The mechanisms by which iron is absorbed are similar to those of divalent metals, particularly manganese, lead, and cadmium. These metals, however, show different toxicokinetics in relation to menarche or menopause, although their interaction with iron is the same. This review focuses on the kinetics of these three toxic metals (manganese, lead, and cadmium) in relation to menarche, pregnancy, and menopause. The iron-manganese interaction is the major factor determining sex-specific differences in blood manganese levels throughout the whole life cycle. The effects of estrogen overshadow the association between iron deficiency and increased blood lead concentrations, explaining why women, despite having lower ferritin concentrations, have lower blood lead concentrations than men. Iron deficiency is associated with elevated cadmium levels in premenopausal women, but not in postmenopausal women or men; these findings indicate that sex-specific differences in cadmium levels at older ages are not due to iron-cadmium interactions, and that further studies are required to identify the source of these differences. In summary, the potential causes of sex-specific differences in the blood levels of manganese, lead, and cadmium differ from each other, although all these three metals are associated with iron deficiency. Therefore, other factors such as estrogen effects, or absorption rate as well as iron deficiency, should be considered when addressing environmental exposure to toxic metals and sex-specific differences in the blood levels of these metals.
Absorption ; Cadmium ; Environmental Exposure ; Estrogens ; Female ; Ferritins ; Humans ; Iron ; Kinetics ; Life Cycle Stages ; Male ; Manganese ; Menarche ; Menopause ; Metals ; Pharmacokinetics ; Pregnancy

BACKGROUND: The objectives of the present study are to: (i) evaluate the effect of environmental and metabolic heat on heat-related illnesses in outdoor workers; and (ii) evaluate the effect of personal factors, including heat acclimation, on the risk of heat-related illnesses in outdoor workers. METHODS: We identified 47 cases of illnesses from exposure to environmental heat in outdoor workers in Korea from 2010 to 2014, based on review of workers' compensation data. We also obtained the information on location, time, and work environment of each heat-related illness. RESULTS: Our major results are that 29 cases (61.7%) occurred during a heat wave. Forty five cases (95.7%) occurred when the maximum estimated WBGT (WBGTmax) was equal to or greater than the case specific threshold value which was determined by acclimatization and metabolic rate. Twenty two cases (46.8%) were not acclimated to the heat. Thirty-seven cases (78.7%) occurred after tropical night (temperature above 25 °C), during which many people may find it hard to sleep. CONCLUSION: Personal risk factors such as heat acclimation as well as environmental factors and high metabolic rate during work are the major determinants of heat-related illnesses.
Acclimatization ; Extreme Heat* ; Hot Temperature ; Humans ; Infrared Rays ; Korea ; Risk Factors ; Workers' Compensation

OBJECTIVES: The present study was performed to evaluate the association between serum ferritin concentrations and bone mineral density (BMD) in a representative Korean general population. METHODS: This was a cross-sectional study based on data obtained in the Korean National Health and Nutrition Examination Survey (2008~2010). The present cross-sectional analysis was restricted to participants > or =20 years of age who completed the health examination survey and BMD measurement (n=15,538).
Bone Density ; Cross-Sectional Studies ; Female ; Ferritins ; Humans ; Iron ; Linear Models ; Male ; Nutrition Surveys ; Prevalence ; Public Health

No abstract available.
Occupational Health Services ; Occupational Health ; Small Business

The authors flagged that the spelling of author YangHo Kim was incorrect. It is published on the original manuscript as Yang Ho Kim, but should be spelt YangHo Kim.

BACKGROUND: To identify work sectors with high risk for work-related musculoskeletal disorders (MSDs) in Korean men and women. METHODS: We analyzed nationwide data to identify ergonomic risk factors in Korean employees. In particular, we analyzed data on exposure to five ergonomic risk factors (painful/tiring postures, lifting/moving heavy materials, standing/walking, repetitive hand/arm movements, and hand/arm vibration) according to employment sector, sex, and age, using the 2014 Fourth Korean Working Conditions Survey. We also used workers' compensation data on work-related MSDs in 2010, which is available by sex. RESULTS: The different work sectors had different gender distributions. “Manufacturing” (27.7%) and “construction” (11.3%) were dominated by males, whereas “human health and social work activities” (12.4%), “hotel and restaurants” (11.7%), and “education” (10.4%) were dominated by females. However, “wholesale and retail trade” and “public administration and defense” employed large numbers of males and females. Furthermore, the work sectors with a greater proportion of work-related MSDs and with multiple ergonomic risk factors were different for men and women. For men, “construction” and “manufacturing” had the highest risk for work-related MSDs; for women, “hotel and restaurants” had the highest risk for work-related MSDs. CONCLUSION: Ergonomic interventions for workers should consider gender and should focus on work sectors with high risk for MSDs, with multiple ergonomic risk factors, and with the largest number of workers.
Employment ; Female ; Humans ; Male ; Posture ; Risk Factors ; Social Work ; Workers' Compensation

Methods: This was a secondary analysis of data from the fifth Korean Working Conditions Survey conducted in 2017. A structural equation model was used for mediation and moderation analysis. Results: Service and sales workers who had more interactions with angry clients had increased risk for depression and anxiety. Experiencing clients' adverse behaviors (acute episodes) mediated the relationship between interacting with angry clients (a chronic situation) on depression and anxiety. Job satisfaction and managers' support moderated the relationship between interacting with angry clients and mental health problems. Conclusion We suggest that employers of service and sales workers should recruit staff based on their aptitude for such work, thus ensuring job satisfaction, and train them to deal with angry clients in such a way that they experience less emotional burden. Employers should also make bylaws requiring managers to directly take care of adverse social behavior by clients. Furthermore, a sociocultural campaign to prevent adverse social behavior by clients is also needed.

Methods: This was a secondary analysis of data from the fifth Korean Working Conditions Survey conducted in 2017. A structural equation model was used for mediation and moderation analysis. Results: Service and sales workers who had more interactions with angry clients had increased risk for depression and anxiety. Experiencing clients' adverse behaviors (acute episodes) mediated the relationship between interacting with angry clients (a chronic situation) on depression and anxiety. Job satisfaction and managers' support moderated the relationship between interacting with angry clients and mental health problems. Conclusion We suggest that employers of service and sales workers should recruit staff based on their aptitude for such work, thus ensuring job satisfaction, and train them to deal with angry clients in such a way that they experience less emotional burden. Employers should also make bylaws requiring managers to directly take care of adverse social behavior by clients. Furthermore, a sociocultural campaign to prevent adverse social behavior by clients is also needed.

Background: The present study examined changes in the working hours of Korean workers from 2010 to 2020 according to employment status and industrial sector. Methods: This was a secondary analysis of data from the third (2010), fourth (2014), fifth (2017) and sixth (2020) Korean Working Conditions Surveys, which were conducted by the Korea Occupational Safety and Health Agency. Results: During the past 10 years, workers classified as employees, self-employed, or employers experienced clear declines in average weekly working hours and in the percentages of individuals who worked more than 48 hours per week. During 2020, the largest proportion of employees (52.8%) had 40-hour work weeks, whereas the largest proportions of selfemployed individuals (26.8%) and employers (25.1%) had very long work weeks (≥ 60 h/ week). Also during 2020, individuals who were self-employed or employers in the sectors of ‘Accommodation and food service’ had the longest weekly work hours, whereas employees in the sector of ‘Transportation’ had the longest weekly work hours. All three groups (employees, self-employed, and employers) in all 21 industrial sectors experienced declines in average weekly working hours from 2017 to 2020. Conclusion From 2010 to 2020, employees, self-employed individuals, and employers experienced clear declines in average weekly working hours, and in the percentages of individuals with long weekly working hours. However, there were also differences in the weekly working hours of those who had different employment status and who worked in different industrial sectors. The implementation of the 40-hour work-week and the 52-hour maximum work-week in Korea reduced excessive work hours by individuals who had different employment status and who worked in different industrial sectors, and probably improved worker quality-of-life. We recommend extension of these regulations to workplaces with fewer than 5 employees.

Background: Among workers who interact with angry clients, there is limited information about the characteristics of workers who are most vulnerable to mental health problems. Thus, we determined the association of multiple demographic, socioeconomic, and modifiable work-related psychosocial factors with the subjective well-being of workers who interact with angry clients. Methods: This was a secondary analysis of data from the fifth Korean Working Conditions Survey, conducted in 2017. The study focused on workers who interacted with angry clients during 25% or more of their work time. Multiple logistic regression was used to determine odds ratios (ORs) and 95% confidence intervals for the association of multiple factors with self-reported subjective well-being after adjustment for demographic, socioeconomic, and modifiable psychosocial factors. Results: Overall, 9.6% of men and 7.4% of women who interacted with angry clients reported poor subjective well-being. Poor well-being was significantly more likely to be reported by men who worked 40 hours or more per week (aOR, 3.97–5.37) and by men who were daily workers (aOR, 2.21). Poor subjective well-being had a significantly positive association with exposure to adverse social behaviors by clients (men: aOR, 1.54, women: aOR, 1.58), and significantly negative associations with unskilled manual work (women only: aOR, 0.30), job satisfaction (men: aOR, 0.70, women: aOR, 0.52), and good social climate (men: aOR, 0.70, women: aOR, 0.44). Conclusion Workers who interact with angry clients were widely distributed over nonmanual labor and manual labor, but not limited to service and sales job. We identified modifiable factors that affect the subjective well-being of workers who interact with angry clients. We suggest that employers provide protection to prevent adverse social behaviors by clients, and also make an effort to establish a good social climate at the workplace.