Suicide mortality following the implementation of tobacco packaging and pricing policies in Korea: an interrupted time-series analysis.

BACKGROUND: To prevent tobacco use in Korea, the national quitline number was added to tobacco packages in December 2012, tobacco prices were raised by 80% in January 2015, and graphic health warning labels were placed on tobacco packages in December 2016. This study evaluated the association of these tobacco packaging and pricing policies with suicide mortality in Korea. METHODS: Monthly mortality from suicide was obtained from Cause-of-Death Statistics in Korea from December 2007 to December 2019. Interrupted time-series analysis was performed using segmented Poisson regression models. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated adjusted for suicide prevention strategies. RESULTS: Suicide mortality was 20 per 1,000,000 in December 2007 and showed a downward trend over the study period. After the implementation of tobacco packaging and pricing policies, suicide mortality immediately declined by - 0.09 percent points (95% CI = - 0.19 to 0.01; P > 0.05) for the national quitline number, - 0.22 percent points (95% CI = - 0.35 to - 0.09; P < 0.01) for tobacco prices, and - 0.30 percent points (95% CI = - 0.49 to - 0.11; P < 0.01) for graphic health warning labels. The corresponding RRs for these post-implementation changes compared with the pre-implementation level were 0.91 (95% CI = 0.83 to 1.00), 0.80 (95% CI = 0.70 to 0.91), and 0.74 (95% CI = 0.61 to 0.90), respectively. Significant associations between tobacco control policies and suicide mortality were observed even when stratified by sex and region. CONCLUSIONS: The findings of this study provide new evidence for an association between tobacco control policies and deaths by suicide. An array of effective tobacco control policies should be considered for prevention programs targeting suicide.

Exposure to earthquakes and development of ischemic heart disease.

BACKGROUND: The evidence regarding the effect of earthquake exposure on the development of cardiovascular diseases is limited. This study evaluated the association between the 2016 Gyeongju earthquake, which had a magnitude of 5.8, and over 600 subsequent aftershocks occurring within a year in Korea, with the development of ischemic heart disease (IHD) among residents of Gyeongju. METHODS: Ten years (2010-2019) of medical records from a randomly selected cohort of residents (n = 540,858) in Gyeongju and 3 control cities were acquired from the national health insurance service. Employing difference-in-difference and meta-analyses, the risks of IHD development of Gyeongju residents before (reference: Sep 2014 to Aug 2015; period 1: Sep 2015 to Aug 2016) and after (period 2: Sep 2016 to Aug 2017; period 3: Sep 2017 to Aug 2018; period 4: Sep 2018 to Aug 2019) the earthquake were estimated. RESULTS: The monthly average incidence of IHD in Gyeongju was 39.5 persons (per 1,000,000) for reference period and 38.4 persons for period 1. However, the number increased to 58.5 persons in period 2, and 49.8 persons in period 3, following the earthquake. The relative risk (RR) [with a 95% confidence interval] of developing IHD among Gyeongju residents increased by 1.58 times (1.43, 1.73) in period 2, 1.33 times (1.21, 1.46) in period 3, and 1.15 times (1.04, 1.27) in period 4, in comparison to both the control cities and the pre-earthquake reference period. The increase in RR was particularly noticeable among women, adults aged 25-44, and individuals with lower incomes. CONCLUSIONS: The major earthquake in Korea was associated with an increase in the development of IHD among local residents. Individuals exposed to earthquakes may benefit from cardiovascular health surveillance.

Impact of the Early COVID-19 Pandemic on Emergency Department Visits of Adult Cancer Patients With Fever or Respiratory Symptoms: A Korean Nationwide Population-Based Study, 2016-2020.

BACKGROUND: We performed a nationwide analysis to evaluate the impact of the early coronavirus disease 2019 (COVID-19) pandemic on emergency department (ED) visits by adult cancer patients having COVID-like symptoms. METHODS: We analyzed the National Emergency Department Information System (NEDIS) data on ED visits by adult cancer patients who presented with chief complaints of fever or respiratory symptoms (FRS) indicative of COVID-19, from 2016 to 2020. An interrupted time series analysis with a quasi-Poisson regression model was performed, adjusting for seasonality and time, to evaluate whether underlying trends for monthly ED visits and the in-hospital mortality rate (%) per month changed with the pandemic among these patients. We also estimated the adjusted odds ratio (aOR) of in-hospital deaths among cancer patients using multivariable logistic regression analysis. RESULTS: ED visits by cancer patients with FRS decreased during the COVID-19 pandemic (relative risk [RR] with 95% confidence interval [CI]: slope change, 0.99 [0.98-1.00] and step change, 0.84 [0.76-0.92]). However, the in-hospital mortality rate (%) for these patients was increased (slope change, 1.14 [1.04-1.25] and step change, 0.99 [0.98-1.01]). Factors such as urgent triage status, ambulance use, and treatment in hospitals with fewer than 300 staffed beds significantly contributed to increased aOR of in-hospital deaths during the COVID-19 pandemic compared to the pre-pandemic period. CONCLUSION: Further studies are needed to highlight the importance of ED service preparation in planning and managing resources for cancer patients during future pandemics.

Impact of the early phase of the COVID-19 pandemic on emergency department-to-intensive care unit admissions in Korea: an interrupted time-series analysis.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic resulted in significant disruptions to critical care systems globally. However, research on the impact of the COVID-19 pandemic on intensive care unit (ICU) admissions via the emergency department (ED) is limited. Therefore, this study evaluated the changes in the number of ED-to-ICU admissions and clinical outcomes in the periods before and during the pandemic. METHODS: We identified all adult patients admitted to the ICU through level 1 or 2 EDs in Korea between February 2018 and January 2021. February 2020 was considered the onset point of the COVID-19 pandemic. The monthly changes in the number of ED-to-ICU admissions and the in-hospital mortality rates before and during the COVID-19 pandemic were evaluated using interrupted time-series analysis. RESULTS: Among the 555,793 adult ED-to-ICU admissions, the number of ED-to-ICU admissions during the pandemic decreased compared to that before the pandemic (step change, 0.916; 95% confidence interval [CI] 0.869-0.966], although the trend did not attain statistical significance (slope change, 0.997; 95% CI 0.991-1.003). The proportion of patients who arrived by emergency medical services, those transferred from other hospitals, and those with injuries declined significantly among the number of ED-to-ICU admissions during the pandemic. The proportion of in-hospital deaths significantly increased during the pandemic (step change, 1.054; 95% CI 1.003-1.108); however, the trend did not attain statistical significance (slope change, 1.001; 95% CI 0.996-1.007). Mortality rates in patients with an ED length of stay of ≥ 6 h until admission to the ICU rose abruptly following the onset of the pandemic (step change, 1.169; 95% CI 1.021-1.339). CONCLUSIONS: The COVID-19 pandemic significantly affected ED-to-ICU admission and in-hospital mortality rates in Korea. This study's findings have important implications for healthcare providers and policymakers planning the management of future outbreaks of infectious diseases. Strategies are needed to address the challenges posed by pandemics and improve the outcomes in critically ill patients.

Experimental study of endurance characteristics of Al-doped HfO2ferroelectric capacitor.

In this work, the endurance characteristics of Al-doped HfO2(HAO)-based metal-ferroelectric-metal (MFM) capacitors (which were annealed at 1000 °C) with various doping concentrations were investigated. The doping concentration was optimized for the high annealing temperature (1000 °C) process. To investigate the impact of cycling pulses on the endurance characteristics of HAO-based MFM capacitor, the rise/fall time (tr/f) and hold time (th) for the cycling pulses were varied. Moreover, by adopting the recoverable fatigue process, the endurance characteristics under repetitive wake-up/fatigue processes were studied. The HAO capacitors achieved the remnant polarization (2Pr) of 23.767µC cm-2at pristine state under the high annealing temperature. Furthermore, it was demonstrated that the endurance characteristics (∼108cycles) of the HAO capacitors were comparable to them of other HfO2-based ferroelectric capacitors. Lastly but not least, it turned out that the amount of oxygen and oxygen vacancies in the HAO thin film was dependent of doping concentrations for the film. The impact of oxygen and oxygen vacancies was quantitatively analyzed, in detail, with TEM, XPS and GIXRD analysis.

Association of long-term exposure to PM2.5 and survival following ischemic heart disease.

BACKGROUND: Numerous studies have suggested that long-term exposure to particulate matter ≤2.5 µm (PM2.5) may cause cardiovascular morbidity and mortality. However, susceptibility among those with a history of ischemic heart disease is less clearly understood. We aimed to evaluate whether long-term PM2.5 exposure is related to mortality among patients with ischemic heart disease. METHODS: We followed up 306,418 patients hospitalized with ischemic heart disease in seven major cities in South Korea between 2008 and 2016 using the National Health Insurance Database. We linked the modeled PM2.5 data corresponding to each patient's administrative districts and estimated hazard ratios (HRs) of cause-specific mortality associated with the long-term exposure to PM2.5 in time-varying Cox proportional hazard models after adjusting for individual- and area-level characteristics. We also estimated HRs by sex, age group (65-74 vs. ≥75 years), and household income. RESULTS: Of the patients with ischemic heart disease, mean age at the discharge was 76.8 years, and 105,913 died during a mean follow-up duration of 21.4 months. The HR of all-cause mortality was 1.10 [95% confidence intervals (CI): 1.07, 1.14] per 10 µg/m3 increase in a 12-month moving average PM2.5. The HRs of cardiovascular, stroke, and ischemic heart disease were 1.17 (95% CI: 1.11, 1.24), 1.17 (95% CI: 1.06, 1.30), and 1.25 (95% CI: 1.15, 1.35), respectively. The subgroup analyses showed that participants aged 65-74 years were more susceptible to adverse effects of PM2.5 exposure. We did not observe any differences in the risk by sex and household income. CONCLUSION: Mortality from all-cause and cardiovascular disease following hospitalization due to ischemic heart disease was higher among individuals with greater PM2.5 exposure in seven major cities in South Korea. The result supports the association of long-term exposure to air pollution with poor prognosis among patients with ischemic heart disease.

Excess mortality during the Coronavirus disease pandemic in Korea.

BACKGROUND: Although the ongoing epidemics of Coronavirus disease 2019 (COVID-19) may have affected the mortality trend of the nation, the national level assessment of excess mortality (changes in overall mortality in the entire population) is still scarce in Korea. Therefore, this study evaluated the excess mortality during the COVID-19 pandemic in Korea using the certified mortality data. METHODS: Monthly mortality and population data from January 2013 to June 2022 was obtained from the National Health Insurance Service database and Statistics Korea. A quasi-Poisson interrupted time-series model adjusted for age structure, population, seasonality, and long-term trends was used to estimate the counterfactual projections (expected) of mortality during the COVID-19 pandemic (March 2020 to June 2022). The absolute difference (observed-expected) and ratio (observed / expected) of mortality were calculated. Stratified analysis based on pandemic years (years 2020, 2021, and 2022), sex, and age groups (aged 0-4, 5-19, 20-64, and ≥ 65 years) were conducted. RESULTS: An 8.7% increase in mortality was observed during the COVID-19 pandemic [absolute difference: 61,277 persons; ratio (95% confidence interval (CI)): 1.087 (1.066, 1.107)]. The gap between observed and estimated mortality became wider with continuation of the pandemic [ratio (95% CI), year 2020: 1.021 (1.003, 1.040); year 2021: 1.060 (1.039, 1.080), year 2022: 1.244 (1.219, 1.270)]. Although excess mortality across sex was similar, the adult [aged 20-64, ratio (95% CI): 1.059 (1.043, 1.076)] and elderly [aged 65-, ratio (95% CI): 1.098 (1.062, 1.135)] population showed increased excess mortality during the pandemic. CONCLUSIONS: Despite Korea's successful quarantine policy response, the continued epidemic has led to an excess mortality. The estimated mortality exceeded the number of deaths from COVID-19 infection. Excess mortality should be monitored to estimate the overall impact of the pandemic on a nation.

Urinary phthalate metabolites and anemia: Findings from the Korean National Environmental Health Survey (2015-2017).

BACKGROUND: Several animal studies have suggested an association between phthalate exposure and decreased hemoglobin levels. To address the lack of epidemiological evidence, we evaluated the association between urinary phthalate metabolite concentrations and hematologic indices by using nationally representative data from Korea. METHODS: Data from 3722 adults included in the third stage (2015-2017) of the Korean National Environmental Health Survey (KONEHS) were used. The association between various urinary phthalate metabolites and hematologic indices (hemoglobin, hematocrit, mean corpuscular volume [MCV], and red blood cell [RBC], white blood cell [WBC], and platelet counts) was evaluated using linear regression analysis adjusted for potential confounders. Sex-stratified analysis was performed. RESULTS: All urinary phthalate metabolites were negatively associated with hemoglobin levels. A two-fold increase in urinary mono-(2-ethyl-5-carboxy-pentyl) phthalate (MECPP), mono-carboxyoctyl phthalate (MCOP), mono-carboxyonyl phthalate (MCNP), and mono-(3-carboxypropyl) phthalate (MCPP) levels was associated with a -0.099 g/dL (95% confidence interval (CI), -0.137 to -0.060), -0.116 g/dL (95% CI, -0.156 to -0.076), -0.111 g/dL (95% CI, -0.154 to -0.068), and -0.144 g/dL (95% CI, -0.198 to -0.089) change in hemoglobin levels, respectively. The RBC count and MCV showed negative and positive associations, respectively, with urinary phthalate metabolite concentrations. WBC counts were positively associated with MECPP, MCOP, MCNP, and MCPP levels, whereas the platelet count showed no association with urinary phthalate metabolites. CONCLUSIONS: Urinary phthalate metabolite concentration showed a negative association with hemoglobin level. Since this was a cross-sectional study, further longitudinal and experimental studies are needed to identify a clear causal linkage and the pathological mechanism underlying phthalate exposure and anemia.

Impact of Chamber/Annealing Temperature on the Endurance Characteristic of Zr:HfO2 Ferroelectric Capacitor.

The endurance characteristic of Zr-doped HfO2 (HZO)-based metal-ferroelectric-metal (MFM) capacitors fabricated under various deposition/annealing temperatures in the atomic layer deposition (ALD) process was investigated. The chamber temperature in the ALD process was set to 120 °C, 200 °C, or 250 °C, and the annealing temperature was set to 400 °C, 500 °C, 600 °C, or 700 °C. For the given annealing temperature of 700 °C, the remnant polarization (2Pr) was 17.21 µC/cm2, 26.37 µC/cm2, and 31.8 µC/cm2 at the chamber temperatures of 120 °C, 200 °C, and 250 °C, respectively. For the given/identical annealing temperature, the largest remnant polarization (Pr) was achieved when using the chamber temperature of 250 °C. At a higher annealing temperature, the grain size in the HZO layer becomes smaller, and thereby, it enables to boost up Pr. It was observed that the endurance characteristics for the capacitors fabricated under various annealing/chamber temperatures were quite different. The different endurance characteristics are due to the oxygen and oxygen vacancies in ferroelectric films, which affects the wakeup/fatigue behaviors. However, in common, all the capacitors showed no breakdown for an externally applied pulse (up to 108 cycles of the pulse).

Particulate air pollution and survival after stroke in older adults: A retrospective cohort study in Korea.

Although many studies have evaluated the effects of ambient particulate matter with diameters of less than 2.5 µm (PM2.5) on stroke mortality in the general population, little is known about the mortality effects of PM2.5 in post-stroke populations. Therefore, a retrospective cohort was constructed using information from the health insurance database to evaluate whether exposure to PM2.5 is associated with increased mortality in aged stroke survivors residing in seven Korean metropolitan cities. A total of 45,513 older adults (≥65 years) who visited emergency rooms due to stroke and who were discharged alive between 2008 and 2016 were followed up. By using district-level modeled PM2.5 concentrations and a time-varying Cox proportional hazard model, associations between 1-month and 2-month moving average PM2.5 exposures and mortality in stroke survivors were evaluated. The annual average concentration of PM2.5 was 27.9 µg/m3 in the seven metropolitan cities, and 14,880 subjects died during the follow-up period. A 10 µg/m3 increase in the 1-month and 2-month moving average PM2.5 exposures was associated with mortality hazard ratios of 1.07 (95% confidence interval: 1.05, 1.09) and 1.06 (95% confidence interval: 1.03, 1.08), respectively. The effects of PM2.5 were similar across types of stroke (ischemic and hemorrhagic), age groups (65-74, 75-84, and ≥85), and income groups (low and high) but were greater in women than in men. This study highlights the adverse health effects of ambient PM2.5 in post-stroke populations. Active avoidance behaviors against PM2.5 are recommended for aged stroke survivors.

Short-term exposure to air pollution and hospital admission for heart failure among older adults in metropolitan cities: a time-series study.

PURPOSE: We aimed to investigate the association between air pollution concentration levels and hospital admissions for heart failure (HF) among older adults in metropolitan cities in South Korea. METHODS: We used hospital admission data of 1.8 million older adults in seven metropolitan cities from 2008 to 2016, derived from the National Health Insurance Service of South Korea. Daily HF admission data were linked to air pollutants concentrations for the respective dates, including particulate matter less than 2.5 µm in size (PM2.5), 10 µm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone. We estimated the association between air pollutants and daily HF admissions using quasi-Poisson generalized additive models for each city. RESULTS: During the study period, 142,490 hospital admissions for HF were noted. Increases of 10 µg/m3 of PM2.5 and PM10, and 10 ppb of SO2, NO2, and CO were associated with an increased risk of HF admission by 0.93% ([95% confidence intervals 0.51-1.36], 0.55% [0.31-0.80], 6.04% [2.15-10.08], 1.10% [0.38-1.82], and 0.05% [0.01-0.09]), respectively, on the same day. Increases in mean exposure to PM2.5, PM10, and SO2 for 8 days from the concurrent day were also significantly associated with HF admissions. During the warm season, the risk of HF admissions increased shortly after an increase in PM2.5, whereas prolonged effects were observed during the cold season. CONCLUSION: Our study suggests the adverse effects of air pollution on HF. Moreover, the evidence of seasonality may help tailor protection guidelines for older adults.

Source country-specific burden on health due to high concentrations of PM2.5.

Asian countries face frequent spikes in concentrations of particulate matter smaller than 2.5 µm (PM2.5), which may consist of domestic emissions, transported pollutants from neighboring countries, and secondary aerosol formation (SAF). We aimed to estimate the burden on health in South Korea due to PM2.5 exposure from source countries. We computed the health benefits of meeting air quality guidelines during high pollution periods or spike periods. We used daily mortality counts, PM2.5 concentrations, and primary and secondary contributions to pollutant levels in seven cities and nine provinces in South Korea during 2006-2016. Generalized additive mixed modeling with a Poisson distribution and random effects in 16 regions was used to examine the short-term effects of PM2.5 on mortality. We computed attributable burden due to PM2.5 exposure and the potential benefits of meeting the air quality guidelines set by the World Health Organization (WHO, 25 µg/m3) and the Korea Ministry of Environment (50 and 35 µg/m3 before and after 2015, respectively). A concentration-response curve showed a non-linear relationship between daily mortality counts and PM2.5 levels. The short-term health impacts of PM2.5 were suggested to be 1638 non-accidental deaths in 2016 in South Korea due to daily domestic emissions and pollutants transported from neighboring countries. Of these, 1509, 995, or 238 deaths could have been prevented if the daily mean PM2.5 concentration had been kept below 25, 35, or 50 µg/m3. After accounting for the contribution of SAF to PM2.5, primary sources of PM2.5 resulted in 258-860 and 26-88 deaths due to pollution transported from China and North Korea, respectively, and 162-538 deaths were due to domestic emissions. Meeting the air quality guidelines of the WHO could have prevented most of these deaths.

Prenatal exposure to traffic-related air pollution and risk of congenital diseases in South Korea.

BACKGROUND: Previous studies have suggested links between exposure to ambient air pollutants and increased risk of congenital heart defects. However, few studies have investigated the association between other congenital diseases and traffic-related air pollution. In this study, we assessed the relationship between prenatal exposure to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) with congenital diseases in South Korea. METHODS: Patients with one or more congenital diseases and a control group of patients with non-infective gastroenteritis and colitis with a case:control ratio of 1:3 were obtained from the National Health Insurance Service data for 2008-2013 in South Korea. We estimated the associations of PM2.5 and NO2 exposures with congenital diseases using generalized estimation equations after controlling for covariates. RESULTS: Maternal PM2.5 exposure during the first and second trimester showed positive associations with overall congenital diseases, with changes of 14.7% (95% confidence intervals (CI), 9.3%, 20.3%) and 16.2% (95% CI, 11.0%, 21.7%), respectively, per 11.1 µg/m3 and 10.2 µg/m3 increase of PM2.5 interquartile range (IQR). Similarly, NO2 exposure during the first and second trimester was associated with increased numbers of overall congenital anomalies, with 8.2% (95% CI, 4.2%, 12.3%) and 15.6% (95% CI, 9.3%, 22.2%) more cases, respectively, per 10.6 ppb increase of NO2. We found that maternal PM2.5 exposure during the first and second trimesters of pregnancy was significantly associated with increased risk of specific congenital diseases, including subtypes affecting the circulatory, genitourinary, and musculoskeletal system. However, no significant associations were observed during the third trimester. Maternal NO2 exposure across the entire pregnancy was associated with malformations of the musculoskeletal system. CONCLUSIONS: Our study identified significant links between in utero exposure to PM2.5 and NO2 and certain congenital diseases, and suggests that stricter controls on PM2.5 and NO2 concentrations are required.

Association Between Ambient Air Pollution Exposure and Spontaneous Pneumothorax Occurrence.

BACKGROUND: Spontaneous pneumothorax is hypothesized to be associated with air pollution exposure based on pathophysiological mechanisms involving airway inflammation. Therefore, we analyzed the association between daily concentrations of air pollutants [sulfur dioxide, nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), particulate matter (PM) less than 2.5 µm in diameter (PM2.5), PM less than 10 µm in diameter (PM10), and coarse PM (PM10-2.5)] and the number of spontaneous pneumothorax-related hospital visits. METHODS: We analyzed a subset of data from the National Health Insurance Service-National Sample Cohort, a nationally representative dynamic cohort based on health insurance claims data in Korea. Using time series analysis with the Poisson generalized additive model, we evaluated hospital visit data of over 100,000 male cohort members residing in Seoul from 2007 to 2010. RESULTS: We identified 516 hospital visits due to spontaneous pneumothorax. In a single-pollutant model, an interquartile range increase of PM and CO exposure at lag day 1 was associated with spontaneous pneumothorax hospital visits (relative risk, 95% confidence interval: PM2.5: 1.10 (1.01, 1.21); PM10: 1.09 (1.01, 1.18); PM10-2.5: 1.06 (1.00, 1.12); CO: 1.11 (1.01, 1.23)). For lag day 2, NO2 and PM exposure was associated with pneumothorax hospital visits (NO2: 1.15 (1.01, 1.32); PM10: 1.10 (1.02, 1.18); PM10-2.5: 1.07 (1.02, 1.13)). In a multipollutant model, the association was consistent for PM. CONCLUSION: The number of hospital visits due to spontaneous pneumothorax increased with air pollution exposure, especially with PM. Our finding suggests that air pollution is a possible predisposing factor for spontaneous pneumothorax.

Spatial and Temporal Trends of Number of Deaths Attributable to Ambient PM2.5 in the Korea.

BACKGROUND: We aimed to evaluate the spatial and temporal trends of the health burden attributable to particulate matter less than 2.5 µm in diameter (PM2.5) in the metropolitan cities and provinces of the Korea. METHODS: We used modeled PM2.5 concentration data for the basic administrative levels, comprising the cities and the provinces of Korea, the corresponding annual population census data for each level, and the age and cause specific mortality data. We applied cause-specific integrated exposure-response functions to calculate the premature mortality attributable to ambient PM2.5 for four disease end points (ischemic heart disease [IHD], chronic obstructive pulmonary disease [COPD], lung cancer [LC], and cerebrovascular disease [stroke]) for the year 2015. Moreover, the temporal trends of the health burden from 2006 to 2015 were assessed. RESULTS: The annual average PM2.5 concentration for Korea was 24.4 µg/m3, and 11,924 premature deaths were attributable to PM2.5 exposure in 2015. By simulating the reduction in the annual mean values of PM2.5 to 10 µg/m3, about 8,539 premature deaths were preventable. There was spatial variation in mortality burden attributable to PM2.5 across the sub-national regions of Korea. In particular, the high burden was concentrated at Seoul and Gyeonggi province due to the high population density. However, decreasing trends were noted for most of the metropolitan cities and provinces of Korea since 2006. CONCLUSION: Our findings show that further actions to improve air quality in Korea would substantially improve the health burden due to particulate matter.

Association between ambient particulate matter and disorders of vestibular function.

BACKGROUND: Exposure to environmental chemicals has been suggested to alter the physiologic state of the inner and middle ear. However, it is unknown if particulate matter exposure is associated with acute vestibular dysfunction. OBJECTIVES: To estimate the effects of particulate matter exposure on the number of hospital visits related to three major diseases of vestibular dysfunction, Meniere's disease (MD), benign paroxysmal positional vertigo (BPPV), and vestibular neuronitis (VN). METHODS: Our study subject is from Korean National Health Insurance Service-National Sample Cohort, which is dynamic cohort consist of 1 million participants representing the Korean population. Among total cohort participants, we used the hospital visit data of 210,000 individuals who resided in Seoul from 2007 to 2010. Time series analysis using the Poisson generalized additive model and case-crossover analysis using conditional logistic regression were used to investigate the association between daily particulate matter levels (PM2.5, particulate matter <2.5µg/m3; PM10, particulate matter <10µg/m3; PM10-2.5, PM10- PM2.5) and number of MD, BPPV, and VN hospital visits. RESULTS: Time series analysis showed that an interquartile range (IQR) increase in PM10 and PM10-2.5 on lag day 1 was associated with an increased risk of MD hospital visits [relative risk (RR), 95% confidence interval (CI), PM10: 1.09 (1.02-1.15); PM10-2.5: 1.06 (1.02-1.10)]. In addition, elderly individuals (≥60 years old) showed an increased risk of MD hospital visits after particulate matter exposure when compared to younger individuals. An IQR increase in particulate matter on lag day 1 was associated with a marginally significant increase in VN hospital visits [RR (95%CI), PM2.5: 1.11 (0.98-1.25); PM10: 1.07 (0.99-1.15); PM10-2.5: 1.04 (0.99-1.09)]. However, no association between particulate matter exposure and BPPV hospital visits was noted. Case-crossover analyses showed similar results to the time-series analysis across all three diseases. CONCLUSION: MD hospital visits were associated with ambient particulate matter exposure. Elderly individuals, in particular, were more susceptible to particulate matter exposure than younger individuals.

Modulation of blood pressure in response to low ambient temperature: The role of DNA methylation of zinc finger genes.

BACKGROUND: Blood pressure rises with a drop in external temperature, but the role of DNA methylation in such blood pressure modulation has not been studied in detail. We evaluated blood pressure and DNA methylation of vascular disease-related genes in association with low temperature. METHODS: To examine changes in blood pressure and DNA methylation associated with low temperature, we conducted repeated measures analysis among 50 participants over 3 repeated visits, and validated the association among another 52 participants. In addition, the mean of methylation changes in the identified CpG sites was evaluated with changes in blood pressure. Mediation analyses were also conducted to model the indirect association between low ambient temperature and blood pressure through changes in DNA methylation. RESULTS: With a 1°C decrease in temperature, increases of 0.6mmHg (standard error (SE), 0.2) in SBP and 0.3mmHg (SE, 0.1) in DBP occurred (P<0.05). Of 24,490 CpG sites in vascular genes, 2 CpG sites of zinc finger (ZNF) genes were significantly associated with temperature after Bonferroni's correction in discovery and replication data. A 10% increase in methylation expression in 2 CpG sites in ZNF genes was associated with a 4-mmHg elevation in DBP (SE, 1.8; P=0.0236). The hypermethylation was attributable to the association of ambient temperature with DBP (proportion of mediation=11.8-20.4%). CONCLUSIONS: Methylation changes in ZNF genes might be involved in the elevation of blood pressure when the body is exposed to cold temperature.

A nationwide study of the incidence rate of herb-induced liver injury in Korea.

Discrepant incidence has been reported regarding the incidence of herb-induced liver injury (HILI). To address the growing worldwide concern of HILI, we evaluated the risk of HILI in a nationwide prospective study. Between April 2013 and January 2016, 1001 inpatients (360 males and 641 females) from 10 tertiary hospitals throughout South Korea were treated with herbal drugs and had their liver enzymes periodically measured. A total of six patients met the criteria for HILI with RUCAM scores ranging from 4 to 7. All these participants were women and developed the hepatocellular type of HILI. One HILI participant met the criteria for Hy's law; however, none of six cases presented clinical symptoms related to liver injury. This is the first nationwide prospective study that estimated the extent of the incidence of HILI [total: 0.60%, 95% confidence interval (CI) 0.12-1.08; women: 0.95%, 95% CI 0.19-1.68] and described its features in hospitalized participants.

Bisphenol A, Hypertension, and Cardiovascular Diseases: Epidemiological, Laboratory, and Clinical Trial Evidence.

Bisphenol A (BPA) exposure has become one of the most common environmental chemical exposures in humans. There is growing evidence regarding an association between BPA exposure, hypertension, and cardiovascular diseases (CVD). If BPA exposure is indeed associated with raised blood pressure and CVD, it would be a major public health problem. Therefore, we reviewed the epidemiological, laboratory, and clinical trial evidence for an association between BPA exposure, CVD, and hypertension, and discussed the possible mechanisms in this article. Cross-sectional studies in various ethnicities suggested a possible association between BPA exposure and hypertension; this association was supported by a panel study and a randomized clinical trial. Despite the discordance among cross-sectional studies about an association between BPA exposure and CVD, a longitudinal study shows that BPA exposure is a risk factor for CVD. The effects of BPA exposure such as endocrinal disturbance, induction of oxidative stress and inflammation, epigenetic change, and links with other chronic diseases may highlight a possible mechanism between BPA exposure, CVD, and hypertension. To clarify the causal relationship, well-designed studies are needed in the future.

Does cadmium exposure contribute to depressive symptoms in the elderly population?

BACKGROUND: To date, the association of the neurotoxic agent cadmium (Cd) with depression in elderly people has been poorly evaluated. By investigating the relationship between blood cadmium levels and scores on a depression screening test, we aimed to investigate the impact of cadmium exposure on elderly depression. METHODS: From 2008 to 2010, a total of 395 elderly participants residing in Seoul, Korea, were evaluated 3 times. Demographic data and lifestyle information were obtained via a systemised questionnaire, and blood samples were collected for analysis. Participants underwent the Korean Version of the Short Form Generic Depression Scale test (SGDS-K) for screening depression and associations were estimated using logistic regression models adjusted for potential confounders. RESULTS: Blood cadmium levels were associated with depressive symptoms in the first visit data analysis. By analysing the first visit data, the highest quartile blood cadmium group (Q4) showed increased risk for depressive symptoms compared to the lowest quartile group (Q1) (OR 3.50, 95% CI 1.22 to 10.00). However, the data of the second and third visits suggested that blood cadmium may be protective against depressive symptoms (second visit data, Q4 vs Q1, OR 0.78, 95% CI 0.19 to 3.14; third visit data, Q4 vs Q1, OR 0.58, 95% CI 0.04 to 8.77). CONCLUSIONS: Owing to inconsistent results in analyses between blood cadmium levels and depressive symptoms, we cannot conclude any solid association between blood cadmium levels and depressive symptoms in the elderly population. To clarify the relationship, other prospective studies are needed in the future.