Recently, there has been increasing worldwide concern about outdoor air pollution, especially particulate matter (PM), which has been extensively researched for its harmful effects on the respiratory system. However, sufficient research on its effects on cardiovascular diseases, such as hypertension, remains lacking. In this study, we examine the associations between PM levels and hypertension and hypothesize that higher PM concentrations are associated with elevated blood pressure.

A total of 133,935 adults aged ≥ 40 years who participated in the Korean Genome and Epidemiology Study were analyzed. Multiple linear regression analyses were conducted to investigate the short- (1–14 days), medium- (1 and 3 months), and long-term (1 and 2 years) impacts of PM on blood pressure. Logistic regression analyses were conducted to evaluate the medium- and long-term effects of PM on blood pressure elevation after adjusting for sex, age, body mass index, health-related lifestyle behaviors, and geographic areas.

Using multiple linear regression analyses, both crude and adjusted models generated positive estimates, indicating an association with increased blood pressure, with all results being statistically significant, with the exception of PM levels over the long-term period (1 and 2 years) in non-hypertensive participants. In the logistic regression analyses on non-hypertensive participants, moderate PM₁₀ (particulate matter with diameters < 10 μm) and PM_2.5 (particulate matter with diameters < 2.5 μm) levels over the long-term period and all high PM₁₀ and PM_2.5 levels were statistically significant after adjusting for various covariates. Notably, high PM_2.5 levels of the 1 year exhibited the highest odds ratio of 1.23 (95% confidence interval: 1.19–1.28) after adjustment.

These findings suggest that both short- and long-term exposure to PM is associated with blood pressure elevation.

Environmental exposure is characterized by low concentration, chronic, and complex exposure. Traditional epidemiological studies show limitations in reflecting these characteristics since they usually focus on a single or very limited number of exposure factors at a time. In this study, we adopted the methodology of environment-wide association study (EWAS) to figure out the association of human liver function with various environmentally hazardous substances.

We analyzed 2,961 participants from the Korean National Environmental Health Survey Cycle 4 (2018–2020). Using generalized linear model (GLM) analysis, we analyzed the association of 72 variables with 3 liver function indices (aspartate aminotransferase [AST], alanine aminotransferase [ALT], and gamma glutamyl transferase [GGT]). Finally, we visualized our results with Manhattan plot.

In GLM analysis, perfluorooctanesulfonate were positively associated with ALT (odds ratio [OR]: 2.2; 95% confidence interval [CI]: 1.39–3.46; p _adjusted = 0.0147) and perfluorodecanoic acid showed positive association with GGT (OR: 2.73; 95% CI: 1.36–5.5; p _adjusted = 0.0256). Plasma mercury showed positive association with GGT (OR: 1.45; 95% CI: 1.14–1.84; p _adjusted = 0.0315). Using a plastic container while keeping food in the refrigerator was associated with elevated GGT compared to using a glass container (OR: 1.51; 95% CI: 1.16–1.95; p _adjusted = 0.0153). 2-ethyl-5-oxohexyl phthalate, showed a negative trend with all 3 indices, with AST (OR: 0.54; 95% CI: 0.39–0.73; p _adjusted = 0.00357), ALT (OR: 0.5; 95% CI: 0.34–0.75; p _adjusted = 0.036), GGT (OR: 0.55; 95% CI: 0.4–0.76; p _adjusted = 0.00697). Bisphenol S and frequent use of sunblock cream showed negative association with ALT (OR: 0.77; 95% CI: 0.66–0.89), and GGT (OR: 0.25; 95% CI: 0.11–0.55), respectively.

We conducted an exploratory study on environmental exposure and human liver function. By using EWAS methodology, we identified 7 factors that could have potential association with liver function.

Mental health problems are emerging issues in occupational safety and health, whereas the findings on the relationship between physical hazards and mental health are not consistent. The aim of our study was to investigate the association between physical hazard exposure and mental health outcomes including depression and anxiety.

We included 48,476 participants from the fifth Korean Working Conditions Survey (KWCS) in this study. The χ² test and logistic regression analyses were conducted to assess the association between physical hazard exposures and mental health. All statistical analyses were performed sex-specifically.

In logistic regression analysis, the odds ratios (ORs) of depression were significantly increased in male workers who were exposed to vibration (severe OR: 1.54, 95% confidence interval [CI]: 1.21–1.95) and noise (severe OR: 1.93, 95% CI: 1.49–2.48) whereas the ORs of depression were not significant in female workers from vibration (severe OR: 0.86, 95% CI: 0.50–1.38) or noise exposure (severe OR: 1.39, 95% CI: 0.84–2.17). The ORs of anxiety were significantly increased in male workers with vibration (severe OR: 1.76, 95% CI: 1.43–2.15) and noise exposure (severe OR: 2.12, 95% CI: 1.69–2.63) whereas the OR between vibration and anxiety (severe OR: 1.45, 95% CI: 0.91–2.21) was not significant in female workers. High or low temperature exposure had significant associations with depression and anxiety in both male and female subjects.

Results of our study suggest that physical hazard exposures may be associated with increased risk of mental health problems including depression and anxiety. These associations are more prominent in male workers in comparison with female workers.

Phthalates are one of renowned endocrine-disrupting chemicals, although inconsistent results are present around their effect on onset of menarche. Our hypothesis is that pre-pubertal exposure to phthalates is associated with acceleration of menarche.

We analyzed a total of 236 middle school (7th to 9th grade) girls from Korean National Environmental Health Survey 2015–2017. We used multiple linear regression to investigate impact of eight phthalate metabolites on age of menarche. We also conducted logistic regression to evaluate association between phthalate metabolite concentrations and early onset of menarche, adjusting for grade, maternal age of menarche and body mass index (BMI).

In linear regression analysis, no significant association was found for any phthalate metabolites. In logistic regression analysis, however, odds ratios (ORs) of early menarche were significantly increased for mono-n-butyl phthalate (MnBP) and for sum of all phthalates. When compared to group with the lowest level, high concentration group for MnBP presented significantly increased odds of early menarche (OR: 2.09; 95% confidence interval [CI]: 1.03, 4.23) after adjusting for grade, maternal age of menarche and BMI. Furthermore, high concentrations of sum of all phthalates were associated with significant increase of OR of early menarche (OR: 2.22; 95% CI: 1.10, 4.49) after adjustment, compared to the lowest concentration group.

Results of our study suggest that exposure to phthalates around puberty may be associated with increased risk of early menarche.

Rhinitis was the most frequently diagnosed disorder among users of humidifier disinfectants (HDs). The aim of our study was to investigate on the relationship between allergic rhinitis (AR) and HD uses.

Our study used the data from the eighth Panel Study on Korean Children; a total of 1,540 participants were enrolled. The χ² test and multiple logistic regression analyses were conducted to debunk the association between AR and HD uses.

In our analysis, odds ratios (ORs) of doctor-diagnosed AR increased significantly when simply the response of whether HDs were used in the past was considered. When the brands of HD were considered, ORs of doctor-diagnosed AR were found to be increased significantly for those who have used polyhexamethylene guanidine phosphate/oligo(2-[2-ethoxy]-ethoxyethyl)guanidinium-containing HDs (model 3: 1.41, 95% confidence interval [CI]: 1.02–1.95). However, once duration of usage was additionally considered, ORs of doctor-diagnosed AR increased significantly only for those who have used chloromethylisothiazolinone/methylisothiazolinone-containing HDs for more than or equal to 3 months (model 3: 2.08, 95% CI: 1.17–3.69). Further, past use of HD was associated with significantly increased ORs of AR diagnosed before 2013 (model 3: 1.35, 95% CI: 1.02–1.79).

Results of our study suggest that past uses of HDs may be associated with an increased risk of AR.

Depression is considered as a risk factor for cardiovascular disease (CVD) and associated with changes in individuals' health status that might influence CVD risk. However, most studies have scrutinized this relationship on a rather narrower and specific study population. By focusing on general population of Korea, we sought to inspect the association of depression with CVD risk and cardiovascular risk factors.

The data from the first year (2016) of the 7th Korea National Health and Nutrition Examination Survey was used. Participants were classified by the Patient Health Questionnaire-9 (PHQ-9) score as such: normal group (PHQ-9 score 0–4), mild depression (MD) group (PHQ-9 score 5–9) and moderate and severe depression (MSD) group (PHQ-9 score 10–27). General linear model was used to analyze differences and the trend of mean CVD risk according to depression level. Adjusted odds ratios (AORs) were calculated by logistic regression to identify the association between depression and cardiovascular risk factors after adjusting for age.

Mean CVD risk of MSD group was higher than that of normal group (p < 0.05). There was a tendency of CVD risk to increase as depression worsened (p < 0.01). Among men, MSD group was associated with current smoking (AOR, 2.97; 95% confidence interval [CI], 1.78–4.97), taking antihypertensive medications (AOR, 2.42; 95% CI, 1.26–4.66), increased fasting blood sugar (> 125 mg/dL; AOR, 2.37; 95% CI, 1.25–4.50) and taking diabetes medications (AOR, 3.08; 95% CI, 1.65–5.72). MD group was associated with current smoking (AOR, 1.60; 95% CI, 1.18–2.17). Among women, MSD group was associated with high body mass index (≥ 25 kg/m²; AOR, 1.61; 95% CI, 1.11–2.32), large waist circumference (≥ 85 cm; AOR, 1.63; 95% CI, 1.12–2.37), current smoking (AOR, 5.11; 95% CI, 3.07–8.52) and taking diabetes medications (AOR, 2.62; 95% CI, 1.68–4.08). MD group was associated with current smoking (AOR, 1.86; 95% CI, 1.18–2.93).

We suggest that depression is associated with increased risk for CVD occurrence in general population of Korea.

Prevalence of thyroid cancer has been increasing rapidly worldwide, especially among women. There has been a debate as to whether such an increase represents consequences of over-diagnosis or a true increase. To find the occupational risk of Korean female workers in different industry sectors, we analyzed the data of Korean female workers.

National Female Worker Cohort data that contain information on total female workers were used for our analysis of prevalence of thyroid cancer (C73 according to KCD-5, 6 code) derived from National Health Insurance data. By combining industrial codes from National Health Insurance Service and those from Korea Workers’ Compensation and Welfare Service, the classification of industrial codes became to consist of the total of thirty three representing both non-office (NO) and office (O) categories. Both an internal comparison among female workers within the cohort and an external comparison to compare female workers with Korean general female population were carried out.

Among 149,258 female workers, 2,641 cases of thyroid cancers were identified. Differences in prevalence of thyroid cancer between female workers (40.5%) and general Korean female population (32.6%) were observed; however, the differences in prevalence of thyroid cancer between NO workers and O workers were not apparent. An analysis involving workers in Financial and insurance activities sector revealed that, standardized prevalence rate (SPR) of both NO (2.96, 95% CI = 2.01–4.20) and O workers (3.68, 95% CI = 3.10–4.33) increased significantly and that an AOR (adjusted odds ratio) increased marginally (1.38, 95% CI = 0.97–1.96). Further, when stratified in respect to the duration of employment, an AOR of female workers having been employed for more than 8 years showed a significant increase (1.63, 95% CI = 1.07–2.49).

Female workers had a higher risk of thyroid cancer than general female population but the difference between NO workers and O workers was not found to be significant in most industrial sectors. Further studies using data with information regarding specific occupational exposures are needed.

The online version of this article (10.1186/s40557-018-0259-3) contains supplementary material, which is available to authorized users.

Discrimination based on type of employment against non-regular workers is still a social issue. However, there are few studies on job factors that affect the discrimination experience in each type of employment or the association between discrimination and health impact indicators. This study examined occupational health characteristics according to discrimination experience and relating factors that affect discrimination experience.

This study used the 4th Korean Working Conditions Survey (2014) provided by the Korea Occupational Safety and Health Agency. Among the 50,000 workers, 7731 non-regular wage workers were selected as study population. To examine differences in discrimination experience, we used a t-test on occupational risk factors, occupational stress, occupational characteristics, health impact indicators. To identify the factors that affected discrimination experience, we performed binomial logistic regression analysis.

The discrimination experience rate was significantly higher in male, aged less than 40 years old, above high school graduate than middle school graduate, higher wage level, shorter employment period and larger company’s scale. As factors related to discrimination experience, they experienced discrimination more as occupational stress was higher and when they were temporary or daily workers rather than permanent workers, work patterns were not consistent, and the support of boss was low. It showed that physical, musculoskeletal, and mental occupational risk scores and subjective job instability were higher and work environment satisfaction was lower in discrimination experienced group.

The present study showed that the demographic and occupational factors were complexly related to discrimination experience in non-regular workers. The experience of discrimination had increased when occupational stress was higher, they were temporary or daily workers rather than permanent workers, work patterns were not consistent, and their boss’ support was low. Improving various relating factors, (e.g. occupational stresses, employment status and occupational characteristics), this would ultimately expect to improve non-regular workers’ discrimination.

This study involved a survey of the facility investment experiences, which was designed to recognize the importance of health and safety problems, and industrial accident prevention. Ultimately, we hope that small scale industries will create effective industrial accident prevention programs and facility investments.

An individual survey of businesses’ present physical conditions, recognition of the importance of the health and safety problems, and facility investment experiences for preventing industrial accidents was conducted. The survey involved 1,145 business operators or management workers in small business places with fewer than 50 workers in six industrial complexes.

Regarding the importance of occupational health and safety problems (OHS), 54.1% said it was “very important”. Received technical and financial support, and industrial accidents that occurred during the past three years were recognized as highly important for OHS. In an investigation regarding facility investment experiences for industrial accident prevention, the largest factors were business size, greater numbers of industrial accidents, greater technical and financial support received, and greater recognition of the importance of the OHS. The related variables that decided facility investment for industry accident prevention in a logistic regression analysis were the experiences of business facilities where industrial accidents occurred during the past three years, received technical and financial support, and recognition of the OHS. Those considered very important were shown to be highly significant.

Recognition of health and safety issues was higher when small businesses had experienced industrial accidents or received financial support. The investment in industrial accidents was greater when health and safety issues were recognized as important. Therefore, the goal of small business health and safety projects is to prioritize health and safety issues in terms of business management and recognition of importance. Therefore, currently various support projects are being conducted. However, there are issues regarding the limitations of the target businesses and inadequacies in maintenance and follow-up. Overall, it is necessary to provide various incentives for onsite participation that can lead to increased recognition of health and safety issues and practical investments, while perfecting maintenance and follow up measures by thoroughly revising existing operating systems.