The Risk of Major Depressive Disorder Due to Cataracts among the Korean Elderly Population: Results from the Korea National Health and Nutrition Examination Survey (KNHANES) in 2016 and 2018.

Cataracts and major depressive disorder (MDD) both have high prevalence, representing for major health burdens globally. In this study, we examined the risk of MDD due to cataracts. Data from the 2016 to 2018 Korea National Health and Nutrition Examination Survey (KNHANES) were used, including 4122 participants. Logistic regression analysis was performed to evaluate the odds ratio for MDD in association with cataracts. Controlled variables were age, gender, smoking, dyslipidemia and mobility. Subgroup analysis was performed with stratification by gender. The results reveal that cataracts are significantly correlated with MDD. Elderly people with cataracts were found to be more likely to develop MDD compared to those without cataracts (adjusted odds ratio: 1.654; 95% CI = 1.197-2.286). In subgroup analysis, men (adjusted odds ratio: 2.631; 95% CI = 1.247-5.551) were found to be more likely to develop MDD than women (adjusted odds ratio: 1.510; 95% CI = 1.061-2.150). Cataracts may be a risk factor for MDD in the elderly, especially among the male population.

Impact of Wildfire Smoke Exposure on Health in Korea.

PURPOSE: The characteristic topography and climate often affect the occurrence of large-scale wildfires in the Eastern Gangwon-do region of Korea. However, there are no studies on the health effects of these wildfires in Korea. This study aimed to analyze the differences in medical use between a wildfire-affected area and an adjacent non-affected area before and after a wildfire in 2019 in Gangwon-do, Korea. MATERIALS AND METHODS: We used medical usage data from the Korean National Health Insurance Corporation. Rates of medical use were determined for citizens of a wildfire-affected area in the Eastern Yeongdong region and a non-affected area in the Western Yeongseo region. Logistic regression analysis was performed considering an increase in medical use per individual as a dependent variable; age, sex, income, smoking, drinking, and exercise were included as confounding variables. RESULTS: The odds ratio for medical use in Yeongdong region increased significantly after 3 days, 3 months, and 1 year after a fire occurred, compared with Yeongseo region. CONCLUSION: The results of this study confirmed that the use of medical care increased for residents of a wildfire-affected area, compared with those of an adjacent non-affected area. This is the first study on the relationship between wildfires and inpatient medical use in Korea.

Biological monitoring for exposure assessment of volatile organic compounds by Korean firefighters at the fire site.

The VOCs and metabolites in urine for exposed VOCs were evaluated for firefighters who participated in the actual fire fighting to determine whether firefighters were exposed to hazardous chemicals, which is the basic data on cancer risk of firefighters. When the fire extinguishing time is long, the concentration of benzene, PHEMA, and toluene among VOCs and metabolites in the case of fire suppression, rescue, and fire investigation work, which is estimated that the exposure of hazardous substances generated from the fire site at the time of fire suppression was large, significantly increased. In the case where the number of urination is 2 or less, the concentration of TZCA, toluene, and benzene among VOCs and metabolites was significantly increased compared to the number of urinating more than 2 times. In the concentration of VOCs and metabolites in urine corrected with creatinine, the concentrations of toluene and PHEMA in urine were significantly higher. The concentration of PHEMA in urine was higher in the group who participated in the fire suppression for more than 11 hours (long time) than the group who participated in the fire suppression for a short time.

The Interaction of Inflammatory Markers and Alcohol-Use on Cognitive Function in Korean Male Firefighters.

OBJECTIVE: Cognitive functions have been shown to become impaired due to alcoholism. Recently, neuroinflammation gained attention for playing a role in the neurotoxic effect of alcohol. However, there is limited data on the relationship between alcohol and cognitive function, based on the mechanism of inflammation. This study examined whether the interaction between alcohol use and pro-inflammatory biomarkers is related to cognitive function in Korean male firefighters. METHODS: A total of 474 firefighters were assessed for alcohol-related problems using CAGE, cognitive functions, and pro-inflammatory biomarkers (CRP, IL-6, TNF-α). Sequential multiple regression analyses were conducted to determine if inflammatory markers moderate the relationship between alcohol use and cognitive function. RESULTS: Only a decreased attentional function was associated with the interaction of alcohol use and inflammatory markers, after controlling for age, sex, body mass index, lipid profiles, smoking, depression, fatigue, self-reported hypertension, diabetes, and musculoskeletal problems. CONCLUSION: This study revealed that the interaction between alcohol use and inflammation is related to attentional function in Korean male firefighters. Additionally, this cross-sectional study suggests that diminishing attention, related to alcohol use, may be based on the mechanism of inflammation.

Validation of urinary 1,2-dichloropropane concentration as a biological exposure index for workers exposed to 1,2-dichloropropane.

BACKGROUND: The International Agency for Research on Cancer classified 1,2-dichloropropane (1,2-DCP) as a human carcinogen in 2016. It is necessary to establish a health monitoring system for workers exposed to 1,2-DCP. We investigated the correlation between 1,2-DCP concentration in air and urine to determine whether it is appropriate to measure 1,2-DCP in urine as a biological exposure index (BEI). METHODS: Twenty-seven workers from 3 manufacturing industries handling 1,2-DCP participated in this study. Airborne 1,2-DCP was collected by personal air. Urine samples were collected at the end of work and analyzed using gas chromatography-mass spectrometry. Correlation analysis and simple regression analysis were performed to investigate the relationship between 1,2-DCP concentration in urine and air. RESULTS: Pearson correlation coefficients between total 1,2-DCP in air and urine (uncorrected, creatinine-corrected) were 0.720 and 0.819, respectively. For urine samples analyzed within 2 weeks, the Spearman's rho of 1,2-DCP concentration in urine (uncorrected and creatinine-corrected) was 0.906 and 0.836, respectively. Simple regression analysis of 1,2-DCP in air and urinary 1,2-DCP concentrations within 2 weeks, which showed the highest correlation, revealed that the coefficient of determination of 1,2-DCP concentration in urine (uncorrected and creatinine-corrected) was 0.801 and 0.784, respectively. CONCLUSIONS: As a BEI for workers exposed to 1,2-DCP, urinary 1,2-DCP without creatinine correction better reflects the exposure levels of 1,2-DCP in air.

Risk factors including night shift work of colorectal polyp.

BACKGROUND: The destruction of circadian rhythms by night shift work affects major circadian genes, which are known to play a role in advancing or killing the cell cycle through tumor suppressor genes. To find out whether night shift work affects the incidence of colorectal cancer, which was found to be associated with long-term night shift work in previous studies, we surveyed effect of night shift work on colorectal polyps that have a higher incidence than colorectal cancer and can progress to colorectal cancer. METHODS: To examine the correlation between rotating night shifts and colorectal polyps, a survey was conducted with 299 men aged 40-60 years from two university hospitals. We examined lifestyle, work history, work patterns, and colonoscopy results. The differences in prevalence among the groups was compared, and prevalence ratio (PR) was calculated via generalized linear modeling. RESULTS: The prevalence of colorectal polyps in night shift and non-shift workers were 53.0% and 33.5%, respectively. After adjusting for age, smoking status, dietary habits, family history of colorectal cancer, obesity, job type, night shift work (PR: 1.13, 95% CI: 1.02-1.25) was a risk factor of colorectal polyps. CONCLUSIONS: The risk of colorectal polyps was greater in night shift workers than non-shift workers. Also risk of colorectal polyp was higher in older group. Our study investigated colorectal polyp instead of colorectal cancer and lacks information about types and gene mutations of colorectal polyps. Further study is needed to clarify effect of night shift work on development of colorectal cancer.

Association between shift work and biological factors including FGF-23, klotho, and serum 25-(OH) vitamin D3 among Korean firefighters: a cross-sectional study.

STUDY OBJECTIVES: Shift work is known to be detrimental to an individual's health as it disrupts the circadian rhythm and is a risk factor for cancer. It has been reported that elevated fibroblast growth factor (FGF)-23, increased serum soluble α-klotho, and decreased vitamin D3 are associated with cancer progression. We studied the relationship between shift work and the levels of FGF-23, α-klotho, and vitamin D3 amongst firefighters, as they work in long shifts outside the traditional daytime schedule. METHODS: The study consisted of 450 participants who were firefighters. We measured FGF-23, α-klotho, and vitamin D3 levels in their blood and a set of questionnaires were given to the participants to evaluate their health habits. After determining and adjusting for potential confounding factors, we compared the levels of FGF-23, α-klotho, and serum vitamin D3 by job and shift types. RESULTS: FGF-23 and α-klotho levels were significantly higher in shift workers than traditional day workers, and in 3-day cycle shift workers than workers with another shift schedule. When the levels of these substances were compared based on different types of jobs, firefighters had a lower level of vitamin D3. We conclude that shift work is positively correlated with the levels of FGF-23 and α-klotho. CONCLUSIONS: Levels of FGF-23 and α-klotho were linked to shift work and job types. Although vitamin levels did not differ by shift types, vitamin D3 levels were lower in firefighters. These findings suggest that high levels of FGF-23 and α-klotho are potential risk factors for cancer among firefighters.

DNA methylation among firefighters.

Firefighters are exposed to carcinogens and have elevated cancer rates. We hypothesized that occupational exposures in firefighters would lead to DNA methylation changes associated with activation of cancer pathways and increased cancer risk. To address this hypothesis, we collected peripheral blood samples from 45 incumbent and 41 new recruit non-smoking male firefighters and analyzed the samples for DNA methylation using an Illumina Methylation EPIC 850k chip. Adjusting for age and ethnicity, we performed: 1) genome-wide differential methylation analysis; 2) genome-wide prediction for firefighter status (incumbent or new recruit) and years of service; and 3) Ingenuity Pathway Analysis (IPA). Four CpGs, including three in the YIPF6, MPST, and PCED1B genes, demonstrated above 1.5-fold statistically significant differential methylation after Bonferroni correction. Genome-wide methylation predicted with high accuracy incumbent and new recruit status as well as years of service among incumbent firefighters. Using IPA, the top pathways with more than 5 gene members annotated from differentially methylated probes included Sirtuin signaling pathway, p53 signaling, and 5' AMP-activated protein kinase (AMPK) signaling. These DNA methylation findings suggest potential cellular mechanisms associated with increased cancer risk in firefighters.

Acute toxic encephalopathy induced by occupational exposure to 1,2-dichloropropane.

1,2-Dichloropropane (1,2-DCP) is used widely in Korea as a substitute for trichloroethylene or methylene chloride. Some companies mistakenly consider that 1,2-DCP is an eco-friendly detergent because its use is not regulated, but 1,2-DCP is known to inhibit the central nervous system in animals; a few cases of accidental exposure have been reported in humans. We present a case of acute encephalopathy caused by exposure to 1,2-DCP. A 41 yr-old male presented with dizziness, headache, and diplopia after exposure to the detergent without protective equipment. Brain magnetic resonance imaging suggested metabolic encephalopathy, but the patient had no thiamine deficiency and no other metabolic disorder. As the symptoms had commenced after exposure to a large amount of solvent while skimming rust from the surface, and as the symptoms were more severe during the work week, improved on weekends, and disappeared after solvent exposure ceased, the toxic encephalopathy was likely induced by inhalation of the detergent.

The characteristics of asbestos-related disease claims made to the Korea Workers' Compensation and Welfare Service (KCOMWEL) from 2011 to 2015.

BACKGROUND: This study aimed to enhance understanding of the epidemiologic characteristics of asbestos-related diseases, and to provide information that could inform policy-making aimed at prevention and compensation for occupational asbestos exposure, through analyzing asbestos-related occupational disease claims to Korea Workers' Compensation and Welfare Service from 2011 to 2015. METHODS: We analyzed 113 workers who filed medical care claims or survivor benefits for asbestos exposure and occupational-related disease from 2011 to 2015. Among these claims, we selected approved workers' compensation claims relating to malignant mesothelioma and lung cancer, and analyzed the general characteristics, exposure characteristics, pathological characteristics, and occupation and industry distribution. RESULTS: Malignant mesothelioma and lung cancer occurred predominantly in males at 89.7 and 94%, respectively. The mean age at the time of diagnosis for malignant mesothelioma and lung cancer was 59.5 and 59.7 years, respectively, while the latency period for malignant mesothelioma and lung cancer was 34.1 and 33.1 years, respectively. The companies involving exposed workers were most commonly situated within the Busan-Ulsan-Gyeongnam region. Histology results for lung cancer indicated adenocarcinoma as the most common form, accounting for approximately one half of all claims, followed by squamous cell carcinoma, and small cell lung cancer. The most common occupation type was construction in respect of malignant mesothelioma, and shipbuilding in respect of lung cancer. CONCLUSIONS: Considering the long latency period of asbestos and that the peak period of asbestos use in Korea was throughout the mid-1990s, damage due to asbestos-related diseases is expected to show a continued long-term increase. Few studies providing an epidemiologic analysis of asbestos-related diseases are available; therefore, this study may provide baseline data to assist in predicting and preparing for future harm due to asbestos exposure. TRIAL REGISTRATION: DUIH 2018-02-004-001. Registered 28 Februrary 2018.

Comparison of a 10-Year Cumulative Age-Standardized Incidence Rate of Lung Cancer among Metropolitan Cities in Korea (During the 2000⁻2009 Period): Review of Occupational and Environmental Hazards Associated with Lung Cancer.

In Korea, lung cancer is a common cancer, and has the highest mortality rate in both males and females. Approximately 80% of lung cancer is due to smoking, and the remaining cases are known to be due to genetic factors, history of respiratory disease, infection, diet, and occupational and environmental factors. Since the occupational and environmental hazards may differ from region to region, the lung cancer risk may differ too. To identify this, we selected seven metropolitan cities, and compared occupational and environmental hazards. Furthermore, we calculated smoking rate adjusted standardized rate ratio (ratio of 10-year cumulative age-standardized incidence rate of lung cancer during the 2000⁻2009 period at target region versus reference region) to compare the regional lung cancer risk. The result showed that the emissions and concentrations of air pollutant were higher in high-risk regions, and the risk of lung cancer was significantly elevated in such area. In this study, we simultaneously consider the cumulative incidence, age-standardization and smoking rate adjustment. Therefore, we can conclude that the validity of the finding of this study is higher than that of past studies. In conclusion, the occupational and environmental hazards have an effect on lung cancer.

MicroRNA Changes in Firefighters.

OBJECTIVES: Firefighters have elevated cancer incidence and mortality rates. MicroRNAs play prominent roles in carcinogenesis, but have not been previously evaluated in firefighters. METHODS: Blood from 52 incumbent and 45 new recruit nonsmoking firefighters was analyzed for microRNA expression, and the results adjusted for age, obesity, ethnicity, and multiple comparisons. RESULTS: Nine microRNAs were identified with at least a 1.5-fold significant difference between groups. All six microRNAs with decreased expression in incumbent firefighters have been reported to have tumor suppressor activity or are associated with cancer survival, and two of the three microRNAs with increased expression in incumbent firefighters have activities consistent with cancer promotion, with the remaining microRNA associated with neurological disease. CONCLUSION: Incumbent firefighters showed differential microRNA expression compared with new recruits, providing potential mechanisms for increased cancer risk in firefighters.

Mortality due to malignant and non-malignant diseases in Korean professional emergency responders.

OBJECTIVE: This study was conducted to estimate the cause-specific mortality in male emergency responders (ER), compare with that of Korean men. Mortality was also compared between more experienced firefighters (i.e., firefighters employed ≥ 20 years and firefighters employed ≥ 10 to < 20 years) and less experienced firefighters and non-firefighters (i.e., firefighters employed < 10 years and non-firefighters) to investigate associations between mortality and exposure to occupational hazards. METHODS: The cohort was comprised of 33,442 males who were employed as ERs between 1980 and 2007 and not deceased as of 1991. Work history was merged with the death registry from the National Statistical Office of Korea to follow-up on mortality between 1992 and 2007. Standardized mortality ratios (SMR) for ERs were calculated in reference to the Korean male population. Adjusted relative risks (ARRs) of mortalities for firefighters employed ≥ 20 years and ≥ 10 years to < 20 years were calculated in reference to non-firefighters and firefighters employed < 10 years. RESULTS: Overall (SMR = 0.43, 95%CI = 0.39-0.47) and some kinds of cause-specific mortalities were significantly lower among ERs compared with the Korean male population. No significant increase in mortality was observed across the major ICD-10 classifications among ERs. Mortality due to exposure to smoke, fire, and flames (SMR = 3.11, 95% CI = 1.87-4.85), however, was significantly increased among ERs. All-cause mortality (ARR = 1.46, 95% CI=1.13-1.89), overall cancer mortality (ARR = 1.54, 95% CI = 1.02-2.31) and mortality of external injury, poisoning and external causes (ARR = 3.13, 95% CI = 1.80-5.46) were significantly increased among firefighters employed ≥ 20 years compared to those of non-firefighters and firefighters employed < 10 years. CONCLUSIONS: An increase in mortality due to all cancer and external injury, poisoning, and external causes in firefighters employed ≥ 20 years compared with non-firefighters and firefighters employed < 10 years suggests occupational exposure.

Evidence that cognitive deficit in children is associated not only with iron deficiency, but also with blood lead concentration: a preliminary study.

OBJECTIVE: To investigate whether blood lead concentrations are elevated in iron-deficient children, and to examine the association between iron deficiency and/or elevated blood lead concentration and cognitive deficits in children. METHOD: The present study is a component of the Mothers' and Children's Environmental Health (MOCEH) study, a multi-center birth cohort project in Korea that began in 2006. The study cohort consisted of 194 children who underwent testing of blood lead and serum C-reactive proteins (CRPs) and ferritin concentrations, and the Korean version of the Wechsler Preschool and Primary Scale of Intelligence, revised edition (WPPSI-R), at 60 months of age. In addition, the mothers' blood lead concentrations during pregnancy were included in the analyses. Multivariate linear regression analysis was performed to analyze the correlation between high blood lead and low serum ferritin concentrations, after adjustment for covariates, in children, as well as to analyze the association of verbal IQ with serum ferritin and blood lead concentrations. RESULTS: Lead and ferritin concentrations were inversely and significantly associated in children after adjustment for covariates. Moreover, both concentrations were associated with verbal IQ, after adjustment for covariates, and each was associated with cognitive deficits after adjustment for the other. Sobel test statistics showed that blood lead concentration was a significant partial mediator for the relationship between iron deficiency and verbal IQ. CONCLUSION: Due to the results discussed in the present study, cognitive deficit in children seems to be associated not only with iron deficiency, but also with blood lead concentration.

Performance IQ in children is associated with blood cadmium concentration in early pregnancy.

OBJECTIVE: To investigate whether performance IQ in children is associated with maternal blood cadmium concentration in early pregnancy. METHOD: The present study is a component of the Mothers' and Children's Environmental Health (MOCEH) study, a multi-center birth cohort project in Korea that began in 2006. The study cohort consisted of 119 children whose mothers underwent testing of blood cadmium during early pregnancy. All children were evaluated using the Korean version of the Wechsler Preschool and Primary Scale of Intelligence, revised edition (WPPSI-R), at 60 months of age. Multivariate linear regression analysis was performed to analyze the correlation between IQ in children and maternal blood cadmium concentration in early pregnancy, after adjustment for covariates. RESULTS: Maternal blood cadmium concentration during early pregnancy was inversely associated with performance IQ, after adjustment for covariates such as sex, educational levels of both parents, family income, and maternal BMI. Maternal blood cadmium concentration, however, was not associated with cognitive IQ. CONCLUSION: Performance IQ in children is associated with maternal blood cadmium concentration in early pregnancy.

Epidemiologic characteristics of compensated occupational lung cancers among Korean workers.

An understanding of the characteristics of occupational lung cancer is important to establish policies that prevent carcinogen exposure and to compensate workers exposed to lung carcinogens. This study analyzed the characteristics of occupational lung cancers in workers who were compensated under the Industrial Accident Compensation Insurance Law between 1994 and 2011. A total of 179 occupational lung cancers were compensated. The main carcinogenic exposure was asbestos, followed by crystalline silica and hexavalent chromium. The mean exposure duration and latency were 19.8 and 23.2 yr. The most common industry was manufacturing, followed by construction and transportation. The most common occupation was maintenance and repair, followed by foundry work, welding, painting, and spinning or weaving. Although asbestos was predominant carcinogen, the proportion of these cases was relatively low compared to other developed countries. Proper surveillance system is needed to monitor occupational lung cancer and improve prevention measures.

Association between prenatal exposure to cadmium and atopic dermatitis in infancy.

Our objective was to evaluate the relationship between intrauterine exposure to cadmium and the presence of atopic dermatitis in infants 6 months of age, adjusted for covariates including exposure to other heavy metals. The present research is a component of the Mothers' and Children's Environmental Health (MOCEH) study, a multi-center birth cohort project conducted in Korea. Study subjects were restricted to pregnant women in whom cadmium and lead levels were measured at delivery and whose infants were assessed for the presence of atopic disease at 6 months of age. The odds ratio (OR) for the presence of atopic dermatitis in 6-month-old infants whose cord blood had elevated cadmium levels, after adjustment for other covariates, was 2.350 (95% CI, 1.126-4.906). The OR for the presence of atopic dermatitis in infants whose cord blood had elevated lead levels was not significant. In the present study, the cord blood cadmium level was significantly associated with the presence of atopic dermatitis in 6-month-old infants; this was not true of the cord blood lead level. To the best of our knowledge, this is the first prospective study to show a relationship between prenatal exposure to cadmium and atopic dermatitis in infancy.

Cancer morbidity of professional emergency responders in Korea.

BACKGROUND: Many professional emergency responders (ERs) who belong to the Korean National Emergency Management Agency (NEMA) have been cross-trained and serve multiple roles. As such, firefighters and other ERs in Korea are exposed to similar occupational hazards. This study was conducted to estimate cancer morbidity in male ERs and compare that with Korean men. METHODS: The cohort was comprised of 33,416 male ERs working between 1980 and 2007, who were alive on December 31, 1995. Work histories were merged with the Korea National Central Cancer Registry (KNCCR) to assess cancer morbidity between 1996 and 2007. Standardized incidence ratios (SIRs) with reference to Korean men were analyzed. RESULTS: SIRs with reference to national cancer rates were not significantly decreased for overall cancer (SIR = 0.97, 95% CI = 0.90-1.08) in all ERs. However, colorectal (SIR = 1.35, 95% CI = 1.07-1.67), kidney (SIR = 1.59, 95% CI = 1.00-2.41), and bladder (SIR = 1.77, 95% CI = 1.08-2.73) cancer, and non-Hodgkin's lymphoma (SIR = 1.81, 95% CI = 1.12-2.76) morbidities were significantly increased among all ERs. In firefighters, significantly increased cancer types were as same as those of all ERs. In non-firefighter ERs, colorectal (SIR = 2.51, 95% CI = 1.20-4.61) and bone and articular cartilage cancers (SIR = 9.53, 95% CI = 1.07-34.41) were significantly higher than those of Korean men. CONCLUSIONS: Korean firefighters showed excess morbidity in several cancer types, including colorectal and urologic cancers, and non-Hodgkin's lymphoma, demonstrating similar trends to previous studies for firefighters conducted in other countries. Increased incidence in these cancer types suggests occupational exposure to carcinogens and shift work.

Comparison of cancer incidence between production and office workers at a shipyard in Korea: a retrospective cohort study from 1992 to 2005.

BACKGROUND: Cancer is a major concern in shipbuilding. Since 1970s, shipbuilding and repair has been a strategic industry in Korea, which has become currently the world's largest shipbuilding country. The aim of this study is to investigate the cancer incidence in shipyard workers in Korea. METHODS: The cohort comprised 30,288 male employees (20,647 production workers and 9,641 office workers) ever employed between 1992 and 2005 in a shipyard in Korea. The authors compared the cancer incidence between the groups using the participants' hospital medical records and data received from Korea National Cancer Incidence Database and Korean National Statistical Office. RESULTS: The total number of cancers was 135 among office workers and 519 among production workers in the shipyard. The age-standardized cancer rates among office and production workers were 136.2 and 179.7 per 100,000 person-years, respectively. The standardized rate ratios for stomach cancer, liver cancer, and lung cancer in production workers compared with office workers were 1.67 (95% CI: 1.12-2.49), 2.13 (95% CI: 1.37-3.36), and 3.71 (95% CI: 1.68-8.19), respectively. CONCLUSIONS: The observed increase in stomach, liver, and lung cancers among production workers suggests that some occupational factors in the shipyard might have contributed to the increased cancer risk. Further study is needed to clarify the risk of those cancers and to identify the specific factors involved.