Occurrence, distribution and dynamics of perchlorate in soil, water, fertilizers, vegetables and fruits and associated human exposure in Chile.

Perchlorate (ClO4-) has been identified as a persistent environmental contaminant of concern. Perchlorate exposure is a potential health concern because it interferes with hormone production by thyroid gland. Food (fruits and vegetables) and drinking water are an important source of human exposure to perchlorate. However, little is known about the occurrence of perchlorate in Chile. The purpose of this study was to determine the occurrence of perchlorate in 145 samples (soil, drinking water, surface water, groundwater, fertilizers, fruits and vegetables) collected across Chile and estimate associated exposure to consumers. Our results show that perchlorate was detected in soil (median: 22.2 ng g-1), drinking water (median: 3.0 ng mL-1), fruits (median: 0.91 ng g-1 fresh weight [FW]), lettuce (median: 5.0 ng g-1 FW) and chard (median: 4.15 ng g-1 FW). Interestingly, perchlorate concentrations detected in drinking water from three regions (Serena, Copiapo and Illapel) exceeded the USEPA interim drinking water health advisory level of 15 ng mL-1. Median concentrations of perchlorate in non-nitrogenous fertilizers (3.1 mg kg-1) were higher than those in nitrogenous fertilizers (1.3 mg kg-1). Estimated daily intake (EDI) of perchlorate via drinking water was lower than the USEPA's reference dose (7000 ng kg-1 bw day-1). The EDI of perchlorate via vegetables (chard and lettuce) produced in northern Chile was three times higher than those produced in other regions. The results of this study provide information about perchlorate sources in Chile, which will be helpful in modifying current regulations.

Iodine and thyroid status during pregnancy and risk of stillbirth: A population-based nested case-control study.

Prior research suggests that severe iodine deficiency in pregnancy may be associated with stillbirth. However, the relationship between mild to moderate iodine insufficiency, which is prevalent even in developed countries, and risk of stillbirth is unclear. We thus examined associations of iodine status and risk of stillbirth in a prospective population-based nested case-control study in Finland, a mild to moderately iodine insufficient population. Stillbirth cases (n = 199) and unaffected controls (n = 249) were randomly selected from among all singleton births in Finland from 2012 to 2013. Serum samples were collected between 10 and 14 weeks gestation and analysed for iodide, thyroglobulin (Tg) and thyroid-stimulating hormone (TSH). Odds ratios (ORs) and 95% confidence intervals (CIs) for stillbirth were estimated using logistic regression. After adjusting for maternal age, prepregnancy body mass index, socio-economic status and other factors, neither high nor low serum iodide was associated with risk of stillbirth (Q1 vs. Q2-Q3 OR = 0.92, 95% CI = 0.78-1.09; Q4 vs. Q2-Q3 OR = 0.78; 95% CI = 0.45-1.33). Tg and TSH were also not associated with risk of stillbirth in adjusted models. Maternal iodine status was not associated with stillbirth risk in this mildly to moderately iodine-deficient population. Tg and TSH, which reflect functional iodine status, were also not associated with stillbirth risk. The lack of associations observed between serum iodide, TSH and Tg and risk of stillbirth is reassuring, given that iodine deficiency in pregnancy is prevalent in developed countries.

The Joint Role of Iodine Status and Thyroid Function on Risk for Preeclampsia in Finnish Women: a Population-Based Nested Case-Control Study.

Preeclampsia, a pregnancy disorder that includes hypertension and proteinuria, is a major cause of maternal and fetal morbidity and mortality. Some studies, but not all, have found that women with preeclampsia have significantly lower iodine levels than healthy pregnant women. Resolving this issue is important because iodine deficiency in pregnancy is common in the USA and parts of Europe including Finland. We conducted a nested case-control study to determine whether the risk for preeclampsia is associated with iodine status. We measured serum iodine, thyroglobulin (Tg), and thyroid stimulating hormone (TSH) at 10-14 weeks gestational age in 204 women with preeclampsia and 246 unaffected controls selected from all births in Finland. We found no significant difference in iodine (case mean = 26.04 ng/mL, control mean = 27.88 ng/mL, p = 0.995), Tg (case mean = 31.11 ng/mL, control mean = 29.61 ng/mL, p = 0.996), and TSH (case mean = 1.30 mIU/L, control mean = 1.24 mIU/L, p = 0.896) levels between cases and controls. There was no significant relationship between preeclampsia risk and iodine, Tg, or TSH after adjustment for known risk factors. These results are reassuring given the high prevalence of iodine deficiency in pregnancy.

Solid-phase microextraction for the human biomonitoring of environmental chemicals: Current applications and future perspectives.

Sample preparation is one of the crucial steps in the analytical chemistry including human biomonitoring studies. Although there are several traditional approaches available, solid-phase microextraction is emerged as one of the pioneering techniques due to its simplicity, rapidness, wide applicability, and miniaturization of traditional sample preparation (e.g., use of less or no organic solvents). There are few earlier review articles available on the advancements in solid-phase microextraction and its use for the measurement of environmental chemicals in various types of environmental samples. However, a collective information on applicability and current usage of solid-phase microextraction for the human biomonitoring of environmental chemicals are scarce, nonetheless, rising demands on innovative analytical approaches for human biomonitoring studies. Hence, in this review article, we covered the application of solid-phase microextraction as extraction/purification methods for more than 15 classes of environmental chemicals to assess their respective exposure levels and associated health outcomes in various human population reported across the globe. Further, a detailed discussion on various types of matrix used, nature of coupled analytical instrumentations, and limitations and future perspectives of solid-phase microextraction for human biomonitoring studies is presented in this review.

Occurrence and distribution of organophosphate esters in sediment from northern Chinese coastal waters.

Organophosphate esters (OPEs) are used as flame retardants and plasticizers in many consumer products. Owing to OPEs' toxicity, exposure of organisms in aquatic ecosystems is a concern. Information that pertains to the occurrence and distribution of OPEs in marine aquatic environment, however, is scarce. In this study, concentrations and profiles of 14 OPE triesters were determined in sediment collected in coastal waters (Bohai Sea and East China Sea) of northern China. The total concentrations of OPEs (ΣOPEs) in surface sediment were in the range of 1.76-49.9 (median: 9.13) ng/g dry weight (dw), which were comparable to or lower than the range of concentrations reported for surface sediments worldwide. Tris(2-chloro-propyl) phosphate (TCIPP), tris(2-chloroethyl) phosphate (TCEP), tri-isobutyl phosphate (TiBP), and tri-n-butyl phosphate (TnBP) were the predominant OPEs found in surface sediment, collectively accounting for 81% of the total concentrations. ΣOPE concentrations in sediment core (range: 8.58-169, median: 31.6 ng/g dw) were generally higher than those found in surface sediment. The vertical distribution of OPEs in sediment core showed a gradual increasing trend in concentrations during the past decade.

The Joint Role of Thyroid Function and Iodine Status on Risk of Preterm Birth and Small for Gestational Age: A Population-Based Nested Case-Control Study of Finnish Women.

Normal maternal thyroid function during pregnancy is essential for fetal development and depends upon an adequate supply of iodine. Little is known about how iodine status is associated with preterm birth and small for gestational age (SGA) in mildly iodine insufficient populations. Our objective was to evaluate associations of early pregnancy serum iodine, thyroglobulin (Tg), and thyroid-stimulating hormone (TSH) with odds of preterm birth and SGA in a prospective, population-based, nested case-control study from all births in Finland (2012-2013). Cases of preterm birth (n = 208) and SGA (n = 209) were randomly chosen from among all singleton births. Controls were randomly chosen from among singleton births that were not preterm (n = 242) or SGA (n = 241) infants during the same time period. Women provided blood samples at 10-14 weeks' gestation for serum iodide, Tg and TSH measurement. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for preterm birth and SGA. Each log-unit increase in serum iodide was associated with higher odds of preterm birth (adjusted OR = 1.19, 95% CI = 1.02-1.40), but was not associated with SGA (adjusted OR = 1.01, 95% CI = 0.86-1.18). Tg was not associated with preterm birth (OR per 1 log-unit increase = 0.87, 95% CI = 0.73-1.05), but was inversely associated with SGA (OR per log-unit increase = 0.78, 95% CI = 0.65-0.94). Neither high nor low TSH (versus normal) were associated with either outcome. These findings suggest that among Finnish women, iodine status is not related to SGA, but higher serum iodide may be positively associated with preterm birth.

Titanium dioxide nanoparticles oral exposure to pregnant rats and its distribution.

BACKGROUND: Titanium dioxide (TiO2) nanoparticles are among the most manufactured nanomaterials in the industry, and are used in food products, toothpastes, cosmetics and paints. Pregnant women as well as their conceptuses may be exposed to TiO2 nanoparticles; however, the potential effects of these nanoparticles during pregnancy are controversial, and their internal distribution has not been investigated. Therefore, in this study, we investigated the potential effects of oral exposure to TiO2 nanoparticles and their distribution during pregnancy. TiO2 nanoparticles were orally administered to pregnant Sprague-Dawley rats (12 females per group) from gestation days (GDs) 6 to 19 at dosage levels of 0, 100, 300 and 1000 mg/kg/day, and then cesarean sections were conducted on GD 20. RESULTS: In the maternal and embryo-fetal examinations, there were no marked toxicities in terms of general clinical signs, body weight, food consumption, organ weights, macroscopic findings, cesarean section parameters and fetal morphological examinations. In the distribution analysis, titanium contents were increased in the maternal liver, maternal brain and placenta after exposure to high doses of TiO2 nanoparticles. CONCLUSION: Oral exposure to TiO2 during pregnancy increased the titanium concentrations in the maternal liver, maternal brain and placenta, but these levels did not induce marked toxicities in maternal animals or affect embryo-fetal development. These results could be used to evaluate the human risk assessment of TiO2 nanoparticle oral exposure during pregnancy, and additional comprehensive toxicity studies are deemed necessary considering the possibility of complex exposure scenarios and the various sizes of TiO2 nanoparticles.

Occurrence and human exposure to bromate via drinking water, fruits and vegetables in Chile.

Bromate (BrO3-) is an anionic contaminant known possess carcinogenic potential. Although some studies have reported the occurrence of bromate in drinking water, very little is known about its presence in fruits and vegetables, especially in Chile. In this study, we quantified bromate in soils (n = 29), drinking water (n = 43), surface water (n = 6), groundwater (n = 6), fertilizers (n = 7), fruits (n = 12) and vegetables (n = 42) collected across Chile. The highest average concentrations of bromate in soils (11.7 ng g-1) and drinking water (8.8 ng mL-1) were found in northern Chile. Additionally, drinking water collected from four regions of Chile showed higher concentrations of bromate (median:18.5 ng mL-1) than the maximum contaminant level (MCL, 10 ng mL-1). Concentrations of bromate in nitrogenous and non-nitrogenous fertilizers were similar (median: 2.51 µg g-1). Leafy vegetables (median: 9.52 ng g-1) produced in the northern Chile contained higher bromate concentrations than those produced in other regions (median: 0.24 ng g-1). The estimated daily intakes of bromate via drinking water in northern, central and southern were ranged between 58.6 and 447 ng/kg bw/d. Leafy vegetables were an important source of bromate for all age group. The EDI values were below the respective reference dose (RfD) of 4000 ng/kg-day.

Occurrence of and human exposure to organophosphate flame retardants/plasticizers in indoor air and dust from various microenvironments in the United States.

The occurrence and profiles of 15 organophosphate flame retardants/plasticizers (OPFRs) (3 chlorinated [Cl-], 2 aryl-, 5 non-Cl alkyl-, and 5 other types of OPFRs) were investigated in indoor air and dust collected from various microenvironments, including homes in the Albany area of New York State, United States. Concurrent indoor air and dust were collected from floors and window sills at homes and fire stations to investigate the partitioning of OPFRs between the vapor and particulate phases of air and dust. The total concentrations of OPFRs in bulk air (vapor plus particulate phases) were found at several tens to hundreds of ng/m3, with mean concentrations that ranged from 0.12 ng/m3 for tripropyl phosphate (TPP) to 43.8 ng/m3 for tris(1-chloro-2-propyl)phosphate (TCIPP). TCIPP, triethyl phosphate (TEP) and tris(2-butoxyethyl)phosphate (TBOEP) were the predominant compounds found in bulk air, vapor phase, and dust. Among the ten types of microenvironments studied, indoor air samples collected from automobile parts shops contained the highest concentrations of OPFRs (mean: 258 ng/m3), followed by electronics shops, nail salons/shops that sell nail polish, and home construction/interior products shops. Estimated daily intakes of OPFRs via inhalation of air, dermal sorption, and ingestion of dust were 149, 279, and 390 ng/kg bw/day, respectively, which suggested that dust ingestion is an important source of human exposure to OPFRs among the indoor exposure pathways studied.

The joint role of thyroid function and iodine concentration on gestational diabetes risk in a population-based study.

INTRODUCTION: Iodine is essential for thyroid function, and iodine deficiency during pregnancy is common in Europe and the USA. However, no published studies have examined the role of iodine deficiency in the relation between thyroid function and gestational diabetes mellitus (GDM). MATERIAL AND METHODS: We conducted a population-based, nested case-control study within the Finnish Maternity Cohort using pregnancy and perinatal outcome data from the Finnish Maternal Birth Register. We randomly selected 224 GDM cases with singleton pregnancies and 224 controls without GDM from all singleton births occurring in Finland during 2012-2013. Blood was drawn at 10-14 weeks' gestation and analyzed for serum iodide, thyroglobulin, and thyroid-stimulating hormone (TSH) concentrations. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI) of GDM. RESULTS: Very high thyroglobulin concentration (>95% percentile; >83 µg/L) was not associated with significantly altered odds of GDM compared to those with normal levels (OR 0.41; 95% CI: 0.12, 1.38). High concentrations of TSH were also not associated with increased odds of GDM compared to normal levels of TSH (OR 0.45; 95% CI: 0.06, 3.18). Women in the lowest 5th percentile (<1.58 ng/mL) of iodine did not have increased odds of GDM compared to those with iodide in the highest quartile (OR 0.39; 95% CI: 0.11, 1.35). CONCLUSIONS: Low levels of iodide and thyroid function in early pregnancy are not associated with increased risk of GDM in this mildly iodine-deficient population.

Phthalate and Organophosphate Plasticizers in Nail Polish: Evaluation of Labels and Ingredients.

In the 2000s, nail polish manufacturers started promoting "3-Free" products, phasing out three widely publicized toxic chemicals: toluene, formaldehyde, and dibutyl phthalate (DnBP). However, DnBP was sometimes replaced by another endocrine-disrupting plasticizer, triphenyl phosphate (TPHP). Many new " n-Free" labels have since appeared, without any standardization on which n chemicals are excluded. This study aimed to compare measured plasticizer content against nail polish labels. First, we summarized definitions of labels. Then, we measured 12 phthalate and 10 organophosphate plasticizers in 40 nail polishes from 12 brands selected for popularity and label variety. We found labels ranging from 3- to 13-Free; 10-Free was the most inconsistently defined (six definitions). Our samples contained TPHP and bis(2-ethylhexyl) phthalate (DEHP) at up to 7940 and 331 µg/g, respectively. The 5- to 13-Free samples had lower TPHP levels than unlabeled or 3-Free samples (median <0.002 vs 3730 µg/g, p < 0.001). The samples that did not contain TPHP had higher DEHP levels (median 68.5 vs 1.51 µg/g, p < 0.05). We measured plasticizers above 100 µg/g in five brands that did not disclose them and in two that excluded them in labels. This study highlights inconsistencies in nail polish labels and identifies TPHP and DEHP as ingredient substitutes for DnBP.

Mass-flow-based removal and transformation potentials for TBBPA, HBCDs and PBDEs during wastewater treatment processes.

At a sewage treatment plant, 27 polybrominated diphenyl ethers, 17 methoxylated brominated diphenyl ethers, nine hydroxylated brominated diphenyl ethers, three hexabromocyclododecane diastereomers, and tetrabromobisphenol A were monitored at five major treatment stages (the influent, primary settlement stage, biological reaction stage, secondary settlement stage, and the UV irradiation disinfection stage). Hexabromocyclododecanes were the dominant chemicals, contributing 40% of the total concentrations of the chemicals in the dissolved phase of the sewage. Brominated flame retardant mass flow in the wastewater was lower after than before the biological reaction stage, and more than 70% of the inflowing mass load was removed from the mainstream wastewater by becoming associated with the sludge. More than half of mass loads of parent brominated flame retardants in the wastewater were removed after the treatments, but up to 10% of the initial mass loads remained in the final effluent and was expected to be released into the aquatic environment. The hydroxylated and methoxylated brominated diphenyl ether concentrations decreased by <25%, much less than the polybrominated diphenyl ethers. It is possible that hydroxylated and methoxylated polybrominated diphenyl ethers formed through the transformation of polybrominated diphenyl ethers during the biological reactions of treatment processes.

Occurrence and Distribution of Organophosphate Flame Retardants/Plasticizers in Surface Waters, Tap Water, and Rainwater: Implications for Human Exposure.

The occurrence and profiles of 14 triester organophosphate flame retardants (OPFRs) and plasticizers were investigated in surface water, tap water, rainwater, and seawater collected from New York State. In total, 150 samples collected from rivers ( n = 35), lakes ( n = 39), tap water ( n = 58), precipitation/rainwater ( n = 15), and seawater ( n = 3) were analyzed for 14 organophosphate esters (OPEs). An additional nine Hudson River water samples were collected periodically to delineate seasonal trends in OPE levels. The total concentrations of OPEs were found at part-per-trillion ranges, with average concentrations that ranged from 0.01 ng/L for tripropyl phosphate (TPP) in river water to 689 ng/L for tris(2-butoxyethyl)phosphate (TBOEP) in lake water. Tris(1-chloro-2-propyl)phosphate (TCIPP) was the most abundant compound among the investigated OPEs in all types of water. The concentrations of OPEs in river-, lake-, and rainwater were similar but >3 times higher than those found in tap water. Chlorinated alkyl OPFRs accounted for a major proportion of total concentrations. TCIPP, TBOEP, and triethyl phosphate (TEP) were found in >90% of the samples analyzed. Wet deposition fluxes for 14 OPFRs were estimated, on the basis of the concentrations measured in rainwater in Albany, New York, and the values were between 440 and 5250 ng/m2. Among several surface water bodies analyzed, samples from the Hudson River and Onondaga Lake contained elevated concentrations of OPEs. Estimated daily intake of OPEs via the ingestion of drinking water was up to 9.65 ng/kg body weight/day.

A Review of Environmental Occurrence, Fate, Exposure, and Toxicity of Benzothiazoles.

Benzothiazole and its derivatives (BTs) are high production volume chemicals that have been used for several decades in a large number of industrial and consumer products, including vulcanization accelerators, corrosion inhibitors, fungicides, herbicides, algicides, and ultraviolet (UV) light stabilizers. Several benzothiazole derivatives are used commercially, and widespread use of these chemicals has led to ubiquitous occurrence in diverse environmental compartments. BTs have been reported to be dermal sensitizers, respiratory tract irritants, endocrine disruptors, carcinogens, and genotoxicants. This article reviews occurrence and fate of a select group of BTs in the environment, as well as human exposure and toxicity. BTs have frequently been found in various environmental matrices at concentrations ranging from sub-ng/L (surface water) to several tens of µg/g (indoor dust). The use of BTs in a number of consumer products, especially in rubber products, has resulted in widespread human exposure. BTs undergo chemical, biological, and photolytic degradation in the environment, creating several transformation products. Of these, 2-thiocyanomethylthio-benzothiazole (2-SCNMeS-BTH) has been shown to be the most toxic. Epidemiological studies have shown excess risks of cancers, including bladder cancer, lung cancer, and leukemia, among rubber factory workers, particularly those exposed to 2-mercapto-benzothiazole (2-SH-BTH). Human exposure to BTs continues to be a concern.

Method for the Determination of Iodide in Dried Blood Spots from Newborns by High Performance Liquid Chromatography Tandem Mass Spectrometry.

Dried blood spots (DBS), collected for newborn screening programs in the United States, have been used to screen for congenital metabolic diseases in newborns for over 50 years. DBS provide an easy and inexpensive way to collect and store peripheral blood specimens and present an excellent resource for studies on the assessment of chemical exposures in newborns. In this study, a selective and sensitive method was developed for the analysis of iodide in DBS by high performance liquid chromatography electrospray tandem mass spectrometry. Accuracy, inter- and intraday precision, matrix effects, and detection limits of the method were determined. Further validation of the method was accomplished by concurrent analysis of whole blood and fortified blood spotted on a Whatman 903 filter card. A significant positive correlation was found between measured concentrations of iodide in venous whole blood and the same blood spotted as DBS. The method limit of detection was 0.15 ng/mL iodide. The method was further validated by the analysis of a whole blood sample certified for iodide levels (proficiency testing sample) by spotting on a filter card. Twenty DBS samples collected from newborns in New York State were analyzed to demonstrate the applicability of the method. The measured concentrations of iodide in whole blood of newborns from New York State ranged between

PBDEs and their structural analogues in marine environments: Fate and expected formation mechanisms compared with diverse environments.

The concentrations and relative distributions of 27 polybrominated diphenyl ethers (PBDEs) and 17 methoxylated (MeO-) and 8 hydroxylated (OH-) BDEs were determined in marine environments including sediments, bivalves, and seawater along the southern coast of South Korea to understand their fates and possible formation mechanisms. The relative and substituent distributions of the PBDEs and their structural analogues varied according to the characteristics of the media. PBDEs were dominant in marine sediments and seawater, whereas MeO-BDEs made the highest contributions in bivalves. Similar patterns were previously identified in inland environments in Korea, except in river water where OH-BDEs were dominant. The natural formation of structural analogues might be the main mechanism in marine, as ortho-substituted naturally occurring MeO- and OH-BDEs were dominant in all media and seemed to be more produced than in inland environments. In addition, the higher concentrations of meta-substituted MeO-BDEs nearshore than offshore was observed. This is the first study comparing marine (near- and offshore) and inland to understand the differences in their fate and possible formation mechanisms in each environmental conditions.

Occurrence, Removal, and Environmental Emission of Organophosphate Flame Retardants/Plasticizers in a Wastewater Treatment Plant in New York State.

The occurrence and fate of 14 triester organophosphate flame retardants (OPFRs) and plasticizers and their two diester metabolites were investigated in a wastewater treatment plant (WWTP) in the Albany area of New York State. All target OPFRs were found in wastewater, with average concentrations that ranged from 20.1 ng/L for tris(methylphenyl) phosphate (TMPP) to 30 100 ng/L for tris(2-butoxyethyl)phosphate (TBOEP) in influents and from 7.68 ng/L for TMPP to 12 600 ng/L for TBOEP in final effluents. TBOEP was the dominant compound in influents (max: 69 500 ng/L) followed in decreasing order by tris(1-chloro-2-propyl)phosphate (TCIPP; max: 14 500 ng/L), bis(1,3-dichloro-2-propyl)phosphate (BDCIPP; max: 4550 ng/L), tris(1,3-dichloro-2-propyl)phosphate (TDCIPP; max: 3150 ng/L) and tris(2-chloroethyl)phosphate (TCEP; max: 8450 ng/L). The fraction of TMPP sorbed to suspended particulate matter (SPM) was 56.4% of the total mass in wastewater, which was the highest among the target chemicals analyzed. The average concentrations of OPFRs in sludge were between 4.14 ng/g dw for tripropyl phosphate (TPP) and 7290 ng/g dw for TBOEP; for ash, they were between 2.17 ng/g dw for TMPP and 427 ng/g dw for triphenyl phosphate (TPhP). The mass loadings of OPFRs into the WWTP ranged from 0.02 mg/day/person for TPP to 28.7 mg/day/person for TBOEP, whereas the emission from the WWTP ranged from 0.01 mg/day/person for 2-ethylhexyl diphenyl phosphate (EHDPP) to 5.12 mg/day/person for TCIPP. The removal efficiencies for OPFRs were slightly above 60% for TMPP, TBOEP, and tris(2-ethylhexyl)phosphate (TEHP) whereas those for other OPFRs were <40% (TPhP and BDCIPP) to negative values, suggesting incomplete removal in WWTPs.

DNA aptamers for selective identification and separation of flame retardant chemicals.

Polybrominated diphenyl ethers (PBDEs) are group of chemicals which are representative persistent organic pollutants (POPs) and used as brominated flame retardants for many consumer products. PBDEs were phased out since 2009 but are still frequently observed in various environmental matrices and human body. Here, we report ssDNA aptamers which bind to BDE47, one of the PBDE congeners commonly found in various environmental matrices, and show affinity to other major tri-to hepta- BDE congeners. The PBDE specific aptamers were isolated from random library of ssDNA using Mag-SELEX. Two out of 15 sequences, based on their alignment and hairpin loop structures, were chosen to determine dissociation constant with BDE47 and showed from picomolar to nanomolar affinities (200 pM and 1.53 nM). The aptamers displayed high selectivity to the original target, BDE47, and implying general specificity to PBDE backbone with varying affinities to other congeners. Further, we showed that the use of two aptamers together could enhance the separation efficiency of BDE47 and other BDE congeners when dissolved in a solvent compared to use of single aptamer. These aptamers are expected to provide a tool for preliminary screening or quick separation of PBDEs in environmental samples prior to trace quantitative analysis.

Occurrence, removal and release characteristics of dissolved brominated flame retardants and their potential metabolites in various kinds of wastewater.

The dissolved phase compound and congener specific distribution characteristics of three widely used brominated flame retardants (BFRs) comprising 27 polybrominated diphenyl ethers (PBDEs), 12 hydroxylated and methoxylated metabolites (OH- and MeO-BDEs), 3 hexabromocyclododecanes (HBCDs) and tetrabromobisphenol A (TBBPA) were investigated in influents and effluents of various kinds of wastewater treatment plants (WWTPs), with varying source of wastewater and type of treatment, and nearby rivers in Korea. The concentration of total BFRs were the highest in industrial WWTPs nearby large industrial complexes specialized in heavy chemicals. The distribution of BFRs was differed according to composition of wastewater, with predominance of TBBPA in WWTPs with higher portion of inflowing industrial wastewater. Among HBCD diastereomers, γ-HBCD was dominant in industrial wastewater as consistent to the previous reports, however, similar contribution of α- and γ-HBCD was found in sewage and human wastewater. Through treatment process, PBDEs were the most effectively removed with a mean removal efficiency of 68.3%. HBCDs and TBBPA had removal efficiencies of 41.3% and 48.7%, respectively. The lowest removal efficiency (10.3%) was observed for PBDE metabolites and their concentration in effluent of human wastewater was even increased at maximum 1.9 fold compared with influent, implying the possibility of transformation during treatment. The estimated dissolved phase daily load of PBDEs was highest in sewage while that of TBBPA was highest in industrial wastewater.

Perfluoroalkyl substances in serum from South Korean infants with congenital hypothyroidism and healthy infants--Its relationship with thyroid hormones.

Exposure to perfluoroalkyl substances (PFASs) may disrupt thyroid systems, though the specific effects of PFASs are still being elucidated. Since research regarding exposure in infants is highly limited, our goal was to investigate exposure levels of PFASs in infant serum and correlate these levels with thyroid hormones (THs). This was accomplished by analyzing 16 PFASs in sera from a case group of infants with congenital hypothyroidism and a control group. Total PFAS exposure level was 2.63-44.7ng/mL in the case group and 2.44-22.4ng/mL in the control group. Concentrations of serum perfluorooctanoic acid (PFOA, p<0.01), perfluorononanoic acid (PFNA, p<0.001), perfluorooctanoic acid (PFDA, p<0.005), and perfluoroundecanoic acid (PFUnDA, p<0.005) were significantly higher in the case group than the control group. Levels of certain PFASs (PFOA, perfluorotridecanoic acid [PFTrDA], and perfluorohexane sulfonate [PFHxS]) showed a moderate to weak correlation with relevant antibodies.