Concentrations Of Persistent Organic Pollutants Research Articles

Exposure to Persistent Organic Pollutants and Birth Characteristics: The Upstate KIDS Study.

Prenatal exposure to persistent organic pollutants (POPs) may be associated with obesogenic effects in offspring. Our study is the first to investigate associations between concentrations of POPs from newborn dried blood spots (DBS) and birth characteristics. Concentrations of 10 polychlorinated biphenyl congeners (PCBs), polybrominated diphenyl ether-47 (PBDE-47), and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) were measured from DBSs collected at birth from 2,065 singleton infants. DBS samples were pooled in groups of five and assayed together to reach limits of detection. Differences in risk of large for gestational age (LGA, defined as >90th percentile of birth weight for sex and gestational age), small for gestational age (SGA, <10th), and preterm birth (gestational age <37 weeks) were estimated using logistic regression per unit (ng/ml) increase in concentration of each chemical, adjusting for individual-level covariates, including maternal age, race/ethnicity, prepregnancy BMI, education, parity, smoking, and infant sex while assuming a gamma distribution and using multiple imputation to account for pools. There were 215 (11.3%) singletons born LGA, 158 (7.5%) born SGA, and 157 (7.6%) born preterm. Higher concentrations of POPs were positively associated with slightly higher risk of LGA and higher birth weight. Relationships between POPs measured in newborn DBS and birth size were mixed. Pooled analysis methods using DBS could address challenges in limits of detection and costs for population-based research.

Mobilization of Environmental Toxicants Following Bariatric Surgery.

Persistent organic pollutants (POPs) are lipophilic environmental toxicants that accumulate in adipose tissue. Weight loss leads to mobilization and increased redistribution of these toxicants. Many are obesogens and endocrine disruptors. Increased exposure could pose long-term health risks. The study objective was to measure the changes in serum concentrations of lipophilic POPs during significant weight loss. This study enrolled 27 patients at a university hospital in a longitudinal, 6-month, observational study examining changes in POP blood levels after bariatric surgery. The primary outcome was the changes in the concentrations of 24 polychlorinated biphenyls (PCBs), 9 organochlorine pesticides (OCPs), 11 polybrominated diphenyl ethers, 2,2',4,4',5,5'-hexabromobiphenyl, and 4 perfluorochemicals (PFCs). Older adults (those born before 1976) had baseline levels of PCBs, OCPs, and PFCsthat were two- to fivefold higher than younger adults (those born after 1976). Older adults had greater increases in PCBs, OCPs, and polybrominated diphenyl ethers associated with weight loss. Conversely, younger adults had greater increases in PFCs associated with weight loss.On average, blood POPlevels increased as weight loss occurred. Although weight loss is considered beneficial, the release and redistribution of POPs to other lipid-rich organs such as the brain, kidneys, and liver warrant further investigation. Interventions should be considered to limit organ exposure to POPs when weight loss interventions are planned.

Deep Learning Prediction of Polycyclic Aromatic Hydrocarbons in the High Arctic.

Given the lack of understanding of the complex physiochemical and environmental processes of persistent organic pollutants (POPs) in the Arctic and around the globe, atmospheric models often yield large errors in the predicted atmospheric concentrations of POPs. Here, we developed a recurrent neural network (RNN) method based on nonparametric deep learning algorithms. The RNN model was implemented to predict monthly air concentrations of polycyclic aromatic hydrocarbons (PAHs) at the high Arctic monitoring station Alert. To train the RNN system, we used MODIS satellite remotely sensed forest fire data, air emissions, meteorological data, sea ice cover area, and sampled PAH concentration data from 1996 to 2012. The system was applied to forecast monthly PAH concentrations from 2012 to 2014 at the Alert station. The results were compared with monitored PAHs and an atmospheric transport model (CanMETOP) for POPs. We show that the RNN significantly improved PHE and BaP predictions from 2012 to 2014 by 62.5 and 91.1%, respectively, compared to CanMETOP predictions. The sensitivity analysis using the Shapley value reveals that air emissions determined the magnitude of PAH levels in the high Arctic, whereas forest fires played a significant role in the changes in PAH concentrations in the high Arctic, followed by air temperature and meridional wind fields.

Seabird-Transported Contaminants Are Reflected in the Arctic Tundra, But Not in Its Soil-Dwelling Springtails (Collembola).

Arctic-breeding seabirds contain high levels of many anthropogenic contaminants, which they deposit through guano to the tundra near their colonies. Nutrient-rich soil in vicinity to seabird colonies are favorable habitats for soil invertebrates, such as springtails (Collembola), which may result in exposure to seabird-derived contaminants. We quantified a wide range of lipid-soluble and protein-associated environmental contaminants in two springtail species (Megaphorura arctica and Hypogastrura viatica) and their respective habitats (soil/moss) collected underneath seabird cliffs. Although springtails are commonly used in laboratory toxicity tests, this is the first study to measure concentrations of persistent organic pollutants (POPs) and mercury (Hg) in springtails from the field, and to study biotransportation of contaminants by seabirds to soil fauna. We categorized the sites a priori as of low, medium, or high seabird influence, based on the seabird abundance and species composition. This ranking was reflected in increasing δ15N values in soil/moss and springtails with increasing seabird influence. We found clear indications of seabirds impacting the terrestrial soil environments with organic contaminants, and that concentrations were higher in soil and moss close to the bird cliff, compared to farther away. However, we did not find a relationship between contaminant concentration in springtails and the concentrations in soil/moss, or with level of seabird influence. Our study indicates a low uptake of contaminants in the soil fauna, despite seabird-derived contamination of their habitat.

Persistent organic pollutants (POPs) in oriental magpie-robins from e-waste, urban, and rural sites: Site-specific biomagnification of POPs

Plenty of banned and emerging persistent organic pollutants (POPs), including dichlorodiphenyltrichloroethane and its metabolites (DDTs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), dechlorane plus (DP), and decabromodiphenyl ethane (DBDPE), were measured in oriental magpie-robins from an e-waste recycling site, an urban site (Guangzhou City), and a rural site in South China. Median concentrations of DDTs, PCBs, PBDEs, DP, and DBDPE ranged from 1,000–1,313, 800-59,368, 244-5,740, 24.1–127, and 14.7–36.0 ng/g lipid weight, respectively. Birds from the e-waste site had significantly higher concentrations of PCBs and PBDEs than those from urban and rural sites (p < 0.05), implying contamination of PCBs and PBDEs brought by e-waste recycling activities. DDTs were the predominant POPs in birds from urban and rural sites. The values of δ15N were significantly and positively correlated with concentrations of p,p′-DDE and low-halogenated chemicals in samples from the e-waste site (p < 0.05), indicating the trophic magnification of these chemicals in birds. However, concentrations of most POPs were not significantly correlated with the δ15N values in birds from urban and rural sites. PCBs and PBDEs in birds from urban and rural sites were not likely from local sources, and the biomagnification of POPs in different sites needed to be further investigated with caution.

Chlorinated persistent organic pollutants and type 2 diabetes - a population-based study with pre- and post- diagnostic plasma samples

PDS 63: Chemicals and metals: health effects, Exhibition Hall (PDS), Ground floor, August 27, 2019, 10:30 AM - 12:00 PM Background: Persistent organic pollutants (POPs) have been associated with type 2 diabetes (T2D), but causality is uncertain. Objective: Within longitudinal population-based data from northern Sweden, we assessed how POPs associated with T2D prospectively and cross-sectionally, and further investigated factors related to individual changes in POP concentrations. Methods: For 129 case-controls pairs matched by age, sex and date of sampling, plasma concentrations of HCB, p,p´-DDE, dioxin-like PCBs (PCB-118, -156), and non-dioxin like PCBs (PCB-74, -99, -138 -153, -170, -180, -183 -187) were analyzed twice (baseline and follow-up, 9-20 years apart). The cases received their T2D diagnose between baseline and follow-up. Prospective (using baseline data) and cross-sectional (using follow-up data) odds ratios (ORs) for T2D on lipid standardized POPs (HCB, p,p´-DDE, ∑DL-PCBs, ∑NDL-PCBs) were estimated using conditional logistic regression, adjusting for body mass index (BMI) and plasma lipids. The influence of BMI, weight-change, and plasma lipids on longitudinal changes in POP concentrations were evaluated among non-diabetic individuals (n=306). Results: POPs were associated with T2D in both the prospective and cross-sectional assessments. Of a standard deviation increase in POPs, prospective ORs ranged 1.42 (95% CI: 0.99, 2.06) for ∑NDL-PCBs to 1.55 (95% CI: 1.01, 2.38) for HCB (p<0.05 only for HCB), and cross-sectional ORs ranged 1.62 (95% CI: 1.13; 2.32) for p,p´-DDE to 2.06 (95% CI: 1.29, 3.28) for ∑DL-PCBs (p<0.05 for all POPs). In analyses of non-diabetic individuals, higher baseline BMI, decreased weight and decreased plasma lipid concentrations were associated with a slower decrease of POPs. Cases had, besides a higher BMI, reduced cholesterol and weight gain at follow-up compared to controls, which can explain the higher ORs in the cross-sectional assessments. Discussion: The indication that individuals’ body fat history might influence POP-T2D associations through decreased elimination rate, weakens the epidemiological support for a causal association.

River organisms as indicators of the distribution and sources of persistent organic pollutants in contrasting catchments

Persistent organic pollutants (POPs) continue to threaten aquatic organisms, but risk assessments are restricted by poor knowledge of the distribution and quantity of these substances in different biota. Assessments on aquatic invertebrates are particularly scarce. Here, we investigate variation in polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and organochlorines (OCs) in sediments, biofilms, macroinvertebrates and fish across rivers in South Wales (UK). Persistent PCB (−118, −153, −180) and PBDE congeners (BDE-47, -99, −100), and OCs (p,p’-dichlorodiphenyldichloroethylene [p,p’-DDE] and dieldrin [HEOD]) dominated the POPs detected, indicating links to historical emissions. Low concentrations of less persistent PBDEs, PCBs and OCs, however, suggest more contemporary sources. Concentrations of POPs were 2–22 times greater in fish than invertebrates, but their detection frequency (>90%) and concentrations (0–304 ng g−1 wet weight) were higher in these organisms than in sediments or biofilms (<10%; 0–12 ng g−1 wet weight). Invertebrates and fish also contained several PCB congeners (28, 52, 77 and 105) and p,p’-dichlorodiphenyltrichloroethane (p,p’-DDT) that were not detected in the environmental samples. Concentrations of PBDEs, PCBs and OCs differed among invertebrate taxa and feeding guilds. After controlling for significant variation among sample types and taxa, PBDEs were found to increase with urban land cover, while increased PCBs were associated with urban land cover and wastewater discharge. These data illustrate how body burdens of POPs across invertebrate and fish taxa provide valuable information on the spatial variation and likely sources of persistent pollutants in freshwater ecosystems. More work is required to resolve differences in POP contamination between taxonomic groups.

Persistent organic pollutants are still present in surface marine sediments from the Seto Inland Sea, Japan

Although persistent organic pollutants (POPs) are currently banned or strictly controlled under the Stockholm Convention on Persistent Organic Pollutants, POPs are still distributed worldwide due to their environmental persistence, atmospheric transport, and bioaccumulation. Herein we investigated the current concentrations of POPs in the sediments from Seto Inland Sea, Japan and sought to clarify the factors currently controlling the POPs concentration of the surface sediments from Seto Inland Sea. The concentrations of hexachlorocyclohexane isomers (HCHs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), and chlordane isomers (CHLs) in sediments from Seto Inland Sea were <0.002-1.20 ng g-1, 0.01-2.51 ng g-1, and 0.01-0.48 ng g-1, respectively. Resuspension increased the concentrations of HCHs, HCB, and DDTs in the surface sediment with the release of historically contaminated pollutants accumulated in a lower layer. We speculate that CHLs in air that were removed by atmospheric deposition affects the concentration of CHLs in surface sediments.

Urban-rural gradients of polycyclic aromatic hydrocarbons in soils at a regional scale: Quantification and prediction

The quantitative study of urban-rural gradients for persistent organic pollutants (POPs) is extremely important to understand the behavior of POPs as well as for ecological risk assessment and management. In this study, a practical urban-rural gradient model (URGM) was developed using atmospheric point source diffusion combined with a fugacity approach to test potential mathematical relationships among urban and rural soils. The mean value of polycyclic aromatic hydrocarbons (PAHs) for urban soils (0–2-km sites) was 570.80 ng/g, and was approximately 3.5 times higher than rural soils (30–50 km sites). Significant linear correlations were found between the amounts of PAHs in the surface soil and the city population and between the soil concentration and artificial surface area. Urban-rural PAH concentrations were simulated by the URGM and calibrated by city population and land-cover data, with average relative errors of 12.84%. The results showed that the URGM was suitable for simulating urban-rural PAH concentrations at a regional scale. The combustion of fossil fuels, biomass, and coal was the main source of soil PAHs in the study area, and the characteristic ratios of PAHs indicated a transition trend from pyrogenic to petrogenic sources along the urban-rural transects. This study thus provides a combined method for quantifying urban-rural gradients of PAHs and can thereby promote quantitative research on coupling among land cover, socio-economic data, and POP concentrations.

Polyurethane foam disk passive sampler derived air concentrations of persistent organic pollutants in an agricultural region with hot climate

Polyurethane foam (PUF) disks passive air samplers were deployed in an agricultural region with hot climate to determine atmospheric concentrations of 22 organochlorine pesticides (OCPs) and 15 polychlorinated biphenyls (PCBs). Sampling rates (2.39–15.9 m3.day−1) increased with rising ambient air temperatures. Total OCP and PCB concentrations were 0.884–97.0 pg.m−3 and nd-213 pg.m−3, respectively. The most prominent OCPs in the samples were hexachlorocyclohexane (HCH) isomers, chlordane compounds, dichlorodiphenyltrichloroethane (DDT) derivatives, and endosulfan isomers. The isomer ratios of DDT and Chlordane in the samples indicated older usage while endosulfan ratios showed recent input of technical endosulfan in the region. Total PCB levels were dominated by low chlorinated congeners. The contaminant levels in air samples were mainly lower or similar by comparison to other studies conducted at agricultural regions worldwide. Although the production and use of these chemicals have been banned, results of this study show that some of the chemicals could still be found in agricultural areas. Presence of these chemicals in environmental samples may be result of the degradation of formerly used chemicals, atmospheric transport or illegal use of banned chemicals.

Determinants of persistent organic pollutant (POP) concentrations in human breast milk of a cross-sectional sample of primiparous mothers in Belgium

BackgroundBio-accumulation of persistent organic pollutants (POPs) in the environment and in the food chain can lead to high pollutant concentrations in human fat-containing tissues and breast milk. ObjectivesWe aimed to identify the maternal characteristics that determined POP concentrations in breast milk of primiparous mothers in Belgium. MethodsBreast milk samples were obtained from a cross-sectional sample of 206 primiparous mothers in 2014. POP concentrations in breast milk samples were determined by GC-ECNI-MS and GC-EI-MS/MS depending on the analytes' sensitivity. Associations between POP concentrations in breast milk and potential determinants were investigated using two-way contingency tables and multivariable generalized linear models. ResultsFifteen of the 23 screened POPs were detected in the breast milk samples. Four organochlorine compounds (p,p′-DDT, p,p′-DDE, HCB and β-HCH) and two brominated flame retardant congeners (BDE-47, BDE-153) were detected at concentrations above the limit of quantification in >50% of the breast milk samples. Maternal age and BMI were usually associated with higher POP concentrations. Rural residency and consumption of home-produced eggs, fatty fish and fish oil supplements were associated with higher concentrations of DDT and DDE. Consumption of fatty fish and being breastfed during childhood were associated with higher concentrations of HCB and β-HCH. Fish oil supplements and home-produced eggs were associated with higher concentrations of BDEs, but for BDE congeners exposure routes other than diet require further investigation. ConclusionsDietary and non-dietary determinants predict individual POP concentrations in breast milk.

Associations between persistent organic pollutants and risk of breast cancer metastasis

BackgroundBreast cancer (BC) is a major public health concern with over 2 million new cases diagnosed and over 600,000 deaths in 2018 in women worldwide. When distant metastases are present at diagnosis, the 5-year survival rate is only 26%. Recent studies have suggested that persistent organic pollutants (POPs) that accumulate in adipose tissue (AT) can influence tumor phenotype and stimulate cellular processes important for metastasis such as invasion. We, therefore, tested the hypothesis that POP exposure is associated with BC metastasis. MethodsWe conducted an exploratory case-control study in which the concentrations of 49 POPs were measured in both AT and serum samples from BC patients, with or without lymph node metastasis, who underwent partial or total mastectomies, lymph node biopsies and sampling of the adipocytic tumor microenvironment. Adjusted, unconditional logistic models were used to study the associations between the POP concentrations and the risk of metastasis and other hallmarks of cancer aggressiveness. Results2.3.7.8-TCDD concentrations in AT are positively associated with the risk of metastasis in 43 patients who have BMIs equal or higher than 25 kg/m2 (odds ratio: 4.48 (1.32–20.71)). Furthermore, the concentrations of 2.3.7.8-TCDD and two coplanar PCBs (77&169) in AT also were positively associated with the risk of lymph node metastasis and the tumor size. ConclusionOur study suggests that 2.3.7.8-TCDD and some PCBs contribute to the development of tumor metastasis and other hallmarks of cancer aggressiveness. While these results should be considered with caution, this is the first study to identify such potential risk factors. Larger longitudinal studies are necessary to confirm our results.Clinical Trial Protocol Record: 2013-A00663-42.

Association between the persistent organic pollutants and polycystic ovary syndrome: A protocol for a systematic review and meta-analysis.

Background:Current evidence concerning the association between persistent organic pollutants (POPs) and polycystic ovary syndrome (PCOS) is inconsistent. The aim of the present systematic review and meta-analysis is to evaluate the role of POPs in PCOS.Methods:Databases including PubMed, Embase, Web of Science, and CNKI will be searched to identify qualified studies. All qualified studies regarding the association between POPs and PCOS will be included. The primary outcome of the present study is POPs levels in serum of subjects. Pooled analysis with corresponding 95% confidence intervals will be performed.Results:The comprehensive analysis and quantitative assessment will provide a better understanding of POPs concentrations in patients with PCOS.Conclusion:This meta-analysis and systematic review will generate evidence of the association between POPs and PCOS.PROSPERO registration number:PROSPERO CRD42019126373

Associations between Exposure to Persistent Organic Pollutants and Thyroid Function in a Case-Control Study of East China.

Animal studies have indicated that persistent organic pollutants (POPs) affect thyroid hormone homeostasis, while epidemiological studies involving human have not shown consistent results. In this study, we investigated the associations between POP exposure and thyroid function among adult population of East China. One hundred eighty-six participants diagnosed with thyroid disease and 186 participants without thyroid disease from Shandong, China were enrolled in the case-control study during 2016 to 2017. We found that POP exposure was significantly and positively associated with the risk of thyroid disease. The association of thyroid disease with a sum of 17 POPs followed a nonmonotonic dose response, with an adjusted odds ratio of 2.09 (95% confidence intervals: 1.13-3.87, p = 0.019) for the second quartile. Among 186 participants in the control group, concentrations of POPs showed negative associations with triiodothyronine (T3), free T3 (FT3), thyroxine (T4), and free T4 (FT4) in males and positive associations with T4 and FT4 in females. Taken together, these findings suggest that POP exposure can disrupt thyroid hormone homeostasis and increase the risk of thyroid disease.

Tropical seabirds sample broadscale patterns of marine contaminants

Contaminants in the marine environment are widespread, but ship-based sampling routines are much narrower. We evaluated the utility of seabirds, highly-mobile marine predators, as broad samplers of contaminants throughout three tropical ocean regions. Our aim was to fill a knowledge gap in the distributions of, and processes that contribute to, tropical marine contaminants; and explore how species-specific foraging ecologies could inform or bias our understanding of contaminant distributions. Mercury and persistent organic pollutant (POPs) concentrations were measured in adults of five seabird species from four colonies in the central Pacific (Laysan and Tern Islands, Hawaii; Palmyra Atoll) and the eastern Caribbean (Barbuda). Blood-based total mercury (THg) and 89 POPs were measured in two seabird families: surface-foraging frigatebirds (Fregata spp.) and plunge-diving boobies (Sula spp.). Overall, largescale contaminant differences between colonies were more informative of contaminant distributions than inter-specific foraging ecology. Model selection results indicated that proximity to human populations was the best predictor of THg and POPs. Regional differences in contaminants were distinct: Barbudan Magnificent Frigatebirds had more compounds (n=52/89 POP detected) and higher concentrations (geometric mean THg=0.97μgg-1; mean ΣPOP53=26.6ngmL-1) than the remote colonies (34-42/89 POP detected; range of THg geometric means=0.33-0.93μgg-1; range of mean ΣPOP53:7.3-17.0ngmL-1) and had the most recently-synthesized POPs. Moderate differences in foraging ecologies were somewhat informative of inter-specific differences in contaminant types and concentrations between nearshore and offshore foragers. Across species, contaminant concentrations were higher in frigatebirds (THg=0.87μgg-1; ΣPOP53=17.5ngmL-1) compared to boobies (THg=0.48μgg-1; ΣPOP53=9.8). Ocean currents and contaminants' physiochemical properties provided additional insight into the scales of spatial and temporal contaminant exposure. Seabirds are excellent, broad samplers with which we can understand contaminant distributions in the marine environment. This is especially important for tropical remote regions that are under-sampled.

Snow Amplification of Persistent Organic Pollutants at Coastal Antarctica.

Many legacy and emerging persistent organic pollutants (POPs) have been reported in polar regions, and act as sentinels of global pollution. Maritime Antarctica is recipient of abundant snow precipitation. Snow scavenges air pollutants, and after snow melting, it can induce an unquantified and poorly understood amplification of concentrations of POPs. Air, snow, the fugacity in soils and snow, seawater and plankton were sampled concurrently from late spring to late summer at Livingston Island (Antarctica). Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) concentrations in snow and air were close to equilibrium. POPs in soils showed concentrations close to soil-air equilibrium or net volatilization depending on chemical volatility. Seawater-air fugacity ratios were highly correlated with the product of the snow-air partition coefficient and the Henry's law constant (KSA H'), a measure of snow amplification of fugacity. Therefore, coastal seawater mirrored the PCB congener profile and increased concentrations in snowmelt due to snowpack releasing POPs to seawater. The influence of snowpack and glacier inputs was further evidenced by the correlation between net volatilization fluxes of PCBs and seawater salinity. A meta-analysis of KSA, estimated as the ratio of POP concentrations in snow and air from previously reported simultaneous field measurements, showed that snow amplification is relevant for diverse families of POPs, independent of their volatility. We claim that the potential impact of atmospheric pollution on aquatic ecosystems has been under-predicted by only considering air-water partitioning, as snow amplification influences, and may even control, the POP occurrence in cold environments.

Concentrations of organohalogens (PCBs, DDTs, PBDEs) in hunted and stranded Northern sea otters (Enhydra lutris kenyoni) in Alaska from 1992 to 2010: Links to pathology and feeding ecology.

Many organohalogen compounds (OHCs) are persistent organic pollutants (POPs) found in appreciable concentrations in marine predators. While production of some POPs has declined or ceased in recent decades, their capacity for global transport and bioaccumulation results in observations of unchanging or increasing concentrations in marine systems. Sea otters (Enhydra lutris) have been advocated as an environmental sentinel for contaminants due to their longevity, site fidelity and prey species that often overlap with human consumption. Using archived (1992-2010) samples of livers from Northern sea otters (n = 50) from Alaska we examine concentrations of chlordanes (CHLs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDTs), and polybrominated diphenyl ethers (PBDEs) and associated metabolites. We found some evidence for declining ΣPCBs over the two decades, however for most animals concentrations were low compared to toxicological thresholds. Six animals had relatively high concentrations of ΣPCBs (mean = 262,000 ng/g lipid weight), ΣDDTs (mean = 8,800 ng/g lw), and ΣPBDEs (mean = 4,600 ng/g lw), with four of these six animals experiencing hepatic parasitism or hepatitis. In order to assess whether differences in POP concentrations are associated with feeding ecology, we examined stable isotopes of C and N in archived muscle and whisker samples. In general, there were no significant relationships between ΣPOP concentrations and stable isotope ratios. There were small differences in stable isotope profiles in animals with high POP concentrations, although it was unclear if these differences were due to feeding ecology or disease processes. This study highlights the importance of considering feeding ecology and necropsy (health and disease status) data while conducting contaminant surveys, and confirms some previous reports of trends in OHCs in Alaska marine mammals.

Maternal exposures to persistent organic pollutants are associated with DNA methylation of thyroid hormone-related genes in placenta differently by infant sex

Exposure to persistent organic pollutants (POPs) during pregnancy is associated with a disruption in thyroid hormone balance. The placenta serves as an important environment for fetal development and also regulates thyroid hormone supply to the fetus. However, epigenetic changes of thyroid regulating genes in placenta have rarely been studied. This study was conducted to evaluate the association between several POP concentrations in maternal serum and DNA methylation of thyroid hormone-related genes in the placenta. The placenta samples were collected from 106 Korean mother at delivery, and the promoter methylation of the placental genes was measured by a bisulfite pyrosequencing. The deiodinase type 3 (DIO3), monocarboxylate transporter 8 (MCT8), and transthyretin (TTR) genes were selected as the target genes as they play an important role in the regulation of fetal thyroid balance. Because people are exposed to multiple chemicals at the same time, a multiple-POP model using principal component analysis (PCA) was applied to evaluate the association between the multiple POPs exposure and the epigenetic change in placenta. In addition, a single-POP model which includes one chemical each in the statistical model for association was conducted.Based on the single-POP models, serum concentrations of p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE) and brominated diphenyl ether-47 (BDE-47) were significantly associated with an increase in placental DIO3 methylation, but only among female infants. Among male infants, a positive association between serum p,p′-DDT and MCT8 methylation level was found. According to the multiple-POP models, serum DDTs were positively associated with DIO3 methylation in the placenta of female infants, while a positive association with MCT8 methylation was observed in those of the male infants. Our observation showed that in utero exposure to DDTs may influence the DNA methylation of DIO3 and MCT8 genes in the placenta, in a sexually dimorphic manner. These alterations in placental epigenetic regulation may in part explain the thyroid hormone disruption observed among the newborns or infants followed by in utero exposure to POPs.

Arctic cleansing diet: Sex-specific variation in the rapid elimination of contaminants by the world's champion migrant, the Arctic tern

Contamination of Arctic marine environments continues to be a concern for wildlife managers. Because the Arctic is a sink for the long-range transport of persistent organic pollutants (POPs), many studies have detected high concentrations of POPs in various Arctic birds. In this study from high Arctic Canada, we show that male Arctic terns (Sterna paradisaea), which migrate from the Antarctic to the Arctic annually to breed, decline in concentrations of many hepatic POPs through the breeding season. This suggests that local Arctic food webs are less contaminated than regions where terns fed during or migration, despite that the terns appear to feed at a higher trophic level near their colony.

Longitudinal study of age of menarche in association with childhood concentrations of persistent organic pollutants

BackgroundAge at female puberty is associated with adult morbidities, including breast cancer and diabetes. Hormonally active chemicals are suspected of altering pubertal timing. We examined whether persistent organic pollutants (POPs) are associated with age at menarche in a longitudinal study. MethodsWe analyzed data for females enrolled at age 6–8 years in the Breast Cancer and Environment Research Program from California and Ohio. Participants were followed annually 2004–2013 and provided serum (mean age 7.8 years) for measurement of polychlorinated biphenyl (PCB), organochlorine pesticide (OCP), and polybrominated diphenyl ether (PBDE) concentrations. Age of menarche was assigned based on parental and participant reported dates and ages of menarche. Adjusted hazard ratios (aHRs) for menarchal onset were calculated with Cox proportional regression. Body mass index (BMI), potentially on the causal pathway, was added to parallel analyses. ResultsAge of menarche was later with higher summed PCB levels (median 11.9 years in quartile 1 [Q1] versus 12.7 in quartile 4 [Q4]) and OCP levels (12.1 years versus 12.4, respectively). When adjusting for all covariates except BMI, higher POP concentrations were associated with later age at menarche (Q4 versus Q1 aHRs: PBDEs 0.75 [95% CI 0.58, 0.97], PCBs 0.67 [95% CI 0.5, 0.89], and OCPs 0.66 [95% CI 0.50, 0.89]). Additional adjustment for BMI attenuated aHRs; PCB aHR approached the null. ConclusionFindings revealed later onset of menarche with higher concentrations of certain POPs, possibly through an association with BMI. Altered pubertal timing may have long lasting effects on reproductive health and disease risk, so continued attention is important for understanding the biological processes affected by hormonally active chemicals.