Widening Social Inequalities in Cancer Mortality of Children Under 5 Years in Korea

Background@#To investigate the effect of parental social class on cancer mortality in children under 5 in Korea, two birth cohorts were constructed by linking national birth data to under-5 death data from the Statistics Korea for 1995–1999 (3,323,613 births) and 2010–2014 (2,297,876 births). @*Methods@#The Cox proportional hazards model adjusted for covariates was used in this study. @*Results@#Social inequalities of under-5 cancer mortality risk in paternal education and paternal employment status were greater in 2010–2014 than in 1995–1999. The gap of hazard ratio (HR) of under-5 cancer mortality between lower (high school or below) and higher (university or higher) paternal education increased from 1.23 (95% confidence interval, 1.041.46) in 1995–1999 to 1.45 (1.11–1.97) in 2010–2014; the gap of HR between parents engaged in manual work and non-manual work increased from 1.32 (1.12–1.56) in 1995–1999 to 1.45 (1.12–1.89) in 2010–2014 for fathers, and from 1.18 (0.7–1.98) to 1.69 (1.03–2.79) for mothers. When the parental social class was lower, the risk of under-5 cancer mortality was higher in not only adverse but normal births. @*Conclusion@#Social inequalities must be addressed to reduce the disparity in cancer mortality of children under 5 years old.

The Strategy for Improving Work Environment and Working Conditions among Long-term Health Care Workers in Korea / 보건행정학회지

Background@#This study aimed to establish a strategy to improve the poor working environment and working conditions among long-term healthcare workers in Korea. @*Methods@#A total of 600 questionnaires with which long-term health care workers participated in the targeted base areas of each city and province nationwide were distributed directly and 525 responses were collected and 506 responses were analyzed. Surveys, on-site field visits, and in-depth interviews were also conducted to understand the working environment as well as conditions and establish a strategy for improving the working environment among long-term healthcare workers to understand the demands of working conditions and working conditions. @*Results@#Korean long-term care workers firstly and mostly enumerated their risk factors for ill-health when lifting or moving elderly recipients directly by hand (69.9%), followed by increased physical workload with old beds, tools, and facilities (42.3%) in the workplaces, shortage of manpower (32%), and source of infection (30%). To improve the working environment as well as conditions, Korean long-term care workers considered improving low-wage structures, ergonomic improvements to solve excessive physical loads, and increasing various bonus payments as well as implementing the salary system, positive social awareness, and increasing resting time. Of 506 responses, 92.3% replied that the long-term care insurance system for the elderly should be developed to expand publicization at the national level. @*Conclusion@#This study proposes to improve the low-wage structure of Korean long-term care workers, automation and improvement of facilities, equipment, and tools to eliminate excessive physical loads (beneficiary elderly lifting), and reduction of night labor.

Role of Parental Social Class in Preterm Births and Low Birth Weight in Association with Child Mortality:A National Retrospective Cohort Study in Korea

Purpose@#We explored the role of parental social class in preterm birth (PTB) and low birth weight (LBW) in association with child mortality in Korea. @*Materials and Methods@#A total of 7,302,732 births in Korea between 1995 and 2007 were used for designing the national retrospective cohort study. Kaplan-Meier survival curves and Cox proportional hazard models were used to determine the risk of child death after adjusting for covariates. @*Results@#Parental social class was associated with adverse birth outcomes and child mortality in Korea. Parental social class increased the strength of the relationship of adverse birth outcomes with child mortality. Child mortality was higher among PTB and LBW infants from parents with a lower social class than normal births from parents with a higher social class. In particular, the disparity in child mortality according to parental social class was greater for LBW and PTB than intrauterine growth retardation births.When one of the parents had a middle-school education or lower, the disparity in child mortality due to adverse birth outcomes was large regardless of the other spouse’s educational status. Inactive economic status for the father, as well as an occupation in manual labor by the mother, increased the risk of child mortality. @*Conclusion@#Strong relationships for social inequalities and adverse birth outcomes with inequalities in child mortality in South Korea were found in this study. Tackling social inequalities, as well as reducing adverse birth outcomes, are needed to reduce the disparities in child mortality in South Korea.

Trends of Social Inequalities in the Specific Causes of Infant Mortality in a Nationwide Birth Cohort in Korea, 1995–2009

The relationship between social disparity and specific causes of infant mortality has rarely been studied. The present study analyzed infant mortality trends according to the causes of death and the inequalities in specific causes of infant mortality between different parental social classes. We analyzed 8,209,836 births from the Statistics Korea between 1995 and 2009. The trends of disparity for cause-specific infant mortality according to parental education and employment were examined using the Cox proportional hazard model for the birth-year intervals of 1995–1999, 2000–2004, and 2005–2009. Adjusted hazard ratios were calculated after adjusting for infants' gender, parents' age, maternal obstetrical history, gestational age, and birth weight. An increasing trend in social inequalities in all-cause infant mortality according to paternal education was evident. Social inequalities in infant mortality were greater for “Not classified symptoms, signs and findings” (International Classification of Diseases 10th revision [ICD-10]: R00–R99) and “Injury, poisoning and of external causes” (S00–T98), particularly for “Ill-defined and unspecified causes” (R990) and “Sudden infant death syndrome (SIDS)” (R950); and increased overtime for “Not classified symptoms, signs and findings” (R00–R99), “Injury, poisoning and of external causes” (S00–T98) and “Conditions in perinatal period” (P00–P96), particularly for “SIDS” (R950) and “Respiratory distress syndrome of newborns (RDS)” (P220). The specific causes of infant mortality, in particular the “Not classified causes” (R00–R99 coded deaths) should be investigated more thoroughly to reduce inequality in health.

Cancer Mortality Projections in Korea up to 2032

Predicting cancer mortality is important to estimate the needs of cancer-related services and to prevent cancer. Despite its significance, a long-term future projection of cancer mortality has not been conducted; therefore, our objective was to estimate future cancer mortality in Korea by cancer site through 2032. The specially designed Nordpred software was used to estimate cancer mortality. The cancer death data from 1983 to 2012 and the population projection data from 1983 to 2032 were obtained from the Korean National Statistics Office. Based on our analysis, age-standardized rates with the world standard population of all cancer deaths were estimated to decline from 2008-2012 to 2028-2032 (men: -39.8%, women: -33.1%). However, the crude rates are predicted to rise (men: 29.8%, women: 24.4%), and the overall number of the cancer deaths is also estimated to increase (men: 35.5%, women: 32.3%). Several cancer deaths are projected to increase (lung, liver and gallbladder, colon and rectum, pancreas and leukemia in both sexes; prostate cancer in men; and breast and ovarian cancer in women), whereas other cancer deaths are expected to decrease (stomach, esophagus and larynx in both sexes and cervical cancer in women). The largest contribution to increasing cancer deaths is due to the aging of the Korean population. In conclusion, a strategy for primary prevention, early detection, and early treatment to cope with the rapidly increasing death of cancer due to population aging is urgently required.

Regional Deprivation Index and Socioeconomic Inequalities Related to Infant Deaths in Korea

Deprivation indices have been widely used to evaluate neighborhood socioeconomic status and therefore examine individuals within their regional context. Although some studies on the development of deprivation indices were conducted in Korea, additional research is needed to construct a more valid and reliable deprivation index. Therefore, a new deprivation index, named the K index, was constructed using principal component analysis. This index was compared with the Carstairs, Townsend and Choi indices. A possible association between infant death and deprivation was explored using the K index. The K index had a higher correlation with the infant mortality rate than did the other three indices. The regional deprivation quintiles were unequally distributed throughout the country. Despite the overall trend of gradually decreasing infant mortality rates, inequalities in infant deaths according to the deprivation quintiles persisted and widened. Despite its significance, the regional deprivation variable had a smaller effect on infant deaths than did individual variables. The K index functions as a deprivation index, and we may use this index to estimate the regional socioeconomic status in Korea. We found that inequalities in infant deaths according to the time trend persisted. To reduce the health inequalities among infants in Korea, regional deprivation should be considered.

Forecasting Cause-Specific Mortality in Korea up to Year 2032

Forecasting cause-specific mortality can help estimate the future burden of diseases and provide a clue for preventing diseases. Our objective was to forecast the mortality for causes of death in the future (2013-2032) based on the past trends (1983-2012) in Korea. The death data consisted of 12 major causes of death from 1983 to 2012 and the population data consisted of the observed and estimated populations (1983-2032) in Korea. The modified age-period-cohort model with an R-based program, nordpred software, was used to forecast future mortality. Although the age-standardized rates for the world standard population for both sexes are expected to decrease from 2008-2012 to 2028-2032 (males: -31.4%, females: -32.3%), the crude rates are expected to increase (males: 46.3%, females: 33.4%). The total number of deaths is also estimated to increase (males: 52.7%, females: 41.9%). Additionally, the largest contribution to the overall change in deaths was the change in the age structures. Several causes of death are projected to increase in both sexes (cancer, suicide, heart diseases, pneumonia and Alzheimer’s disease), while others are projected to decrease (cerebrovascular diseases, liver diseases, diabetes mellitus, traffic accidents, chronic lower respiratory diseases, and pulmonary tuberculosis). Cancer is expected to be the highest cause of death for both the 2008-2012 and 2028-2032 time periods in Korea. To reduce the disease burden, projections of the future cause-specific mortality should be used as fundamental data for developing public health policies.

The prevalence and risk factors of allergic rhinitis from a nationwide study of Korean elementary, middle, and high school students

PURPOSE: We investigated the prevalence and risk factors of allergic rhinitis (AR), nationwide in random children and adolescents of Korea. METHODS: A modified International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire survey was done in 1,820 children from elementary, middle, and high school nationwide in Korea. The subjects were selected by the stratifying sampling method by school grade and five regions. Current AR was defined as having AR symptoms during the last 12 months with a history of physician-diagnosed AR. Skin prick tests for 18 common allergens were performed. RESULTS: The number of males was 945, and that of females was 875. The mean age of the patients was 12.61+/-3.40 years. The prevalence of current AR and atopic current AR were 29.0% and 18.7%, respectively. Risk factors for current AR were male (adjusted odds ratio [aOR], 1.486; 95% confidence interval [CI], 1.189-1.856), family history of paternal AR (aOR, 3.208; 95% CI, 2.460-4.182), family history of maternal AR (aOR, 3.138; 95% CI, 2.446-4.025), antibiotic use in infancy (aOR, 1.547; 95% CI, 1.228-1.949), mold exposure during infancy (aOR, 1.416; 95% CI, 1.103-1.819), mold exposure during the last 12 months (aOR, 1.285; 95% CI, 1.012-1.630), and sensitization on skin prick tests (aOR, 2.596; 95% CI, 2.055-3.279). Risk factors for atopic current AR were the same as those of current AR, whereas breast-milk feeding (aOR, 0.720; 95% CI, 0.530-0.976) was a protective factor. Sensitized allergens as risk factors for current AR were Dermatophagoides pteronyssinus, Dermatophagoides farina, ragweed, mugwort, oak, alder, birch, Japanese hop, cat, and dog. CONCLUSION: The prevalences of current AR and atopic current AR were 29.0% and 18.7%, respectively. Male, sex parental AR, antibiotic use in infancy, mold exposure during the last 12 months, mold exposure during infancy, and atopic sensitization were risk factors for current AR. Breast-milk feeding was a protective factor for atopic current AR. Aeroallergen sensitization was an important risk factor for AR.

Socioeconomic Disparities in Pregnancy Outcome and Infant Mortality: Extremely Low Birth Weight and Very Low Birth Weight Infants / 보건행정학회지

BACKGROUND: This study investigates the relationship of socioeconomic status with adverse birth outcomes (low birth weight and preterm birth) and the relationship of socioeconomic status with infant mortality, using the birth cohort in Korea, 1995-2010. METHODS: In Korea, 8,648,035 births from 1995 to 2010 were studied with respect to social variation in adverse birth outcomes and infant mortality. The effect of social inequality was examined against adverse birth outcomes and infant mortality using multivariate logistic regression after controlling for other covariates. RESULTS: Social inequality were observed in adverse birth outcomes: low birth weight (LBW, 1,500-2,499 g), very LBW (1,000-1,499 g), and extremely LBW (500-999 g) as well as moderately preterm birth (PTB, 33-36 weeks), very PTB (28-32 weeks), extremely PTB (22-27 weeks), and infant mortality. The effect of social inequality was higher among moderately LBW (1,500-2,499 g) and PTB (33-36 weeks) than very or extremely LBW and PTB. CONCLUSION: The social inequality in adverse birth outcomes (low birthweight and preterm) and infant mortality existed and increased in Korea from 1995 to 2010. The effect of maternal education on adverse birth outcomes as well as infant mortality was apparent in the study results. Especially, social inequality in infant mortality was greater among the sub-normal births (low birth weight [1,500-2,499 g] or preterm birth [33-36 weeks]), which suggests, social interventions should aim at more among the subnormal births. This study suggest that tackling inequality in births as well as infant mortality should be focused on the social inequality itself.

Social Inequality in Birth Outcomes in Korea, 1995-2008

Social inequality in adverse birth outcomes has been demonstrated in several countries. The present study examined the separate and joint effects of parental education and work in order to investigate the causal pathways of social class effects on adverse birth outcomes in Korea. The occurrence of low birth weight, preterm births, and intrauterine growth retardation was examined among 7,766,065 births in Korea from 1995 to 2008. The effect of social inequality, as represented by parental education and work, was examined against adverse birth outcomes using multivariate logistic regression after controlling for other covariates. Parental education had the most significant and greatest effect on all three adverse outcomes, followed by parental work and employment, which had lesser effects. For adverse birth outcomes, the gap between educational levels increased steadily in Korea from 1995 to 2008. Throughout the analysis, the effect of maternal manual work on adverse birth outcomes was apparent in the study results. Given this evidence of social inequality in education and employment, social interventions should aim at more in-depth and distal determinants of health.

Occupational Lymphohematopoietic Cancer in Korea

The purpose of this study was to review the existing studies on lymphohematopoietic (LHP) cancer in Korea, estimate the prevalence of workers exposed to carcinogens, and determine the population attributable fraction (PAF) of leukemia. Two case series and 4 case reports were reviewed. Using official statistics, the prevalence of benzene exposure and ionizing radiation exposure was estimated. Based on the prevalence of exposure and the relative risk, The PAF of leukemia was calculated. Between 1996 and 2005, 51 cases of LHP cancer were reported from the compensation system. Greater than 50% of occupational LHP cancer was leukemia, and the most important cause was benzene. In a cohort study, the standardized incidence ratio was 2.71 (95% CI, 0.56-7.91). The prevalence of exposure was 2.5% and 2.2% in 1995 and 2000, respectively. Using the 1995 prevalence, 3.6-4.8% and 0.1% of cases with leukemia were attributable to benzene and ionizing radiation exposure, respectively, which resulted in 39.7-51.4 cases per year. Benzene is the most important cause of occupational leukemia in Korea. Considering the estimated PAF in this study, the annual number of occupational LHP cancer (51 cases during 10-yr period), might be underreported within the compensation system.

The Relationship between Cerebrovascular Mortality and Community Health Indicators in Gangwon-do / 農村醫學 地域保健

OBJECTIVES: The aim of this study was to characterize the community health indicators affecting standardized mortality rate of cerebrovascular diseases(CVD) and to identify the relationship between CVD mortality and community health indicators in Gangwon-do. METHODS: The community health indicators included material deprivation index, medical resource, rates of road pavement and local tax. CVD mortality and the material deprivation index were calculated in the registered death data and the 2000 census which were obtained from the Korean National Statistics Office. The community health indicators were measured using 2001 statistical year book of Ganwon-do. Data were analyzed by using Excel 2003, SAS 9.1. CVD mortality and material deprivation index were visualized by Arcview 9.1. RESULTS: CVD mortality varied by region and sex in Gangwon-do. The highest CVD mortality in male and female were noted at Goseong-gun, the lowest CVD mortality in male was at Yangyang-gun as it of female at Pyeongchang-gun. In Taebaek city where material deprivation index was also the highest; in Pyeongchang-gun was the lowest. Also the higher material deprivation index in some regions was the higher CVD mortality was. CVD mortality was not related with community health indicators. CONCLUSIONS: The results showed the regional difference of mortality of CVD among counties and cities in Gangwon-do. It is recommended that other community health indicators besides material deprivation index, road pavement rate, medical resources and local tax affecting CVD mortality need to be considered to improve the preventive strategies.

Trends in Educational Differentials in Suicide Mortality between 1993 - 2006 in Korea

PURPOSE: This study aims to examine how inequalities in suicide by education changed during and after macroeconomic restructuring following the economic crisis of 1997 in South Korea. MATERIALS AND METHODS: Using Korea's 1995, 2000, and 2005 census data aggregately linked to mortality data (1993 - 2006), relative and absolute differentials in suicide mortality by education were calculated by gender and age among Korean population aged 35 and over. RESULTS: Average annual suicide mortality rates have steadily increased from 1993 - 1997 to 2003 - 2006 in almost all sociodemographic groups stratified by gender, age, and education. Based on the relative index of inequality (RII) and slope index of inequality (SII), educational differentials in suicide mortality generally increased over time in men and women aged 45 years +. Although RII did not increase with year among men and women aged 35 - 44 years, SII showed a significantly increasing trend in this age group. CONCLUSION: These worsening absolute inequalities in suicide mortality indicate that the governmental suicide prevention policy should be directed toward socially disadvantaged groups of the Korean population.

Trends in Educational Differentials in Suicide Mortality between 1993 - 2006 in Korea

PURPOSE: This study aims to examine how inequalities in suicide by education changed during and after macroeconomic restructuring following the economic crisis of 1997 in South Korea. MATERIALS AND METHODS: Using Korea's 1995, 2000, and 2005 census data aggregately linked to mortality data (1993 - 2006), relative and absolute differentials in suicide mortality by education were calculated by gender and age among Korean population aged 35 and over. RESULTS: Average annual suicide mortality rates have steadily increased from 1993 - 1997 to 2003 - 2006 in almost all sociodemographic groups stratified by gender, age, and education. Based on the relative index of inequality (RII) and slope index of inequality (SII), educational differentials in suicide mortality generally increased over time in men and women aged 45 years +. Although RII did not increase with year among men and women aged 35 - 44 years, SII showed a significantly increasing trend in this age group. CONCLUSION: These worsening absolute inequalities in suicide mortality indicate that the governmental suicide prevention policy should be directed toward socially disadvantaged groups of the Korean population.

The Proportional Mortality Ratios of Specific-cause Mortality by Occupation and Education among Men Aged 20-64 in Korea (1993-2004) / 예방의학회지

OBJECTIVES: This study investigated the relationship of occupational class and educational background with proportional mortality ratios in Korea. METHODS: Mortality was investigated using the entire registered death data from 1993 to 2004, obtained from the Korean National Statistics Office. Proportional mortality ratios (PMRs) for specific diseases were calculated according to the occupational class and educational background of men aged 20-64. RESULTS: Manual workers were found to have higher PMRs for liver disease and traffic accidents, as did the lower educated group. Especially, this study showed trends of an increasing of the wide gap between lower and higher socioeconomic stati for liver disease, traffic accidents, diabetes mellitus and cerebral vascular disease. The mortality for cerebrovascular disease, diabetes mellitus, heart disease, traffic accident and liver disease showed increasing trends according to the calendar year for the lower than the higher social class. CONCLUSIONS: The specific conditions that had higher PMRs in the Korean lower social class were liver disease and traffic accidents. Especially, there was an increasing trend for a widening of the gap between manual and nonmanual groups in relation to mortality from liver disease, diabetes mellitus and traffic accidents.

Developing an Occupational Stress Scale for Korean Employees / 대한산업의학회지

BACKGROUND AND PURPOSES: Over the past three decades, numerous studies performed in Korea have reported that job stress is a determinant risk factor for chronic diseases and work disability. Every society has its own culture and occupational climate particular to their organizations, and hence experiences different occupational stress. An occupational stress measurement tool therefore needs to be developed to estimate it objectively. The purpose of this study is to develop and standardize the Korean Occupational Stress Scale (KOSS) which is considered to be unique and specific occupational stressors in Korean employees. Subjects and METHODS: Data were obtained from the National Study for Development and Standardization of Occupational Stress (NSDSOS Project: 2002-2004). A total of 12,631 employees from a nationwide sample proportional to the Korean Standard Industrial Classification and the Korean Standard Occupational Classification were administered. The KOSS was developed for 2 years (2002- 2004). In the first year, we collected 255 items from the most popular job stress measurement tools such as JCQ, ERI, NIOSH and OSI, and 44 items derived from the a qualitative study (depth interview). Fortythree items of KOSS, in the second year, were retained for use in the final version of the KOSS by using Delphi and factor analysis. Items were scored using conventional 1-2-3-4 Likert scores for the response categories. RESULTS: We developed eight subscales by using factor analysis and validation process: physical environment (3 items), job demand (8 items), insufficient job control (5 items), interpersonal conflict (4 items), job insecurity (6 items), organizational system (7 items), lack of reward (6 items), and occupational climate (4 items). Together they explained 50.0% of total variance. Internal consistency alpha scores were ranged from 0.51 to 0.82. Twenty-four items of the short form of the KOSS (KOSS-SF) were also developed to estimate job stress in the work setting. Because the levels of the subscales of occupational stress were gender dependent, gender-specific standard norms for both the 43-item full version and the 24-item short form using a quartile for the subscales of KOSS were presented. CONCLUSION: The results of this study suggest that KOSS might be an appropriate measurement scale to estimate occupational stress of Korean employees. Further and more detailed study needs to be conducted to improve the validity of this scale.

The Relationship between Musculoskeletal Symptoms and Job Stress & Intensity of Labor among Shipbuilding Workers / 대한산업의학회지

OBJECTIVES: This study aimed to reveal the multiple factors that are related to the work-related musculoskeletal disorders (WMSDs) of shipbuilding workers, and to elucidate the relationship between musculoskeletal symptoms and factors such as the change of working conditions, job stress and physical workload. METHODS: The study sample comprised 1,059 shipbuilding workers. A structured-questionnaire was used to assess the general characteristics, job stress, psychosocial well-being index (PWI), physical workload, change of working conditions and information concerning musculoskeletal symptoms. We estimated the relations of job stress, physical workload and intensity of labour to musculoskeletal symptoms using univariate and multiple logistic regression analyses. RESULTS: The symptom prevalence of musculoskeletal disorders in any part of the body was 89.5% by 'criteria 1'in the order of back (58.6%) and shoulder (56.3%). After adjustment for sociodemographic factors, posture factor (Odds ratio [OR]=1.06, 95% confidence interval [ C I ] = 1 . 0 0~1.12), non-posture factor (OR=1.17, CI=1.05~1.31), Borg scale (OR=1.15, C I = 1 . 0 0~1.32), relative work intensity increase (OR=1.92, CI=1.08~3.41), labor flexibility increase (OR=2.04, CI=1.04~4.01), high job demand (OR=2.68, CI=1.48~4.88), and high risk stress group (OR=13.50, CI=3.15~57.97) were all found to be significantly associated with musculoskeletal disorders. CONCLUSION: These results suggest that WMSDs have multiple risk factors such as stress, physical workload and change of working conditions. High job demand, increased relative intensification of work and increased flexibility, especially such as subcontract, outsourcing and importing of contingent work, were very important factors associated with increasing WMSDs.

The relationship of working hours and work intensity with sleep disturbance among continuous 12 hours day and night shift workers in the automobile factory in Korea / 대한산업의학회지

BACKGROUNDS: The objective of this study is to explore the relationships of working hours and work intensity with sleep disturbance among 12-hour shift workers in the automobile factory in Korea. METHODS: A questionnaire and a sleep diary were distributed among 2200 (25% of total workers) and 300 workers who were randomly selected in the 8700 workers in one car factory. Among the 300 randomely selected workers, who were randomly selected, 262 workers filled out a sleep diary. For a questionnaire, 2200 (25%) among 8700 workers were randomly selected, 1200 (54% response rate) of whom filled out the questionnaire. The cross-sectional questionnaire and the sleep diary during 14 consecutive days were distributed and collected by workers' representatives, who were trained for the participatory action research in this study. One hundred and sixty workers' sleep diaries and questionnaires were merged by the same worker and used for the analysis in this study. Logistic regression analysis for repeated measurements was modeled using the prevalence of severe sleepiness at work (i.e. Karonlinska Sleepiness Scale 7 or higher) as dependent variable and working hours, sleep pattern, work intensity and health behaviours as independent variables. RESULTS: The prevalence of severe sleepiness at the end of work was more than 60% after finishing night shift in the automobile factory. The main risk factors related to the severe sleepiness at the end of work were the night shift, long working hours more than 10 hours, the higher frequency of night shift per month, less free time between shifts, poor quality of sleep, deficit of sleeping hours and intensified work (reducing tendency of rest time per day and increasing tendency of additional working time) such as increasing tendency of absolute surplus value. DISCUSSION: We suggest that the 12-hour shift system, long working hours, intensified work and poor quantity as well as quality of sleep were the main risk factors for the severe sleepiness among the shift workers in the automobile factory in Korea.

Effects of Physical Workload on Salivary Cortisol Level / 대한산업의학회지

OBJECTIVE: Workload is known to affect the hypothalamus-pituitary-adrenal axis. Although many studies had revealed that job stress related factors could affect the neuroendocrine system among blue-collar workers, these studies had limitations as they had not evaluated the workload by objective methods which took into consideration individual physiological differences. This study was conducted to evaluate the effects of physical workload adjusted job stress on cortisol regulation by using objective tools for workers having various job tasks. METHODS: Among 110 foundry workers, shipyard workers, and fine machine assemblers for whom saliva samples were obtained, 102 without any past history of conditions that could affect hormonal regulation such as diabetes, and hypertension were included in this study. Among the 102 study participants, 15 workers whose saliva for morning or afternoon or heart rate monitoring data was not attained were excluded from the final analysis. Workload was evaluated by RHR (relative heart rate) using a heart rate monitor, and job stress was evaluated by Karasek's Job Content Questionnaire. Saliva samples were gathered during 8 - 9 am and 5 - 6 pm, and salivary cortisol levels were analysed by radioimmunoassay. RESULTS: After adjusting several variables which could effect cortisol secretion including job stress, among the higher RHR group morning salivary cortisol level was increased (beta=60.32, S.E.=26.35, p=0.0266), afternoon salivary cortisol level was decreased (beta=-7.43, S.E.=29.73, p=0.8044), and salivary cortisol level difference between morning and afternoon was increased (beta=72.10, SE=35.50, p=0.0509). CONCLUSIONS: As physical workload increases morning cortisol level, which is caused by the effect of arousal, and decreases afternoon cortisol level, which is caused by exhaustion, physical workload enlarges the width of diurnal cortisol variance. Therefore, physical exhaustion due to excessive workload could have adverse effects on the neuroendocrine system.

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.