Changes in Adolescent Health Behavior and the Exacerbation of Economic Hardship During the COVID-19 Pandemic: A Cross-sectional Study From the Korea Youth Risk Behavior Survey.

OBJECTIVES: This study investigated the association between exacerbated economic hardship during the coronavirus disease 2019 (COVID-19) pandemic and changes in the health behaviors of Korean adolescents. METHODS: We analyzed data from the 2021 Korea Youth Risk Behavior Survey and included 44 908 students (22 823 boys and 22 085 girls) as study subjects. The dependent variables included changes in health behaviors (breakfast habits, physical activity, and alcohol use) that occurred during the COVID-19 pandemic. The aggravation of economic hardship by COVID-19 and the subjective economic status of the family were used as exposure variables. Multiple logistic regression analysis was utilized to calculate the prevalence odds ratios (PORs). RESULTS: Severe exacerbation of a family's economic hardship due to COVID-19 was negatively associated with the health behaviors of adolescents, including increased breakfast skipping (POR, 1.85; 95% confidence interval [CI], 1.55 to 2.21 for boys and POR, 1.56; 95% CI, 1.27 to 1.92 for girls) and decreased physical activity (POR, 1.37; 95% CI, 1.19 to 1.57 for boys and POR, 1.38; 95% CI, 1.19 to 1.60 for girls). These negative changes in health behaviors were further amplified when combined with a low subjective family economic status. CONCLUSIONS: The experience of worsening household hardship can lead to negative changes in health behavior among adolescents. It is crucial to implement measures that address the economic challenges that arise from stressful events such as COVID-19 and to strive to improve the lifestyles of adolescents under such circumstances.

Area-Level Socioeconomic Inequalities in Intracranial Injury-Related Hospitalization in Korea: A Retrospective Analysis of Data From Korea National Hospital Discharge Survey 2008-2015.

BACKGROUND: Although inequality in traumatic brain injury (TBI) by individual socioeconomic status (SES) exists, interventions to modify individual SES are difficult. However, as interventions for area-based SES can affect the individual SES, monitoring or public health intervention can be planned. We analyzed the effect of area-based SES on hospitalization for TBI and revealed yearly inequality trends to provide a basis for health intervention. METHODS: We included patients who were hospitalized due to intracranial injuries (ICIs) between 2008 and 2015 as a measure of severe TBI with data provided by the Korea National Hospital Discharge Survey. Area-based SES was synthesized using the 2010 census data. We assessed inequalities in ICI-related hospitalization rates using the relative index of inequality and the slope index of inequality for the periods 2008-2009, 2010-2011, 2012-2013, and 2014-2015. We analyzed the trends of these indices for the observation period by age and sex. RESULTS: The overall relative indices of inequality for each 2-year period were 1.82 (95% confidence interval, 1.5-2.3), 1.97 (1.6-2.5), 2.01 (1.6-2.5), and 2.01 (1.6-2.5), respectively. The overall slope indices of inequality in each period were 38.74 (23.5-54.0), 36.75 (21.7-51.8), 35.65 (20.7-50.6), and 43.11 (27.6-58.6), respectively. The relative indices of inequality showed a linear trend for men (P = 0.006), which was most evident in the ≥ 65-year age group. CONCLUSION: Inequality in hospitalization for ICIs by area-based SES tended to increase during the observation period. Practical preventive interventions and input in healthcare resources for populations with low area-based SES are likely needed.

Maternal socioeconomic position and inequity in child deaths: An analysis of 2012 South Korean birth cohort of 466,636 children.

Background: Inequalities in child mortality occur via interactions between socio-environmental factors and their constituents. Through childhood developmental stages, we can observe changing patterns of mortality. By investigating these patterns and social inequalities by cause and developmental stage, we aim to gain insights into health policies to reduce and equalize childhood mortality. Methods: Using vital statistics, we examined the Korean birth cohort of 2012, including all children born in 2012 up to five years of age (N = 466,636). The dependent variables were all-cause and cause-specific mortality by developmental stage (i.e., neonatal, post-neonatal, and childhood). A Cox proportional hazard regression model was built to compare child mortality according to maternal education. The distribution of inequalities in cause-specific mortality by child age was calculated using the slope index of inequality (SII). Results: Inequalities in child mortality due to maternal education occur during the neonatal period and increase over time. After adjusting for covariates, the Cox proportional hazard models showed that "injury and external causes" (HR = 2.178; 95% CI = [1.283-3.697]) and "unknown causes" (HR = 2.299; 95% CI = [1.572-3.363]) in the post-neonatal period, and "injury and external causes" (HR = 2.153; 95% CI = [1.347-3.440]) in the childhood period significantly contributed to socioeconomic inequalities in child mortality. For each period, the leading causes of inequality were identified as follows: "congenital" (96.7%) for the neonatal period, "unknown causes" (58.2%) and "injury and external causes" (28.4%) for the post-neonatal period, and "injury and external causes" (56.5%) for the childhood period. Conclusion: We confirmed that the main causes of death in mortality inequality vary according to child age, in accordance with the distinctive context of child development. Strengthening the health system and multisectoral efforts that consider families' and children's needs according to spatial contexts (e.g., home, community) may be necessary to address the social inequalities in child health.

Cause-specific mortality in Korea during the first year of the COVID-19 pandemic.

OBJECTIVES: This study aimed to examine the trends in total mortality between 1998 and 2020 and to compare the changes in a wide range of detailed causes of death between 2020 (i.e., during the coronavirus disease 2019 [COVID-19] pandemic) and the previous year in Korea. METHODS: We used registered population and mortality data for the years 1998-2020 obtained from Statistics Korea. The age-standardized all-cause mortality rate and the annual percent change between 1998 and 2020 were determined. The rate ratio and rate difference of the age-standardized mortality rate between 2019 and 2020 were calculated. RESULTS: The age-standardized all-cause mortality rate in Korea has been on a downward trend since 1998, and the decline continued in 2020. In 2020, 950 people died from COVID-19, accounting for 0.3% of all deaths. Mortality decreased for most causes of death; however, the number of deaths attributed to sepsis and aspiration pneumonia increased between 2019 and 2020 for both men and women. Age-specific mortality rates decreased or remained stable between 2019 and 2020 for all age groups, except women aged 25-29. This increase was mainly attributed to a higher number of suicide deaths. CONCLUSIONS: This study shed light on the issues of sepsis and aspiration pneumonia despite the successful response to COVID-19 in Korea in 2020. Cases of death from sepsis and aspiration pneumonia should be identified and monitored. In addition, it is necessary to develop a proactive policy to address suicide among young people, especially young women.

Workplace Violence in Workers with Multi-Party Employment Arrangements: Results from the Korean National Representative Survey.

Background: Despite a growing number of investigations exploring the health problems in precarious workers, there is still a paucity of studies investigating workplace violence in workers with multi-party employment arrangements (WMPEAs). This study was aimed at comparing the prevalence of workplace violence between non-WMPEA and WMPEA. Methods: The 5th Korean Working Conditions Survey data were used. The study subjects were employees aged 20-74, with 26,239 non-WMPEA and 1,556 WMPEA. WMPEA included temporary agency workers and workers providing outsourced services. Workplace violence including verbal abuse, unwanted sexual attention, threats, and humiliating behaviors were used as outcome variables. The odds ratios of risk of workplace violence were calculated using multiple logistic regression. Results: The age-standardized prevalence of workplace violence was significantly higher among WMPEA. After adjusting for all covariates, the risk of workplace violence among WMPEA was still significant (OR 1.80, 95% CI 1.5-2.2) compared with non-WMPEA. The odds ratio of workplace violence among female WMPEA was 1.99 (95% CI 1.53-2.59), which is higher than that of male WMPEA (OR 1.52, 95% CI 1.18-1.96). Conclusion: We found that WMPEA were exposed to higher risk of workplace violence. Discrimination against WMPEA in the working environment and management policy need to be corrected. It is also necessary to identify the risk factors of workplace violence in WMPEA and to make efforts to prevent violence.

Smoking, drinking, and physical activity among Korean adults before and during the COVID-19 pandemic: a special report of the 2020 Korea National Health and Nutrition Examination Survey.

OBJECTIVES: This study aimed to describe trends in health behaviours between 2011 and 2020 and compare the changes in these behaviours between the 2020 COVID-19 pandemic and previous periods according to socio-demographic variables. METHODS: This study used data from the 2011 to 2020 Korea National Health and Nutrition Examination Survey. Current cigarette smoking, high-risk drinking, and inadequate physical activity levels were used as health behaviour indicators. The age-standardized prevalence, differences in prevalence between the periods, and the annual percentage change (APC) were calculated. RESULTS: Current cigarette smoking showed a decreasing trend (APC, -2.6), high-risk drinking remained unchanged, and inadequate physical activity levels increased (APC, 3.5) during 2011-2020. There were significant differences in high-risk drinking (3.1%p; 95% confidence interval [CI], 0.3 to 5.9) and inadequate physical activity levels (4.3%p; 95% CI, 0.4 to 8.1) between 2019 and 2020 in men. Among men, increased high-risk drinking was found in those aged 40-49 years, non-single households, urban residents, and the middle and highest income groups between 2019 and 2020. The low educational group and manual workers among men aged 30-59 years also showed an increased proportion of high-risk drinking. Inadequate physical activity levels also increased among men between 2019 and 2020 in those aged 30-39 years, non-single households, urban residents, and the upper-middle-income group. CONCLUSIONS: In the first year of the COVID-19 pandemic, Korean men's high-risk drinking and inadequate physical activity levels increased. In addition to social efforts to reduce the spread of infectious diseases, active measures to positively change health behaviour are needed.

Area-based inequalities and distribution of healthcare resources for managing diabetes in South Korea: a cross-sectional multilevel analysis.

OBJECTIVES: We aimed to identify area-based socioeconomic inequalities in diabetes management and to examine whether the distribution of healthcare resources could explain area-based inequalities in diabetes management. DESIGN: Cross-sectional multilevel analysis from national survey data. SETTING AND PARTICIPANTS: Data were derived from the 2018 Korean Community Health Survey. Study subjects included 23 760 participants aged 30 years or older with diabetes diagnosed by a doctor. MAIN OUTCOME MEASURES: The dependent variables were self-reported good glycaemic control, haemoglobin A1c (HbA1c) testing, recognition of the term HbA1c, and diabetic complications testing. Area Deprivation Index was used as an area-based measure of socioeconomic position. Factors related to regional healthcare resources-the coefficient of variation (CV) value of clinics and the number of physicians per 1000-were considered as potential mediating variables in explaining the association between diabetes management and area deprivation. A multilevel logistic regression analysis was used. RESULTS: Compared with the least deprived quintile, the likelihoods of not taking HbA1c tests, not recognising the term HbA1c, and not taking diabetic complication tests in the most deprived quintile were approximately 1.5 times (95% CI 1.25 to 1.80), 2.6 times (95% CI 1.97 to 3.45) and two times (95% CI 1.67 to 2.48) higher, respectively. In the most deprived quintile, CV value of clinics was the highest and the number of doctors was the lowest. Regional healthcare resource factors explained inequalities in managing diabetes by 14%-18%, especially in the most deprived quintile. CONCLUSIONS: The results in this study suggest that socioeconomic inequalities in diabetes management may be explained by regional healthcare resource disparities. Policy interventions for a more even distribution of healthcare resources would likely reduce the magnitude of regional socioeconomic inequalities in diabetes management.

Household decision-making and the mental well-being of marriage-based immigrant women in South Korea.

OBJECTIVE: We assessed the association between household decision-making and mental well-being among Asian immigrant women residing in Korea. We also investigated if the impact varies by the regional origin and examined potential factors for joint decision-making. METHODS: We conducted a cross-sectional study using the Korean National Survey of Multicultural Families 2015 and logistic regression. We analyzed data from 11,188 married immigrant women ages 20 to 59 who were originally from East Asia or Southeast/South Asia and co-living with their spouses. We defined households as joint-decision, wife-decision, or husband-decision based on who decides how living expenses are spent. Mental well-being encompassed a depressive mood for two consecutive weeks, and life and marital satisfaction. RESULTS: After controlling for covariates, we showed that immigrant women in husband-decision households were more likely to have depressive mood (odds ratio [OR] 1.26, 95% confidence interval [CI]: 1.14-1.38), poorer life satisfaction (OR 1.49, 95% CI: 1.24-1.78), and poorer marital satisfaction (OR 1.81, 95% CI: 1.47-2.22) than women in joint-decision households. Immigrant women in wife-decision households had a similar but slightly lower odds of poor mental well-being. This association was less prominent for Southeast/South Asian origin than East Asian origin, while the age-adjusted prevalence rates of poor mental well-being among them were higher than their East Asian counterparts. Factors that restricted the odds of husband-decision did not necessarily guarantee wife-decision. CONCLUSIONS: This study suggests one-sided decision-making can be a risk factor for immigrant women's poor mental well-being, while joint decision-making is protective. Differences across regional origins suggest domestic decision-making might be a less important predictor for mental well-being in immigrants more occupied with adapting to the host society. Factors for joint decision-making should be addressed to improve the mental well-being of immigrant women.

Employment status and mortality among Korean men over a 13-year period.

OBJECTIVES: This study explored the effect of employment status on mortality over a 13-year period in Korean men. METHODS: Data were used from the Korean Labor and Income Panel Study from 1999 to 2012. This study started with 2,737 subjects and included employed men in good health, aged 30-69 years. Deaths were tracked for 13 years from 2000 to 2012. Employment status classifications were: (1) regular employees, (2) precarious employees, (3) petty bourgeoisie, and (4) employers. Hazard ratios (HRs) were calculated using a Cox proportional hazards model, and were adjusted for age, education, income, and occupation, with regular employees as the reference category. To examine the effect of employment status and include employment history, the risk ratios of mortality were measured using the Poisson regression model, considering the duration of each employment and using 0 years as the reference category. RESULTS: Over the course of the 13-year study, being a precarious employee (HR, 1.84) or petty bourgeoisie (HR, 1.87) at a particular point in time had a negative effect on mortality when compared with regular employees. Furthermore, working as precarious employees or petty bourgeoisie had no positive effect on mortality. A positive effect was observed, however, on the overall mortality risk for regular employees. CONCLUSIONS: These results suggest that a healthy social policy is needed for precarious employees and petty bourgeoisie to avoid disadvantages in the workplace and the social safety net.

A national pilot program for chronic diseases and health inequalities in South Korea.

BACKGROUND: To achieve the health equity, it is important to reduce socioeconomic inequalities when managing chronic diseases. In South Korea, a pilot program for chronic diseases was implemented at the national level. This study aimed to examine its effect on socioeconomic inequalities in chronic disease management at the individual and regional levels. METHODS: Korean National Health Insurance data from September 2016 to October 2017 were used. Study subjects in the national pilot program for chronic diseases included 31,765 participants and 5,741,922 non-participants. The dependent variable was continuity of prescription medication. Socioeconomic position indicators were health insurance contribution level and the area deprivation index. Covariates were gender, age, and the Charlson Comorbidity Index (CCI). A multilevel logistic regression model was used to address the effects at both the individual and regional levels. This is a cross-sectional study. RESULTS: Unlike the group of non-participants, the participants showed no inequality in prescription medication continuity according to individual-level socioeconomic position. However, continuity of prescription medication was higher among those in less deprived areas compared to those in more deprived areas in both the participation and non-participation groups. CONCLUSIONS: This study found that the pilot program for chronic diseases at the least did not contribute to the worsening of health inequalities at the individual level in South Korea. However, there was a trend showing health inequalities based on the socioeconomic level of the area. These findings suggest that additional policy measures are needed to attain equality in the management of chronic diseases regardless of the regional socioeconomic position.

The Contribution of Avoidable Mortality to the Life Expectancy Gains in Korea between 1998 and 2017.

This study evaluated the contribution of avoidable causes of death to gains in life expectancy between 1998 and 2017 in Korea. This is a multi-year, cross-sectional study using national data. Death certificate data from 1998 to 2017 were obtained from Statistics Korea. The difference in life expectancy between 1998 and 2017 by age and cause of death were decomposed using Arriaga's method. Life expectancy rose 7.73 years over 20 years in Korea, which was largely (more than 50%) due to changes in avoidable causes of death. As age increased, the contribution to changes in life expectancy increased, and the gain in life expectancy due to avoidable causes also tended to increase. The major factors that drove that gain in life expectancy were avoidable causes such as cerebrovascular diseases and traffic accidents. The gain in life expectancy from preventable diseases was greater in men than in women. The results of this study indicate that active public health programs have been effective in improving life expectancy in Korea. Moreover, avoidable mortality could be further improved with good public health policy. Health policy aimed at reducing amenable and preventable deaths should be further implemented to promote population health.

A publicly well-accepted measure versus an academically desirable measure of health inequality: cross-sectional comparison of the difference between income quintiles with the slope index of inequality.

OBJECTIVES: The difference between income quintiles in health is relatively well accepted by the general public as a measure of health inequality. However, the slope index of inequality (SII) in health reflects the patterns of all social groups, including the middle 60%, and it could therefore be considered more academically desirable. If these two measures are closely correlated, the widespread use of the difference between income quintiles in health would be better supported. This study was conducted to compare differences between income quintiles in life expectancy (LE) and healthy life expectancy (HLE) with the SII. DESIGN: Cross-sectional comparison using correlational analysis of district level income differences in LE and HLE with associated SII. SETTING: All 252 subnational districts of Korea. PARTICIPANTS: A total of 342 439 895 subjects (171 287 729 men, 171 152 166 women) and 1 753 476 deaths (970 928 men, 782 548 women) between 2008 and 2014 were analysed. PRIMARY AND SECONDARY OUTCOME MEASURES: Difference in LE and HLE by income quintile and associated SII. RESULTS: The Pearson correlation coefficients between differences between income quintiles and the SII were generally high: 0.97 (95% CI 0.96 to 0.98) for LE in men and women combined and 0.96 (95% CI 0.94 to 0.97) for HLE in men and women combined. In most districts, the SII was greater than the difference between income quintiles. CONCLUSION: Differences between income quintiles were closely correlated with the SII. The widespread use of differences between income quintiles in health as a measure of health inequality may be preferable for communicating results of health inequality measurements to the public.

Neo-Marxian social class inequalities in oral health among the South Korean population.

AIM: The aims of this study were to examine inequalities in periodontitis and tooth loss among South Korean adults using the Wright's Neo-Marxian social class (NMSC) indicator and to assess the impact of material, psychosocial, health behavioural and workplace environmental factors in the association of social class with oral health. METHODS: This study used the data from the 4th Korea National Health and Nutrition Examination Survey with 6710 participants aged 19-54 years old. Participants were classified into 12 social class positions based on the Wright's social class map. Healthy gum and absence of tooth loss were the health outcomes. Mediating factors were material (M), psychosocial (PS), health behavioural (HB) and workplace environmental (WPE) factors. A series of logistic regressions were performed to analyse the data. Odds ratio (OR) and 95% confidence interval (CI) were used to report the results. RESULTS: For the absence of periodontal pockets status, expert supervisors were the healthiest periodontal group among the social classes (OR = 2.15 95% CI 1.59-2.90) in the age and gender adjusted model. For the absence of tooth loss, skilled workers had the highest OR for absence of tooth loss (OR = 1.64 95% CI 1.31-2.05) in the age- and gender-adjusted model. For absence of periodontal pockets, the explanatory power of the M factor was the highest in all social class positions except for nonskilled supervisors followed by the HB factor. Additionally, the absence of tooth loss had a fairly similar pattern. The explanatory power of the M factor was the highest in all social class positions except for the petty bourgeoisie (highest: HB) and nonskilled supervisors (highest: WPE) followed by the HB and WPE factors. CONCLUSION: There were nongradient oral health inequalities among the South Korean population according to the NMSC. Oral health promotion programmes that focus on changing the socioeconomic environment and health behaviours should be implemented.

Employment Status and Self-Reported Unmet Healthcare Needs among South Korean Employees.

We aimed to examine the association between employment status and self-reported unmet healthcare needs and to identify factors influencing self-reported unmet healthcare needs by employment status. Nationally representative data from the 2012 Korea National Health and Nutrition Examination Survey were used. Participants were classified by employment status as either permanent or precarious workers. Explanatory variables included sociodemographic, labor-related, and health-related factors. Multivariate logistic regression ascertained the association between employment status and self-reported unmet healthcare needs and explanatory factors associated with self-reporting of unmet healthcare needs. Precarious workers had a higher prevalence of self-reported unmet healthcare needs than permanent workers, with a statistically significant odds ratio (OR) (1.74; 95% confidence interval (CI), 1.19⁻2.54). Male precarious workers working >40 h per week were more likely to self-report unmet needs than male precarious workers working <40 h (OR, 3.90; 95% CI, 1.40⁻10.87). Female precarious workers with a lower household income were about twice as likely to self-report unmet needs. Working hours and household income were significantly influential factors determining self-reporting of unmet healthcare needs, especially among precarious workers. Policy interventions to improve access to healthcare for precarious workers are needed.

The Change of Self-Rated Health According to Working Hours for Two Years by Gender.

OBJECTIVE: The aim of this study was to confirm the association between working hours and self-rated health, and to find the degree of changes in health level by working hours according to gender. METHODS: This study was based on the 929 workers (571 men and 358 women) from the Korean Labor and Income Panel Study during 2004⁻2006. To minimize the healthy worker effects, the study subjects included only those who did not have any chronic diseases, and who answered their health status as "moderate" or above in the baseline. Logistic regression analysis was used to confirm the associations between working hours and self-rated health. RESULTS: In men, working hours per week of 47⁻52 h, 53⁻68 h, and >68 h were associated with 1.2, 1.3, and 1.1 times increases, respectively, in the odds ratio on worsened self-rated health, compared with the reference group (40⁻46 h). On the other hand, the risks were 1.0, 2.2, and 2.6 times increases in women. However, the results were different according to gender in the group with less than 40 h. The men with less than 40 h had a 0.9 times odds ratio on worsened self-rated health. For the women with less than 40 h, the odds ratio on self-rated health was 5.4 times higher than the reference group. CONCLUSIONS: Working more than 52 h per week had a negative effect on health, regardless of gender. However, in the group with less than 40 h, the negative association between working hours and self-rated health were shown only in women. Health outcomes due to working hours may differ by gender. Therefore, further studies are needed to explore the causes of these results.

Working hours and depressive symptoms: the role of job stress factors.

BACKGROUND: South Korea is one of the countries with the longest working hours in the OECD countries. The aim of this study was to evaluate the effect of working hours on depressive symptoms and the role of job stress factors between the two variables among employees in South Korea. METHODS: This study used data from the Korea Working Conditions Survey in 2014. Study subjects included 23,197 employees aged 19 years or older who work more than 35 h per week. Working hours were categorized into 35-39, 40, 41-52, 53-68, and more than 68 h per week. Depressive symptoms were assessed using the WHO's Well-Being Index with a cut-off score of 13. We calculated prevalence ratios of depressive symptoms according to working hours using log-binomial regression. Through the percentage change in prevalence ratios, we identified the extent of the role of job stress factors that explain depressive symptoms. RESULTS: The risks of depressive symptoms were significantly higher in people who worked 35-39 h per week (PR: 1.09, CI: 1.01-1.18), 53-68 h/week (PR: 1.21, CI: 1.16-1.25), and more than 68 h/week (PR: 1.14, CI: 1.07-1.21) than 40 h/week, after adjusting for confounding variables. Job stress explained the effects of long working hours on depressive symptoms in about 20-40% of the groups working more than 40 h/week. Among the factors of job stress, social support was 10-30%, which showed the highest explanatory power in all working hours. Reward explained 15-30% in the more than 52 h working group, and reward was the most important factor in the working group that exceeded 68 h. CONCLUSIONS: We showed the working hours could be an independent risk factor for depressive symptoms in employees. To improve workers' mental health, it is important to strengthen social support in the workplace, to provide adequate rewards as they work, and ultimately to regulate the appropriate amount of working hours.

Toxic Effects of Methanol among Illegally Dispatched Workers at Aluminum CNC Cutting Process in Small-Scale, Third-Tier Subcontractor Factories of Smartphone Manufacturers in the Republic of Korea.

An outbreak of occupational methanol poisoning occurred in small-scale, third-tier factories of large-scale smartphone manufacturers in the Republic of Korea in 2016. To investigate the working environment and the health effects of methanol exposure among co-workers in the methanol poisoning cases, we performed a cross-sectional study on 155 workers at five aluminum Computerized Numerical Control (CNC) cutting factories. Gas chromatography measured air and urinary methanol concentration. In the medical examination, symptom surveys, ophthalmological examinations, and neurobehavioral tests were done. Multiple logistic regression analyses controlling for age and sex were conducted to reveal the association of employment duration with symptoms. Air concentrations of methanol in factory A and E ranged from 228.5 to 2220.0 ppm. Mean urinary methanol concentrations of the workers in each factory were from 3.5 mg/L up to 91.2 mg/L. The odds ratios for symptoms of deteriorating vision and central nervous system (CNS) increased according to the employment duration after adjusting for age and sex. Four cases with an injured optic nerve and two cases with decreased neurobehavioral function were founded among co-workers of the victims. This study showed that the methanol exposure under poor environmental control not only produces eye and CNS symptoms but also affects neurobehavioral function and the optic nerve. The role of subcontracting production and dispatched work under poor environmental control was discussed.

The Combined Effect of Long Working Hours and Low Job Control on Self-Rated Health: An Interaction Analysis.

OBJECTIVES: The aim of this study was to investigate the combined effects of long working hours and low job control on self-rated health. METHODS: We analyzed employees' data obtained from the third Korean Working Conditions Survey (KWCS). Multiple survey logistic analysis and postestimation commands were employed to estimate the relative excess risk due to interaction (RERI). RESULTS: The odds ratio (OR) for poor self-rated health was 1.24 [95% confidence interval (95% CI): 1.13 to 1.35] for long working hours, 1.04 (95% CI: 0.97 to 1.13) for low job control, and 1.47 (95% CI: 1.33 to 1.62) for both long working hours and low job control. The RERI was 0.18 (95% CI: 0.02 to 0.34). CONCLUSION: These results imply that low job control may increase the negative influence of long working hours on self-rated health.