Association between Several Persistent Organic Pollutants and Thyroid Hormone Levels in Cord Blood Serum and Bloodspot of the Newborn Infants of Korea

<div><p>Current knowledge on adverse endocrine disruption effects of persistent organic pollutants (POPs) among newborn infants is limited and often controversial. To investigate the associations between prenatal exposure to major POPs and thyroid hormone levels among newborn infants, both cord serum or maternal serum concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs) were compared with five thyroid hormones in cord serum of newborn infants as well as TSH in bloodspot collected at 2 day after birth (n=104). Since cord serum thyroid hormones could be affected by those of mothers, thyroid hormone concentrations of the matching mothers at delivery were adjusted. In cord serum, BDE-47, -99, and Σchlordane (CHD) showed significant positive associations with cord or bloodspot TSH. At the same time, <i>p</i>,<i>p'</i>-dichlorodiphenyldichloroethylene (<i>p</i>,<i>p'</i>-DDE) and hexachlorbenzene (HCB) showed negative associations with total T3 and total T4 in cord serum, respectively. Maternal exposure to <i>β</i>-hexachlorhexane (<i>β</i>-HCH), ΣCHD, ΣDDT, or <i>p</i>,<i>p'</i>-DDE were also associated with neonatal thyroid hormones. Although the sample size is small and the thyroid hormone levels of the subjects were within the reference range, our observation supports thyroid disrupting potential of several POPs among newborn infants, at the levels occurring in the general population. Considering the importance of thyroid hormones during gestation and early life stages, health implication of thyroid hormone effects by low level POPs exposure deserves further follow up investigations.</p></div

Associations between POPs concentrations in maternal blood and thyroid hormone levels in cord blood serum or in bloodspot of newborn infant population in Korea (n = 104).

<p>Signs * and ^ indicate statistical significance of regression parameter at p<0.05, and 0.1, respectively. All POPs concentrations and thyroid hormone levels were natural log—transformed. Results of association regarding free T3, total T3, free T4, total T4, and TSH were adjusted for age, gestation period, mode of delivery, parity, pre-pregnancy BMI, smoking status during pregnancy, and maternal weight gain during pregnancy. While infant sex was added as covariate and smoking status was removed for analysis of bloodspot TSH. Chemicals that were detected > = 75% of the population at concentrations greater than the limit of quantification, a proxy value of ‘limit of quantification divided by square root 2’ was used. For chemicals that were detected in <75% but > = 60%, statistical analysis was conducted with detected values only. Such chemicals are indicated by ‘+’. Since BDE-99 were detected below 60% in maternal serum samples, they were not statistically analyzed.</p><p>Associations between POPs concentrations in maternal blood and thyroid hormone levels in cord blood serum or in bloodspot of newborn infant population in Korea (n = 104).</p

Characteristics of the study population.

<p>^a Normal spontaneous vaginal delivery.</p><p>^b Caesarean section.</p><p>^c Bloodspot TSH was measured from bloodspot samples collected at day 2–7 post-partum. Most newborn babies were collected for bloodspot on day 2 (within 48 hrs) post-partum, but 3 and 2 infants were collected on day 5 and 7 post-partum, respectively.</p><p>Characteristics of the study population.</p

Associations between prenatal POPs concentrations in either maternal or cord blood and thyroid hormone levels of newborn infants.

<p>‘-’ no association;</p><p>‘↑’ positive association;</p><p>‘↓’ negative association (p<0.05);</p><p>Blank cell means data not available. ‘fT3’ free T3; ‘TT3’ total T3; ‘fT4’ free T4; ‘TT4’ total T4. In the present study, cord thyroid hormone levels were adjusted with maternal thyroid hormone levels in the model. Unless otherwise noted, all thyroid hormone measurements were from cord blood or cord serum. ‘s’ indicates the measurement in bloodspot of newborn infant.</p><p>Associations between prenatal POPs concentrations in either maternal or cord blood and thyroid hormone levels of newborn infants.</p

Associations between serum POPs concentrations and thyroid hormones in the sensitivity analysis.

<p>Signs * and ^ indicate statistical significance of regression parameter (β) at p<0.05, and 0.1, respectively. ‘CI’ confidence interval; ‘fT3’ free T3; ‘TT3’ total T3; ‘fT4’ free T4. For the calculation of association, two or more independent variables that were determined as significant predictors to a given thyroid hormone, and at the same time were correlated each other, were added in the multiple regression analysis, in order to identify major predictors. In the regression model, interaction terms between the selected POPs were not included.</p><p>Associations between serum POPs concentrations and thyroid hormones in the sensitivity analysis.</p

Spatial–Temporal Dispersion of Aerosolized Nanoparticles During the Use of Consumer Spray Products and Estimates of Inhalation Exposure

We evaluated the spatial-temporal dispersion of airborne nanomaterials during the use of spray consumer products and estimated the level of consumer inhalation exposure. A total of eight spray products including five propellant and three pump types were selected to evaluate the dispersion of airborne nanoparticles across time and space in a cleanroom which could control the background particles. Four products were advertised to contain silver and one contained titanium nanoparticles, while three products were specified no ENM but as being manufactured through the use of nanotechnology. We used direct-reading instruments with a thermodesorber unit to measure the particles (number, mass, surface area), as well as filter sampling to examine physicochemical characteristics. Sampling was conducted simultaneously at each location (1 m, near-field; 2, 3 m, far-field) by distance from the source. We estimated the inhaled doses at the breathing zone, and the doses deposited in each part of the respiratory tract using the experimental data and mathematical models. Nanoparticles released from the propellant sprays persisted in the air and dispersed over a large distance due to their small size (1466–5565 particles/cm³). Conversely, the pump sprays produced larger droplets that settled out of the air relatively close to the source, so the concentration was similar to background level (<200 particles/cm³). The estimates of inhalation exposure also suggested that exposure to nanoparticles was greater with propellant sprays (1.2 × 10⁸ ± 4.0 × 10⁷ particles/kgbw/day) than pump sprays (2.7 × 10⁷ ± 6.5 × 10⁶ particles/kgbw/day). We concluded that the propellant sprays create a higher risk of exposure than the pump sprays

Association between Several Persistent Organic Pollutants in Serum and Adipokine Levels in Breast Milk among Lactating Women of Korea

Exposure to several persistent organic pollutants (POPs) has been linked to alteration of lipid metabolism. Adipokines, such as leptin and adiponectin, are hormones that play roles in lipid metabolism, and have been suggested as markers of health effects that may lead to obesity. To date, only serum adipokines have been associated with POPs exposure. In the present study, for the first time, the associations between leptin and adiponectin in breast milk, and several POPs in serum were investigated among 82 lactating Korean women between 25 and 46 years of age. Breast milk adipokines are important because adipokine intake of infant through breastfeeding may influence the growth of infants. The median concentrations of leptin and adiponectin in skimmed milk of the Korean lactating women were 17.9 ng/L and 16.5 μg/L, respectively. Leptin concentrations in breast milk were negatively associated with ∑hexachlorohexane (HCH), oxychlordane, ∑chlordane, or 2,2′,4,4′,5,5′-hexachlorobiphenyl (CB 153) levels in maternal serum. Linear relationships between adiponectin and POPs concentrations were not observed, however, nonmonotonic relationship which showed generally positive associations was suggested for <i>p</i>,<i>p</i>′-dichlorodiphenyltrichloroethane (DDT) and ∑chlordane in quartile analysis. Our observations show that POPs at the current level of exposure may be associated with the alteration of lipid metabolism among lactating women. Implication of adipokine transfer to breastfed infants is of concern and deserves further investigation