Modern Korean society is experiencing fundamental transformations in industrial structures and working environments driven by complex factors, including demographic shifts, the Fourth Industrial Revolution, the coronavirus disease 2019 pandemic, and digital transformation. The evolving dynamics between the manufacturing and service industries, the emergence of technology-driven sectors, and the proliferation of new occupational categories are reshaping traditional employment models. This has directed the labor market toward nonstandard employment forms, including temporary, contract-based, and platform labor. Consequently, issues such as employment instability and reduced accessibility to workplace health programs, including occupational safety training, health examinations, and workplace health management, have become increasingly prominent. Although occupational and environmental medicine has subsequently gained significance, the current occupational health and safety framework inadequately addresses the nuances of emerging labor forms. Legal gaps persist, leaving vulnerable groups such as nonregular workers, platform laborers, and older workers insufficiently protected under existing systems. Furthermore, systemic issues are evident in the inadequate follow-up care during occupational health examinations, lacking continued adherence to hazard-centric approaches, and insufficient attention to chronic diseases and mental health challenges. This study proposes strategies that occupational and environmental medicine can address these issues. First, legal and institutional reforms must encompass new labor forms, accompanied by modernized safety and health guidelines. Second, state-of-the-art technologies should be leveraged to enhance predictive disease management and personalized healthcare for workers. Third, a preventive approach integrating chronic disease management, mental healthcare, and psychosocial risk factors must be established. Fourth, fostering interdisciplinary research collaboration across medicine, engineering, and psychology is essential for developing practical solutions to emerging challenges. In conclusion, occupational and environmental medicine in Korea must adapt to effectively address the evolving labor landscape. Through systematic innovation, integrated health-management approaches, technological advancements, and interdisciplinary cooperation, the health and safety of all workers in the rapidly changing world can be ensured.

A comprehensive list of occupational diseases among farmers is crucial for both compensation and prevention efforts. In Korea, most farmers are self-employed, and some occupational diseases are compensated through farmer safety insurance. However, it is not harmonized with industrial accident compensation insurance and does not adequately reflect the true burden of occupational diseases among farmers. To address this gap, the authors compiled a list of occupational diseases tailored to Korean farmers by reviewing the International Labor Organization's list of occupational diseases, the Korean Industrial Accident Compensation Insurance List, the occupational disease lists of other countries, and relevant literature on farmers' work-related diseases.

The Korean Work, Sleep, and Health Study (KWSHS) was launched in 2022 as a longitudinal panel study to examine the interactions between work conditions, sleep health, and labour market performance among the Korean workforce. Baseline data were collected from 5,517 participants aged 19 to 70, encompassing diverse occupations. Follow-up surveys occur biannually, accommodating seasonal variations in sleep and health dynamics. To ensure stability, refreshment samples were integrated in later waves, maintaining a cohort size of 5,783 participants in wave 5. Key data include socio-demographics, employment characteristics, sleep patterns, health outcomes, and workplace performance. Early findings highlight critical associations, such as the adverse effects of occupational physical activity on productivity, the impact of emotional labour on health-related productivity loss, and the significance of sleep disruptions on mental health. The cohort's design enables detailed analyses of longitudinal and cross-sectional trends, offering insights into how changing work environments influence health and productivity. The KWSHS could serve as a vital resource for evidence-based interventions aimed at improving occupational health and productivity in Korea's evolving labour landscape. Data access is available through the study's principal investigator upon request.

Background: Commuting is essential for working life; however, prolonged travel times can negatively affect health, particularly musculoskeletal pain. This study aims to examine the relationship between commuting time and musculoskeletal pain (back, upper extremity, and lower extremity pain), in the context of working time. Methods: This cross-sectional study used data from the Sixth Korean Working Conditions Survey conducted in Korea between October 2020 and April 2021. Variables such as commuting time, weekly working hours, and shift work were assessed using the survey questions. Musculoskeletal pain was determined based on self-reported pains in the previous year. The covariates included demographics, employment status, ergonomic risks, and job stress. The association between commuting time and musculoskeletal pain stratified by weekly working hours or shift work was analyzed by survey-weighted logistic regression analysis. Results: This study found a significant association between longer commuting times and increased prevalence of musculoskeletal pain, particularly back, upper extremity, and lower extremity pain. When commuting time was ≤60, 61-120, >120 minutes, the odds ratio was 1.00, 1.33 (95% confidence interval [CI]: 1.16-1.52), and 2.41 (95% CI: 1.77-3.29) for back pain; 1.00, 1.29 (95% CI: 1.13-1.46), and 2.27 (95% CI: 1.71-3.00) for upper extremity pain; and 1.00, 1.24 (95% CI: 1.05-1.45), and 1.53 (95% CI: 1.13-2.08) for lower extremity pain, respectively. Furthermore, except for upper extremity pain, this trend was amplified when participants were concurrently exposed to long working hours, and for lower extremity pain, this trend was aggravated among shift workers. Conclusions: Long commuting time may be a risk factor for musculoskeletal pain, and its' effects could be aggravated when combined with long working hours or shift work. This study observed the detrimental impact of prolonged commuting on musculoskeletal health, particularly among employees with extended working hours or shift work.

Background: Humans are exposed to mercury primarily in its highly toxic form, methyl mercury, which is known to have adverse effects on various organs and systems. The negative impact of mercury exposure on the growth, development, and mental health of children, from infancy to adolescence, is well-documented. However, there are no internationally standardized safe limits for mercury exposure. This study investigated the impact of dietary habits and higher body mass index (BMI) on blood mercury levels in adolescents. Methods: This study analyzed the data from the 4th Korean National Environmental Health Survey (KoNEHS) 2018-2020. The focus was on 825 middle and high school students aged 13-18 years, whose blood mercury levels were measured. A survey on dietary and lifestyle habits was also conducted. Blood mercury levels were categorized by geometric median values, and associations with overweight status and seafood consumption were examined using a generalized linear model. Results: The geometric mean blood mercury level for the entire sample was 1.37 ㎍/L, with levels of 1.31 ㎍/L in normal-weight individuals and 1.43 ㎍/L in overweight individuals, showing a statistically significant difference between the two groups. After adjusting for other variables, blood mercury levels were significantly associated with overweight status (estimate: 0.084; p = 0.018; 95% confidence interval [CI]: 0.015-0.153), consumption of large fish and tuna more than once a week (estimate: 0.18; p = 0.001; 95% CI: 0.077-0.284), and consumption of fish once a week or more (estimate: 0.147; p = 0.004; 95% CI: 0.043-0.250). Conclusions: In adolescents, a higher BMI and an increased consumption of large fish, tuna, and fish were associated with higher blood mercury levels. Notably, a stronger association was found between large fish consumption and blood mercury levels in the overweight group. These findings suggest the need to moderate seafood consumption and establish more proactive mercury exposure standards for adolescents.

Background: This study analyzed occupational diseases compensated through the government system in the Korean electronics industry and observed changes in the rationale for compensation. Methods: Data from the Korea Workers' Compensation and Welfare Service (KWCWS) from 2012 to 2023 were analyzed to examine occupational disease issues in South Korea's semiconductor and display industries. Results: KWCWS received 174 occupational disease claims between 2012 and 2023, with 88 (50.6%) approved. The case of a 22-year-old semiconductor worker who died from leukemia has raised awareness and appears to be leading to more claims and higher approval rates. Cancer-related claims, particularly for breast and blood cancers, were the most common. Since 2018, the approval rate for occupational diseases has increased to 60%, which may have been influenced by the Supreme Court's Principle of Presumption of Occupational Diseases and the government's reduction of the burden of proof. However, approval rates remain lower in small- and medium-sized enterprises (38.0%) compared to large corporations (55.6%), likely because of better documentation and unionization in the latter. The semiconductor industry had more claims and approvals than the LCD industry, primarily due to its longer operational history and greater chemical exposure. Conclusions: In South Korea, the increasing approval rate of occupational diseases in the electronics industry from 2012 to 2023 appears to reflect changes in how causal relationships and occupational health policies have been implemented and this is likely due to stakeholder involvement and relevant legal decisions.

Background: In Malaysia, occupational allergic contact dermatitis (ACD) is often under-reported. This case report describes a chemical engineer who developed possible ACD, likely due to workplace allergen exposure. Case presentation: He presented with a 4-month history of intensely itchy rashes on both hands, which improved during work breaks. A dermatological examination revealed lichenified, pruritic papules with well-defined borders on the palmar surfaces of both hands. A skin patch test identified reactions to five allergens, including 'fragrance mix,' 'methyldibromo glutaronitrile,' 'clioquinol,' 'epoxy resin,' and 'textile dye mix.' However, among these, only 'bisphenol A diglycidyl ether,' a component of 'epoxy resin,' was listed in the safety data sheet as a confirmed occupational exposure. In accordance with local regulations, this case was reported as 'occupational dermatitis' to the Department of Occupational Safety and Health. The patient was prescribed symptomatic topical treatments, including emollients and topical corticosteroids. Additionally, he was advised to switch to hypoallergenic products. On follow-up, his chronic inflammatory skin lesions showed improvement. Conclusions: Thorough occupational history-taking and patch testing are essential for diagnosing ACD. Personalized health education and regular follow-ups, is crucial in monitoring lesion resolution and evaluating the effectiveness of preventive measures in workplace settings.

Background: PM_2.5 (particulate matter less than 2.5 ㎛) causes various health problems. Recent studies suggest that long-term exposure to PM_2.5 may have a negative impact on vision. This study examined the effects of long-term exposure to concentrations of PM_2.5 exceeding Korean standards on myopia prevalence. Methods: This study was conducted on adults aged 40-69 years. The PM_2.5 concentrations were calculated as the 1-5-year moving averages based on the participants' residential areas. The relationships between the PM_2.5 levels, categorized by the annual average concentration standard in Korea, and the prevalence of myopia were analyzed using binary logistic regression. The results were evaluated using the 95% confidence interval. Results: PM_2.5 concentrations averaged over 1-3 years were not significantly associated with the prevalence of myopia. On the other hand, the prevalence of myopia was significantly higher in areas where the 4-5-year moving average PM_2.5 levels exceeded the Korean standards. These findings suggest that long-term exposure to PM_2.5 may have a detrimental effect on vision. Conclusions: This study revealed the impact of long-term PM_2.5 exposure on the prevalence of myopia, highlighting the importance of managing PM_2.5 levels. Nevertheless, further cohort studies focusing on adults and in-depth research into the effects of longterm exposure will be necessary.

Background: In August 2021, three female semiconductor workers applied for occupational disease compensation due to congenital diseases diagnosed in their children: patient A (immunoglobulin A nephropathy, vesicoureteral reflux, renal agenesis), patient B (renal agenesis, esophageal atresia with tracheoesophageal fistula), and patient C (congenital megacolon). The Occupational Safety and Health Research Institute (OSHRI) initially assessed the relatedness of these conditions to occupational exposure as low. However, the Occupational Disease Adjudication Committee of the Korea Workers' Compensation and Welfare Service (KWCWS) overturned this assessment, officially recognizing these cases as occupational diseases in March 2024-the first such recognition in South Korea. Case presentation: The mother of Patient A worked in optical processes for 9 years, the mother of patient B worked in diffusion processes for 10 years, and the mother of patient C worked in molding and inspection processes for 7 years. Their jobs involved exposure to benzene, organic solvents, pyrolysis products, ionizing radiation, and X-rays. All three women continued working during pregnancy, and none had a family history of related illnesses. Conclusions: OSHRI estimated that the occupational exposure levels of these workers were low and noted insufficient reproductive research focused on congenital anomalies in the Korean semiconductor industry before 2010. However, KWCWS cited frequent miscarriages among female semiconductor workers as indirect evidence of an increased risk of congenital anomalies. KWCWS ultimately concluded that substantial evidence supports an association between occupational exposure and congenital diseases in the children of female semiconductor workers. This case series highlights a landmark recognition of occupational disease related to congenital anomalies in the semiconductor industry, emphasizing the need for further reproductive health research and improved worker protections.

Background: This study aimed to develop standard job categories for constructing a job-exposure matrix (JEM) for police officers in South Korea and to evaluate their applicability. Methods: We examined standard job codes related to police personnel management and compared them with job classifications from police publications. Using R Shiny, we developed a web-based search tool for standard codes. A pilot survey of 130 police officers assessed the codes' applicability and relevance to health-related hazardous factors. Results: Eighty-seven standard functional codes used in the police personnel management system POOL were organized into minor categories as the basic units of standard jobs. These were grouped into 20 sub-major categories and further consolidated into 10 major categories to develop the standard job codes. The responses to the standard job codes in the pilot survey were 75% accurate compared with the final expert evaluation results and 99.2% accurate compared with the algorithm-based automatic allocation results. The results of the job-hazardous factor network analysis revealed that the most frequently reported hazardous factor was emotional labor, followed by night shifts and electromagnetic waves. Emotional labor was identified as the top hazardous factor in six out of the nine standard job categories. Conclusions: The standard job codes developed in this study were designed in connection with the personnel management system for police officers, making them well-suited for constructing a comprehensive JEM for the entire police force.

Background: The Korean Occupational Stress Scale (KOSS) was developed in 2004. During this time, industrial structures have evolved, and societal awareness of occupational stress has changed. This study aims to develop and validate a revised version of the Korean Occupational Stress Scale (KOSS^®19), tailored for workers, reflecting these changes. Methods: The KOSS^®19 was developed based on the 26-item KOSS-short form (SF) through a review by eight experts. A survey was conducted including 359 service industry workers, comprising the KOSS^®19, Burnout, and Depression scales. The KOSS^®19 subscales were restructured, and their reliability and validity were evaluated. Results: The KOSS^®19 composed of eight subscales: hazardous physical environment (2 items), high job demand (3 items), insufficient job control (2 items), low social support (2 items), job insecurity (2 items), organizational injustice (4 items), lack of reward (2 items), and work-life imbalance (2 items). The reliability and validity of the KOSS^®19 were found to be satisfactory. Conclusions: The KOSS^®19 is a suitable tool for assessing occupational stress, effectively replacing the original KOSS and KOSS-SF.

Background: Emotional labor refers to the management of emotions and expressions to meet the emotional requirements of a job role. This study aimed to develop a revised version of the Korean Emotional Labor Scale (KELS ^®11), based on the first edition (KELS-24) introduced in 2014, and to provide practical applications and guidelines for its use in the Korean workplace through a validation process. Methods: The revised version of KELS ^®11 was derived from the 24-item KELS, following a review process involving eight experts. To validate the scale's reliability and validity, a self-administered survey was conducted among 359 service industry workers using KELS ^®11, burnout, and depression scales. KELS ^®11 was reclassified, and its reliability and validity were evaluated. Receiver operating characteristic curve analysis was conducted to establish sex-specific cutoff values (normal vs. high-risk groups). Results: KELS ^®11 was designed to account for individual, organizational, and cultural contexts. It consists of four subscales and 11 items: "emotional regulation" (2 items), "emotional dissonance" (3 items), "organizational monitoring" (2 items), and "organizational protective system for emotional labor" (4 items). KELS ^®11 demonstrated good validity (content validity ratio: 0.84; item convergence/discriminant validity success rates: 100%; correlation with burnout: r = 0.185-0.436, p < 0.01; correlation with depression: r = 0.128-0.339, p < 0.05) and reliability (Cronbach's alpha: 0.597-0.795). Additionally, sex-specific reference values were established to determine risk groups based on the intensity of emotional labor exposure. Conclusions: KELS ^®11 is a validated and reliable measurement tool designed to assess the intensity and magnitude of emotional labor in the workplace. The revised tool reflects critical considerations in the development of emotional labor measurement scales.

Background: Workplace violence refers to any act or threat of physical violence, verbal abuse, harassment, intimidation, bullying, mobbing, or other aggressive and disruptive behaviors that occur at work. This study aims to develop and validate a revision of the Korean Workplace Violence Scale (KWVS^®13), based on the first edition of the Korean Workplace Violence Scale (KWVS-24), and to provide practical applications and guidelines for the Korean workplace environment. Methods: The revised KWVS^®13 was developed by restructuring the 24-item KWVS through a review process involving eight experts. To validate the reliability and validity of KWVS^®13, a self-administered survey comprising KWVS^®13, burnout, and depression scales was conducted among 359 service industry workers. KWVS^®13 was reclassified, and its reliability and validity were assessed. Receiver operating characteristic curve analysis was performed to establish sex-specific cutoff values (normal vs. risk) of the scale. Results: KWVS^®13 consists of 13 items across four subscales: "psychological and sexual violence from customers" (4 items), "psychological and sexual violence from supervisors or coworkers" (4 items), "physical assault from customers, supervisors, or coworkers" (2 items), and "organizational protective system for workplace violence" (3 items). We found that KWVS^®13 shows relatively good validity (content validity ratio for content validity: 0.888; success rate of item convergent and discriminant validity: 100%, and significant correlation coefficient with burnout (r = 0.115-0.83, p < 0.05) and depression (r = 0.098-0.348, p < 0.05) with the exception of Organizational Violence Protection System for Workplace Violence) and reliability (Cronbach's alpha: 0.827-0.860). The reference values for determining risk groups according to the intensity of exposure to workplace violence are presented separately by sex. Conclusions: KWVS^®13 is a robust and useful measurement tool to objectively and quantitatively assess the intensity and magnitude of workplace violence. It incorporates important considerations for workplace violence assessment and provides a reliable framework for evaluating workplace violence in various professional settings.

Background: Lead poisoning is a serious public health issue that can arise from various sources, including nonoccupational exposure. This can make it challenging to manage, as lead poisoning can arise from unexpected sources. This case study examined lead poisoning in a 52-year-old man linked to hobbyist activities involving lead pellets, high-lighting the diagnostic and therapeutic challenges associated with this uncommon source of exposure. Case presentation: A 52-year-old man with a history of sports fishing presented with confusion, balance disorders, and memory loss. The initial medical evaluation revealed anemia and elevated lead levels. Further investigations, including imaging and blood tests, confirmed the presence of ingested lead pellets. The patient underwent chelation therapy, which led to a reduction in blood lead levels and improvement in symptoms. Follow-up over 46 months showed a gradual decrease in lead levels and partial recovery of cognitive function, although a few lead-related effects persisted. Conclusions: This case underscores the need for awareness of non-traditional sources of lead exposure, such as hobbyist activities. Effective diagnosis and treatment, including chelation therapy, can significantly alleviate the effects of lead poisoning. Ongoing monitoring is essential to manage long-term health outcomes related to chronic lead exposure.

Background: South Korean on-site workers in the public sector, fully covered by the Occupational Safety and Health Act, often perform hazardous tasks. However, their status and injury rates remain poorly documented. This study aimed to analyze changes in injury rates and the proportion of work-related diseases (WRDs) among on-site workers in basic local governments (BLGs) following workforce reductions between 2016 and 2018. Methods: Data from two sources provided by the Ministry of Employment and Labor were analyzed: organizational data on the number of on-site workers, and cases of injuries, deaths, and diseases among on-site workers in 226 BLGs from 2016 to 2018; and workers' compensation claims data (individual data) for on-site workers in BLGs during the same period. Injury, mortality, and disease incidence rates were calculated and compared between BLGs with increased and decreased workforce. The proportion of WRDs among all the injuries was also examined. Results: The total number of on-site workers in BLGs decreased by 18.1% in 2018 compared with 2016. The injury rate increased from 0.46% in 2016 to 0.62% in 2018. BLGs with workforce reductions showed higher injury rates, particularly in those with fewer than 1,000 on-site workers. The proportion of WRDs among all injuries increased by 1.34 times in 2018 compared with 2016. Conclusions: Workforce reductions among on-site workers in BLGs are associated with higher injury rates and a great proportion of WRDs. These findings highlight the need for improved occupational safety and health practices within the public sector and serve as an important basis for establishing workforce management and injury prevention policies. However, limitations in the available data made it challenging to identify worker groups particularly vulnerable to WRDs. Further research is needed, as it is critical for the development of effective occupational safety and health policies.

Background: Fishing is a physically demanding occupation with a high risk of musculoskeletal disabilities (MSDs). Although previous studies have focused on ergonomic risk factors, little attention has been paid to sex differences in the prevalence of MSDs among fishers. This study aimed to assess whether female fishers experience a higher prevalence of MSDs than male fishers and to examine whether this difference persists after adjusting for socioeconomic and occupational factors. Methods: We analyzed cross-sectional data from 898 Korean fishers (513 men and 385 women) who participated in the 2021-2022 Fisher Health Survey. MSDs in the upper extremities, lower back, and knees were defined as scores in the top 25% of the Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH), Oswestry Disability Index, and Western Ontario and McMaster Universities Arthritis Index Short Form (WOMAC-SF), respectively. Modified Poisson regression was used to calculate the prevalence ratios (PRs) by sex, with stepwise adjustments for age, socioeconomic factors, and occupational factors. Results: Female fishers had significantly higher MSD risk than male fishers across all body regions (fully adjusted PRs: upper extremity, 1.59; lower back, 1.63; knee, 1.44). Sex disparities were most pronounced among those under 60 years of age and remained significant even in older age groups. Conclusions: The elevated MSD risk among female fishers persisted despite adjusting for conventional risk factors, suggesting the influence of additional factors such as biological susceptibility, domestic labor, and gendered health reporting. Therefore, MSD prevention strategies should include sex-sensitive multidimensional approaches beyond ergonomic interventions.

Background: As South Korea experiences rapid population aging, preventing early retirement has become a critical concern. Ill health contributes to early retirement, and educational level moderates this relationship. Although well-studied in Europe, it remains less explored in Northeast Asia, where labor markets and educational attainment differ significantly. This study investigated the moderating role of education in the relationship between chronic diseases and labor force non-participation in South Korea, considering disease severity, type, and employment status. Methods: Using data from the Korean Longitudinal Study of Elderly Employment, this study analyzed 5,758 individuals born between 1964 and 1976. Chronic diseases were categorized by severity and type. Labor force participation and retirement from lifetime primary occupation were measured. Education was categorized as low (≤high school) or high (≥college). Logistic regression analyses were conducted, adjusting for sociodemographic and lifestyle covariates, with stratification by education level, employment status, severity, and disease characteristics. Results: Chronic diseases were significantly associated with labor market non-participation and early retirement, with stronger associations among individuals with lower educational levels. Educational disparities were particularly evident for severe and psychiatric disorders. Among wage workers, those with lower education were more likely to exit the labor market due to chronic diseases, whereas those with higher education generally maintained employment, except in cases of musculoskeletal diseases. Low-educated individuals with chronic diseases were also more likely to retire early from their lifetime primary occupations. Conclusions: Education moderates the relationship between chronic diseases and labor non-participation, with greater disparities in severe or psychiatric illnesses and among wage workers. Low-educated workers are more vulnerable to early retirement due to ill health, highlighting the need for targeted policy interventions to support this group and prevent early exit from the workforce.

The experience of the coronavirus disease 2019 pandemic has highlighted the importance of paid sick leave and sickness benefits, and is creating an international movement to introduce or improve real-world systems. The Organisation for Economic Co-operation and Development (OECD) countries except Korea and the United States already have statutory paid sick leave or sickness benefits, with the United Kingdom extending statutory paid sick leave to low-income workers in 2025, and Ireland introducing statutory paid sick leave in 2023. In the United States, 19 states, including Minnesota in 2024 and Alaska and Missouri in 2025, as well as the District of Columbia, have introduced statutory paid sick leave (as of December 2024). Furthermore, an analysis of 33 OECD countries with statutory paid sick leave or sickness benefits suggests that 21 countries comply with the International Labour Organization (ILO) Convention standards for adequacy of benefits and comprehensiveness of coverage, while six countries with social assistance have high comprehensiveness of coverage but low adequacy of benefits. There was not a single country with a program that had low levels of both benefit adequacy and coverage. In Korea, the pilot sickness benefit program has been extended until 2027, and the system has been delayed. The principles of benefit adequacy and coverage comprehensiveness must be upheld for the purpose and intent of the program to ensure adequate care and rest. Consequently, in addition to adhering to the standards outlined in the ILO Convention, the implementation of paid sick leave should be codified in legislation to enhance employer accountability.

South Korea remains one of the few Organization for Economic Cooperation and Development countries without a statutory paid sick leave system or a public sickness benefit program. This paper examines the necessity of introducing statutory paid sick leave in South Korea and outlines key considerations for its implementation. The "right to rest when sick" is a fundamental health and labor right that ensures workers can recover from illness without risking job loss or income insecurity. A comparative review of international systems demonstrates that most countries have institutional mechanisms to support workers during non-work-related illnesses or injuries through paid sick leave and/or sickness benefits. In contrast, South Korean workers-especially those in small workplaces or non-regular employment-face limited access to such protections. The absence of these systems exacerbates social inequality and increases the risk of presenteeism and delayed medical care. Introducing statutory paid sick leave is not only a public health investment but also a measure to promote labor rights, reduce productivity losses, and prevent poverty caused by illness. The implementation of such a system must ensure universal coverage, prohibit employer retaliation, and be integrated with future sickness benefit programs to create a comprehensive social safety net.

This study explores the theoretical foundations and practical applications of medical certification within the sickness benefit systems, particularly in the context of Korea's pilot program and its planned national rollout. While sickness benefit systems have long existed in many Organization for Economic Cooperation and Development (OECD) countries, Korea has only recently initiated pilot projects, largely prompted by the coronavirus disease 2019 pandemic. These systems aim to compensate for income loss due to illness or injury, and medical certification plays a central role in determining eligibility and work ability. This study defines medical certification as a two-stage process: clinical diagnosis and formal assessment of a worker's ability to return-to-work. The dual nature highlights the distinct objectives of the medical treatment and social security policies. Drawing on international practices, this study reviews the International Classification of Functioning, Disability, and Health (ICF) as a key global framework for assessing disability and work ability, although it acknowledges the limitations of its application to sickness benefits. The research emphasizes a shift in global trends toward return-to-work-oriented certification models, such as the UK's "fit note" system, which focuses on evaluating fitness-for-work rather than merely documenting illness. Sweden and Japan also offer models that integrate rehabilitation with flexible work accommodations. Three key issues were identified in Korea's system: the role of medical certification and concerns about moral hazard, the burden of proof and workload on physicians, and public perceptions of the program's purpose. We believe that medical certification should not only verify illness but also support early intervention and a healthy workforce. Ultimately, this study advocates for a balanced and efficient medical certification system tailored to Korea's healthcare context closely aligning with labor market policies to ensure long-term sustenance and integration of the sickness benefit program.

Work disability evaluation plays a central role in medical certification in sickness benefit schemes. This guides effective decision making for return-to-work timelines. Countries that incorporate it have varied approaches. To improve fairness and consistency, Sweden adopted disease-specific guidelines, particularly for complex health conditions such as mental disorders, cancer, and neurological diseases, whereas in the United Kingdom, a fit note system highlights the ease of fitness-for-work assessments in clinical settings. For a successful implementation of the sickness benefit scheme in Korea, it is essential to review international acumen in work disability evaluation and medical certification. This study also examines challenges that physicians face in certification, factors influencing assessments, and the usefulness of disease-specific guidelines. In many countries, administrative burdens, uncertainty in diagnosis, and ethical conflicts complicate physicians' tasks. Countries such as Sweden, France, and Ireland, have addressed these issues by developing structured certification tools and support systems. Learnings from the recent Korean pilot programs, this review identifies the following core priorities: developing disease-specific guidelines, providing clinical support for physicians' decisions, and integrating occupational health expertise. These guidelines should function not only as administrative checklists, but also as potential clinical tools that consider both patient functionality and job characteristics. Finally, this study offers policy and practical insights to help design a consistent and fair medical certification system for Korea's sickness benefit program that encourages timely medical intervention, prevents presenteeism, and promotes sustainable workforce reintegration.

South Korea's pilot sickness benefit program, launched in 2022 across six regions and currently operating in 14 regions as of 2025, represents a critical juncture in the country's social protection development. While ostensibly designed with inclusive eligibility criteria, the program reveals fundamental paradoxes that illuminate deeper structural inequalities within Korea's dualized labor market. This opinion piece examines how current design choices risk undermining universal health coverage goals by systematically excluding the most precarious workers. The program's design features-including low replacement rates (60% of the minimum wage) and extended waiting periods-created perverse incentives where the most vulnerable workers accepted the least favorable conditions. This pattern exemplifies what Korpi and Palme termed the "paradox of redistribution," where targeted approaches ultimately prove less effective than universal ones, with the second phase's restriction to the bottom 50% income bracket threatening to exacerbate this paradox. Successful implementation will depend on integrating equity, people-centered design, and gender-transformative perspectives into every phase-design, operation, evaluation, and reform. In doing so, South Korea has the opportunity to offer a model of sickness protection that does not simply patch gaps, but actively reshapes the structures that produce health and economic inequalities in the first place.

Background: Mercury, particularly in its methylmercury form, significantly affects neurological and developmental functions. In Gyeongsangbuk-do, Republic of Korea, blood mercury levels are elevated due to high fish consumption, especially shark meat. Vulnerable groups, such as pregnant women, are at increased risk as methylmercury can cross the placenta and accumulate in breast milk. This study aimed to investigate the risks of mercury exposure from shark meat consumption among young and middle-aged women in Gyeongsangbuk-do. Methods: The data of women aged 19-55 years from the 2018 Gyeongsangbuk-do Community Health Survey were included. Survey questions focused on frequency and amount of shark meat consumption, as well as pregnancy status, recent childbirth, and breastfeeding status. The Complex Sample Analysis was used to determine the prevalence and risk of overconsumption. Weekly mercury intake was calculated for respondents who reported their body weight, and the population size exceeding Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA) and Ministry of Food and Drug Safety (MFDS)'s threshold was estimated. Results: Regions where the consumption rate of shark meat exceeds the average for Gyeongsangbuk-do are found to be distributed in the southeastern part of the province. Population estimates revealed that approximately 9,895 women aged 19-55, including 255 who had breastfed in the past year, consumed shark meat exceeding the recommended intake. Based on the maximum recorded mercury concentration (8.93 ㎍/g), an estimated 2,645 women surpassed the JECFA's mercury exposure threshold, while 845 exceeded the MFDS's threshold. Conclusions: In young and middle-aged women of Gyeongsangbuk-do, approximately 7.1% exceed the single intake limit, while up to 1.9% exceed the JECFA's provisional tolerable weekly intake (PTWI) and 0.6% exceed the MFDS's PTWI, suggesting considerable risk that warrants monitoring and guidance. More stringent advisory measures regarding shark meat consumption and updated standards on mercury concentration in shark meat are essential for young and middle-aged women in the province.

Background: Polycyclic aromatic hydrocarbons are generated from the incomplete combustion of organic materials such as fossil fuels and wood. These compounds, often inhaled, cause respiratory issues like asthma and chronic obstructive pulmonary disease due to oxidative stress and inflammation. Pohang, South Korea's iron and steel hub, experiences significant polycyclic aromatic hydrocarbons emissions from extensive industrial activities and heavy truck movements. This study investigates the link between urinary polycyclic aromatic hydrocarbons metabolites and respiratory diseases among Pohang residents, considering their cumulative exposure and duration of residency. Methods: Utilizing data from the National Environmental Research Institute's health impact assessment conducted between 2012 and 2015, this study included 1,189 participants from Pohang. Urinary concentrations of polycyclic aromatic hydrocarbons metabolites served as exposure indicators. The study assessed the correlation between these metabolite levels and self-reported respiratory diseases, considering variables such as duration of residence, smoking status, and occupational exposures. Statistical analyses involved logistic regression and fixed-effect meta-analysis. Results: The findings indicate a significant association between elevated levels of polycyclic aromatic hydrocarbons metabolites and an increased risk of respiratory diseases, particularly among those in the highest exposure quartile. The study also found a notable dose-response relationship, emphasizing the heightened risk with longer residency durations near the industrial complex. Despite yearly fluctuations, the trend suggests a persistent risk associated with high polycyclic aromatic hydrocarbons exposure. Conclusions: Elevated exposure to polycyclic aromatic hydrocarbons near industrial areas such as the Pohang Industrial Complex is significantly associated with an increased prevalence of respiratory diseases. The study underscores the importance of implementing public health strategies to reduce polycyclic aromatic hydrocarbons exposure, especially in industrial regions. Future research should broaden the scope of polycyclic aromatic hydrocarbons metabolites analyzed and consider comprehensive exposure histories to better understand the relationship between polycyclic aromatic hydrocarbons exposure and respiratory health outcomes.

Background: This study investigates the association between serum iron levels and frequency-specific hearing loss in Korean female population, a topic previously unexplored in auditory health research. Methods: This study enrolled Korean female participants from the general population. Serum iron levels and hearing thresholds at low (1 kHz) and high (4 kHz) frequencies were assessed, adjusting for potential confounders. Participants were stratified into quartiles based on serum iron levels. Results: The mean age of the study population was 51.1 ± 10.1 years. Among the 2,987 participants, 344 (11.5%) had abnormal low-frequency hearing thresholds, and 719 (24.1%) had abnormal high-frequency thresholds. Multiple linear regression analysis demonstrated a significant negative association between serum iron levels and low-frequency hearing thresholds (β = -0.012, p = 0.017), whereas no significant association was observed with high-frequency thresholds (β = -0.006, p = 0.352). In a stratified analysis using 50 years (the average menopausal age) as a cutoff, no statistically significant association was identified in participants younger than 50 years. However, in those aged 50 years and older, the negative association between serum iron levels and low-frequency hearing thresholds remained statistically significant. Conclusions: This study is the first to identify an association between serum iron levels and low-frequency hearing loss in females aged 50 years and older, underscoring the potential role of iron in auditory function. These findings highlight the importance of further research in diverse populations to elucidate the underlying mechanisms and broader clinical implications.

Background: Occupational skin diseases are common in industrial settings; however, few studies have examined workers involved in the production of lithium-ion battery cathode-active materials. This study aimed to investigate the patterns and factors associated with skin diseases in these workers. Methods: Overall, 37 workers with a history of skin disease were recruited from two cathode-active material manufacturing companies. Onsite investigations, semi-structured interviews, and workplace observations were conducted. Information on skin symptoms, affected areas, symptom frequency, and aggravating factors was collected. Results: The most commonly reported symptoms were pruritus (27.5%), erythema (20.3%), and chemical burns (15.9%). The most commonly affected areas were the hands and forearms (67.6%), whereas 27.0% of workers reported symptoms in unexposed areas, such as the thighs. The symptoms tended to worsen on workdays and improved during holidays. Less-experienced workers reported more frequent symptoms. Conclusions: Skin diseases during cathode material production appear to be primarily caused by irritants and allergic contact dermatitis, as well as chemical burns caused by exposure to metal dust, such as lithium, nickel, and cobalt. An urgent need exists for appropriate personal protective equipment, improved work environments, and targeted education for new workers.

Background: School food service workers are highly likely to develop heat-related illnesses because of their work environment. However, studies that have examined the risk of heat-related illnesses among them are limited. The purpose of this study was to investigate the status of heat exposure, implementation of heat wave countermeasures, and prevalence of heat-related illness symptoms among school food service workers in Korea, and to explore the relationship between them. Methods: A cross-sectional study was conducted through an online survey of school food service workers from May 25 to June 12, 2023, via three labor unions. We analyzed 6,244 valid responses. We assessed general characteristics, heat-related illness symptoms (heat rash, heat cramps, heat edema, heat exhaustion, heat syncope), duration of heat exposure during heat waves, and heat wave preventive measures. Multiple logistic regression analyses were performed, with adjustments for age, occupation, hypertension, diabetes, and school type. Results: More than one-third of school food service workers reported heat exposure between May and September exceeding 4 hours daily, and 94.6% experienced at least one heat-related illness symptom during the last year. A dose-response relationship was observed between heat exposure duration and heat-related illness symptoms (p for trend < 0.001). School food service workers who did not have increased rest periods or did not reduce high-heat prepared foods showed significantly higher odds ratios for heat-related illness symptoms. Conclusions: School food service workers experience substantial heat exposure and a high prevalence of heat-related illness symptoms. The risk of heat-related illness symptoms was associated with extended duration of heat exposure. Increasing rest periods and reducing high-heat food preparation were effective preventive measures. These findings underscore the need for improved heat exposure management and implementation of effective preventive measures to protect the health of school food service workers, with particular attention to appropriate rest periods.

Background: Although weekend work makes up a significant part of work patterns in modern society, research on the health effects of weekend work is relatively limited compared to other types of nonstandard work. This study was conducted to examine the impact of weekend work on the health of Korean workers, aiming to provide evidence to support the development of welfare policies that promote workers' health. Methods: This study was conducted using data from the 6th Korean Working Conditions Survey, targeting 35,957 Korean workers who met the research criteria. Based on the survey responses, information was collected on weekend work status and health outcomes, including general health, musculoskeletal pain, headaches or eye pain, fatigue, sleep disorders, depression, anxiety, absenteeism and presenteeism. To examine the association between weekend work and health outcome variables, logistic regression analysis was performed adjusting for sociodemographic and occupational characteristics, with additional stratified analyses conducted according to employment status. Results: Among the final study population, 11,255 workers, accounting for 30.5% of the total, were weekend workers. After adjusting for sociodemographic and occupational characteristics, weekend work was found to be significantly associated with depression (odds ratio [OR]: 1.08; 95% confidence interval [CI]: 1.00-1.18), anxiety (OR: 1.35; 95% CI: 1.16-1.58), musculoskeletal pain (OR: 1.45; 95% CI: 1.34-1.58), fatigue (OR: 1.49; 95% CI: 1.36-1.62), absenteeism (OR: 1.70; 95% CI: 1.43-2.03), and presenteeism (OR: 1.82; 95% CI: 1.62-2.04). The health effects of weekend work differed between the self-employed and employees, as shown in the results of the stratified analysis. Conclusions: Weekend work was found to increase the risk of both physical and mental health problems of Korean workers, and the effect varied according to employment status. There is a need to design a comprehensive occupational health policy that reflects the characteristics of different employment statuses.

The Occupational and Environmental Health Screening Cohort of Yangsan Korea (OEC-YK) was established to monitor long-term health outcomes in workers and environmental high-risk citizens through systematic periodic health examinations. The cohort integrates 623,402 examination instances from 105,768 participants at Pusan National University Yangsan Hospital (2012-2023), encompassing general health checkups, occupational exposure surveillance, cancer screenings, and others including asbestos-related surveillance. Examination types included general health examination (32.4%), cancer screening (20.6%), special health examination (16.2%), night-shift work examination (16.0%), chronic disease screening (4.8%), pre-placement examinations (2.1%), and asbestos-related surveillance (3.6%). At baseline, 59.0% were male and 75.5% were aged between 20 and 59 years. Follow-up rates reached 35.0% at 1 year, 31.9% at 2 years, and 3.2% at 11 years. Notably, the inclusion of systematic asbestos examinations, combined with a national asbestos job exposure matrix, allows detailed study of long-latency occupational diseases. This large-scale longitudinal dataset supports exposure-disease linkage analysis, job-exposure integration, and time-series modeling of worker health trajectories in Korea.

Background: The impact of global integration has led to an increase in non-standard work patterns, threatening workers' health. Psychological health problems, such as anxiety and fatigue, negatively affect workers' health and safety. Sudden work recall, a situation where workers are asked to return to work under unpredictable circumstances, is associated with uncertainty. Research on the relationship between sudden work recall and anxiety and fatigue is limited, and this study aims to investigate this relationship among Korean workers. Methods: The study used data from the 6th Korean Working Conditions Survey. To analyze the pure effects of sudden work recall, the final sample was limited to 15,702 nonshift workers with a 'good' subjective health status. The presence of sudden work recall was categorized into three frequency groups: "several times a month," "rarely," and "never." Anxiety and fatigue were each categorized into "yes" or "no" responses. Multiple logistic regression analysis was performed. Results: After adjusting for demographic and occupational characteristics, the odds ratio (OR) for anxiety in the 'several times a month' group was 4.066 (95% confidence interval [CI]: 2.787-5.931), indicating a significantly higher risk. Conversely, the OR for the 'rarely' group was 1.363 (95% CI: 0.921-2.017), which was not statistically significant. A similar pattern was observed for fatigue: the 'several times a month' group had a significantly higher risk (OR: 1.875; 95% CI: 1.490-2.359), but the 'rarely' group (OR: 0.955; 95% CI: 0.750-1.215) did not. Conclusions: The relationship between sudden work recall and psychological health may not be a simple linear one. The results suggest that only a high frequency of sudden work recall is associated with an increased risk of anxiety and fatigue. Therefore, it is necessary to establish appropriate measures and to conduct additional research in this area.

Normative values for the physical fitness of Mexican police officers (POs) by sex and age are scarce. This study describes physical performance percentiles by sex and age group and developed percentile values for POs of northeastern Mexico. A retrospective analysis was conducted on database of 7,519 men and 1,050 women aged 20-59 years. Fitness assessments included anthropometric measures, handgrip strength, Abalakov vertical jump, agility circuit, and 1,000-m run. Officers aged 20-29 outperformed other groups in all tests, except for grip strength, which peaked in the 30-39 group. In both sexes, fitness declined with age. Percentile tables by sex and age offer benchmarks to support performance standards, guide targeted physical activity programs and inform future research on Mexican POs.