Mina Ha

Association of maternal folate nutrition and serum C-reactive protein concentrations with gestational age at delivery

Background/objectives:C-reactive protein (CRP) is the most extensively studied inflammatory risk marker, and elevated serum CRP concentrations in pregnant women are known to be associated with subsequent development of preeclampsia and preterm delivery. Researchers have suggested that folate intake may help to control the inflammation process. We examined whether folate nutrition modifies the relationship between serum CRP concentration and gestational age at delivery.Subjects/methods:Serum CRP concentrations were analyzed in 815 pregnant women between 12 and 28 weeks of gestation. Dietary intakes were assessed using a 24-h dietary recall. The serum folate and high-sensitivity CRP concentrations were analyzed by radioassay and latex agglutination tests, respectively.Results:Serum CRP concentration was negatively correlated (P<0.001) with gestational age at delivery. Serum folate concentration was negatively correlated (P<0.01) with serum CRP concentration, and total dietary folate intake was positively correlated (P<0.001) with serum folate concentration. Multiple regression analysis after adjustment for covariates revealed that maternal CRP concentrations were negatively associated with gestational age at delivery; these negative associations existed only when folate intake during pregnancy was below the Korean estimated average requirements (520u2009μg dietary folate equivalent per day), and serum folate concentrations were above the normal (6u2009ng/ml).Conclusions:We found that adequate maternal folate intake during pregnancy may have a beneficial role against shorter gestational age at delivery, which is associated with higher serum CRP concentrations in pregnant women.

Air pollution interacts with past episodes of bronchiolitis in the development of asthma.

Exposure to ambient air pollution and bronchiolitis are risk factors for asthma. The aim of this study was to investigate the effect of air pollution on the development of asthma in children with past episodes of bronchiolitis.

Hebei spirit oil spill exposure and subjective symptoms in residents participating in clean-up activities.

Objectives This study was conducted to examine the relationship between crude oil exposure and physical symptoms among residents participating in clean-up work associated with the Hebei Spirit oil spill, 2007 in Korea. Methods A total of 288 residents responded to a questionnaire regarding subjective physical symptoms, sociodemographic characteristics and clean-up activities that occurred between two and eight weeks after the accident. Additionally, the urine of 154 of the respondents was analyzed for metabolites of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) and heavy metals. To compare the urinary levels of exposure biomarkers, the urine of 39 inland residents who were not directly exposed to the oil spill were analyzed. Results Residents exposed to oil remnants through clean-up work showed associations between physical symptoms and the exposure levels defined in various ways, including days of work, degree of skin contamination, and levels of some urinary exposure biomarkers of VOCs, metabolites and metals, although no major abnormalities in urinary exposure biomarkers were observed. Conclusions This study provides evidence of a relationship between crude oil exposure and acute human health effects and suggests the need for follow-up to evaluate the exposure status and long-term health effects of clean-up participants.

Children's mental health in the area affected by the Hebei Spirit oil spill accident

Objectives Children are one of the most vulnerable populations to the impact of disasters. We aimed to examine childrens mental health in the area affected by the Hebei Spirit oil spill accident on December 7, 2007. Methods A cross-sectional questionnaire survey was conducted using the Korean versions of the Childrens Depression Inventory and State Anxiety Inventory for Children on 1,362 children attending elementary schools in the affected area. The information on distances between the nearest contaminated coastline to the childs residential house or attending school were obtained using a web-based map by inputting two address points. The symptom risks of depression and state anxiety were estimated by multiple logistic regression analyses adjusted for age, gender, and other covariates. Results Children with the closest distance (in the fourth quartile) to the school from the contaminated coastline showed a significantly higher symptom risk of depression compared to those with the farthest distance (first quartile)(odds ratio, 2.73; 95% confidence interval, 1.40-5.33), while there was no significant association between anxiety symptoms and distance. Conclusions Children, a vulnerable population for mental health impact by the oil spill accident, should be included in mental health programs in the community along with their family as victims of the disaster.

Fruit and vegetable intake influences the association between exposure to polycyclic aromatic hydrocarbons and a marker of oxidative stress in pregnant women.

Background/Objectives:Exposure to polycyclic aromatic hydrocarbons (PAHs) during pregnancy is known to increase oxidative stress, which may influence pregnancy outcomes and health of the child.Subjects/Methods:This study investigated whether fruit and vegetable intake modifies the relationship between exposure to PAHs and oxidative stress status during pregnancy. Urinary levels of 2-naphthol and 1-hydroxypyrene (biomarkers of exposure to PAHs), and malondialdehyde (MDA; a biomarker of oxidative stress) were analyzed in 715 pregnant women at 12–28 weeks of gestation. The dietary antioxidant intake during pregnancy was estimated using the 24-h recall method. Urinary 2-naphthol, 1-hydroxypyrene and MDA levels were analyzed by high-performance liquid chromatography–fluorescence detection.Results:The urinary MDA level was positively correlated with the 2-naphthol level (r=0.255, P<0.001) and 1-hydroxypyrene level (r=0.240, P<0.001). Multiple regression analysis after adjustment for covariates revealed that the urinary 1-hydroxypyrene level was positively associated with the MDA level; these positive associations only existed in pregnant women, with either the fruit and vegetable intake or the vitamin C intake in the first tertile (<390.1u2009g/day) or in the first and second tertiles (<141.5u2009mg/day), respectively.Conclusions:These results suggest that an adequate maternal intake of fruit, vegetables and vitamin C is beneficial to the defense against the oxidative stress associated with exposure to PAHs in pregnant women.

Relationship among attention-deficit hyperactivity disorder, dietary behaviours and obesity

BACKGROUNDnAttention-deficit hyperactivity disorder (ADHD) is one of the most common psychiatric disorders of childhood and can be associated with obesity. The aim of this study was to reveal the connection between ADHD symptoms, food habits and obesity.nnnMETHODSnWe examined 12u2009350 children (6010 boys, 6340 girls) from 27 elementary schools in Cheonan, the Republic of Korea. The study subjects were 5- to 13-year-old children (9.4 ± 1.7 years). Parents completed the DuPaul ADHD Rating Scale. Food habits were measured by a questionnaire adapted from the Korea Youth Risk Behavior Web-based Survey and a validated mini-dietary assessment tool. The full set of hypothesized associations was tested using covariance structural modelling.nnnRESULTSnThe prevalence of ADHD was 7.6% and that of obesity was 4.5% in our study population. The data was well fit by the model. ADHD was associated with body mass index (BMI; standardized β = 0.086, P < 0.001). Bulimic dietary behaviours was related to BMI (standardized β = 0.548, P < 0.001). Socio-economic status was associated with BMI (standardized β = -0.017, P = 0.027).nnnCONCLUSIONnOur analysis suggested that ADHD was a risk factor for obesity through dietary behavioural change and socio-economic status.

Characteristics of Humidifier Use in Korean Pregnant Women: The Mothers and Children's Environmental Health (MOCEH) Study

Objectives The current use of humidifier detergent and its harmful impact on humans has arisen as a societal environmental health issue. Therefore, in this study we aimed to explore the relationship between demo-socio characteristics and humidifier use, as well as the monthly usage changes in pregnant women; thus, we report the actual status of humidifier usage of Koreas pregnant population. Methods From a birth cohort of a Mothers and Childrens Environmental Health (MOCEH) study, 1,144 pregnant women who responded through questionnaires including demo-socio characteristics, obstetric status and household environment including whether they use humidifier and frequency of use were included in this study. Statistical analyses were performed to explore the relationship between maternal characteristics and the relevance of the use of humidifiers was performed using a chi-square test, a t-test and univariate logistic regression analysis. The monthly usage rate was demonstrated in the graph. Results The humidifier usage rate in pregnant women was 28.2%. The average frequency of humidifier usage was 4.6 days per week, 7.3 hours per day. The usage rate was higher in the multipara group and the above the age of 34 age group than in the primipara and below the age of 34 groups. Seoul showed a higher usage rate than Cheonan and Ulsan and as the education level and income increased, the usage rate of humidifiers among pregnant women also increased. In the monthly trend of usage rate, the winter season showed the highest usage rate of over 45% and the lowest in late summer and beginning of fall with a value of 12% or less. Conclusions During pregnancy, the mothers body is especially vulnerable to hazardous environmental exposure that not only affects the pregnant woman but also the fetus. Further research is still needed to elucidate the route and effect of environmental risk factors. Therefore, based on precautionary and preventive principles, special interest and caution in harmful environments are strongly needed not only at an individual level but also at a national level.

Urinary metabolic profiling of volatile organic compounds in acute exposed volunteers after an oil spill in Republic of Korea

The Herbei Spirit oil spill occurred in western Korea. A large number of people who participated in the cleanup tasks of the contaminated area were exposed to crude oil component. We developed a method to monitor volatile organic compound (VOC) metabolites in urine, and evaluate the acute exposure caused by the oil spill in exposed volunteer workers (n = 100, 20.7 +/- 2.1 years, mean +/- SD). Acidified urine samples were extracted by SPE, derivatized with trimethylsilyl, and analyzed using gas chromatography-mass spectrometry. Calibration curves were found to be linear from 3 to 1000 ng/mL (r(2) > 0.993). Accuracy was over 82.4%, and precision was less than 24.8%. Using this method, the VOC metabolites, except hippuric acid, were present at higher levels in the urine samples of volunteers after cleanup work. The levels of mandelic acid (MA) and trans,trans-muconic acid (t,t-MU) were increased significantly (p < 0.001). The exposure effect was greater in women than in men. The effect of smoking was analyzed in all exposed and non-exposed groups, with non-smokers showing increased MA and t,t-MU levels related to exposure. The present method was reliable to determine VOC metabolites in urine and could be useful for biomonitoring of acute exposure effects of VOCs.

Relationship between body-mass index and serum folate concentrations in pregnant women.

The concentration of micronutrients impacts fetal development and pregnancy outcome and has been suggested to be negatively correlated with the body-mass index (BMI). We evaluated the relationship between BMI and the serum folate concentration in 802 and 660 Korean pregnant women in mid- and late pregnancy, respectively, who participated in a multicenter prospective study. There was a significant negative correlation between BMI value and the serum folate concentration at mid- and late pregnancy (P for trend 0.001 and 0.024, respectively). A general linear model confirmed this correlation at both time points after adjusting for gestational age and total folate intake. These findings are important as the serum folate concentration is a rate-limiting factor for placental folate transport to the fetus, and an inadequate folate supply may cause various malformations.

Causal inference in environmental epidemiology

Inferring causality is necessary to achieve the goal of epidemiology, which is to elucidate the cause of disease. Causal inference is conducted in three steps: evaluation of validity of the study, inference of general causality, and inference of individual causality. To evaluate validity of the study, we propose a checklist that focuses on biases and generalizability. For general causal inference, we recommend utilizing Hill’s 9 viewpoints. Lastly, individual causality can be inferred based on the general causality and evidence of exposure. Additional considerations may be needed for social or legal purposes; however, these additional considerations should be based on the scientific truth elucidated by the causal inference described in the present article.