Background: Gender disparities in the intention to leave research careers after marriage have not been investigated. This study aimed to clarify the gender-specific associations of marital status and nurturing children with the intention to leave research careers among medical researchers.

Methods: A cross-sectional study was conducted from December 2022 to January 2023. The study was based on a web-based survey targeting medical researchers affiliated with 141 Japanese academic societies. Participants who disagreed with continuing their research careers were classified as intending to leave. Multivariable-adjusted logistic regression analysis was used to evaluate the gender-specific association of marital status and having children with the intention to leave research careers.

Results: Among 3,009 participants, 812 (27.0%) were women, and 342 (11.4%) expressed an intention to leave. A total of 2,481 participants (82.5%) were married, and 2,267 (75.3%) had children. Marital status was associated with intention to leave research careers in opposite directions for men and women, with significant interactions on both multiplicative (P = 0.015) and additive (P = 0.001) scales. Specifically, married men had a significantly lower intention to leave compared with unmarried men (adjusted odds ratio [aOR] 0.63, 95% confidence interval [CI]: 0.40–0.97). In contrast, among women, marriage was associated with a higher intention to leave compared with being unmarried (aOR 1.41, 95% CI: 0.86–2.32), although this increase was not significant. In post hoc subgroup analyses by medical license status, the gender-specific association between marital status and intention to leave research careers was more evident among medical doctors (MDs) than non-MDs, among whom the proportion reporting intention to leave was lower (4% to 6% across groups). However, estimates among non-MD researchers were imprecise due to the small number of events. Similar gender disparities were observed for having children, although the interaction did not reach statistical significance (P for additive interaction = 0.083).

Conclusions: The present results suggest that marital status showed opposite associations with intention to leave research careers between men and women, a pattern primarily observed among MD researchers. Our finding highlights the need to consider gender difference when developing strategies to support retention of medical researchers.

Background: Although marital status is a key social determinant of health, its prognostic relevance in cardiopulmonary exercise testing (CPX) cohorts remains unclear. We aimed to evaluate the association between marital status and mortality risk in patients with cardiac disease (CD) who underwent CPX.

Methods: This retrospective, single-center observational study involved consecutive patients with CD who underwent post-discharge CPX between 2008 and 2020. Participants (mean age: 69 years; 73% male) were categorized as either unmarried (never married, divorced, or widowed) or married. The primary outcome was all-cause mortality, and the secondary outcome was cardiovascular mortality. We used Cox proportional hazards models to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs). Model 1 was adjusted for age and sex to estimate the overall association between marital status and outcomes. Model 2 was adjusted for Model 1 covariates and peak VO₂ to account for objectively measured exercise capacity.

Results: Of 4,681 patients analyzed, 1,117 were unmarried and 3,564 were married. In Model 1, being married was associated with a lower risk of all-cause mortality (aHR: 0.75, 95% CI: 0.62–0.91, P < 0.001). This association persisted after adjusting for peak VO₂ in Model 2 (aHR: 0.79, 95% CI: 0.65–0.96, P = 0.002). For cardiovascular mortality, the estimates were consistent in direction (Model 1; aHR: 0.64, 95% CI: 0.44–0.93, P = 0.019, Model 2; aHR: 0.69, 95% CI: 0.47–1.02, P = 0.061).

Conclusions: In a large CPX cohort of patients with CD, married status was associated with a lower risk of all-cause mortality. The association was attenuated but remained after adjustment for peak VO₂, suggesting that differences in exercise capacity may contribute but do not fully account for the observed association. Marital status should be interpreted as a social marker rather than a causal or interventional exposure, and future studies should clarify modifiable factors related to prognosis.

Background: Evidence regarding the association between ambient polycyclic aromatic hydrocarbon (PAH) mixtures and non-neoplastic gastrointestinal diseases in general populations remains limited. This study examined whether provincial ambient particulate-phase PAH burden was associated with prevalent gastrointestinal disease among middle-aged and older adults in China.

Methods: Provincial annual mean concentrations of particulate-phase PAHs for 2015 were compiled from published monitoring studies across 12 Chinese provinces and linked to participants in the 2015 wave of the China Health and Retirement Longitudinal Study. Gastrointestinal disease was defined as a self-reported physician diagnosis and/or current treatment, excluding tumors and cancer. Using multivariable logistic regression, we estimated odds ratios and 95% confidence intervals for prevalent gastrointestinal disease per doubling (log2) of total PAHs and of 17 individual PAHs, adjusting for demographic, socioeconomic, and health-related covariates. The Benjamini–Hochberg procedure controlled the false discovery rate. Likelihood ratio tests for interaction were used to assess effect modification.

Results: Of 3,671 adults aged 45 years or older, 1,056 (28.8%) reported a gastrointestinal disease. In fully adjusted models, each doubling of total PAH concentration was associated with increased odds of gastrointestinal disease (odds ratio 1.07, 95% confidence interval 1.02–1.12; false discovery rate–adjusted q = 0.014). Following multiple-comparison correction, naphthalene, fluorene, phenanthrene, and pyrene each demonstrated consistent positive associations. The association for total PAHs was more pronounced among non-drinkers (odds ratio 1.43, 95% confidence interval 1.19–1.71; P for interaction = 0.015) and rural residents (odds ratio 1.37, 95% confidence interval 1.15–1.65; P for interaction = 0.035).

Conclusions: Higher provincial ambient particulate-phase PAH burden was associated with a greater prevalence of self-reported non-neoplastic gastrointestinal disease among middle-aged and older Chinese adults, with potential heterogeneity by residence and alcohol consumption. Given the cross-sectional design and province-level exposure assignment, longitudinal studies with individual-level exposure assessment and validated outcomes are needed.

Background: New tobacco products, including heated tobacco products and electronic cigarettes, are rapidly increasing in popularity among younger populations worldwide, particularly in Japan. Thus, clarifying the effects of both active and passive smoking of new tobacco products during pregnancy is an urgent public health concern. We focused on nausea and vomiting in pregnancy (NVP) which is traditionally and epidemiologically considered an indicator of healthy pregnancy progression. In this study, we classified maternal and paternal smoking status focussing on new tobacco product use and investigated its association with the absence of NVP.

Methods: This cross-sectional study used control data from a case–control study designed to explore modifiable factors for anorectal malformations. The questionnaire survey was conducted within seven Japanese regions between December 2019 and March 2023, enrolling a total of 1,522 postpartum women. The study included 1,450 postpartum women who delivered singleton babies and provided complete information. The main outcome was the absence of NVP. The exposure was the smoking status of mothers and their partners, classified into four categories: dual users (combustible cigarettes and new tobacco products), new tobacco product-only users, combustible cigarette-only users, and non-smokers (reference). Logistic regression analysis was performed to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the absence of NVP.

Results: Based on maternal smoking status, the absence of NVP was reported in 27.1% of dual users, 25.0% of new tobacco product–only users, 18.0% of combustible cigarette–only users, and 15.2% of non-smokers. Maternal dual use was associated with an increased OR of the absence of NVP (adjusted OR = 2.07, 95% CI: 1.02–4.22). After restricting to non-smoking mothers, the adjusted OR for paternal combustible cigarette smoking was 2.62 (95% CI: 1.25–5.50).

Conclusion: Our main finding was the positive association between maternal dual use of new tobacco products and combustible cigarettes during pregnancy and the absence of NVP. This suggests that smoking cessation guidance during pregnancy, including new tobacco products, is particularly warranted.

Trial registration: Not applicable.

Background: Thyroid hormones support endothelial repair, whereas bedtime snacking is linked to a higher risk of chronic kidney disease (CKD). Since endothelial dysfunction is a core feature of CKD, bedtime snacking could potentially contribute to subclinical hypothyroidism (SCH) by elevating the demand for endothelial repair. This study aimed to explore the association between bedtime snacking and SCH.

Method: In this cross-sectional study, 1,478 Japanese individuals aged 40–69 years with normal thyroid function were enrolled; normal thyroid function was defined as free triiodothyronine (T3) and free thyroxine (T4) levels within the reference ranges and the absence of thyroid-related medication use. Individuals with elevated serum concentrations of TSH (>4.01 µIU/mL) were defined as having SCH. Bedtime snacking was determined in the basis of participants’ affirmation to the question “Do you consume a night meal or snack after dinner, within two hours of bedtime, three or more times per week? (Yes, No)”.

Results: In the study population, 263 individuals reported a bedtime snacking habit, whereas SCH was identified in 81 individuals. A statistically significant association was found between bedtime snacking and SCH. The sex- and age-adjusted odds ratios (OR) and 95% confidence intervals (CI) were 1.77 (1.05, 2.99). This association remained significant after additional adjustment for skipping breakfast and late dinner; 1.83 (1.07, 3.11), and further adjustment for free T4, atherosclerosis, hypertension, diabetes, CKD, and thyroid cysts; 1.93 (1.11, 3.35), respectively.

Conclusion: Bedtime snacking is positively associated with SCH, potentially due to an increased physiological demand for endothelial repair. This finding is not only an efficient tool for diagnosing the early stages of endothelial and thyroid dysfunction, but also for clarifying the mechanism underlying the regulation of thyroid hormones related to endothelial health.

Background: Competing endogenous RNAs (ceRNAs) represent a novel mechanism involving interactions among different RNAs, playing a crucial role in the gene regulatory networks throughout the life cycle. CeRNAs are implicated in cardiovascular diseases (CVDs) caused by environmental endocrine disruptors (EDCs); however, existing studies are not yet systematic, and the mechanisms underlying their effects remain unclear.

Objective: This study aimed to systematically elucidate the role of ceRNAs in EDC-induced CVDs and provide valuable insights regarding disease mechanisms and developing new therapeutic strategies.

Methods: Comprehensive searches for research related to EDC-induced cardiovascular diseases were conducted across PubMed, Web of Science, and ScienceDirect databases. Eligible studies were screened, and those containing information on the regulatory mechanisms of ceRNAs were extracted and analyzed.

Results: Notably, ceRNA-mediated effects of EDC exposure on CVDs mainly occurred through four pathways. First, upon exposure to EDCs, micro RNAs, messenger RNAs (mRNAs), long-chain non-coding RNAs, circular RNAs are differentially regulated, activating signaling pathways such as nuclear factor erythroid 2-related factor 2 and p38 mitogen-activated protein kinase/nuclear factor-κB, which lead to atherosclerosis. Second, EDC exposure alters mRNAs and proteins involved in ceRNA networks, activating the PTEN-induced kinase 1/Parkin and transforming growth factor-β1/LIM domain kinase 1 signaling pathways, leading to cardiomyopathy. Third, EDCs increase ceRNA-related mRNA levels, thereby raising the risk of CVDs. Lastly, ceRNAs participate in EDC exposure to upregulate nitric oxide or reactive oxygen species, ultimately causing vascular diseases.

Conclusion: Altogether, the findings of this study show that ceRNAs hold significant potential for identifying target genes and signaling pathways associated with CVDs, which may facilitate deeper studies into CVD management.

Background: This letter highlights the importance of clinical epidemiology in COVID-19 prevention and control, based on experiences at a core hospital in northern Okinawa, Japan, and relevant literature.

Methods: Using data from 5,097 COVID-19 patients, we conducted: (1) a descriptive cross-sectional study analyzing cases by person, time, and place; (2) an analytical cross-sectional study linking health checkup data to identify factors associated with severity (published in Environmental Health and Preventive Medicine); and (3) a cohort study of healthcare workers exploring determinants of post-vaccination antibody titers (published in Journal of Clinical Virology Plus).

Results: The descriptive study showed cases rose from 70 in 2020 to 891 in 2021 and 3,995 in 2022, before declining to 141 in 2023. In the analytical cross-sectional study (n = 1,353), protective factors against severity included vaccination (odds ratio [OR] [2 doses vs. 0 or one doses]: 0.223, 95% confidence interval [CI] 0.114–0.436; OR [≥3 doses vs. 0 or one doses]: 0.090, 95% CI 0.035–0.229) and regular exercise (OR [“yes” vs. “no”]: 0.458, 95% CI 0.242–0.866). In the cohort study (n = 354), lower antibody titers (lowest quartile) were more likely among older adults (hazard ratio [HR] 5.82 for 40s vs. 20s, 95% CI 2.05–16.51; HR 9.96 for 60s vs. 20s, 95% CI 3.07–32.34) and drinking habits (HR 2.26 for “daily” vs. “never”, 95% CI 1.17–4.34).

Conclusion: These findings, supported by related literature, demonstrate that clinical epidemiology played vital roles in monitoring infection trends, evaluating diagnostic and preventive measures, establishing treatment strategies, optimizing healthcare resources, and guiding policy. Its continued application will be essential for preparedness against future emerging infectious diseases.

Background: Olfactory stimulation with hinoki cypress essential oil reportedly reduces stress hormones and enhances parasympathetic activity, which may in turn increase salivary secretion and facilitate swallowing. However, its effects on swallowing in older adults with dysphagia remain unclear.

Methods: In this placebo-controlled, single-blind, randomized crossover study, older adults with dysphagia (Food Intake Level Scale ≤9) underwent 5-minute olfactory stimulation with hinoki cypress essential oil or rice oil (placebo) in two sessions one week apart. Repetitive saliva swallowing test (RSST), 3 mL modified water swallowing test (MWST), 30 mL water swallowing test (WST), saliva secretion for 5 minutes, blood pressure, and heart rate were measured before and after each stimulation. Changes from pre- to post-stimulation were compared within each condition and between conditions using Wilcoxon’s signed-rank test.

Results: Thirty-four participants (47% women; 80 ± 10 years) were included. Hinoki cypress essential oil significantly improved RSST (median difference 0.5, 95% CI 0.0–1.0; p = 0.004), MWST (0.5, 95% CI 0.0–1.0; p = 0.003), and saliva secretion (1.0 mL, 95% CI 0.5–2.0; p = 0.002), whereas placebo produced no significant change (all p > 0.05). Improvements in swallowing function were greater with hinoki than with placebo. The increase in saliva secretion following hinoki stimulation was not associated with changes in RSST or MWST scores.

Conclusions: Brief olfactory stimulation with hinoki cypress essential oil improved swallowing function and increased saliva secretion in older adults with dysphagia compared with placebo in a randomized crossover design. Hinoki cypress essential oil inhalation may represent a simple, noninvasive adjunctive strategy for dysphagia management, warranting confirmation in larger and longer trials.

Trial registration: This study was registered in the UMIN Clinical Trials Registry (UMIN-CTR) under registration number UMIN000053271.

Background: Per- and polyfluoroalkyl substances (PFAS) have raised significant health concerns. In 2019, drinking water source was changed due to PFAS contamination in the Tama region, Tokyo, Japan. This study aims to determine the PFAS exposure levels after reduction in drinking water contamination, and to estimate the half-lives of linear isomers of perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorooctanoic acid (PFOA) in serum samples from residents.

Methods: 17 participants in 2020 and 2023 from Tama region, Tokyo, Japan (all females, age 53–83 years) were examined. PFAS concentrations in serum in 2023 were measured using gas chromatography-mass spectrometry. Biological half-lives were estimated using first-order kinetics model.

Results: The investigated population was exposed to six PFAS at levels associated with potential health risks, with 95% of them having total PFAS concentrations exceeding 20 ng/mL in 2023. Serum PFOS, PFHxS and PFOA levels decreased from 2000 to 2023 (p < 0.05 by paired t-test). The estimated half-lives for PFOS, PFHxS, and PFOA were 3.9 years (95% CI: 3.4–4.6), 5.7 years (95% CI: 4.6–7.5), and 8.0 years (95% CI: 6.0–10.0), respectively. After subtraction of background values in Japan, the estimated half-lives were 2.7 years (95% CI: 2.3–3.4) for PFOS, 5.6 years (95% CI: 4.5–7.4) for PFHxS, and 5.1 years (95% CI: 4.1–6.8) for PFOA.

Conclusions: This study demonstrates participants had still higher serum PFAS levels and these PFAS elimination half-lives in the investigated Japanese population are at years order.

Background: Optimizing nutrient intake is crucial for the health and development of preschool children. While previous studies assessed the risks and benefits of selenium (Se) from fish and seafood, few have examined its intake from common foods and its association with children’s growth.

Objective: In this study, we evaluated optimal foods for achieving a dietary Se surplus and the implications for the growth performance of preschool children.

Methods: Mercury (Hg) and Se concentrations were analyzed in 108 commercially available foods to conduct a dietary risk-benefit assessment of Se intake. Hg exposure was evaluated using hair samples from 349 preschool children enrolled between August 2017 and July 2022. Information on food consumption frequencies and nutrient compositions was obtained through dietary surveys.

Results: Overall, 42.4% of children had hair Hg levels above the US Environmental Protection Agency’s reference dose of 1 µg/g, showing that Hg exposure among preschool children in Taiwan remains a significant issue. The risk-benefit assessment revealed that eggs and fish are superior sources of Se compared to other animal- and plant-based foods. Although marine fish contained higher Hg concentrations than eggs, their relatively high Se and ω-3 polyunsaturated fatty acid (PUFA) contents supported a favorable nutritional profile when consumed in moderation. The minor negative health benefit value of Se (HBV_Se) observed for fruit does not pose a health concern, as it is offset by other Se-rich foods in the diet. The cumulative HBV_Se across food groups indicated that the children’s overall dietary Se intake was positive and nutritionally advantageous. Dietary Se, mainly from fish and eggs, was positively associated with weight and height development, whereas excessive fruit consumption may slightly reduce Se intake and adversely affect growth.

Conclusions: Moderate consumption of fish and eggs should be encouraged to support optimal growth and neurodevelopment. Overall, dietary patterns of Taiwanese preschool children provide beneficial levels of Se and ω-3 fatty acids while maintaining low Hg-related risks, emphasizing the need for continued monitoring of Hg levels in locally consumed foods to ensure dietary safety.

Background: The creatinine (Cre) concentration in urine is used as an adjustment factor in chemical exposure and nutritional intake assessments. Because Cre excretion varies by sex, age, race, and anthropometric measurements such as height and weight, developing a method suitable for estimating one-day Cre excretion is necessary. Accordingly, this study aimed to develop a predictive equation for individual one-day Cre excretion in Japanese school children.

Methods: Urine samples were collected from 113 boys and 91 girls (aged 6–12 years) from the Aichi Prefecture, Japan, who were free from diseases affecting the renal, muscle, or nervous systems. Urinary concentrations and one-day excreted amounts of Cre were measured and compared with the values obtained using previously reported equations or a fixed value, totaling 11 methods. Subsequently, we developed a new equation using machine learning and multiple regression analyses. Additionally, the estimated one-day sodium excretion value calculated using this equation was compared with the measured value.

Results: Among the 11 methods to predict Cre excretion, 7 overestimated—5 of which showed a positive trend bias with larger differences at higher average concentrations—and 3 underestimated—2 of which showed a negative trend bias with larger differences at lower average concentrations. A new machine learning model using sex, age, and body surface area (calculated from height and weight) yielded the most accurate prediction. Multiple regression analysis, which demonstrated the most accurate prediction, used sex, age, and body surface area as independent variables with or without the first void Cre concentration divided by urination duration from the previous night’s urination to the first void. Moreover, the difference in one-day sodium excretion from first-void urine predicted using our newly developed Cre equation increased as the measured values increased.

Conclusions: Our study suggests that the estimation of one-day Cre excretion based on sex, age, and body surface area is most appropriate for Japanese schoolchildren, particularly in assessing their chemical exposure and dietary nutrient intake.

Trial registration: Trial registration is not applicable as this observational study did not involve any intervention or randomization requiring registration in a clinical trials registry.

Background: Difficulty in chewing has been shown to be associated with increased mortality, geriatric syndromes, and poor activities of daily living, indicating the need for intervention. Chewing difficulties are related to tooth loss, periodontitis, dry mouth, and a number of oral health conditions. Diabetes mellitus (DM) is one of the major causes of global burden of diseases, and has been associated with poor oral health. Prospective association between oral health status and the development of diabetes has also been reported. However, relationship between glycemic control and self-reported chewing difficulty remains less explored in working-age populations. The objective of this study is to cross-sectionally explore the association between fasting blood glucose (FBG) and self-reported chewing difficulty in adults working in a Japanese worksite.

Methods: Participants from the Aichi Workers’ Cohort Study who responded to the 2018 survey were included. Participants were categorized into five FBG groups (<100, 100–109, 110–125, 126–159, and ≥160 mg/dl). Multivariable odds ratios (ORs) and 95% confidence intervals (CIs) for chewing difficulty were estimated using logistic regression adjusted for age, sex, body mass index, smoking and alcohol consumption status, number of teeth, presence of periodontal disease and the number of anti-diabetic medication classes.

Results: A total of 164 participants (4.2%) reported difficulty with chewing, the prevalence of which tended to increase with increasing FBG level. FBG ≥160 mg/dl was significantly and strongly associated with difficulty with chewing in the final multivariable model (multivariable OR 3.84 [95% CI 1.13–13.0]).

Conclusions: A relationship between higher FBG levels and difficulty with chewing was observed, independent of potential confounding factors. However, prospective or interventional studies are needed to determine causality.

Background: Dental caries is a chronic childhood disease and one of the most prevalent public health problems worldwide. Lead is a heavy metal that is taken up by the teeth and bones. However, the association between lead exposure during pregnancy, when the tooth germs are formed, and the prevalence of dental caries in the primary dentition remains unclear. This study aimed to examine the association between maternal blood lead levels and the prevalence of dental caries in the primary dentition of children.

Methods: This cross-sectional study was conducted as an Adjunct Study to the Japan Environment and Children’s Study (JECS), which is an ongoing nationwide birth-cohort study. Among children participating in the JECS at the University of Occupational and Environmental Health Sub-Regional Center, those aged 7–8 years underwent oral examination and questionnaire administration. The dft (i.e., sum of the number of decayed and filled primary teeth) was then determined. The dft numerically expresses the dental caries prevalence in the primary dentition (larger value indicates more prevalent dental caries). Poisson regression analyses with robust standard errors were performed to evaluate the association between maternal blood lead levels during pregnancy, measured using frozen samples, and the dft.

Results: The study included 139 children, of whom 54.7% were girls, and 89.2% were 7 years old. The median maternal blood lead level was 6.1 ng/g (25–75 percentile, 5.0–7.3). The median dft was 0 (25–75 percentile, 0–4). After adjusting for covariates including age, sex, and oral health status and behavior, maternal blood lead levels were significantly associated with increased dft (prevalence ratio, 1.6; 95% confidence interval, 1.3–1.8; per one standard deviation increase in natural log-transformed maternal blood lead levels).

Conclusions: This study found an association between maternal blood lead levels and the prevalence of dental caries in the primary dentition of children aged 7–8 years. Maternal exposure to lead during mid- to late-term pregnancy may affect the caries susceptibility of children after birth.

Background: Self-care is increasingly recognized as the foundation of person-centered healthcare and a key driver for simultaneously improving population health outcomes and reducing healthcare expenditures. While the Self-Care Inventory (SCI) has been validated in several languages, Japan lacks a standardized instrument for assessing self-care in the general adult population. Moreover, it remains unclear whether the SCI reflects culturally specific self-care behaviors and retains its psychological measurement properties in non-Western contexts. Addressing both aspects, this study aimed to evaluate the Japanese version of the SCI (JSCI) in terms of its psychometric properties and its association with concrete health behaviors.

Methods: We adapted the JSCI following COSMIN guidelines using forward/backward translation, expert review, and cognitive debriefing. Psychometric evaluation was based on two samples: a nationwide web-based survey (n = 504) and a community-based paper survey (n = 75). Structural validity was examined via CFA; internal consistency via Cronbach’s alpha and McDonald’s omega; and test–retest reliability via ICCs. Convergent and criterion validity were assessed through correlations with relevant psychological constructs. Measurement invariance and DIF across modes were tested, and associations with five external self-care behaviors were evaluated using AUC.

Results: The hypothesized three-factor structure of the JSCI was supported across both administration modes (CFI = 0.926–0.942; SRMR < 0.06), although some subscales had elevated RMSEA. Internal consistency was acceptable to high (α = 0.75–0.85; ω = 0.81–0.92). ICCs indicated moderate to good temporal stability. JSCI scores correlated with self-care efficacy and other related constructs, supporting convergent and criterion validity. Configural invariance was confirmed, and no significant DIF was detected across modes. JSCI scores modestly discriminated individuals engaging in concrete self-care behaviors such as physical activity, strength training, Helicobacter pylori testing, and having a regular primary or dental care provider (AUCs = 0.62–0.80).

Conclusions: The JSCI demonstrated satisfactory psychometric properties and structural validity across diverse research settings. Its observed associations with a range of meaningful self-care behaviors support the scale’s ecological and practical relevance in the Japanese context. The JSCI may serve as a reliable tool for evaluating and promoting self-care in both research and population health initiatives.

Background: Long screen time hours may be associated with behavioral problems in children. To better understand the relationship between children’s behavioral problems and screen time, it the associated risk factors must be subdivided based on the purpose underlying screen use. This study examined the relationship between screen time based on intended usage and behavioral problems in Japan.

Methods: This study included 3,332 children aged between 7–17 years from the Hokkaido Study on Environment and Children’s Health. From October 2020 to October 2021, the children and their parents answered questionnaires on the children’s screen use duration (never used, <30 min, ≥30 min & <1 hour, ≥1 h & <2 h, ≥2 h) based on seven intended usage categories: watching television/video, video gaming, reading books/comics, sending/receiving e-mail/messages, browsing/posting on social networking services, studying for classes/homework, drawing/editing pictures/photos/videos, along with the Strengths and Difficulties Questionnaire (SDQ). Logistic regression was used to analyze the association between screen time, purpose of children’s screen use, and behavioral problems across the 13 SDQ total scores.

Results: The mean ± standard deviation age of the participants was 12.4 ± 2.4-years-old, 487 (14.6%) children were determined to have behavioral problems, and the duration of screen time increased with their age. The children’s primary purposes for screen use were watching television/video, video gaming, sending/receiving e-mail/messages, and browsing/posting on social networking services. Children who reported playing video games for ≥2 hours on weekdays had higher odds of problematic total difficulties scores than never user (Odds Ratio: 2.10, 95% confidence interval: 1.45–3.06).

Conclusion: Long video gaming screen time is associated with behavioral issues, hyperactivity/inattention, and prosocial behaviors in children. Conversely, watching television and videos for 30 min–1 h per day, using e-mail or messaging, and using social networking services were significantly association with reduced odds ratio for peer relationship problems as compared to children who never engaged in these activities. Longitudinal follow-up is needed to further examine screen time and problem behaviors.

Background: Japan lacks comprehensive reports on the nationwide voluntary vaccine coverage. The effectiveness of public subsidies in promoting vaccination has not been fully investigated. Therefore, we aimed to estimate the nationwide coverage of voluntary vaccines, compare it with that of national immunization program (NIP)-included vaccines, and investigate the effectiveness of public subsidies.

Methods: We obtained nationwide monthly vaccine market data for rotavirus, Haemophilus influenzae type b (Hib), diphtheria, tetanus toxoid, acellular pertussis, inactivated poliovirus (DTaP-IPV), and mumps vaccines; estimated recipient numbers; and calculated coverage as the proportion of children from October 2011 to March 2022. Regarding the NIP-included vaccine, we compared vaccine coverage calculated from nationwide annual market data with that estimated by World Health Organization (WHO)/United Nations Children’s Fund (UNICEF), using Bland-Altman analysis.

Results: The estimates of Hib and DTaP-IPV vaccine coverage derived from market data were slightly higher than the WHO/UNICEF estimates, with mean differences of 0.05 (95% CI: 0.02–0.07) for Hib and 0.03 (95% CI: 0.01–0.05) for DTaP-IPV. The coverage of the rotavirus vaccine gradually increased long before the implementation of national subsidies, reaching 0.9 in 2020. Hib vaccine coverage had already achieved 1.0 by January 2012. The coverage of the DTaP-IPV vaccine was approximately 0.6–0.8 in 2013, reaching 1.0 in 2014. The coverage of mumps vaccine increased gradually from 2011 to 2021.

Conclusions: Despite the possibility of overestimation, our estimates may serve as a valuable surrogate for actual vaccine coverage in Japan. An increasing trend in rotavirus and mumps vaccine coverage was observed when these vaccines were categorized as voluntary. Although vaccination policies differ from country to country, it would be beneficial to share findings on the impact of subsidies in Japan with other countries.

Background: Children’s respiratory health demonstrates particular sensitivity to air pollution. Existing evidence investigating the association between short-term ozone (O₃) exposure and childhood pneumonia remains insufficient and inconsistent, especially in low- and middle-income countries (LMICs).

Method: To provide more reliable and persuasive evidence, we implemented a multi-city, time-stratified case-crossover design with a large sample size, using data from seven representative children’s hospitals across major geographical regions in China. To avoid the impact of the COVID-19 pandemic, individual-level medical records of inpatient children under 6 years of age diagnosed with pneumonia during 2016–2019 were collected. Conditional logistic regression models were fitted for each city, and city-specific estimates were pooled through a meta-analysis using a random-effects model.

Results: In total, the study included 137,470 pediatric pneumonia hospital admissions. The highest pooled estimate for O₃ occurred at lag0–1, with a 10 µg/m³ increase in O₃ associated with a 1.57% (95% CI: 0.67%–2.48%) higher risk of pediatric pneumonia hospital admissions. Stratified analyses indicated that the effects of O₃ were robust across different sexes, age groups, and admission seasons. We also observed a statistically significant increase in risk associated with O₃ concentrations exceeding the World Health Organization Air Quality Guidelines (WHO-AQGs).

Conclusions: This study revealed a significant positive association between O₃ and pediatric pneumonia hospital admissions. Our findings substantially strengthen the evidence base for the adverse health impacts of O₃, underscoring the importance of O₃ pollution control and management in reducing the public health burden of pediatric pneumonia.

Background: Supporting the mental health of researchers is essential to maintaining human resources and advancing science. This study investigated the association between Japanese medical researchers’ perceptions of research evaluation processes and their psychological well-being.

Methods: We performed a web-based self-administered questionnaire survey. The questionnaires were distributed to each academic society through the Japanese Association of Medical Sciences from December 2022 to January 2023. These questionnaires targeted medical researchers. Exposure was the medical researchers’ perceptions of quantitative indicators for evaluating medical research and researchers. The outcome was psychological well-being, measured using the Japanese version of the World Health Organization-Five Well-Being Index (WHO-5). Multivariable-adjusted logistic regressions were conducted to investigate the association between individual attitudes toward research evaluation and psychological well-being. Stratified analyses by research fields, i.e., clinical, basic, and social medicine, were also performed.

Results: A total of 3,139 valid responses were collected. After excluding 176 responses from research fields of other than clinical, basic, or social medicine, 2,963 researchers (2,185 male, 737 female, and 41 other) were analyzed. Prevalence of poor well-being (WHO-5 score <13) was 28.3% in the researchers. The highest number of medical researchers was in clinical medicine (n = 500) followed by basic medicine (n = 217) and social medicine (n = 121). Medical researchers who considered research funding slightly important/not important for researcher evaluation had poorer psychological well-being than those who considered it especially important (slightly important: adjusted odds ratio (aOR) 1.33, 95% confidence interval (CI) 1.03–1.71; not important: aOR 1.53, 95%CI 1.10–2.12). This tendency was stronger among basic medical researchers than clinical or social medical researchers. The research field significantly modified the relationship between research funding received and interaction with poor psychological well-being both additively (P = 0.030) and multiplicatively (P = 0.024).

Conclusions: The discrepancy between medical researchers’ attitudes toward research evaluation and the current state of research evaluation in their research community may worsen their psychological well-being. The influence of this discrepancy differs among clinical, basic, and social medicine. Appropriate evaluation of medical research and researchers in each field can facilitate improving their psychological well-being via the resolution of this discrepancy.

Per- and polyfluoroalkyl substances (PFAS) have recently been shown to affect human health at low levels in the blood, according to epidemiological evidence. Consequently, human exposure to these chemicals should be strictly controlled to prevent health risks. This review reports on the potential sources of PFAS using Japan as an example. Tap water has attracted attention as a source of exposure to PFAS. PFAS have also been detected in the air, in household dust, and in consumer products. Furthermore, in the general population, diet is the most common source of exposure, and there is particular concern about human exposure to PFAS accumulated in seafood. Continuous monitoring is important for appropriate management of exposure for both humans and the environment.

Background: Previous studies have shown that old age and cold temperatures are risk factors for bathing-related accidents (BRAs) in Japan. The differences between outdoor and indoor temperatures are believed to depend on the housing type (detached houses or apartment buildings). This study aimed to investigate the associations between age, temperature, and BRAs according to housing type in Japan.

Methods: We included cases in which patients were transported by ambulance from domestic bathrooms between April 2016 and March 2022 in Nagoya city. Age-specific BRA incidence rates measured by 5-year age groups, temperature-specific age-adjusted standardized incidence rates (SIRs) for BRA calculated by temperature quintile groups, and the BRA risk regarding temperature based on a time-stratified case-crossover (CCO) design were compared between detached houses and apartment buildings.

Results: We observed 4,848 ambulance dispatches owing to BRAs (3,083 in detached houses and 1,765 in apartment buildings; SIR for detached houses compared to apartment buildings: 1.37; 95% confidence interval [CI]: 1.33–1.43). The ratio of detached houses to apartment buildings in the age-specific BRA incidence was almost the same in middle-aged people, but it significantly increased from the age of 70 years onward (incidence rate ratio for the 70–74-years age group: 1.74; 95% CI: 1.43–2.11). Temperature-specific SIR for detached houses compared to apartment buildings was not significantly different in the hottest temperature quintile but increased significantly in the other colder temperature quintiles (SIR in coldest quintile: 1.56; 95% CI: 1.47–1.66). BRA risk based on CCO design increased significantly with a decrease in temperature in detached houses (risk ratio [RR] for 3 °C: 1.25; 95% CI: 1.05–1.47), but not in apartment buildings (RR for 3 °C: 1.07; 95% CI: 0.86–1.34).

Conclusions: Detached houses had higher BRA incidence rates than apartments. Older age and lower temperatures, which are risk factors for BRAs, were more prevalent in detached houses than in apartment buildings. Thus, public health measures that focus on detached houses are necessary for preventing BRAs in Japan.