The association between occupational hazard exposures and health inequality among Korean employees

Abstract

Abstract

Introduction From birth to retirement, living conditions substancially influence health. Unfair social relationships have created a social environment in which persons with low socioeconomic status (SES) could be exposed to more harmful living conditions. Working conditions and employment status significally affect health in the economically active ages. Joining in the labor market can have a positive impact on health

conversely, working might mean more exposure to harmful working conditions. Work is the main source of income for most people. Occupations have linkages to social status

peoples self-esteem could be affected by their jobs and the workplace is an important place for making social relationships in adulthood. On the other hand, work is associated with various exposures which can be harmful to health. Employees could be exposed to physical, chemical, ergonomic, and psycho-social hazards by joining the labor market, and workers in low socioeconomic status have a higher tendency to work in harmful working conditions. These unequal exposures to occupational risk factors among different occupations could be an important pathway to understanding health inequality. Since the publication of the Whitehall Study II, the majority of studies investigated health inequalities linked with psychosocial risk factors in the workplace. Health inequality can be explained by different levels of exposures to psychosocial factors including low job control, job strain, effort-reward imbalance, organizational injustice. The link between psychosocial working conditions and health inequality has been extensively studied in European countries. The interest in psychosocial working conditions reflected the social circumstances of post-industrialized society. The decrease in the numbers of workers in traditional industries such as manufacturing decreased the number of workers exposed to traditional occupational hazards such as noise and ergonomic strains. However, according to surveys on working conditions in both Korea and EU countries, significant proportions of workers are exposed to traditional occupational hazards and are working in dangerous working circumstances which are prone to industrial accidents and toxic exposure. Furthermore, in Korea industrial accidents and intoxications are much more frequent than in European countries due to the improper implementation of safety and health regulations at the workplace. Several studies of European countries investigated health inequalities which are related to occupational hazard exposures including physical, chemical, and ergonomic risk factors. Yet, health inequality related to physical, chemical, and ergonomic occupational hazard exposures have been insufficiently explored, particularly in Korea. Considering the situation mentioned above, broad working conditions, including workplace safety as well as physical, chemical, biological, ergonomic, and psychosocial hazards, need to be investigated as factors generating health inequality, particularly in working ages.

Chapter 1 Objectives: The purpose of the chapter was to assess exposure to occupational hazards across different occupations and the contribution of occupational exposures to poor self-rated health (SRH) and work-related injury. Methods: Employees from the sample of the Third Korean Working Conditions Survey (KWCS) were the study population. Survey weighted chi-square tests and multiple survey logistic analyses were undertaken for statistical analysis. A DAG (Directed Acyclic Diagram) was employed to identify the minimal sufficient adjustment set. Results: For most occupational hazards, the gradient of exposures were observed. Higher proportions of employees in a low SES were exposed to occupational hazards. Occupatinal hazard exposures incresed the risk of poor self-rated health and work-related injury. Conclusions: Occupational hazard exposure could be linked to health inequality among Korean employees.

Chapter 2 Objectives: The purpose of the chapter was to decompose the health gap between manual workers and non-manual workers into direct effect (the effect of SES per se) and indirect effect (the effect of mediators) by undertaking the mediation analysis. Methods: The author used employee data from the Third Korean Working Conditions Survey (KWCS) as the population. Mediators were perceived risk, low job control, long working hours, low income, and financial imbalance. For the mediation analysis, user-made commands paramed and medeff were utilized in Stata Program. Results:The proportion of effect mediated by perceived risk at work was 39% (95%CI: 28-65%). The proportion of effect mediated by financial imbalance was 22% (95%CI:16%-39%). The proportion of effect mediated by low job control was 7% (95%CI:5%-13%). The proportion of effect mediated by less than median income was 5% (95%CI:3%-9%). The proportion of effect mediated by unstable employment was 20% (95%CI:15%-34%).The proportion of effect mediated by long working hours was 28% (95%CI: 20%-47%). Conclusions: Perceived risk at work and long working hours might contribute to a health gap between non-manual workers and manual workers with greater magnitude than other mediators.

Chapter 3 Objectives: The purpose of the chapter was to investigate the simultaneous effect of exposure to perceived risk and unstable employment on self-rated health in both Korean and the EU. Methods: The author carried out analyses using the employee data from the Third Korean Working Conditions Survey (KWCS) and Fifth European Working condition survey (EWCS). Survey logistic analysis and post-estimation commands were employed for interaction analysis. Interaction analyses was undertaken by both additive scale (Relative Excess of Risk due to interaction) and multiplicative scale (The Ratios of Odds Ratios). Results: The odds ratio (OR) of poor self-rated health was 2.00 (95% confidence interval [CI]: 1.80–2.22) for perceived risk at work, 1.18 (95% CI: 1.09–1.28) for unstable employment, and 3.22 (95% CI: 2.72–3.81) for both for perceived risk at work and unstable employment. The RERI was 1.03 (95% CI: 0.48–1.58) among Korean employees. The odds ratio (OR) for poor self-rated health was 3.20 (95%CI: 2.93–3.49) for perceived risk at work, 1.04 (95% CI: 0.97–1.13) for unstable employment, and 3.41 (95% CI: 2.93–3.98) for both for perceived risk at work and unstable employment. The RERI was 0.18 (95% CI: -0.36–0.71) among European employees. Conclusions: Among Korea employees a supra-additive interaction between perceived risk at work and unstable employment on poor self-rated health was observed. However, among European employees a supra-additive interaction was not observed.

Chapter 4 (This Chapter was accepted and will be published in JOEM) Objectives: The aim of the chapter was to investigate the combined effects of long working hours and low job control on self-rated health. Methods: Employees from the Third Korean Working Conditions Survey (KWCS) were the study population. Survey logistic analysis was conducted and then post-estimation 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 [CI]: 1.13–1.35) for long working hours, 1.04 (95% CI: 0.97–1.13) for low job control, and 1.47(95% CI: 1.33–1.62) for both long working hours and low job control. The RERI was 0.18 (95% CI: 0.02–0.34). Conclusions: These results imply that low job control may increase the negative influence of long working hours on self-rated health.

Acknowledgement The author would like to express appreciation to Korea Occupational Safety and Health Agency (KOSHA) for providing the raw data of the third Korean Working Condition Survey.