were not associated with cardiovascular risk factors. Compared to the lower strain group (low strain+passive+active group), the high strain group had a less favorable cardiovascular risk profile with higher levels of blood pressure, glucose, homocysteine, and clotting factor, 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 lower strain group and high strain group was 13.2% 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. This result suggests that decreased HRV found in the high-strain group are not a direct indicator of disease. However, it can induce cardiovascular abnormalities or dysfunctions related to the onset of heart disease among high risk groups.

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 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.

Job Characteristics and Psychosocial Distress of Atypical Workers / 대한산업의학회지

OBJECTIVE: This study was conducted to compare the job characteristics (work demand, decision latitude, and job insecurity) and psychosocial stress levels of typical workers in the parent firm, to those of atypical workers in subcontracted firms. In addition the risk factors for psychosocial stress of atypical workers are evaluated. METHOD: The study design was cross-sectional, and 1,713 shipbuilding workers (681; typical workers, 1,032; atypical workers) were recruited. A structured-questionnaire was used to assess the general characteristics, job characteristics and psychosocial stress levels. We used the chi-square test for univariate and multiple regression analyses. RESULTS: In univariate analyses, there were significant differences in smoking, hobby, insufficient sleeping, work hours per week, quitting, unemployment, job demand, job decision latitude and job insecurity. The job strain was significantly higher in the atypical workers than in the typical workers. The proportion of iso-strain groups was significantly greater in the atypical workers than typical workers. Using psychosocial stress as the dependent variable, multiple regression models were estimated. After adjustment for sociodemographic factors, unemployment, quitting, employment type, job demand, job decision latitude and job insecurity were all found to be significantly associated with psychosocial stress. CONCLUSION: This result suggests that the psychosocial stress of atypical workers is related to job characteristics such as job insecurity and labor flexibility.

The Exposure Status and Biomarkers of Bisphenol A in Shipyard Workers / 예방의학회지

OBJECTIVES: Because shipyard workers are involved with various manufacturing process, they are exposed to many kinds of hazardous materials. Welders especially, are exposed to bisphenol-A (BPA) during the welding and flame cutting of coated steel. This study was conducted to assess the exposure status of the endocrine disruptor based on the job-exposure matrix. The effects of the genetic polymorphism of xenobiotic enzyme metabolisms involved in the metabolism of BPA on the levels of urinary metabolite were investigated. METHODS: The study population was recruited from a shipyard company in the K province. A total of 84 shipbuilding workers 47 and 37 in the exposed and control groups, respectively, were recruited for this study. The questionnaire variables included, age, sex, use of personal protective equipment, smoking, drinking and work duration. The urinary metabolite was collected in the afternoon and correction made for the urinary creatinine concentration. The of the CYP1A1, CYP2E1 and UGT1A6 genotypes were investigated using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods with the DNA extracted from venous blood. RESULTS: The urinary BPA level in the welders group was significantly higher than in the control group (p< 0.05). The urinary BPA concentration with the wild type UGT1A6 was higher than the other UGT1A6 genotypes, but with no statistical significant. From themultiple regression analysis of the urinary BPA, the regression coefficient for job grade was statistically significant (p< 0.05). CONCLUSIONS: The grade of exposure to BPA affected the urinary BPA concentration was statistically significant. However, the genetic polymorphisms of xenobiotics enzyme metabolism were not statistically significant. Further investigation of the genetic polymorphisms with a larger sample size is needed.

Assessment on Quality Improvement of the Abstracts of the Original Research Articles in the Korean Journal of Preventive Medicine / 예방의학회지

OBJECTIVES: To compare the quality improvement of the abstracts of original articles, according to the revised manuscript format, of the Korean Journal of Preventive Medicine (Korean J Pre Med) was adopted in 1999. METHODS: A total 63 abstracts for 1997, and 49 for 2001, were selected as the original articles from the Kor J Pre Med. This study was carried out by the separate-sample pretest-posttest design. The quality of the abstracts was measured by a checklist of Narine' evaluation criteria, and the other information related to the articles were also surveyed by e-mail and fax or telephone using a self-made questionnaire. From the response rate, a total of 62 abstracts for 1997 and 49 for 2001 were finally analyzed. RESULTS: The mean number of words in an abstract decreased from 285 in 1997, to 250 by 2001. The mean number of key words per abstract decreased from 3.9 in 1997, to 3.6 by 2001. The mean number of inappropriate usage of key words per abstract, by the MeSH standard, decreased from 1.9 in 1997, to 0.4 by 2001. Also, the overall mean score of abstract quality increased from 0.54 in 1997 to 0.61 by 2001. The range of scores for the abstract quality was better in 2001 (0.40~0.77) than in 1997 (0.20~0.81). From the multiple regression analyses of the 1997 and 2001 databases, the intervention of the manuscript format's revision, and the number of English words to the quality score of the abstract, were the only statistically significant factors. CONCLUSIONS: In conclusion, the quality of abstracts in the Kor J Pre Med has improved since the revised manuscript format was adopted in 1999. The Korean Society for Preventive Medicine will continuously recommend proposals for more informative abstracts in their journal, and will evaluate the abstracts' content with quality criteria. Future studies should address these issues, and compare the quality of abstracts between different international and domestic journals.

The Impact of New Work Organizational System on Job Strain, and Psychosocial Distress / 예방의학회지

OBJECTIVES: New organizational work systems, and their impact on the mental health of employees, are considered to beone of the most important topics in the area of industrial health. This study was conducted to compare job characteristics (job demand and decision latitude) levels, and psychosocial distress of workers in acompany introducing to new organizational work systems, to those of workers managed by traditional work systems. METHODS: A study sample of 627 shipbuilding workers (446the new work organizational system and 181the traditional system) were recruited for this study. A structured-questionnaire was used to assess general characteristics, job characteristics (work demand, decision latitude), and psychosocial distress. RESULTS: The decision latitude was not significantly higher in the new work system compared to the traditional system. However, the job demand was significantly higher in the new work system than in the traditional system. The psychosocial distress was higher within the new work system than the traditional system, but no significant relationships were found. The proportion of increased strain was significantly greater with the new system than the traditional system. CONCLUSION: These results suggest that increases in the decision latitude did not sufficiently compensate for higher job strain or increased work intensity. If the increase in the decision latitude was temporary, with the typical job demand remaining high, such work can be still be considered to have a job strain. Future research should consider psychosocial distress and fatigue as important problems caused by new work organizational systems, and should be performed to assess their impact through out industry.

The Metabolism and Liver Toxicity of N,N-dimethylformamide in the Isolated Perfused Rat Liver

N,N-dimethylformamide (DMF) is metabolized by the microsomal cytochrome p-450 into mainly N-hydroxymethyl- N-methylformamide (HMMF), which further breaks down to N-methyformamide (NMF). However, the detailed mechanism of its toxicity remains unclear. We investigated the metabolism and the toxicity of DMF using the isolated perfused liver model. DMF was added to the recirculating perfusate of the isolated perfused rat liver at concentrations of 0, 10 and 25 mM. Samples were collected from the inferior vena cava at 0, 30, 45, 60, 75, and 90 minutes following addition of the DMF. The metabolites of DMF were analyzed using Gas-chromatography (GC). The changes in the rate of oxygen consumption by the DMF were monitored during perfusion. The enzyme activities (aspartic aminotransferase:AST, alanine aminotransferase:ALT, and lactic dehydrogenase:LDH)) in the perfusate were monitored to see if DMF caused hepatotoxicity. As the perfusion progressed, the DMF concentration in the perfusate decreased, but the level of NMF increased to a maximum of 1.16 mM. The rate of oxygen consumption increased at DMF concentrations of 10 mM and 25 mM. However, when a known inhibitor of cytochrome p-450, SKF 525A (300 micro M), was used to pretreat the perfusate prior to the addition of the DMF, the rate of oxygen consumption was significantly inhibited, indicating the cytochrome p-450 system was responsible for the conversion of DMF to NMF. On addition of the DMF, the activities of the enzymes AST, ALT and LDH were significantly increased a time and dose dependent manner. However, following pretreatment with SKF 525A, their releases were inhibited.

Clinical Significance of Serum PDGF-BB and IGF-1 in Coal Workers' Pneumoconiosis / 결핵

BACKGROUND: Coal workers' pneumoconiosis(CWP) is a fibrotic lung disease resulting from the chronic inhalation of coal dust. Various cytokines and growth factors secreted from macrophages and monocytes play a key r ole in the pathogenesis of penumoconiosis. The platelet-derived growth factor (PDGF)-BB and the insulin-like growth factor(IGF)-1 secreted from the macrophages and monocytes are believed to stimulate the accumulation of mesenchymal cells and fibrosis of the lower respiratory tract that is observed in fibrotic lung disease. The serum concentration of PDGF-BB and IGF-1 in 30 CWP patients and 10 healthy controls were measured in order to determine if PDGF-BB and IGF-1 can be used as sensitive biomarkers in CWP. METHODS: Serum was collected from 30 patients with CWP (13 with simple CWP and 17 with complicated CWP) and 10 healthy controls. The serum concentrations of PDGF-BB and IGF-1 were measured using ELISA (RandD system, Minneapolis, MN). RESULTS: The serum PDGF-BB concentration in patients with complicated CWP (10083.76+/-639.07 pg/ml) was significantly higher than in the patients with simple CWP(8493.88+/-848.51 pg/ml) and the healthy controls (3726.17+/-292.20pg/ml)(p0.05). CONCLUSIONS: These results show the important role of the PDGF-BB mediated pathways in the pathogenesis of CWP. These data suggests that the PDGF-BB serum concentration is a useful biomarkers of the fibrotic extent in CWP patients.