Family-based case-control study of exposure to household humidifier disinfectants and risk of idiopathic interstitial pneumonia.

BACKGROUND: In Korea, several household humidifier disinfectants (HDs) were clinically confirmed to cause HD-associated lung injury (HDLI). Polyhexamethylene guanidine (PHMG) phosphate is the main ingredient of the HDs found to be associated with lung disease. However, the association of HDs with other interstitial lung disease including idiopathic interstitial pneumonia (IIP) is not clear. We examined the relationship between HD exposure and IIP in a family-based study. METHODS: This case-control study included 244 IIP cases and 244 family controls who lived with the IIP patients. The IIP cases were divided into two groups, HDLI and other IIP, and were matched to family controls based on age and gender. Information on exposure to HDs was obtained from a structured questionnaire and field investigations. Conditional logistic regression was used to estimate odds ratio (ORs) and their corresponding 95% confidence interval (CI), investigating the association of HD-related exposure characteristics with IIP risk. RESULTS: The risks of IIP increased two-fold or more in the highest compared with the lowest quartile of several HD use characteristics, including average total use hours per day, cumulative sleep hours, use of HD during sleep, and cumulative exposure level. In analyses separated by HDLI and other IIP, the risks of HDLI were associated with airborne HD concentrations (adjusted OR = 3.01, 95% CI = 1.34-6.76; Q4 versus Q1) and cumulative exposure level (adjusted OR = 3.57, 95% CI = 1.59-8.01; Q4 versus Q1), but this relationship was not significant in the patients with other IIP. In comparison between HDLI and other IIP, the odds ratios of average total use hours, cumulative use hours, and cumulative sleeps hours was higher for other IIP. CONCLUSION: The use of household HDs is associated not only with HDLI but also with other IIP.

Trends in the Prevalences of Selected Birth Defects in Korea (2008⁻2014).

Little information is available on the prevalences of birth defects in Korea. The aims of this study were to estimate recent prevalences of selected birth defects and to analyze the prevalence trends of these defects during the period from 2008 to 2014. Prevalences were calculated for 69 major birth defects using health insurance claim data obtained from the Korea National Health Insurance Service (NHIS). Prevalence rate ratios were calculated using Poisson regression to analyze trends over the 7-year study period. The overall prevalence of a major birth defect was 446.3 per 10,000 births (95% CI: 444.0⁻448.6); 470.9 per 10,000 births (95% CI: 467.6⁻474.2) for males and 420.2 per 10,000 births (95% CI: 417⁻423.4) for females. The prevalence rates of the most common birth defects over the study period were; septal defect (138.2 per 10,000; 95% CI: 136.9⁻139.5), congenital hip dislocation (652 per 10,000; 95% CI: 64.1⁻65.9), and ventricular septal defect (62.62 per 10,000; 95% CI: 61.7⁻63.5). During the study period, a significant increase in the prevalence of a major birth defect was observed with a prevalence rate ratio (PRR) of 1.091. The strongest trend was observed for renal dysplasia, which had a PRR of 1.275 (95% CI: 1.211⁻1.343), and upward trends were observed for urogenital anomalies, such as, renal agenesis (PRR 1.102, 95% CI: 1.067⁻1.138), undescended testis (PRR 1.082, 95% CI: 1.072⁻1.093) and hypospadias (PRR 1.067, 95% CI: 1.044⁻1.090). This study shows an overall increase in the prevalences of birth defects, including hypospadias and undescended testis, which are known to be associated with endocrine factors. In the future, standardized birth defect registries should be established to enable these trends to be monitored.

Effects of traffic-related air pollution on susceptibility to infantile bronchiolitis and childhood asthma: A cohort study in Korea.

OBJECTIVE: This study examined the role of exposure to traffic-related air pollution (TRAP) on susceptibility to asthma in children with past episodes of bronchiolitis. METHODS: The baseline data included 2,627 school children aged 6-14 years who had participated in the longitudinal follow-up survey of the Children's Health and Environmental Research of Korea. Lifetime wheezing, past episodes of bronchiolitis, and doctor-diagnosed asthma were evaluated using an International Study of Asthma and Allergies in Childhood questionnaire. We used generalized linear regression with binomial distribution to calculate the relative risk (RR) between TRAP, assessed by proximity to a main road and the total length of roads, and asthma. RESULTS: Compared with the subjects who had less than 100 m of road length within 200-m radius from their home, those with more than 500 m of road length had significantly increased odds for infantile bronchiolitis (adjusted OR [aOR]: 1.57, 95% confidence interval [CI]: 1.01-2.42). Positive exposure-response relationships were found between residential proximity to the main road and asthma (aOR: 1.79, 95% CI: 1.05-3.06; <75 m vs. >700 m from a main road, P for the trend = 0.02). Closer residential proximity to the main road (<75 m) and bronchiolitis combined increased the risks of newly diagnosed asthma (adjusted RR: 3.62, 95% CI: 1.07-12.26) compared with those without bronchiolitis and living ≥ 75 m away from the main road. CONCLUSIONS: TRAP appeared to be associated with an increased asthma among children with bronchiolitis, indicating the importance of modifying effects of bronchiolitis in asthma pathogenesis.

Associations between prenatal lead exposure and birth outcomes: Modification by sex and GSTM1/GSTT1 polymorphism.

Maternal lead exposure is associated with poor birth outcomes. However, modifying effects of polymorphism in glutathione S-transferases (GST) gene and infant sex remain unexplored. Our aim was to evaluate whether associations between prenatal lead and birth outcomes differed by maternal GST genes and infant sex. Prospective data of 782 mother-child pairs from Mothers and Children's Environmental Health (MOCEH) study were used. The genotyping of GST-mu 1 (GSTM1) and theta-1 (GSTT1) polymorphisms was carried out using polymerase chain reaction. Multivariable linear regression was used to examine whether the association between blood lead (BPb) level and birth outcomes (birthweight, length, and head circumference) varied by maternal GST genes and sex. We did not find a statistically significant association between prenatal BPb levels and birth outcomes; in stratified analyses, the association between higher BPb level during early pregnancy and lower birthweight (ß=-224 per square root increase in BPb; 95% confidence interval (CI): -426, -21; false discovery rate p=0.036) was significant in males of mothers with GSTM1 null. Results were similar for head circumference model (ß=-0.78 per square root increase in BPb; 95% CI: -1.69, 0.14, p=0.095), but the level of significance was borderline. Head circumference model showed a significant three-way interaction among BPb during early pregnancy, GSTM1, and sex (p=0.046). For combined analysis with GSTM1 and GSTT1, GSTM1 null and GSTT1 present group showed a significant inverse association of BPb with birthweight and head circumference in males. Our findings of the most evident effects of BPb on the reduced birthweight and head circumference in male born to the mother with GSTM1 null may suggest a biological interaction among lead, GST genes and sex in detoxification process during fetal development.

Impact of prenatal exposure to polycyclic aromatic hydrocarbons from maternal diet on birth outcomes: a birth cohort study in Korea.

OBJECTIVE: Polycyclic 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. DESIGN: Prospective 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. SETTING: Republic of Korea, 2006-2011. SUBJECTS: Pregnant women (n 778) at 12-28 weeks of gestation enrolled in the Mothers and Children's Environmental Health (MOCEH) study. RESULTS: The 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 (ß=-17·48 g, P<0·05 for every 1 point higher in meat score). Further adjusting for biomarkers of airborne PAH did not alter this association. There was no evidence that higher consumption level of PAH-rich meat shortens the duration of gestation (P=0·561). Regression models performed for birth length and head circumference produced negative effects that were not statistically significant. CONCLUSIONS: Consumption 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.

Association of infant and young child feeding practices with under-nutrition: evidence from the Nepal Demographic and Health Survey.

BACKGROUND: Childhood undernutrition remains a highly influential risk factor in terms of the global burden of disease. Increasing evidence links infant and young child feeding (IYCF) practices to undernutrition. However, the results are inconsistent, and more country-specific studies are needed. OBJECTIVES: To determine the associations between IYCF practices and nutritional outcomes among children aged 0-23 months using a nationally representative dataset. METHODS: The study used data from the 2011 Nepal Demographic and Health Survey, and the data were analysed for children aged 0-23.9 months who had corresponding data for the outcome variables of interest (n = 890). Multiple linear and logistic regressions were undertaken and adjusted for the complex design of the survey, controlling for child, maternal, household and community characteristics. RESULTS: Of the 890 children included in the study, 83% received age-appropriate breastfeeding but only 48% were breastfed within 1 hour of birth. Exclusive breastfeeding under 6 months of age was associated with a higher weight-for-age Z-score (WAZ) and a lower probability of wasting, but the estimated effects were of borderline significance. A significant negative association was found between continued breastfeeding at 1 year and WAZ and weight-for-height Z-score (WHZ). Timely introduction of complementary feeding in children aged 6-8 months was associated with a higher WAZ [effect size (ES) 0.6, P < 0.01] and higher WHZ (ES 0.6, P < 0.05). Higher dietary diversity index (DDI) was associated with higher height-for-age Z-score (ES 0.1, P < 0.05 for each DDI point). Children who achieved minimum meal frequency had a higher WAZ (ES 0.3, P < 0.05). CONCLUSION: This is the first study to relate the wide ranges of IYCF indicators with child nutritional outcomes in Nepal, and it underscores the need to improve age-appropriate complementary feeding practices with a sustained focus on exclusive breastfeeding to reduce undernutrition in infants and young children.

Association of infant and young child feeding practices with undernutrition in children: evidence from the Nepal Demographic and Health Survey.

BACKGROUND: Childhood undernutrition remains a highly influential risk factor in terms of the global burden of disease. Increasing evidence links infant and young child feeding (IYCF) practices to undernutrition. However, the results are inconsistent, and more country-specific studies are needed. OBJECTIVES: To determine the associations between IYCF practices and nutritional outcomes among children aged 0-23 months using a nationally representative dataset. METHODS: The study used data from the 2011 Nepal Demographic and Health Survey, and the data were analysed for children aged 0-23.9 months who had corresponding data for the outcome variables of interest (n = 890). Multiple linear and logistic regressions were undertaken and adjusted for the complex design of the survey, controlling for child, maternal, household and community characteristics. RESULTS: Of the 890 children included in the study, 83% received age-appropriate breastfeeding but only 48% were breastfed within 1 hour of birth. Exclusive breastfeeding under 6 months of age was associated with a higher weight-for-age Z-score (WAZ) and a lower probability of wasting, but the estimated effects were of borderline significance. A significant negative association was found between continued breastfeeding at 1 year and WAZ and weight-for-height Z-score (WHZ). Timely introduction of complementary feeding in children aged 6-8 months was associated with a higher WAZ [effect size (ES) 0.6, P < 0.01] and higher WHZ (ES 0.6, P < 0.05). Higher dietary diversity index (DDI) was associated with higher height-for-age Z-score (ES 0.1, P < 0.05 for each DDI point). Children who achieved minimum meal frequency had a higher WAZ (ES 0.3, P < 0.05). CONCLUSION: This is the first study to relate the wide ranges of IYCF indicators with child nutritional outcomes in Nepal, and it underscores the need to improve age-appropriate complementary feeding practices with a sustained focus on exclusive breastfeeding to reduce undernutrition in infants and young children.