Fine particulate matter aggravates smoking induced lung injury via NLRP3/caspase-1 pathway in COPD.

BACKGROUND: Exposure to noxious particles, including cigarette smoke and fine particulate matter (PM2.5), is a risk factor for chronic obstructive pulmonary disease (COPD) and promotes inflammation and cell death in the lungs. We investigated the combined effects of cigarette smoking and PM2.5 exposure in patients with COPD, mice, and human bronchial epithelial cells. METHODS: The relationship between PM2.5 exposure and clinical parameters was investigated in patients with COPD based on smoking status. Alveolar destruction, inflammatory cell infiltration, and pro-inflammatory cytokines were monitored in the smoking-exposed emphysema mouse model. To investigate the mechanisms, cell viability and death and pyroptosis-related changes in BEAS-2B cells were assessed following the exposure to cigarette smoke extract (CSE) and PM2.5. RESULTS: High levels of ambient PM2.5 were more strongly associated with high Saint George's respiratory questionnaire specific for COPD (SGRQ-C) scores in currently smoking patients with COPD. Combined exposure to cigarette smoke and PM2.5 increased mean linear intercept and TUNEL-positive cells in lung tissue, which was associated with increased inflammatory cell infiltration and inflammatory cytokine release in mice. Exposure to a combination of CSE and PM2.5 reduced cell viability and upregulated NLRP3, caspase-1, IL-1ß, and IL-18 transcription in BEAS-2B cells. NLRP3 silencing with siRNA reduced pyroptosis and restored cell viability. CONCLUSIONS: PM2.5 aggravates smoking-induced airway inflammation and cell death via pyroptosis. Clinically, PM2.5 deteriorates quality of life and may worsen prognosis in currently smoking patients with COPD.

Effect of job satisfaction on depression after adjusting for satisfaction with other life domains.

Background: Studies on the association between job satisfaction and depression have often been reported. However, no study has examined how job satisfaction impacts depression while considering satisfaction with other aspects of life. In this study, we evaluated the effect of job satisfaction on depression after adjusting for satisfaction with other domains of life. Methods: We used data from the 16th wave of the Korean Welfare Panel Study. A total of 3568 current employees without depression who completed a survey were included. Depression was measured using the abbreviated version of the CES-D scale. Various types of satisfaction, including job satisfaction, were measured using single-item questions and a 5-point Likert scale. The association between job satisfaction and depression after considering satisfaction with other life domains was analyzed using a multiple logistic regression model. Results: Crude models showed a significant association between job satisfaction and depression in males (odds ratio [OR]: 7.90; 95% confidence interval [CI]: 4.11-15.23) and females (OR: 7.12; 95% CI: 4.40-11.50). When adjusted for sociodemographic factors, health-related factors, and work-related factors, the association remained significant in males (OR: 6.20; 95% CI: 3.10-12.41) and females (OR: 6.28; 95% confidence interval (CI): 3.79-10.40). However, when satisfaction with other life domains was included, the association remained significant only in females (OR: 3.55; 95% CI: 1.93-6.50). Conclusions: This study shows an association between job satisfaction and depression in Korean employees. However, when satisfaction with other life domains was considered, this association remained significant only in women. Regular screening of job satisfaction should be considered as a means of preventing and managing depression among female employees.

Association between Work-related Communication Devices Use during Work Outside of Regular Working Hours and Depressive Symptoms in Wage Workers.

Background: This study aimed to investigate the relationship between work-related communication devices use during work outside of regular working hours and depressive symptoms in wage workers. Methods: Data from 50,538 workers aged 15 years or older who had participated in the 6th Korean Working Condition Survey (KWCS) were used. The final sample was 32,994 wage workers. The questionnaire asked the respondents how often they used communication devices for work during work outside of regular working hours. Depressive symptoms were assessed using WHO-5 Well-Being Index. Multiple logistic regression analysis was used to analyze the association between work-related communication devices use during work outside of regular working hours and depressive symptoms. Results: The rate of depressive symptoms was highest among workers who did not use work-related communication devices during work outside of regular working hours. After adjusting for socio-demographic and work-related factors, the odds ratio of depressive symptoms among workers who used communication devices when working outside of regular working hours was 1.20 (95% CI: 1.09-1.32); the odds ratio of depressive symptoms in the group not using communication devices for free-time work was 1.66 (95% CI: 1.37-2.00), which was higher than that of the reference group, that is, workers who did not work outside of regular working hours, and was statistically significant. Conclusion: Regardless of whether work-related communication devices are used, working outside of regular working hours increases depressive symptoms. The use of work-related communication devices during work outside of regular working hours can reduce the rate of depressive symptoms.

Ambient particulate matter and surrounding greenness in relation to sleep quality among pregnant women: A nationwide cohort study.

Background: Particulate air pollution and residential greenness are associated with sleep quality in the general population; however, their influence on maternal sleep quality during pregnancy has not been assessed. Objective: This cross-sectional study investigated the individual and interactive effects of exposure to particulate matter (PM) air pollution and residential greenness on sleep quality in pregnant women. Methods: Pregnant women (n = 4933) enrolled in the Korean Children's Environmental Health Study with sleep quality information and residential address were included. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). The average concentrations of PM (PM2.5 and PM10) during pregnancy were estimated through land use regression, and residential greenness in a 1000 m buffer area around participants' residences was estimated using the Normalized Difference Vegetation Index (NDVI1000-m). Modified Poisson regression models were used to estimate the associations between PM and NDVI and poor sleep quality (PSQI >5) after controlling for a range of covariates. A four-way mediation analysis was conducted to examine the mediating effects of PM. Results: After adjusting for confounders, each 10 µg/m3 increase in PM2.5 and PM10 exposure was associated with a higher risk of poor sleep quality (relative risk [RR]: 1.06; 95% confidence interval [CI]: 1.01, 1.11; and RR: 1.09; 95% CI: 1.06, 1.13, respectively), and each 0.1-unit increase in NDVI1000-m was associated with a lower risk of poor sleep quality (RR: 0.97; 95% CI: 0.95, 0.99). Mediation analysis showed that PM mediated approximately 37%-56% of the association between residential greenness and poor sleep quality. Conclusions: This study identified a positive association between residential greenness and sleep quality. Furthermore, these associations are mediated by a reduction in exposure to particulate air pollution and highlight the link between green areas, air pollution control, and human health.

Development of occupation-based exposure matrix of lead for Korean workers: challenges and opportunities.

OBJECTIVES: Industry- and occupation-based carcinogen exposure matrices play a pivotal role in preventing occupational cancer. While the Korean CARcinogen EXposure (K-CAREX) has been developed in recent years to assess exposure prevalence and intensity by industry, the feasibility of constructing an occupation-based exposure matrix remains unexplored. Hence, the objective of this study is to explore the potential of combining the nationwide work environment measurement database (WEMD) and the special health examination database (SHED) to develop a comprehensive occupation-based exposure matrix. METHODS: The WEMD provides information on airborne lead measurements, including industry codes, but it does not include data related to occupations. In contrast, the SHED contains information on both occupation and blood lead levels. By integrating these 2 databases, we attempted to assess airborne lead exposure levels by occupation. Additionally, we performed a rank correlation analysis to compare the airborne exposure levels with corresponding blood lead levels according to occupation. RESULTS: A total of 35 425 workers who both wore air samplers for lead and underwent special health examinations for lead were extracted between 2019 and 2021. An occupation-based exposure matrix was developed to evaluate the intensity of lead exposure across a range of occupations, encompassing 51 minor occupations and 70-unit occupations. Rank correlation analyses showed strong positive correlations between airborne lead and blood lead measurements according to occupation. CONCLUSIONS: Our study findings suggest that combining 2 nationwide surveillance databases can be an effective approach for creating an occupation-based exposure matrix. However, our results also highlight several limitations that need to be addressed in future studies to improve the accuracy and reliability of such matrices.

Evaluation on the Sex-Specific Association Between Cigarette Smoke Exposure and Inflammation Markers-C-Reactive Protein and White Blood Cell Count.

INTRODUCTION: Cigarette smoke increases peripheral white blood cell (WBC) count. However, the dose-dependent association between smoking and C-reactive protein (CRP), an important inflammatory marker, has been reported as inconsistent. AIMS AND METHODS: Here, we evaluated the associations between smoking and CRP using both smoking questionnaires and urine cotinine as exposure markers. The Korea National Health and Nutrition Examination Survey data were used for analyzing the associations. Multiple regression analyses were performed to examine the associations between cigarette smoke exposure, as assessed by questionnaires and urine cotinine, and health effects, as measured by CRP and WBC count, controlling for potential confounders. The confounders, including age, sex, body mass index, blood pressure, cholesterol, glucose, alanine aminotransferase, and uric acid, were selected a priori based on the literature. RESULTS: A total of 11 435 participants were included for analysis. For the exposure-response relationship, the results indicated a significant increase in CRP levels in male smokers compared to male nonsmokers (p = .002), whereas no significant increase was found in female smokers compared to female nonsmokers (p = .680). For the dose-response relationship, a significant positive association was observed between urine cotinine and CRP in male smokers (p = .018), whereas no significant association was found in female smokers (p = .508). WBC count consistently showed significant exposure-response and dose-response relationships in both sexes. CONCLUSIONS: WBC count was found to be a consistent effect marker of cigarette smoke exposure, while the association between CRP level and smoking was inconsistent and varied by sex. The sex-specific response to cigarette smoke exposure warrants further exploration in future studies. IMPLICATIONS: Cigarette smoke exposure is known to increase inflammation and has been thought to increase CRP, a significant inflammation marker. However, recent studies have reported conflicting results regarding the dose-dependent association between cigarette smoke exposure and CRP. This study found that the association between smoking and CRP is inconsistent and varies by sex, showing significant exposure response in men but not in women. Furthermore, the study suggests that WBC count is a more consistent marker for cigarette smoke exposure.

The relationship between working time mismatch and depression according to actual hours worked.

OBJECTIVES: The effect of the combination of working hours and working time mismatch on depression is unknown. This study was undertaken to confirm the relationship between working time mismatch and depression with respect to hours worked. MATERIAL AND METHODS: The data of 45 514 adult workers that participated in the 6th Korean Working Conditions Survey (KWCS-VI 2020) were reviewed. Depression was defined using the World Health Organization 5 Well-Being Index (WHO-5) cut-off score of 50. Working time mismatch was defined as a difference between actual and desired working hours. To identify associations between working hour mismatch and depression according to weekly hours worked, stratification analysis was conducted by dividing the study subjects into 3 groups based on actual hours worked weekly (<40 h, 40-<52 h, or ≥52 h). Multiple logistic regression analysis adjusted for potential confounders was performed to calculate odds ratios of depression. RESULTS: In the <40 h, 40-<52 h, and ≥52 h groups, the odds ratios (OR) of working more hours than desired were 1.51, 95% CI: 1.20-1.92 (<40 h), 1.70, 95% CI: 1.58-1.84 (40-<52 h), and 1.55, 95% CI: 1.41-1.69 (≥52 h), respectively, compared to a matched actual versus desired working hours group (the matched group). On the other hand, the odds ratios of working fewer hours than desired were 1.17, 95% CI: 1.07-1.27 (<40 h), 1.38, 95% CI: 1.20-1.60 (40-<52 h), and 1.98, 95% CI: 1.24-3.17 (≥52 h), respectively. The risk of depression was found to increase significantly with working time mismatch within all 3 working hour groups. CONCLUSIONS: Working time mismatch increases the risk of worker depression regardless of hours worked. Int J Occup Med Environ Health. 2023;36(6):788-97.

Statement by the Korean Society of Occupational and Environmental Medicine on the proposed reform of working hours in South Korea.

The current 52-hour workweek in South Korea consists of 40 hours of regular work and 12 hours of overtime. Although the average working hours in South Korea is declining, it is still 199 hours longer than the Organisation for Economic Co-operation and Development average of 1,716 hours per year. In view to this, the South Korean government has now proposed to reform the workweek, mainly intending to increase the workweek to 69 hours when the workload is heavy. This reform, by increasing the labor intensity due to long working hours, goes against the global trend of reducing work hours for a safe and healthy working environment. Long working hours can lead to increased cerebrovascular and cardiovascular diseases, industrial accidents, mental health problems, and safety accidents due to lack of concentration. In conclusion, the Korean government's working hour reform plan can have a negative impact on workers' health, and therefore it should be thoroughly reviewed and modified.

Randomised controlled trial of a behavioural intervention to reduce exposure to PM2.5 in patients with COPD.

BACKGROUND: Fine particulate matter (PM2.5) is a well-known risk factor for worse outcomes of chronic obstructive pulmonary disease (COPD). However, evidence-based guidance on effective personal behavioural strategies to minimise the effects of PM2.5 is limited. This study aimed to assess the effectiveness of a behavioural intervention in reducing PM2.5 exposure and improving clinical outcomes in patients with COPD. MATERIALS AND METHODS: Participants were 1:1 randomised, and the intervention group received a behavioural intervention consisting of five activities, while the control group received usual care. The participants were followed up for 9 months. The primary outcomes were differences in the score of St. George's Respiratory Questionnaire for patients with COPD (SGRQ-C) and COPD assessment test (CAT) from baseline. RESULTS: A total of 106 participants were enrolled and 102 completed the study. At the end of the study, the intervention group showed significant improvements in the primary outcomes compared to the control group, with a group difference of -5.9 in the reduction of total SGRQ-C (-3.4 vs. 2.5; p = 0.049) and -3.8 in the CAT score (-1.2 vs. 2.7; p = 0.001). Participants with good adherence to the intervention demonstrated a greater extent of improvement in CAT score and lower PM2.5 levels compared to those who had poor adherence or were in the control group. Regular checking of air quality forecasts was significantly associated with a reduction in CAT scores among all the intervention activities. CONCLUSION: Individual-level behavioural interventions can be an effective strategy for mitigating the health hazards associated with PM2.5. CLINICALTRIALS: gov Identifier: NCT04878367.

Occupational stress changes and new-onset depression among male Korean manufacturing workers.

Background: Studies on the association between occupational stress and depression have been frequently reported. However, the cross-sectional designs of studies limited insight into causal associations. In this study, we investigated the longitudinal association between occupational stress and new-onset depression among employees in a single manufacturing plant. Methods: The annual health checkup data of employees at a manufacturing plant in Korea were collected. A total of 1,837 male employees without depression who completed a health checkup during two consecutive years were included. Occupational stress was measured using a short form of the Korea Occupational Stress Scale (KOSS-SF), and depression was assessed using a Patient Health Questionnaire-2. The association between occupational stress change over the two years and newly developed depression was investigated using two logistic regression models. Results: Across all sub-factors of KOSS-SF, employees who reported increased occupational stress had a higher risk of new-onset depression. Newly developed depression was significantly associated with job demand (odds ratio [OR]: 4.34; 95% confidence interval [CI]: 2.37-7.96), job insecurity (OR: 3.21; 95% CI: 1.89-5.48), occupational climate (OR: 3.18; 95% CI: 1.91-5.31), lack of reward (OR: 2.28; 95% CI: 1.26-4.12), interpersonal conflict (OR: 2.14; 95% CI: 1.18-3.86), insufficient job control (OR: 1.93; 95% CI: 1.05-3.56), and the organizational system (OR: 1.84; 95% CI: 1.01-3.36). Conclusions: For every sub-factor of the KOSS-SF, occupational stress increase and persistent high stress were associated with the risk of developing new-onset depression. Among the seven sub-factors, job demand had the most significant effect. Our results show that occupational stress should be managed to promote employee mental healthcare.

The relationship between fatigue and sickness absence from work.

Background: Although many studies have been conducted on worker fatigue and sickness absence, the association between fatigue and sickness absence is unclear in Korean workers. This study was conducted to investigate the effect of worker fatigue on future sickness absence. Methods: The study was conducted on workers who received medical check-ups at a university hospital for two consecutive years (2014-2015). During check-ups in the first year, the Fatigue Severity Scale (FSS) was used to assess fatigue levels, and during check-ups in the second year, sickness absence was surveyed to determine whether they had been absent from work due to physical or mental illness during previous 12 months. The χ2 test was used to analyze relationships between sociodemographic and occupational characteristics, fatigue levels, and sickness absence. Odds ratios (ORs) were calculated by logistic regression analysis controlled for confounding factors. Results: A total of 12,250 workers were included in the study, and 396 (3.2%) workers experienced more than one day of sickness absence during the study period. Adjusted ORs for sickness absence were 3.35 (95% confidence interval [CI]: 2.64-4.28) in the moderate-fatigue group and 6.87 (95% CI: 4.93-9.57) in the high-fatigue group versus the low-fatigue group. For men in the moderate- and high-fatigue groups, adjusted ORs for sickness absence were 3.40 (95% CI: 2.58-4.48) and 8.94 (95% CI: 6.12-13.07), and for women in the moderate- and high-fatigue groups, adjusted ORs for sickness absence were 2.93 (95% CI: 1.68-5.10) and 3.71 (95% CI: 1.84-7.49), respectively. Conclusions: Worker fatigue is associated with sickness absence during the following 12 months, and this association appears to be stronger for men than women. These results support the notion that sickness absence can be reduced by evaluating and managing work-related fatigue.

Evaluation of Temporal Trends of Lead Exposure in Korean Workers Using Workplace Monitoring Data.

BACKGROUND: Lead, which is widely used in various industrial settings, is a major health hazard for manufacturing workers. Therefore, control of lead exposure has been implemented in an effort to prevent lead-related health problems. In this study, our aim was to evaluate temporal trends in occupational lead exposure in Korean lead workers using data from monitoring of workplace exposure. METHODS: A nationwide work environment monitoring database, data from a work environment monitoring institution, and data extracted from a review paper were utilized. Different versions of standard industrial classification codes were aligned with the 10th Korean Standard Industrial Classification, which is generally consistent with the 4th revision of the International Standard Industrial Classification. The multiple data sources were combined and temporal trends over the period from 1994-2021 were estimated. In addition, separate estimation of temporal trends in the storage battery manufacturing industry over the period from 1987-2021 was also performed. RESULTS: A total of 444,296 personal airborne lead measurements were used for the estimation process. The temporal trends in occupational exposure to lead declined by -6% annually over the study period. In particular, levels of lead exposure in the storage battery manufacturing industry showed a steeper decline of -12% annually. CONCLUSIONS: Findings of our study showed that occupational exposure to lead declined over the period from 1994 to 2021 in Korea. However, adverse effects of exposure to lead on health should be regarded with caution. The results will be useful in conduct of epidemiological studies examining lead-related effects on health.

Lifestyle practices that reduce seasonal PM2.5 exposure and their impact on COPD.

Particulate matter (PM) is a major air pollutant that has led to global health concerns and can cause and exacerbate chronic obstructive pulmonary disease (COPD). We asked patients with COPD to complete a detailed questionnaire about their lifestyle practices to reduce PM2.5 exposure and analyzed the relationship between ambient PM2.5 concentrations and lifestyle practices. We prospectively enrolled 104 COPD patients from four hospitals in different areas of Korea. They completed detailed questionnaires twice (at enrollment and the end of the study) and Internet of Things-based sensors were installed in their homes to continuously measure PM2.5 for 1 year. The relationship between PM2.5 concentrations, lifestyle practices, and COPD exacerbations were analyzed in each season. The PM2.5 concentration was higher outdoors than indoors in all seasons except summer, and the difference was largest in winter. The six lifestyle practices that significantly lowered the annual indoor PM2.5 concentration compared with the outdoors. The higher the economic status and educational level of patients, the lower the indoor PM2.5 concentration. Some lifestyle practices were associated with reduced small airway resistance, presented as R5-R20 determined by impulse oscillometry, and scores of the St. George's Respiratory Questionnaire. Some lifestyle practices are associated with reduced indoor PM2.5 concentrations and can even affect clinical outcomes, including small airway resistance and quality of life of COPD patients.

Toxic hepatitis after exposure to humidifier disinfectant: A case series report.

Health damage from humidifier disinfectants is an unprecedented environmental health disaster. Humidifier disinfectants were used broadly in Korea from 1994 to 2011. Most studies have focused on respiratory problems because of the exposure route and primary respiratory symptoms. This overlooks the previous research results that humidifier disinfectants could move to extrapulmonary organs and induce toxic effects. Thus, the objective of this study was to examine toxic hepatitis cases developed after inhaling humidifier disinfectant. We focused on the indications of toxic hepatitis in two pediatric cases and one female adult case. All patients were exposed to humidifier disinfectants in a residential space. These disinfectants all contained polyhexamethylene guanidine (PHMG). Rapid increases in blood hepatic enzyme levels were seen. Two patients were discharged after treatment. Death occurred in one patient who was diagnosed with fulminant hepatitis of unknown cause. This human case series study supports prior knowledge that hepatotoxicity can occur by inhaling humidifier disinfectant.

Particulate matter exposure during pregnancy increases risk of childhood asthma: modified by gender and NRF2 genotype.

BACKGROUND: Exposure to particulate matter (PM) has been known to develop asthma in children and the oxidative stress-related mechanisms are suggested. For the development of asthma, not only the exposure dose but also the critical window and the risk modifying factors should be evaluated. OBJECTIVE: We investigated whether prenatal exposure to PM10 increases the risk of childhood asthma and evaluated the modifying factors, such as gender and reactive oxidative stress-related gene. METHODS: A general population-based birth cohort, the Panel Study of Korean Children (PSKC), including 1572 mother-baby dyads was analyzed. Children were defined to have asthma at age 7 when a parent reported physician-diagnosed asthma. Exposure to PM10 during pregnancy was estimated by land-use regression models based on national monitoring system. TaqMan method was used for genotyping nuclear factor, erythroid 2-related factor, NRF2 (rs6726395). A logistic Bayesian distributed lag interaction model (BDLIM) was used to evaluate the associations between prenatal PM10 exposure and childhood asthma by gender and NRF2. RESULTS: Exposure to PM10 during pregnancy was associated with the development of asthma (aOR 1.03, 95% CI 1.001.06). Stratifying by gender and NRF2 genotype, exposure to PM10 during 26-28 weeks gestation increased the risk of childhood asthma, especially in boys with NRF2 GG genotype. CONCLUSIONS: A critical window for PM10 exposure on the development of childhood asthma was during 26-28 weeks of gestation, and this was modified by gender and NRF2 genotype.

The impact of ambient air pollution on lung function and respiratory symptoms in elite athletes.

BACKGROUND: Air pollution has become a significant public health concern. During exercise, many physiological factors are thought to increase the effects of air pollution. Air pollution most affects lung function and respiratory symptoms. We investigated the association between lung function, respiratory symptoms, and air pollutant concentration with meteorological factors in elite sports athletes. METHODS: A total of 59 elite sports athletes from the Korea National Sports University participated in this prospective, observational study from September 2019 to June 2020. At ten visits, lung function and respiratory symptoms were obtained after a training session. We measured six air pollutants, including SO2, CO, O3, NO2, PM10, and PM2.5, and two meteorological factors, including humidity and temperature. Air pollutants and meteorological factors were measured by two nearest depositories of the national air pollution information system in Korea. RESULTS: In a single-pollutant model, PM2.5, PM10, NO2, and CO were inversely associated with both FEV1 and FEV6, 10 µg/m3 in PM2.5 was associated with a 32.31 mL decrease in FEV1 and a 36.93 mL decrease in FEV6. Meanwhile, O3 and temperature had positive associations with both FEV1 (13.00 and 3.15 mL) and FEV6 (16.91 and 4.76 mL) and humidity with FEV6 (11.98 mL). In the multi-pollutant model at lag 0, FEV1 was associated negatively with O3 and NO2 (-50.68 and -6.87 mL) and positively with SO2 and temperature (65.76 and 8.08 mL). In the multi-pollutant model at lag 6, temperature was associated with FEV1 and FEV6 (6.01 and 8.89 mL). PM2.5, PM10, NO2, CO, and temperature were significantly associated with FEV1 and FEV6 through lag 0-6. CONCLUSIONS: Air pollutants and meteorological factors are associated with lung function and respiratory symptoms and have cumulative effects among elite athletes. In the multi-pollutant model, temperature has the most significant effect on lung function.

A Pilot Establishment of the Job-Exposure Matrix of Lead Using the Standard Process Code of Nationwide Exposure Databases in Korea.

Background: The purpose of this study is to construct a job-exposure matrix for lead that accounts for industry and work processes within industries using a nationwide exposure database. Methods: We used the work environment measurement data (WEMD) of lead monitored nationwide from 2015 to 2016. Industrial hygienists standardized the work process codes in the database to 37 standard process and extracted key index words for each process. A total of 37 standardized process codes were allocated to each measurement based on an automated key word search based on the degree of agreement between the measurement information and the standard process index. Summary statistics, including the arithmetic mean, geometric mean, and 95th percentile level (X95), was calculated according to industry, process, and industry process. Using statistical parameters of contrast and precision, we compared the similarity of exposure groups by industry, process, and industry process. Results: The exposure intensity of lead was estimated for 583 exposure groups combined with 128 industry and 35 process. The X95 value of the "casting" process of the "manufacture of basic precious and non-ferrous metals" industry was 53.29 µg/m3, exceeding the occupational exposure limit of 50 µg/m3. Regardless of the limitation of the minimum number of samples in the exposure group, higher contrast was observed when the exposure groups were by industry process than by industry or process. Conclusion: We evaluated the exposure intensities of lead by combination of industry and process. The results will be helpful in determining more accurate information regarding exposure in lead-related epidemiological studies.

Impacts of presenteeism on work-related injury absence and disease absence.

Background: Many studies have been conducted on presenteeism and absenteeism, but the relationship between presenteeism and absenteeism is unclear. This study was undertaken to investigate the effect of presenteeism on future absenteeism. Methods: This study was conducted on non-white collar workers that underwent general health examinations in 2014 and 2015. We asked subjects to fill out a questionnaire about their experiences of presenteeism for the past one year in 2014. In 2015, it was checked whether the same subjects had any experience of absence from work due to injury or disease during the past year. The χ2 test was used to analyze relationships between sociodemographic and occupational characteristics, presenteeism, and absence. Odds ratios (ORs) were calculated by logistic regression analysis controlled for confounding factors. Results: A total of 12,572 workers were included in the study. For workers who experienced presenteeism, the OR for injury absence was 2.705 (95% confidence interval [CI]: 2.044-3.581), and the OR for disease absence was 4.906 (95% CI: 3.996-6.024) after adjusting for sociodemographic and occupational confounding factors. For men that experienced presenteeism, the OR for injury absence was 3.035 (95% CI: 2.258-4.081), and the OR for disease absence was 5.508 (95% CI: 4.340-6.989). For women that experienced presenteeism, the OR for injury absence was 1.322 (95% CI: 0.577-3.028), which was not significant, and the OR for disease absence was 3.629 (95% CI: 2.405-5.475). Conclusions: This study suggests that presenteeism can influence future absenteeism. The effect of presenteeism may depend on cause of absence. Men who experienced presenteeism showed greater effects on injury and disease absence than women. For women, experience of presenteeism had a significant effect on disease absence but not on injury absence.

Development of Korean CARcinogen EXposure: Assessment of the Exposure Intensity of Carcinogens by Industry.

Background: Occupational cancer is a global health issue. The Korean CARcinogen EXposure (K-CAREX), a database of CARcinogen EXposure, was developed for the Korean labor force to estimate the number of workers exposed to carcinogens by industry. The present study aimed to estimate the intensity of exposure to carcinogens by industry, in order to supply complementary information about CARcinogen EXposure intensity to the K-CAREX. Methods: We used nationwide workplace monitoring data from 2014 to 2016 and selected target carcinogens based on the K-CAREX list. We computed the 95th percentile levels of measurements for each industry by carcinogens. Based on the 95th percentile level relative to the occupational exposure limit, we classified the CARcinogen EXposure intensity into five exposure ratings (1-5) for each industry. Results: The exposure ratings were estimated for 21 carcinogenic agents in each of the 228 minor industry groups. For example, 3,058 samples were measured for benzene in the manufacturing industry of basic chemicals. This industry was assigned a benzene exposure rating of 3. Conclusions: We evaluated the CARcinogen EXposure ratings across industries in Korean workers. The results will provide information on the exposure intensity to carcinogens for integration into the K-CAREX. Furthermore, it will aid in prioritizing control efforts and identifying industries of concern.

Case-only approach applied in environmental epidemiology: 2 examples of interaction effect using the US National Health and Nutrition Examination Survey (NHANES) datasets.

INTRODUCTION: By substituting the general 'susceptibility factor' concept for the conventional 'gene' concept in the case-only approach for gene-environment interaction, the case-only approach can also be used in environmental epidemiology. Under the independence between the susceptibility factor and environmental exposure, the case-only approach can provide a more precise estimate of an interaction effect. METHODS: Two analysis examples of the case-only approach in environmental epidemiology are provided using the 2015-2016 and 2017-2018 US National Health and Nutritional Examination Survey (NHANES): (i) the negative interaction effect between blood chromium level and glycohemoglobin level on albuminuria and (ii) the positive interaction effect between blood cobalt level and old age on albuminuria. The second part of the methods (theoretical backgrounds) summarized the logic and equations provided in previous studies about the case-only approach. RESULTS: (i) When a 1 µg/L difference of both blood chromium level (mcg/L) and a 1% difference in blood glycohemoglobin level coincide, the multiplicative interaction contrast ratio (ICRc/nc) was 0.72 (95% CI 0.35-1.60), with no statistical significance. However, when only the cases were analyzed, the case-only ICR (ICRCO) was 0.59 (95% CI 0.28-0.95), with a statistical significance (a negative interaction effect). (ii) When a 1 µg/L difference of both blood cobalt levels and a 1-year difference in age coincide, the multiplicative interaction contrast ratio (ICRc/nc) was 1.13 (95% CI 0.99-1.37), with no statistical significance. However, when only the cases were analyzed, the case-only ICR (ICRCO) was 1.21 (95% CI 1.06-1.51), with a statistical significance (a positive interaction effect). DISCUSSION: The discussion suggested the theoretical background and previous literature about the possible protective interaction effect between blood chromium levels and blood glycohemoglobin levels on the incidence of albuminuria and the possible aggravating interaction effect between blood cobalt levels and increasing ages on the incidence of albuminuria. If the independence assumption between a susceptibility factor and environmental exposure in a study with cases and non-cases is kept, the case-only approach can provide a more precise interaction effect estimate than conventional approaches with both cases and non-cases.