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Background Sleep-related problems are highly prevalent comorbidities in Attention-Deficit/Hyperactivity Disorder (ADHD). Objective This study aimed to investigate the associations between sleep-disordered breathing (SDB) and behavioral and cognitive functions in children with and without ADHD. Methods A total of 341 children were included (ADHD group: 155, control group: 186; age: 6–10 years). The participants' sleep-related symptoms were assessed using a parent-rated questionnaire, and they were categorized into low- and high-risk SDB groups based on their scores. Behavioral symptoms were assessed using the Behavioral Assessment System for Children, Second Edition (BASC-2), and cognitive sustained attention and inhibitory control were assessed using a computer-based continuous performance test. Results In the ADHD group, the high-risk SDB children showed significantly higher scores than the low-risk SDB group in externalizing problems (F = 4.22; P = 0.042), including hyperactivity (F = 4.65; P = 0.033) and attention problems (F = 8.19; P = 0.005), but not internalizing problems. Meanwhile, in the control group, the high-risk SDB children showed significantly higher scores than the low-risk SDB group in internalizing problems (F = 9.89; P = 0.002), depression (F = 9.45; P = 0.002), and somatization (F = 7.83; P = 0.006), as well as in externalizing problems (F = 7.72; P = 0.006), including hyperactivity (F = 6.23; P = 0.013), aggression (F = 5.00; P = 0.027), and conduct problems (F = 6.79; P = 0.010). Contrary to the behavioral outcomes, none of the attention performance subscale scores showed significant differences between the high- and low-risk SDB groups in either the ADHD or control group. Conclusions The present findings suggest that SDB is associated with behavioral problems in children with ADHD and controls, with stronger associations in control children. On the contrary, SDB has no association with cognitive attention performance. This study extends our understanding of the associations of SDB with behavioral symptoms and cognitive functions in children.

Background: Depressive disorders have various symptom presentations, which may have complex and dynamic interactions. This study aimed to investigate the network structures underlying the symptoms and to identify the central symptoms of depression in school-aged children. Methods: Participants were a large community sample of elementary school children aged 6 to 12 years (N = 10,233). To assess the depressive symptoms, we utilized the Children's Depression Inventory (CDI). We binarized the scores on the CDI to generate a symptom network using the eLasso method, based on the Ising model. We evaluated the centralities in individual symptoms using the network centrality indices and the associations between symptoms. Results: Of the symptoms, loneliness, self-hatred, school dislike, and low self-esteem were the most central symptoms in the network of depressive symptoms. School work difficulty–school performance decrement, sadness–crying, self-hatred–negative body image, low self-esteem–fight, anhedonia–school dislike, sadness–loneliness, self-deprecation–school work difficulty, and school dislike–lack of friendship had significantly higher edge weight than most edges. The estimated network between the symptoms was robust to stability and accuracy tests. Limitations: Participants were not clinical but community samples, who show lower level of symptoms. Conclusion: The present symptom network analysis provided important insights on various interconnectivities between individual symptoms in childhood depression and on the central symptoms. In addition, our findings presented both similarities and differences with a previous Western study, thus, warranting future cross-cultural studies.

This study investigated the association between parental age at birth and attention-deficit/hyperactivity disorder (ADHD) symptoms in their children. A total of 30,552 children aged 6–12 years participated in the study. ADHD symptoms were rated using the Korean version of the ADHD Rating Scale (K-ARS) by parents. K-ARS scores and odds ratio (OR) for children with high-risk ADHD presented a U-shape curve depending on the age of both parents at birth. The total K-ARS scores and OR for high-risk ADHD were highest in children of fathers and mothers belonging to the youngest age group (aged ≤20) (K-ARS = 12.33, OR = 2.89 vs K-ARS = 10.98, OR = 2.63) and second highest in children whose father's or mother's age at birth was the oldest (K-ARS = 9.63, OR = 1.65 vs K-ARS = 9.95, OR = 1.95). Our study identified that both spectrums of age—young and old of either parent—were associated with ADHD in children. These are new findings considering that old age of parents as the correlates of offspring ADHD is the inconsistent finding with previous studies and warrant future studies in other cultures that include more detailed information on ADHD symptoms of children and their parents are needed to confirm the present findings.

Objective : Habitual snoring is a common problem in children. We evaluated the association between a high risk for sleep-disordered breathing and attention deficit/hyperactivity symptoms. Methods Parents of 13,560 children aged 6 to 12 years responded to questionnaires including items on habitual snoring and the Korean attention deficit/hyperactivity disorder rating scale. The snoring score comprised the number of "yes" responses to habitual-snoring items, and a high risk for sleep-disordered breathing was defined as a snoring score ≥ 2. Results The odds ratio (OR) of a high risk for sleep-disordered breathing was significantly higher in boys (OR = 1.47; p < 0.001), overweight children (OR = 2.20; p < 0.001), and children with current secondhand-smoking exposure (OR = 1.38; p < 0.001). The Korean attention deficit/hyperactivity disorder rating scale score increased significantly with the snoring score (0 vs. 1, B = 1.56, p < 0.001; 0 vs. 2, B = 2.44, p < 0.001; 0 vs. 3, B = 2.48, p < 0.001; 0 vs. 4, B = 3.95; p < 0.001). Conclusion Our study confirms several risk factors of sleep-disordered breathing, namely male sex, overweight, and exposure to tobacco smoking, and found a positive association between habitual snoring and attention deficit/hyperactivity symptoms.

Objective Bisphenol A (BPA) is a widely produced synthetic chemical used to manufacture polycarbonate plastics and epoxy resins. We aimed to investigate the association between exposure to BPA and behavioral and cognitive function in children with attention-deficit/hyperactivity disorder (ADHD) and healthy controls. Methods The study included 444 children aged from 6 to 10 years. The ADHD and control groups included 195 and 249 children, respectively. BPA levels were assessed via urinalysis, while behavior was assessed using the Korean version of the ADHD Rating Scale (K-ARS) and the Behavior Assessment System for Children (BASC-2). Cognitive function was assessed using the Continuous Performance Test (i.e., ADHD Diagnostic System [ADS]). Participants were categorized into tertile groups based on urinary BPA concentration. Results Scores on the K-ARS and the hyperactivity, aggression, anxiety, and depression subscales of the BASC-2 were significantly different among tertile groups for urinary BPA levels. Scores on visual omission error, commission error, response time variability, and auditory commission error of the ADS were significantly different among three BPA groups. Subgroup analysis revealed that these differences of behavior and cognition among three BPA groups were observed in only boys and normal controls. Conclusion Exposure to BPA was associated with unfavorable behavioral and cognitive outcomes. Our study extends the findings of previous studies regarding the association between BPA exposure and behavior/cognitive function by including children with ADHD. Further studies are required to determine the mechanisms underlying sex- and group-based differences in these associations.

Introduction: We used data from MOBI-Kids, a 14-country international collaborative case-control study of brain tumors (BTs), to study clinical characteristics of the tumors in older children (10 years or older), adolescents and young adults (up to the age of 24). Methods: Information from clinical records was obtained for 899 BT cases, including signs and symptoms, symptom onset, diagnosis date, tumor type and location. Results: Overall, 64% of all tumors were low-grade, 76% were neuroepithelial tumors and 62% gliomas. There were more males than females among neuroepithelial and embryonal tumor cases, but more females with meningeal tumors. The most frequent locations were cerebellum (22%) and frontal (16%) lobe. The most frequent symptom was headaches (60%), overall, as well as for gliomas, embryonal and 'non-neuroepithelial' tumors; it was convulsions/seizures for neuroepithelial tumors other than glioma, and visual signs and symptoms for meningiomas. A cluster analysis showed that headaches and nausea/vomiting was the only combination of symptoms that exceeded a cutoff of 50%, with a joint occurrence of 67%. Overall, the median time from first symptom to diagnosis was 1.42 months (IQR 0.53-4.80); it exceeded 1 year in 12% of cases, though no particular symptom was associated with exceptionally long or short delays.Conclusions: This is the largest clinical epidemiology study of BT in young people conducted so far. Many signs and symptoms were identified, dominated by headaches and nausea/vomiting. Diagnosis was generally rapid but in 12% diagnostic delay exceeded 1 year with none of the symptoms been associated with a distinctly long time until diagnosis. This work was supported by the MOBI-Kids study and the work in this study was obtained from the European Community's Seventh Framework Programme under Grant Agreements Number 226873—the MOBI-Kids Project—and 603794—the GERoNiMO project. Additional funds for the coordination of MOBI-Kids were obtained from the Spanish Ministry of Science and Innovation (MINECO), while complementary funds for the conduct of MOBI-Kids in Spain were obtained from the Spanish Health Research Fund (FIS) of the National Institute for Health Carlos III. Italian participation is partially supported by a Ministry of Health grant (RF-2009-1546284). In Canada, funding was provided by a grant from the Canadian Institutes for Health Research under a peer-reviewed university-industry partnership program that involved the Canadian Wireless Telecommunications Association, who provided technical data on wireless telecommunications practices in Canada. The German study centre received additional support by the Federal Office for Radiation Protection (BfS). Japanese participation in MOBI-Kids was supported by the Ministry of Internal Affairs and Communications. New Zealand participation was supported by Health Research Council and Cure Kids. In France, this study received funds from the French National Agency for Sanitary Safety of Food, Environment and Labour (ANSES, contract FSRF2008-3), French National Cancer Institute (INCa), Pfizer Foundation and League against cancer. India received funding from Board of Research in Nuclear Sciences (BRNS). The funding sources had no role in: the study design; the collection, analysis, and interpretation of data; the writing of the report; and the decision to submit the article for publication.

This study evaluated the time trends in mobile phone subscriber number by mobile network generation (G) and brain cancer incidence by type in Korea. We obtained data from the Information Technology Statistics of Korea (1984-2017) and Korea Central Cancer Registry (1999-2017). The average annual percent change was estimated using Joinpoint regression analysis. We evaluated 29,721 brain cancer cases with an age-standardized incidence rate (ASR) of 2.89/100,000 persons. The glioma and glioblastoma annual ASR significantly increased in 2.6% and 3.9% of males and 3.0% and 3.8% of females, respectively. The ASR for frontal lobe involvement was the highest. The ASR of gliomas of unspecified grade annually increased by 7.8%; those for unspecified topology and histology decreased. The incidence of glioma, glioblastoma, frontal, temporal, and high-grade glioma increased among those aged ≥60 years. No association was observed between the mobile phone subscriber number and brain cancer incidence in Korea. Furthermore, long-term research is warranted because of the latency period of brain cancer. © 2021 Bioelectromagnetics Society.

Purpose This study evaluated the association between night-shift work (NSW) and breast cancer risk as well as subtypes of breast cancer in Korean women. Patients and methods The study population included 1721 female breast cancer cases and 1721 female controls matched by age. The subtypes of breast cancer were determined based on estrogen, progesterone, and human epidermal growth factor receptor 2 statuses by reviewing pathology reports. Odds ratios (ORs) for NSW experience, age at commencement of NSW, frequency, and duration were estimated using conditional logistic regression and were adjusted for confounders such as parity and socioeconomic status-related factors. Results Among 1721 pairs, 10.58% of cases and 9.59% of controls had ever engaged in NSW. NSW was not associated with breast cancer risk in terms of ever having night-shift exposure (adjusted OR was 1.11, 95% confidence interval [CI] =0.89-1.40), duration, frequency, or cumulative working time. The OR for >10 years of lifetime duration of NSW was 1.55 (95% CI 0.89-2.69, P=0.124). In addition, the OR for >35,000 hrs for cumulative frequency of night work was OR=1.42 (95% CI=0.73-2.74, P=0.304). There was no heterogeneity in ORs of ever having NSW and cumulative duration of NSW between four subtypes of breast cancer. Conclusion NSW including long-term and heavy working exposure was not associated with breast cancer risk.

Results from studies evaluating potential effects of prenatal exposure to radio-frequency electromagnetic fields from cell phones on birth outcomes have been inconsistent. Using data on 55,507 pregnant women and their children from Denmark (1996-2002), the Netherlands (2003-2004), Spain (2003-2008), and South Korea (2006-2011), we explored whether maternal cell-phone use was associated with pregnancy duration and fetal growth. On the basis of self-reported number of cell-phone calls per day, exposure was grouped as none, low (referent), intermediate, or high. We examined pregnancy duration (gestational age at birth, preterm/postterm birth), fetal growth (birth weight ratio, small/large size for gestational age), and birth weight variables (birth weight, low/high birth weight) and meta-analyzed cohort-specific estimates. The intermediate exposure group had a higher risk of giving birth at a lower gestational age (hazard ratio = 1.04, 95% confidence interval: 1.01, 1.07), and exposure-response relationships were found for shorter pregnancy duration (P < 0.001) and preterm birth (P = 0.003). We observed no association with fetal growth or birth weight. Maternal cell-phone use during pregnancy may be associated with shorter pregnancy duration and increased risk of preterm birth, but these results should be interpreted with caution, since they may reflect stress during pregnancy or other residual confounding rather than a direct effect of cell-phone exposure. The Generalized EMF Research Using Novel Methods (GERoNiMO) Project was supported by the European Union (grant 603794). The Amsterdam Born Children and Their Development Study (ABCD) was supported by the Netherlands Organization for Health Research and Development (grant 2100.0076) and the Electromagnetic Fields and Health Research program (grants 85600004 and 85800001). The Danish National Birth Cohort Study (DNBC) was supported by the Danish Epidemiology Science Centre, the Lundbeck Foundation (grant 195/04), the Egmont Foundation, the March of Dimes Birth Defect Foundation, the Augustinus Foundation, and the Medical Research Council (grant SSVF 0646). The Spanish Environment and Childhood Project (INMA) was supported by the European Union (grants FP7-ENV-2011, 282957, and HEALTH.2010.2.4.5-1); Instituto de Salud Carlos III (grants G03/176, CB06/02/0041, FIS-FEDER 03/1615, 04/1509, 04/1112, 04/1931, 05/1079, 05/1052, 06/1213, 07/0314, 09/02647, 11/01007, 11/02591, CP11/00178, FIS-PI06/0867, FIS-PS09/00090, FIS-PI041436, FIS-PI081151, FIS-PI042018, FIS-PI09/02311, FISPI13/1944, FIS-PI13/2429, FIS-PI14/0981, FIS-PI13/141687, CP13/00054 (including FEDER funds), and MS13/00054); the Conselleria de Sanitat Generalitat Valenciana; the Generalitat de Catalunya (grants CIRIT1999SGR and 00241); Obra Social Cajastur; the Universidad de Oviedo; the Department of Health of the Basque Government (grants 2005111093 and 2009111069); and the Provincial Government of Gipuzkoa (grants DFG06/004 and DFG08/001). The Korean Mothers and Children’s Environment Health Study (MOCEH) was supported by the National Institute of Environmental Research, the Ministry of the Environment, and the Information and Communication Technology (ICT) research and development program of the Ministry of Science and ICT (grants 2017-0-00961 and 2019-0-00102), South Korea.

Perfluoroalkyl acids (PFAAs) have been widely used in human environment, and their exposure among general population has been frequently reported. However, extent of PFAAs exposure and their potential effects among children are not well characterized. In this study, children of between 3 and 18 years of age (n = 150) were recruited in Seoul and Gyeonggi, Korea, and the serum levels of 16 PFAAs along with lipids and thyroid hormones were measured. Questionnaire survey was conducted for dietary and behavioral characteristics of the children. Among the measured PFAAs, PFOA, PFNA, PFHxS, and PFOS were detected in all the samples, and PFUnDA and PFDA were detected in over 75% of the samples. PFOS was detected at the highest concentration with a median of 5.68 ng/mL. PFUnDA was detected at higher levels (median of 0.652 ng/mL) compared to those reported for children in USA. Serum PFAA levels were not different by sex among the children of10 years of age, but in older children, those of boys are significantly higher than girls. Physiological characteristics like menstruation may explain lower PFAAs levels of the girls. In addition, breastmilk consumption, fish/shellfish consumption, non-stick frying pan use, and waterproof cloth use were identified as potential sources of PFAAs exposure. Serum PFUnDA level was positively associated with total cholesterol and low-density lipoprotein level of the children. PFNA was positively associated with free T4 level. High levels of PFUnDA among children and its association with serum lipids warrant replication and confirmation in other populations and/or supports by experimental studies.

Background: There have been few studies of children's cognitive development in relation to mothers' cell phone use, and most were limited to outcomes at age 3 years or younger. We examined the relationship between maternal cell phone use during pregnancy and cognitive performance in 5-year old children. Methods: This study included data from 3 birth cohorts: the Danish National Birth Cohort (DNBC) (n = 1209), Spanish Environment and Childhood Project (INMA) (n = 1383), and Korean Mothers and Children's Environment Health Study (MOCEH) (n = 497). All cohorts collected information about maternal cell phone use during pregnancy and cognitive performance in children at age 5. We performed linear regression to compute mean differences (MD) and 95% confidence intervals (CI) in children's general, verbal, and non-verbal cognition scores comparing frequency of maternal prenatal cell phone use with adjustments for numerous potential confounding factors. Models were computed separately for each cohort and using pooled data in meta-analysis. Results: No associations were detected between frequency of prenatal cell phone use and children's cognition scores. Scores tended to be lower in the highest frequency of use category; MD (95% CI) in general cognition scores were 0.78 (−0.76, 2.33) for none, 0.11 (−0.81, 1.03) for medium, and −0.41 (−1.54, 0.73) for high compared to low frequency of use. This pattern was seen across all cognitive dimensions, but the results were imprecise overall. Conclusion: We observed patterns of lower mean cognition scores among children in relation to high frequency maternal prenatal cell phone use. The causal nature and mechanism of this relationship remain unknown. Keywords: Cell phones, Children, Cognition, Pooled analysis, Meta-analysis, Intelligence

The present study investigated associations between urinary cotinine levels as a biomarker of secondhand smoke exposure and symptoms of attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD).A total of 520 child participants (200 with ADHD, 67 with ASD, and 253 normal control subjects) were assessed using the Korean version of the ADHD rating scale (K-ARS), Autism spectrum screening questionnaire (ASSQ), and Behavioral Assessment System for Children, second edition (BASC-2). The Korean version of the computer-based continuous performance test was used to assess cognitive function. Urinary cotinine was evaluated as a biomarker of secondhand smoke exposure.Urinary cotinine levels were significantly and positively associated with K-ARS score (B = 4.00, p 0.001), ASSQ score (B = 1.71, p = 0.030), the behavioral problem subscales of the BASC-2 (B = 1.68-3.52, p 0.001-0.045), and omission and commission errors in the continuous performance test (B = 6.21-8.42, p 0.001-0.019). Urinary cotinine levels were also associated with the increased odds ratio of ADHD (OR = 1.55, 95% CI 1.05-2.30, p = 0.028) and ASD (OR = 1.89, 95% CI 1.12-3.21, p = 0.018).Urinary cotinine levels were associated with lower behavioral adaptation and cognitive function and increased odds ratios of ADHD and ASD, indicating a negative effect of secondhand smoke exposure on the symptomatic manifestation of ADHD and ASD.

Brain tumours (BTs) are one of the most frequent tumour types in young people. We explored the association between tap water, exposure to trihalomethanes (THM) and nitrate and neuroepithelial BT risk in young people. Analysis of tap water consumption were based on 321 cases and 919 appendicitis controls (10–24 years old) from 6 of the 14 participating countries in the international MOBI-Kids case-control study (2010–2016). Available historical residential tap water concentrations of THMs and nitrate, available from 3 countries for 86 cases and 352 controls and 85 cases and 343 for nitrate, respectively, were modelled and combined with the study subjects’ personal consumption patterns to estimate ingestion and residential exposure levels in the study population (both pre- and postnatal). The mean age of participants was 16.6 years old and 56% were male. The highest levels and widest ranges for THMs were found in Spain (residential and ingested) and Italy and in Korea for nitrate. There was no association between BT and the amount of tap water consumed and the showering/bathing frequency. Odds Ratios (ORs) for BT in relation to both pre- and postnatal residential and ingestion levels of THMs were systematically below 1 (OR = 0.37 (0.08–1.73)) for postnatal average residential THMs higher than 66 μg/L. For nitrate, all ORs were above 1 (OR = 1.80 (0.91–3.55)) for postnatal average residential nitrate levels higher than 8.5 mg/L, with a suggestion of a trend of increased risk of neuroepithelial BTs with increasing residential nitrate levels in tap water, which appeared stronger in early in life. This, to our knowledge, is the first study on this topic in young people. Further research is required to clarify the observed associations.

Background Prenatal exposure to bisphenol A (BPA) and phthalates could trigger immune response. Few studies have investigated the association between prenatal BPA and phthalate exposure and atopic dermatitis (AD) in infants. Objective We aimed to clarify the joint association of prenatal exposure to BPA and phthalate metabolites with AD incidence in 6-month-old infants. Methods We included 413 mother-child pairs from the Mothers and Children's Environmental Health (MOCEH) in a prospective birth cohort study. Maternal urinary BPA, mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP), and mono-n-butyl phthalate (MnBP) concentrations were measured during early and late pregnancy. We applied the Bayesian kernel machine regression (BKMR) with probit regression to estimate the association of BPA and phthalate metabolites with AD incidence after adjusting for potential confounders. Individual association was estimated by differences in predicted probabilities comparing each individual chemical concentration at 75th versus 25th percentiles, while other chemicals were set at their median. Overall joint effect was estimated by differences in predicted probabilities comparing all chemical concentrations at 75th versus 25th percentiles. Results Individual effect of MEHHP in late pregnancy was strongly associated with incident AD [Difference: 0.244 (95% credible interval: −0.066, 0.554)] in the model including both early and late exposures. Furthermore, we confirmed overall joint association of urinary BPA and phthalate metabolites during pregnancy with a higher risk of AD [0.347 (0.168, 0.526) for late pregnancy exposure, and 0.307 (0.094, 0.521) for both early and late pregnancy]. Additionally, the joint association was more prominent among girls than that in boys. Conclusions The joint association of prenatal exposure to BPA and phthalates could be associated with the incident AD in 6-month-old infants. Further studies are needed to confirm the synergistic effect of BPA and phthalate exposures on AD in children.

Aims: Bisphenol A (BPA)-based dental composites have commonly been used to fill dental cavities or seal pits and fissures on teeth. However, epidemiological evidence with regard to the BPA exposure from dental composites among children has rarely been reported. This study investigated whether there is a relationship between the BPA concentration in urine and the presence of composite restorations and sealants among South Korean children. Methods: Oral examinations and urine sample analyses were conducted on a total of 495 children aged 8–9 years. We classified the participants into four groups by the number of resin composites and sealant surfaces (0, 1–5, 6–10 and 11+). Results: BPA concentrations in urine were higher in children with 11 or more surfaces restored with sealants and resin composites than in those with zero restored surfaces, although no difference was seen in the group with 1–10 surfaces. After adjusting for gender and age, the urinary BPA concentration in children with 11 or more resin composite surfaces was 2.67 lg ⁄ g creatinine, which was higher than the concentration found in those with no filling surfaces ( P< 0.01). Conclusions: Having many dental composite filling surfaces on teeth may increase the urinary BPA concentration in children.

Background Prenatal exposure to polycyclic aromatic hydrocarbons (PAH) has been linked to allergic disease onset. Variations in the glutathione S-transferase (GST) gene family can impact the progression of allergic diseases. We sought to examine the association between prenatal PAH exposure and infantile allergic diseases in 6-month-old infants, and how maternal glutathione S-transferase M1 (GSTM1) or T1 (GSTT1) polymorphism affects the association between prenatal PAH exposure and allergic diseases in the Mothers and Children's Environmental Health (MOCEH) study. Methods The study sample comprised 349 infants and their mothers from the MOCEH study, for whom 1-hydroxypyrene (1-OHP) and 2-naphthol were measured in both the early period of pregnancy and late period of pregnancy. An infant was deemed to be affected by an allergic disease if diagnosed with or if developed at least one of the allergic diseases. A logistic regression analysis was performed to study the association between urinary 1-OHP and 2-naphthol levels during pregnancy and allergic diseases in 6-month-old infants. Furthermore, analyses stratified by maternal GSTM1 or GSTT1 present/null polymorphisms were performed. Results The risk of allergic diseases in 6-month-old infants was significantly increased in accordance with an increase in urinary 1-OHP during the early period of pregnancy (odds ratio [OR]: 1.84; 95% confidence interval [CI]: 1.05, 3.23; by one log-transformed unit of 1-OHP μg/g creatinine). The increased risk of infantile allergic diseases associated with urinary 1-OHP during the early period of pregnancy was limited to the maternal GSTT1 null type (OR: 2.69; 95% CI: 1.17, 6.21, by one log-transformed unit of 1-OHP μg/g creatinine); however, the Relative Excess Risk due to Interaction was not statistically significant. Conclusions The present study found that infantile allergic diseases could be affected by intrauterine PAH exposure, particularly in the early prenatal period and the risk was limited to the maternal GSTT1 null type.

OBJECTIVE We aimed to investigate symptom trajectory of attention-deficit hyperactivity disorder (ADHD) in Korean school-age children. METHODS Four hundred fifty six elementary school children were enrolled when they were in 1st grade and assessed once per year until 4th grade. Symptom severity was assessed by parents using the Korean version of the ADHD rating scale (K-ARS). High-risk was defined as a K-ARS score >18; 377, 325, and 284 children participated in the subsequent assessments. Symptom trajectory was analyzed using a mixed-model approach consistent with the longitudinal nature of the present study including missing data. RESULTS K-ARS scores demonstrated significant main effects of time (F=35.33; p

A systematic review was conducted to provide an overview of the health effects of occupational radiation exposure from interventional fluoroscopy procedures on medical radiation workers. Among the 34 studies that met the inclusion criteria, most studies were cross-sectional (76%) and published after 2011 (65%) in a handful of countries. Although diverse outcomes were reported, most studies focused on cataracts. Radiation health effects were rarely assessed by risk per unit dose. Interventional radiation medical workers represent a small subset of the population studied worldwide. Further epidemiologic studies should be conducted to evaluate health outcomes among interventional radiation medical workers.

Objectives In this prospective cohort study, the effects of prenatal Hg exposure on neurocognitive development during the first 3 years of life were investigated. Methods The maternal blood levels of Hg were assessed during pregnancy and in cord blood. Maternal fish intake was assessed by interviewing the weekly frequency of fish intake during pregnancy. Maternal n-3 and n-6 fatty acid intake was estimated based on 24 h recall food intake interview. The mental (MDI) and psychomotor (PDI) development index scores were assessed using the Bayley Scales of Infant Development at 6, 12, 24, 36 months of age. Results The geometric mean of the maternal blood Hg concentration was 3.3 μg/L (10th percentile = 1.81; 90th = 5.91) during the early pregnancy, 3.0 μg/L (10th = 1.68; 90th = 5.57) during late pregnancy, and 5.1 μg/L (10th = 2.94; 90th = 8.93) in cord blood. After adjusting for weekly frequency of fish intake, the blood Hg concentrations during early pregnancy showed association with the adjusted MDI (β = − 0.408, p = 0.048) and PDI scores (β = − 0.550, p = 0.031) at 6 months. After further adjusting for n-3 and n-6 fatty acids estimated based on 24 h recall of food intake, the blood Hg concentrations during early pregnancy showed association with the MDI (β = − 0.489, p = 0.026) and PDI (β = − 0.664, p = 0.015) at 6 months. Conclusion These results show that prenatal Hg exposure during early pregnancy adversely associated with early neurodevelopment during infancy, after adjusting for fish and n-3, n-6 fatty acid intake. Consuming fish high in fatty acids and low in Hg during early pregnancy may be important to neurocognitive development at early infancy.

The objective of this study was to investigate stability of cognitive development during the first five years of life in relation to heavy metal concentrations in umbilical cord blood in Korean children. This research is part of the Mothers' and Children's Environmental Health (MOCEH) study, a multi-center prospective birth cohort study of pregnant women in Korea who were recruited from 2006 to 2010. We analyzed the complete follow-up data of children who were 5years-old in 2016. We measured lead, mercury, and cadmium levels in the umbilical cord blood of 251 children, and analyzed them, for whom neurodevelopmental data were available. We determined stability of cognitive development scores using three methods. First, we used partial correlation analyses to examine the stability of cognitive development at each measurement time. Second, we used Cramer's V to investigate the magnitude and direction of changes in cognitive development scores at each follow-up period among three groups (high, medium, and low scores). The results showed that cognitive development scores measured at the closest times had the strongest correlations, and the stability of cognitive development scores increased with age, from 6 to 60months. Groups at the extreme ends of cognitive development (high or low scores) had more stable scores, and this tendency was also stronger in infants >24months-old. The stability of cognitive development was unrelated to the umbilical cord level of heavy metals, based on analysis with Fisher's transformation. In conclusion, the present study showed that the cognitive development scores in a cohort of infants (6 to 60months-old) were stable.

This study aimed to estimate the radiation organ doses from occupational exposure in 94 396 Korean medical radiation workers. Data on badge doses (i.e. personal dose equivalent at 10 mm) between 1996 and 2011 obtained from a national dosimetry registry, survey data from 2012 to 2013, and organ dose conversion coefficients provided by the International Commission on Radiological Protection (ICRP) were used for the estimation. The highest mean cumulative badge doses (26.87 mSv) were observed in radiologists, followed by radiologic technologists (15.96 mSv). Male workers exhibited higher mean cumulative badge doses, across occupational groups. The estimated organ doses showed similar trends with those of badge doses. Organs located outside the apron’s coverage such as the thyroid showed higher mean organ doses than those protected by the apron. Our findings could contribute to future radiation epidemiologic studies to investigate health effects from occupational radiation exposure in Korea.

This study evaluated risk factors for sustained psychological symptoms in affected residents, nine years after the Hebei Spirit oil spill in Korea in 2007. The participants included residents of high-exposure areas, living within 2 km from the contaminated coast (n = 2013), among the cohort of the Health Effect Research on Hebei Spirit oil spill study from 2009 to 2016. Symptoms for post-traumatic stress disorder (PTSD), depression, psychosocial distress, and anxiety, as well as sociodemographic information were assessed through questionnaire interviews. Trajectory analysis was conducted to identify the group with sustained symptoms over time and logistic regression analysis was performed to identify risk factors for sustained symptoms adjusted for covariates. A longer duration of clean-up work, lower household income, and presence of a chronic disease in all type of symptoms, and being female, younger age, and higher educational level in all symptoms but PTSD, showed a significant association with increased risk of sustained symptoms. The highest risk was found in the subgroup with a longer clean-up together with offshore and maritime occupations or lower income in PTSD, depression, and anxiety, compared with those with a shorter clean-up and other occupation or higher income. Increased risk of sustained PTSD in relation to a longer clean-up was limited to those with a lower educational level (p-interaction = 0.009). The results suggested that participating longer in clean-up work increased sustained psychological symptoms, synergistically with socioeconomic factors such as offshore and maritime occupations, lower household income, or economic losses related to educational level.

Hyperlipidemia is a known risk factor for cardiovascular diseases. A common biologic mechanism between systemic diseases, such as cardiovascular diseases, and periodontal diseases has been suggested. The aim of this study is to examine the association between blood lipid profile and periodontitis.The study included 6,905 Korean adults, aged ≥ 20 years. Individuals with incomplete data on blood lipid levels, those who lacked results of periodontitis examination using the Community Periodontal Index system in the Fifth Korean National Health and Nutrition Examination Survey for 2010 and 2012 and those diagnosed with diabetes mellitus, hypertension, and hyperlipidemia were excluded from the study. All analyses involved complex sampling design. The association was assessed using multiple logistic regression analysis adjusted for covariates.Women with low high-density lipoprotein (HDL) cholesterol levels showed a significantly higher risk of periodontitis (odds ratio (OR) [95% confidence interval (CI)]: 1.65 [1.03 to 2.66] for the lowest group) than those with high HDL levels. Women with high low-density lipoprotein (LDL) cholesterol levels showed a higher risk of the disease (OR [95% CI]: 2.38 [1.01 to 5.60] for the highest group) than those with low LDL levels. There were significant dose-response relationships between disease risk and levels of HDL and LDL (P trend of 0.001 and 0.04, respectively). There was no significant difference in the risk between pre- and postmenopausal women. Men did not show any significant association between blood lipid levels and periodontitis.There was a significant association between periodontitis and low HDL and high LDL cholesterol levels in women. J Periodontol 2018;89:000-000.

Background Studies examining prenatal exposure to mobile phone use and its effect on child neurodevelopment show different results, according to child's developmental stages. Objectives To examine neurodevelopment in children up to 36 months of age, following prenatal mobile phone use and radiofrequency radiation (RFR) exposure, in relation to prenatal lead exposure. Methods We analyzed 1198 mother-child pairs from a prospective cohort study (the Mothers and Children's Environmental Health Study). Questionnaires were provided to pregnant women at ≤20 weeks of gestation to assess mobile phone call frequency and duration. A personal exposure meter (PEM) was used to measure RFR exposure for 24 h in 210 pregnant women. Maternal blood lead level (BLL) was measured during pregnancy. Child neurodevelopment was assessed using the Korean version of the Bayley Scales of Infant Development-Revised at 6, 12, 24, and 36 months of age. Logistic regression analysis applied to groups classified by trajectory analysis showing neurodevelopmental patterns over time. Results The psychomotor development index (PDI) and the mental development index (MDI) at 6, 12, 24, and 36 months of age were not significantly associated with maternal mobile phone use during pregnancy. However, among children exposed to high maternal BLL in utero , there was a significantly increased risk of having a low PDI up to 36 months of age, in relation to an increasing average calling time (p-trend=0.008). There was also a risk of having decreasing MDI up to 36 months of age, in relation to an increasing average calling time or frequency during pregnancy (p-trend=0.05 and 0.007 for time and frequency, respectively). There was no significant association between child neurodevelopment and prenatal RFR exposure measured by PEM in all subjects or in groups stratified by maternal BLL during pregnancy. Conclusions We found no association between prenatal exposure to RFR and child neurodevelopment during the first three years of life; however, a potential combined effect of prenatal exposure to lead and mobile phone use was suggested.

In December 2007, the Hebei Spirit oil spill occurred on the west coast of South Korea. Association between crude oil exposure and the levels of urinary oxidative stress biomarkers was reported among the local residents, 1.5 years after the accident. The aim of this study was to follow-up possible longer-term effects of the oil spill among the residents near the oil spill. Six years after the accident, urinary oxidative stress biomarkers of the residents were associated with surrogates of oil exposure. The target subjects were divided into two groups based on the distance of their residence to the spill site, i.e., those near the spill site (‘Near’ group, n = 476), and those far from the spill (‘Far’ group, n = 152). A questionnaire was administered by trained interviewers or self-reporting, and demographic information and other parameters of the participants, such as socioeconomic status, smoking and drinking behaviors, disease history, and duration of clean-up activities after the spill, were collected. The participants' levels of 8–hydroxy–2–deoxyguanosine (8–OHdG) and malondialdehyde (MDA) in 12 h urine samples were measured as indicators of oxidative DNA damage and lipid peroxidation, respectively. A general linear model was used for statistical analysis. Urinary MDA and 8-OHdG levels measured from ‘Near’ group, i.e., geometric mean of 2.19 μmol/g creatinine, and 5.41 μg/g creatinine, respectively, were higher than those of ‘Far’ group. Especially, urinary 8-OHdG levels in the ‘Near’ group were significantly higher than those of ‘Far’ after adjusting relevant covariates. In addition, the duration of clean–up activities showed a significant association with both urinary 8–OHdG and MDA levels. Even 6 years after the oil spill, positive associations between oxidative stress biomarkers and surrogates of oil exposure were evident. While the present study design lacks biomarkers of exposure, the results of this study suggest that the consequences of oil pollution may last for years.

Background: The Mothers and Children's Environmental Health study (MOCEH) is a multi-centric prospective birth cohort study investigating effects of various environmental pollutants like heavy metals, endocrine disruptors, air pollutants, nutrition and lifestyle on birth outcomes, growth and development, health and disease of children. In this study, we report all the outcomes from the MOCEH study describing the different environmental pollutants affecting children’s health and disease. Methods: In MOCEH study, 1,751 pregnant women in their first trimester were recruited at 3 centers from 2006 to 2010 in South Korea. The children were followed from birth up to 6 years. Information on health outcomes of children including birth parameters, demographic characteristics, medical and child-rearing history, and nutritional status, were repeatedly obtained through the follow-ups by questionnaires administration, clinical evaluation, and biological specimen collection and measurements. Prenatal and postnatal measurement in biospecimen, i.e., lead, mercury, cadmium, manganese, 1-hydroxypyrene, 2-naphthol, malonadialdehyde, hippuric acid, bisphenol A and phthalate metabolites, and measurement in air samples, i.e., particulate matter, nitrogen dioxide, and total volatile organic compounds were performed. Results: The results show the adverse effect of prenatal exposure to heavy metals like mercury, lead and cadmium on children’s physical, cognitive and neurobehavioral development. Exposure to endocrine disruptors, air pollution, second hand smoke, and mother’s lifestyle during pregnancy affects children’s growth and development. We also identified specific window periods of exposure of pollutants significantly related to children’s health outcomes. Conclusion: The collective results from MOCEH study provide strong scientific evidence that exposures to prenatal and postnatal environmental pollutants have a negative effect on growth and development of children, which will be useful in implementing effective national policy to improve children’s environmental health. Keywords: Birth cohort, Children Environmental health, Environmental pollutants

Background and aims Previous studies have suggested that mercury exposure and folate levels during pregnancy may influence early childhood neurodevelopment. Rapid catch-up growth in children is associated with an increased risk of pathological nervous system development. We evaluated whether the association between prenatal folate and mercury-related neuropsychological dysfunction was modified by growth velocity during childhood. Methods The Mothers and Children's Environmental Health (MOCEH) birth cohort study began in 2006 and by 2010, 1751 women had been enrolled before the second trimester of their pregnancy along with their partners. Participants visited the research center at birth and 6, 12, 24, and 36 months. We measured mercury levels in maternal and cord blood and folate in maternal serum. Questionnaires to evaluate the environment and health of their child were administered and anthropometric factors including body weight and height were measured. Certified investigators used the Bayley test to measure neurobehavioral outcomes. We calculated postnatal growth change as the change in infant weight for-age z-score between birth and 3 years. Multiple linear regression and mixed models were used to examine the association between mercury exposure and children's neurodevelopment as well as the modifying effects of folate and growth velocity. Results A total of 30.6% of children experienced rapid growth during the first 3 years of life. Median values of mercury in the low folate group were significantly higher in rapid growers (3.41 μg/L in maternal blood and 5.63 μg/L in cord blood) than in average/slow growers (3.05 μg/L in maternal blood and 5.19 μg/L in cord blood). Rapid growers were also significantly associated with decreased psychomotor development scores during the first 3 years of life and with having mothers who had low prenatal folate levels, even after adjusting for potential confounders. Conclusion Prenatal mercury exposure adversely affects infant neurodevelopment and is associated with rapid growth during the first 3 years of life. This effect was limited to children whose mothers had low prenatal folate levels, suggesting a protective effect of folate against developmental neurotoxicity due to mercury exposure and rapid catch-up growth.

Background Atopic dermatitis is a chronic and relapsing inflammatory skin disease. Although mercury has been suggested as a risk factor, the underlying mechanism and the relationship between mercury and atopic dermatitis remains unclear. The objective of the present study was to investigate the relationship between mercury exposure and the presence of atopic dermatitis in early childhood. Methods This study is part of the prospective Mothers and Children's Environmental Health cohort study. A total of 1,751 pregnant women were enrolled in Mothers and Children's Environmental Health. After delivery, children were followed up. Blood samples were collected and mothers were asked about the presence of atopic dermatitis in their children via a questionnaire at 6, 12, 24, 36, and 60 months of age. Results After excluding participants who did not meet the inclusion criteria, a total of 1,061 mother-children pairs were included in the analysis. The geometric mean of mercury concentrations in cord blood was 5.1 µg/L. In adjusted models, cord blood mercury exposure (odds ratio [OR] = 1.1; 95% confidence interval [CI] = 1.0, 1.2 at 12-24 months) and postnatal mercury exposure (OR = 1.2; 95% CI = 1.0, 1.5 at 24-36 months, OR = 1.4; 95% CI = 1.1, 1.8 at 48-60 months) were associated with the presence of atopic dermatitis in children. Conclusions Postnatal mercury exposure at 24 months of age increases the risk of atopic dermatitis in children.

Background The association between exposure to secondhand smoke (SHS) during pregnancy and a child’s neurodevelopment has not been established yet. We explored the association between prenatal exposure to SHS and neurodevelopment at 24 months of age considering genetic polymorphism and breastfeeding in 720 mothers and their offspring enrolled in the Korean multicenter birth cohort study (Mothers and Children Environmental Health, MOCEH). Methods We quantified urine cotinine concentrations in mothers once from 12th to 20th gestational weeks and excluded those whose urine cotinine levels exceeded 42.7 ng/ml to represent SHS exposure in early pregnancy. Mental developmental index (MDI) and psychomotor developmental index (PDI) values were measured using the Korean version of the Bayley Scales of Infant Development II (K-BSID-II) at 24 months of age. A general linear model was used to assess the relationship between maternal urinary cotinine level and neurodevelopment. Results MDI scores were inversely associated with cotinine [β = − 2.73; 95% confidence interval (CI): − 5.32 to − 0.15] in children whose mothers had early pregnancy urinary cotinine levels >1.90 ng/ml. No association was evident in children whose mothers had cotinine levels ≤1.90 ng/ml. This negative association was more pronounced in children whose mothers had both Glutathione S-transferases mu 1 (GSTM1) and theta 1 (GSTT1) null type [β = − 5.78; 95% CI: -10.69 to − 0.87], but not in children whose mothers had any present type of GSTM1/GSTT1 [β = − 1.64; 95% CI: -4.79 to 1.52]. The association was no longer significant when children received breast milk exclusively for up to 6 months [β = − 0.24; 95% CI: -4.69 to 4.20] compared to others [β = − 3.75; 95% CI: -7.51 to 0.00]. No significant association was found for PDI. Conclusions Maternal exposure to SHS during pregnancy may result in delayed MDI in early childhood. This effect might be modified by genetic polymorphism and breastfeeding behavior. Electronic supplementary material The online version of this article (10.1186/s12940-019-0463-9) contains supplementary material, which is available to authorized users.

This study investigated the social outcomes of the Environmental Health Studies of National Industrial Complex (EHSNIC), which have been conducted by the National Institute of Environmental Research (NIER) in eight National Industrial Complex Areas (NICAs) since 2003. Eighteen sessions of focus-group interviews with 85 people were conducted from October 2016 to January 2017. Interviewees were stakeholders from eight NICAs and included resident representatives, environmental nongovernment organizations, local government officials, and environmental health and safety officers from companies. Interview results were divided into six categories: EHSNIC awareness, EHSNIC outcomes, EHSNIC limitations, EHSNIC continuation, EHSNIC improvement directions, and EHSNIC results use. They were then further indexed into 23 divisions. EHSNIC awareness varied across stakeholders. A major EHSNIC outcome is that a continued result database was established, which was used as a reference for environmental improvements. EHSNIC limitations included no proper healthcare actions taken during the EHSNIC study period, a lack of EHSNIC results disclosure, a failure to reflect local specificity, and a lack of validity in the results. Regarding EHSNIC continuation, all stakeholders said EHSNIC should be conducted continuously. EHSNIC improvement directions included conducting studies tailored to each NICA, identifying correlations between pollutant exposure and disease, increasing the sample size, and performing repeated studies. Regarding EHSNIC results use, respondents wanted to use the results as a reference to relocate residents, ensure distance between NICAs and residential areas, provide healthcare support, develop local government policies, and implement firms’ environmental controls. Since EHSNIC aims to identify the health effects of NICAs on residents and take appropriate actions, it should be continued in the future. Even during the study period, it is important to take steps to preventively protect residents’ health. EHSNIC also needs to reflect each NICA’s characteristics and conduct reliable research based on stakeholder participation and communication.

Background Increasing evidence shows that prenatal environmental exposures is a risk factor for restricted intrauterine growth. However, only a few studies have examined the effects of multiple environmental exposures on fetal growth. Objective To investigate the effects of prenatal exposure on multiple environmental pollutants (heavy metals, bisphenol, phthalates, and air pollutants) on birth weight. Methods The Mothers and Children's Environmental Health study is a prospective birth cohort comprising a total of 719 mother-child pairs, including 466 pairs undergoing early pregnancy exposure and 542 pairs of late pregnancy exposure. The concentrations of three heavy metals (mercury, lead, and cadmium) in the maternal blood samples were measured. The concentrations of three phthalate metabolites [mono(2-ethyl-5-hydroxyhexyl) phthalate, mono(2-ethyl-5-oxohexyl) phthalate, and mono-n-butyl phthalate] and bisphenol A in maternal urine samples were measured. Daily exposure to ambient particulate matter (PM10) and nitrogen dioxide (NO2) exposure was estimated based on residence and averaged by gestational age. To assess the combined effect of multiple pollutants, principal components analysis (PCA) and supervised principal components analysis (SCPA) were conducted. Results Based on PCA, the components representing PM10 and NO2 exposure during early pregnancy were significantly associated with birth weight of −32.68 g (95% CI: -64.45 g to −0.91 g) per unit increase of the corresponding component. In SCPA model, the components representing NO2 exposure during early pregnancy and the combined exposure to mercury and lead during late pregnancy were negatively associated with birth weight of −46.63 g (95% CI: -90.65 g to −2.62 g) and −55.32 g (95% CI: -99.01 g to −11.64 g), respectively, per unit increase of the corresponding component. Conclusion Based on our multi-pollutant model, PM10 and NO2 exposure in early pregnancy and the combined effect of Pb and Hg in late pregnancy were associated with reduced birth weight. Our results suggest that exposure to various pollutants during pregnancy has a significant cumulative effect on birth weight, even if each pollutant is at a level below the concentration required for direct effect.

The purpose of this review is to summarize the results of studies on of the association between exposure to dental X-rays and health risk. To perform the systematic review, We searched the PUBMED, EMBASE, and MEDLINE databases for papers published before December 15, 2016. A total of 2 158 studies, excluding duplicate studies, were found. Two reviewers independently evaluated the eligibility of each study. The final 21 studies were selected after application of exclusion criteria. In terms of health outcomes, there were 10 studies about brain tumors, 5 about thyroid cancer, 3 about tumors of head and neck areas, and 3 related to systemic health. In brain tumor studies, the association between dental X-ray exposure and meningioma was statistically significant in 5 of the 7 studies. In 4 of the 5 thyroid-related studies, there was a significant correlation with dental diagnostic X-rays. In studies on head and neck areas, tumors included laryngeal, parotid gland, and salivary gland cancers. There was also a statistically significant correlation between full-mouth X-rays and salivary gland cancer, but not parotid gland cancer. Health outcomes such as leukemia, low birth weight, cataracts, and thumb carcinomas were also reported. In a few studies examining health effects related to dental X-ray exposure, possibly increased risks of meningioma and thyroid cancer were suggested. More studies with a large population and prospective design are needed to elaborate these associations further.

Background Neighborhood greenness appears to be beneficial to human health. However, there are few studies on the relationship between greenness of children's residential communities and their neurobehavioral health. Objective In this cross-sectional study, we examined the association between neighborhood greenness of children's residential area and their neurobehavioral health. Methods We used a population-representative sample of school children (n = 1817) from 2012 and 2013 in South Korea. Parents or guardians of children completed the Child Behavior Checklist (CBCL) to assess their children's neurobehavioral health. As a measurement for greenness, the modified soil-adjusted vegetation index (MSAVI) at a 30-m resolution was retrieved from the Landsat satellite data operated by NASA. The MSAVI values were categorized into tertiles (low, moderate, high greenness) and each child was assigned the mean MSAVI within a 1.6-km radius of residence. We applied survey regressions of the CBCL transformed scores on the 3 levels of greenness, controlling for age, sex, physical activity, monthly family income, exposure to second-hand smoke, exposure to NO2, and blood lead level. Results High greenness was associated with a lower Total CBCL score compared to low greenness (−2.33, 95% CI, −4.10 to −0.56). Externalizing Behavior showed a slightly stronger association with greenness than did Internalizing Behavior. The inverse relationship with greenness was strongest for Attention Problems (−1.32; 95% CI: -2.58, −0.06). The magnitudes of the association were strongest when the buffer distance was 1600 m. Conclusions Greenness of residential neighborhood was associated with lower problematic behavior scores in children, especially aggressive behaviors and attention problems.

Concerns over adverse effects of air pollution on children's health have been rapidly rising. However, the effects of air pollution on childhood growth remain to be poorly studied. We investigated the association between prenatal and postnatal exposure to PM10 and children's weight from birth to 60 months of age. This birth cohort study evaluated 1129 mother-child pairs in South Korea. Children's weight was measured at birth and at six, 12, 24, 36, and 60 months. The average levels of children's exposure to particulate matter up to 10 μm in diameter (PM10) were estimated during pregnancy and during the period between each visit until 60 months of age. Exposure to PM10 during pregnancy lowered children's weight at 12 months. PM10 exposure from seven to 12 months negatively affected weight at 12, 36, and 60 months. Repeated measures of PM10 and weight from 12 to 60 months revealed a negative association between postnatal exposure to PM10 and children's weight. Children continuously exposed to a high level of PM10 (>50 μg/m3) from pregnancy to 24 months of age had weight z-scores of 60 that were 0.44 times lower than in children constantly exposed to a lower level of PM10 (≤50 μg/m3) for the same period. Furthermore, growth was more vulnerable to PM10 exposure in children with birth weight 3.3 kg. Air pollution may delay growth in early childhood and exposure to air pollution may be more harmful to children when their birth weight is low. Keywords: Air pollution, Particulate matter, Children growth, Weight

Objectives: No children-specified review and meta-analysis paper about the short-term effect of fine particulate matter (PM2.5) on hospital admissions and emergency department visits for asthma has been published. We calculated more precise pooled effect estimates on this topic and evaluated the variation in effect size according to the differences in study characteristics not considered in previous studies. Methods: Two authors each independently searched PubMed and EMBASE for relevant studies in March, 2016. We conducted random effect meta-analyses and mixed-effect meta-regression analyses using retrieved summary effect estimates and 95% confidence intervals (CIs) and some characteristics of selected studies. The Egger’s test and funnel plot were used to check publication bias. All analyses were done using R version 3.1.3. Results: We ultimately retrieved 26 time-series and case-crossover design studies about the short-term effect of PM2.5 on children’s hospital admissions and emergency department visits for asthma. In the primary meta-analysis, children’s hospital admissions and emergency department visits for asthma were positively associated with a short-term 10 μg/m3 increase in PM2.5 (relative risk, 1.048; 95% CI, 1.028 to 1.067; I2=95.7%). We also found different effect coefficients by region; the value in Asia was estimated to be lower than in North America or Europe. Conclusions: We strengthened the evidence on the short-term effect of PM2.5 on children’s hospital admissions and emergency department visits for asthma. Further studies from other regions outside North America and Europe regions are needed for more generalizable evidence.

ObjectivePolycyclic aromatic hydrocarbons (PAH) are common dietary exposures that cross the human placenta and are classified as a probable human carcinogen. The aim of the present study was to investigate the potential impact of exposure to PAH-containing meat consumed during pregnancy on birth outcomes.DesignProspective birth cohort study. Only non-smoking women with singleton pregnancies, who were free from chronic disease such as diabetes and hypertension, were included in the study. Maternal consumption of PAH-rich meat was estimated through FFQ. Multiple linear regression was used to assess factors related to higher intake and the association between dietary PAH and birth outcomes.SettingRepublic of Korea, 2006–2011.SubjectsPregnant women (n 778) at 12–28 weeks of gestation enrolled in the Mothers and Children’s Environmental Health (MOCEH) study.ResultsThe multivariable regression model showed a significant reduction in birth weight associated with higher consumption level of foods rich in PAH, such as grilled or roasted meat, during pregnancy (β=−17·48 g, PP=0·561). Regression models performed for birth length and head circumference produced negative effects that were not statistically significant.ConclusionsConsumption of higher levels of barbecued, fried, roasted and smoked meats during pregnancy was associated with reduced birth weight. Dietary risk of PAH exposure in Korean women is of concern.

Our objective is to evaluate the relationships between prenatal maternal stress and depressive symptoms, respectively, and infant neurodevelopment at 6 months, adjusted for heavy metals and oxidative stress. This research is a part of a multi-center birth cohort study in South Korea. Information on stress and depressive symptoms was collected during the first trimester using Psychosocial Well-Being Index Short Form (PWI-SF) and Center for Epidemiological Studies Depression Scale (CES-D). The Korean Bayley Scales of Infant Development-II assessment (BSID-II), which includes the standardized mental development index (MDI) and psychomotor developmental index (PDI), and Korean Ages & Stages Questionnaires (K-ASQ) were applied to infants at six months of age. A higher index score indicates better development. Among 641 babies, 320 were female (50%). Maternal PWI ≥ 29 (vs. PWI ≤ 18) during early pregnancy was associated with a decrease in MDI scores of 5.37 points (P = 0.02) after adjusting for socioeconomic factors. Maternal CES-D ≥ 26 (vs. CES-D ≤ 10) during early pregnancy was associated with a decrease in MDI scores of 8.18 points (P = 0.01). The associations remained significant even after adjustment for lead, cadmium, and MDA levels (P < 0.05). However, no association was found between maternal PWI/CES-D and PDI score. No interaction was observed between stress and lead exposure. We found an inverse association between prenatal maternal stress and depressive symptoms, and MDI scores in 6-month-old infants after adjustment for prenatal lead exposure, which is known to affect cognitive function negatively., Graphical Abstract

Background Exposure to mixture of neurotoxic metals such as lead, mercury and cadmium occurs at a specific point of time. When exposed to metal mixtures, one metal may act as an agonist or antagonist to another metal. Thus, it is important to study the effects of exposure to a combination of metals on children's development using advance statistical methods. Objectives In this study, we explored the effects of prenatal metal exposure including lead, mercury and cadmium in early pregnancy (12–20 weeks), late pregnancy (>28 weeks), and at birth on neurodevelopment of infants at 6 months of age. Methods We included 523 eligible mother-child pairs from the mothers and children environmental health (MOCEH) study, a prospective birth cohort study in Korea. We used linear regression, Bayesian kernel machine regression (BKMR) and generalized additive models (GAM), to evaluate the effects of exposure to metal mixtures on neurodevelopment of infants aged 6 months. The Korean version of Bayley scale of infant and toddler development-II was used to measure the child's neurodevelopment. Results Linear regression models showed a significant negative effect of lead exposure during late pregnancy on the mental development index (MDI) [β = -2.51 (−4.92, −0.10)] scores of infants aged 6 months following co-exposure to mercury. Further, linear regression analysis showed a significant interaction between late pregnancy lead and mercury concentrations. BKMR analysis showed similar results as those obtained in linear regression models. These results were also replicated in the GAM. Stratification analysis showed that greater than 50 percentile concentration of mercury in late pregnancy potentiated the adverse effects of lead in late pregnancy on MDI [β = −4.33 (−7.66, −1.00)] and psychomotor development index (PDI) [β = −5.30 (−9.13, −1.46)] at 6 months of age. Prenatal cadmium exposure did not show a significant association with MDI and PDI at 6 months in the linear regression or BKMR analysis. Conclusion Based on all the statistical methods used, we demonstrated the effect of combined exposure to metals on the neurodevelopment of infants aged 6 months, with significant interaction between lead and mercury.

Autism Spectrum Disorders is a syndrome with multiple causes and different mechanisms leading to abnormal development. Only a few longitudinal studies have investigated the associ...

Introduction: It is controversial whether RF (radiofrequency) exposure during pregnancy is hazardous to fetus. The aim of the present study is to elucidate the association between maternal RF expos...

Background/AimEnvironmental factors may play a role in the development of neurodevelopment and some studies have shown that ambient air pollution is associated with the autistic behaviours. The stu...

The Korean CHildren's ENvironmental health Study (Ko-CHENS) is a nationwide prospective birth cohort showing the correlation between the environmental exposures and the health effects to prevent the environmental diseases in children, and it provides the guidelines for the environmental hazardous factors, applying the life-course approach to the environmental-health management system. The Ko-CHENS consists of 5000 Core and 65,000 Main Cohorts. The children in the Core Cohort are followed up at 6 months, every year before their admission into the elementary school, and every 3 years from the first year after this admission. The children in the Cohort will be followed up through the data links (Statistics Korea, National Health Insurance Service [NHIS], and Ministry of Education). The individual biospecimens will be analyzed for 19 substances. The long-term-storage biological samples will be used for the further substance analysis. The Ko-CHENS will investigate whether the environmental variables including the perinatal outdoor and indoor factors and the greenness contribute causally to the health outcomes in the children and adolescents. In addition to the individual surveys, the assessments of the outdoor exposures and health outcomes will use the national air-quality monitoring data and claim data of the NHIS, respectively. The two big-data forms of the Ko-CHENS are as follows: The Ko-CHENS data that can be linked with the nationally registered NHIS health-related database, including the medical utilization and the periodic health screening, and the birth/mortality database in the Statistics; the other is the Big-CHENS dataset that is based on the NHIS mother delivery code, for which the follow-up of almost 97% of the total birth population is expected. The Ko-CHENS is a very cost-effective study that fully exploits the existing national big-data systems with the data linkage.

On December 7th, 2007, an estimated 12,547 kL of crude oil was spilled from the collision of Hebei Spirit near residential area. Our previous study demonstrated worsening of children's asthma symptoms one year after the accident. This study investigated long-term effect of the oil spill on children's asthma symptoms up to five years after the accident. All elementary and middle school students in the exposure area were surveyed on one year (n = 655), three years (664), and five years (611) after the accident. Oil spill exposure was estimated using two estimates including distance from the oil spill (A) and modeled estimates of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds (B), and each was dichotomously categorized (A: high-exposure vs low-exposure; B: ≥20 mg/m3 vs

Although studies have shown that a low socioeconomic status (SES) is associated with high blood lead levels (BLLs) in children, the mechanism underlying this observation is not well known. To determine how SES influences BLLs via environmental factors in Korean children, we conducted a population-based cross-sectional study of 4744 children aged 5&ndash, 13 years. Questionnaires on sociodemographic information, environmental factors, and food consumption were administered to the children&rsquo, s parents. BLLs in the study subjects were measured.The complete set of hypothesized associations was assessed using regression analysis and structural equation modeling. SES was associated with high BLLs. The total effects of nutritional factors, lead in the air and total length of nearby roads, and agriculture on BLLs were &minus, 0.062 (p &lt, 0.001), 0.068 (p = 0.005), and 0.038 (p = 0.035), respectively. The direct effects of playing outdoors and SES on BLLs were 0.113 (p &lt, 0.001) and &minus, 0.111 (p &lt, 0.001), respectively. Although playing outdoors had a greater direct effect on BLLs than did SES, the total effect of SES (standardized &beta, = &minus, 0.132, p &lt, 0.001) was greater than that of other sources owing to indirect effects (&beta, 0.020, p = 0.004). A low SES was a major risk factor for elevated BLLs via environmental factors.