The effect of commonly used oral contraceptives (OCs) on blood pressure is still unclear. The aim of this study was to examine the relationship between OCs use and blood pressure and the prevalence of hypertension in a population-based sample of Korean women.

4-Nonylphenol (4-NP) and 4-t-octylphenol (4-t-OP) are xenoestrogen compounds to which humans are exposed via contaminated food, water, and air. This study assessed the body burden of 4-NP and 4-t-OP in Koreans aged 18–69 years using data from the Korean National Human Biomonitoring Survey conducted in 2009. Based on data from 1865 representative Koreans, 83.2% and 91.8% had urinary 4-NP and 4-t-OP concentrations >0.05 ng/mL (limit of detection). Of the Korean adult population, the geometric mean urinary concentrations of 4-NP and 4-t-OP were 3.70 ng/mL (95% confidence interval (CI) = 3.20–4.27) and 0.60 ng/mL (95% CI = 0.55–0.66), respectively. Urine 4-NP concentrations were significantly associated with place of residence and smoking status, whereas urine 4-t-OP concentrations were not correlated with any of the demographic factors. These findings suggest that most Koreans have detectable levels of 4-NP and 4-t-OP in their urine and that the body burden of 4-NP, but not 4-t-OP, varies according to some demographic factors.

Menopause is associated with depressive symptoms that can significantly affect a woman’s quality of life. The objective of this study was to evaluate the association between depression and health-related quality of life (HRQoL) in postmenopausal women. In this cross-sectional descriptive study, participants (n = 3860) were selected from the 2013–2015 Korea National Health and Nutrition Examination Survey (KNHANES). The sociodemographic characteristics, medical history of depression, and EQ-5D scores of the participants were obtained from the KNHANES dataset. Age, educational level, and income were associated with HRQoL in these participants. Moreover, depression exerted a considerable influence on HRQoL in postmenopausal women. The adjusted odds ratios in participants with depression for the EQ-5D dimensions were as follows: 5.52 (95% CI = 4.04–7.55, p < 0.001) for anxiety/depression, 3.86 (95% CI = 2.78–5.36, p < 0.001) for usual activities, and 2.52 (95% CI = 1.68–3.78, p < 0.001) for self-care. Our findings suggest a strong association between depression and HRQoL. Hence, preventing the onset or exacerbation of depression may significantly improve quality of life in postmenopausal women.

Atopic dermatitis (AD) is a widely prevalent skin disease that affects both children and adults. The aim of the study was to assess the association of perceived stress (single-item, self-reported) with AD (self-reported) in a sample of Korean adults using a cross-sectional research design. A cross-sectional study was conducted using data from 33,018 adults aged 20 years and older collected in the 2007–2012 Korea National Health and Nutrition Examination Surveys (KNHANES). An increased level of self-reported stress was positively associated with an increased prevalence of AD in Korean adults (p for trend <0.001). After adjusting for covariates, the odds ratios (ORs) of AD among participants reporting high and very high levels of stress were 1.81 (95% confidence interval (CI): 1.22, 2.67) and 2.17 (95% CI: 1.38, 3.42), respectively, compared with those who reported low levels of stress. This study found a statistically significant association between perceived stress and AD among Korean adults.

Humans are exposed to the environmental pollutants 2,4-dichlorophenol (2,4-DCP) and 2,5-dichlorophenol (2,5-DCP) through air, the use of water and the consumption of products. In this study, we evaluated the urinary concentrations of these compounds in Korean people between the ages of 18 to 69 years, by making use of data from the Korean National Human Biomonitoring Survey that was completed in 2009. Of 1865 representative Koreans, 63.4% and 97.9% were found to have concentrations of 2,4-DCP and 2,5-DCP > 0.05 μg/L (limit of detection) in their urine, respectively. The geometric mean of urinary concentrations was 0.14 μg/L (confidence interval of 95% = 0.13–0.16) and 0.44 μg/L (confidence interval = 0.41–0.48), respectively. It was found that the adjusted proportional changes in 2,4-DCP concentrations were significantly associated with body mass index, whereas those of 2,5-DCP concentrations were influenced by place of residence. From these findings, it is evident that most adults in Korea have levels of 2,4-DCP and 2,5-DCP that are detectable in their urine and the burden of these compounds on their bodies varies depending on numerous demographic factors.

Lead, mercury, and cadmium are common environmental pollutants in industrialized countries, but their combined impact on hypercholesterolemia (HC) is poorly understood. The aim of this study was to compare the performance of various machine learning (ML) models to predict the prevalence of HC associated with exposure to lead, mercury, and cadmium. A total of 10,089 participants of the Korea National Health and Nutrition Examination Surveys 2008–2013 were selected and their demographic characteristics, blood concentration of metals, and total cholesterol levels were collected for analysis. For prediction, five ML models, including logistic regression (LR), k-nearest neighbors, decision trees, random forests, and support vector machines (SVM) were constructed and their predictive performances were compared. Of the five ML models, the SVM model was the most accurate and the LR model had the highest area under receiver operating characteristic (ROC) curve of 0.718 (95% CI: 0.688–0.748). This study shows the potential of various ML methods to predict HC associated with exposure to metals using population-based survey data.