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ZnO nanorod arrays (NRs) with a large number of sharp tips and uniform shapes were grown on the carbon cloth (CC) by a simple hydrothermal method. Titanium nitride (TiN) nanoparticles with various thicknesses were deposited on the ZnO NRs by magnetron sputtering to obtain ZnO/TiN core-shell arrays. Field emission (FE) performance of ZnO NRs show close dependence on TiN coating thickness. The turn-on field first decreases and then increases with increasing TiN coating thickness from 60 nm to 300 nm. The arrays with a design architecture can strike a balance between increased emission sites and limited field shielding effects. ZnO/TiN240 core-shell NRs have the lower turn-on electric field at 0.79 V/μm and the higher current densities at 9.39 mA/cm2. The field enhancement factor (β) of ZnO/TiN240 is about 3.2 times that of the bare ZnO NRs. On the other hand, the electrochemical properties were improved due to the formation of core-shell heterojunction on the ZnO/TiN interface and porous structure, which makes the ion and charge transport more convenient. Hence, this work not only revealed that the ZnO/TiN core-shell structure exhibited excellent improvement in both FE and supercapacitors applications, but also that growing arrays on CC was expected to achieve flexible display.

Eight organic-inorganic hybrid salts [(HL1)(SbCl4)] (1) (L1 = N,N-dimethylbenzylamine), [(HL2)2(ZnCl4)] (2) (L2 = 4-chlorobenzylamine), [(HL2)(L2)(CuCl3)(H2O)2] (3), [(HL3)2(Sb2OCl6)] (4) (L3 = qui...

In the present work, we report a high activity Ti3C2 MXene nanosheet/TiO2 (Ti3C2/TiO2) composite photocatalyst synthesized by a solvent-thermal method using tetrabutyl titanate (Ti(OBu)4) as Ti source and HF as assistant. The Ti3C2/TiO2 composites were characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV–Vis spectroscopy (UV–vis), fluorescence spectrometer (PL) and N2 adsorption-desorption. The photocatalytic performance of the Ti3C2/TiO2 composites was explored for the degradation of rhodamine B (RhB) under visible light irradiation. The results showed that more highly-active (001) crystal surfaces of TiO2 were exposed in the Ti3C2/TiO2 composites assisted by HF. The composite consisted of TiO2 microspheres and multilayer Ti3C2 exhibited optimal photocatalytic performance with relatively large specific surface area, large photocurrent and much lower impedances as compared to commercial TiO2 (P25) and pure TiO2. The optimized sample exhibited a degradation rate of 93.7% in 60 min, which was 20.5-fold higher than that of P25. The addition of the Ti3C2 effectively increased the lifetimes of the Ti3C2/TiO2 composites and suppressed the recombination of the electron-hole pairs. The density functional theory (DFT) calculations also revealed that the photogenerated electrons in the composites flowed from TiO2 to Ti3C2. The Schottky barrier at the TiO2–Ti3C2 interfaces effectively inhibited the electronic reflow to TiO2. The as-developed new Ti3C2-based complex with high photocatalytic activity under visible light irradiation might have effective and feasible application in the treatment of dye-containing wastewater.

ZnO thin film with different morphologies from seed, array to grass was grown by simple aqueous solution method under room temperature. The morphologies, structure, optical properties and photocatalytic properties of the samples were characterised by transmission electron microscope, scanning electron microscope, X-ray diffraction, fluorescence spectrometer, UV-Vis spectrophotometer and photocurrent response. The results showed that the ZnO arrays and grassy ZnO were both hexagonal wurtzite with uniform distribution and regular growth on the glass substrate. ZnO thin film with different morphologies affected the utilisation efficiency of the ultraviolet light. Multiple light reflections inside the grassy ZnO greatly increase the light efficiency. The methyl blue degradation rate of grassy ZnO photocatalyst was superior under the UV light compared to the other ZnO morphologies. Grassy ZnO showed favourable stability after five cycles. The comparison of the ZnO semiconductor in different dimensions is helpful for further research on other photocatalysts as well as their potential application.

Background: As a result of evidence suggesting phthalate toxicity, their use has decreased in recent years. However, new phthalates and non-phthalate replacements have emerged in their place, with unknown potential impacts on health. Methods: We measured 15 phthalate, two di(2-ethylhexyl)terephthalate (DEHTP), and two di(isononyl)cyclohexane-1,2-dicarboxylate (DINCH) urinary metabolites, collected up to three times during pregnancy from 994 women in Northern Puerto Rico (2011-2017). We used tests of linear trend to asses changes in concentrations over time and linear mixed models to identify predictors of exposure (sociodemographic characteristics, drinking water sources, diet, product use). Results: Several phthalate metabolites decreased over the study period indicating decreased exposure, while the geometric mean of DEHTP metabolites (molecular sum) increased 3-fold between 2014-2017. Intraclass correlations revealed low to moderate reproducibility of these biomarkers across pregnancy. Several metabolites were associated with maternal age, income, education, pre-pregnancy BMI, drinking public water, use of cleaning and personal care products and ice cream consumption. DINCH metabolite concentrations remained low throughout the study period. Conclusion: Although exposure to some phthalates may be decreasing, exposure to replacements, such as DEHTP, is increasing. Additional studies are needed to further characterize sources of phthalate replacement chemicals and potential exposure-related health effects among vulnerable populations.

International audience; Background: Within-subject biospecimens pooling can theoretically reduce bias in dose-response functions from biomarker-based studies when exposure assessment suffers from classical-type error. However, collecting many urine voids each day is cumbersome. We evaluated the empirical validity of a within-subject pooling approach and compared several options to avoid sampling each void.Methods: In 16 pregnant women who collected a spot of each urine void over several nonconsecutive weeks, we compared concentrations of 10 phenols in daily, weekly, and pregnancy within-subject pools. We pooled either three or all daily samples. In a simulation study using these data, we quantified bias in dose-response functions when using one to 20 urine samples per subject to assess methylparaben (a compound with moderate within-subject variability) and bisphenol A (high variability) exposures.Results: Correlations between exposure estimates from pools of all and of only three voids per day were above 0.80 for all time windows and compounds, except for benzophenone-3 and triclosan in the daily time window (correlations, 0.57-0.68). With one spot sample to assess pregnancy exposure, correlations were all below 0.74. Using only one biospecimen led to attenuation bias in the dose-response functions of 29% (methylparaben) and 69% (bisphenol A); four samples for methylparaben and 18 for bisphenol A decreased bias to 10%.Conclusions: For nonpersistent chemicals, collecting and pooling three samples per day instead of all daily samples efficiently estimates exposures over a week or more. Collecting around 20 biospecimens can strongly limit attenuation bias for nonpersistent chemicals such as bisphenol A.

A novel ZnO nanorod array/reduced graphene oxide (ZnO array/rGO) composite coating was synthesised via the combination of seed layers-growth and aqueous solution reaction for the formation of ZnO nanorod arrays, which was further combined with rGO using a simple water bath method. The results revealed that perpendicular arrays with hexagonal planes were successfully fabricated. The size and density of the arrays could be optimised by adjusting the reactant concentrations. The influence of the rGO fraction in the ZnO array/rGO composites on the photocatalytic degradation of the methylene blue under UV radiation was investigated. It was found that the photocatalytic performance could be significantly improved by adding rGO. The enhanced photocatalytic activities were attributed to the interactions between ZnO nanorod arrays and rGO nanosheets and subsequently effective separation of photo-generated electron-hole pairs via rGO as electron sinks. The ZnO array/rGO composites presented advantages including facile and green preparation, long photo-electron lifetime, easy particle agglomeration and recovery, and therefore is expected to be an ideal photocatalysts for the future utilisation.

The TiO 2 modified carbon nanotube composites (TiO 2 /CNT) and Ag deposited ternary multilayered composites (Ag/TiO 2 /CNT) were prepared by chemical deposition and sonochemical reaction, respectively. The composites were characterised by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and ultraviolet-visible (UV-vis). The results showed that anatase TiO 2 layers were wrapped on the surfaces of the CNTs. The face-centred-cubic structure of Ag nanoparticles (NPs) was dispersedly formed on the surfaces of the Ag/TiO 2 /CNT composites. The expected formation and good dispersion of Ag was obtained by high-intensity ultrasound irradiation assistance. All the resulted TiO 2 /CNT and Ag/TiO 2 /CNT composites exhibited a higher photocatalytic performance than that of TiO 2 for the degradation of methylene blue. The novel nanocomposite photocatalysts were developed through structural changes and double effects of carbon materials and noble metals as electron acceptors. Inhibited recombination of electron-hole pairs allows effective electron transfer and active redox reaction on the surfaces of the composites. The novel composite combines the CNTs with excellent electronic nature and nobel metallic NPs with the special semiconductor-metal junction. It can provide new guidance for the application of carbon nanotube-based photocatalytic materials in photocatalysis field from UV-vis spectrum.

Novel zinc oxide (ZnO) array/polyurethane (PU) nanocomposite coatings on the stainless steel substrates was fabricated via a simple process. ZnO arrays were prepared using zinc nitrate and hexamethylenetetramine by a seed growth method, followed by the spinning of PU. The morphologies, structure, wettability, mechanical performance and infrared radiation properties were characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, surface contact angle, nanoindentation and infrared radiation tests. The corrosion properties of the ZnO array/PU nanocomposite coating were evaluated by the electrochemical tests. The results showed that the ZnO arrays were hexagonal wurtzite and well dispersed in the composite coatings, resulting in slight increase in hydrophilicity. The mechanical properties of the coatings were improved with increased content of the ZnO arrays. The as-prepared ZnO array/PU nanocomposite coatings exhibited excellent corrosion resistance. The infrared radiation performance was observed to be slightly improved as well. It is believed that the unique organic/inorganic nanocomposite coating offers the effective strategy and potential applications for designing the functional coatings of good corrosion resistance and mechanical properties in various polymer systems.

Background: Because phthalates are quickly metabolized and excreted in urine, and human exposures tend to be episodic, phthalate metabolite concentrations measured in a maternal spot urine sample are only indicative of recent exposure. Objective: To examine temporal variability of pregnant women's phthalate exposure using multiple first morning voids (FMV) and pooled samples. Methods: We quantified 14 metabolites of eight phthalates in 577 urine samples collected from 188 pregnancies in the MARBLES (Markers of Autism Risk in Babies – Learning Early Signs) study. We calculated intraclass correlation coefficients (ICCs) using two samples of the same urine type (i.e., two FMVs or two pools) collected across the 2nd and 3rd trimesters. We also calculated ICCs and FMV/pool concentration ratios using two samples (i.e., two FMVs or one FMV and one pool) collected within the same trimester. Results: Overall, ICCs were higher in pooled samples (0.24–0.87) than in FMVs (0.08–0.69). Regardless of the sample type, ICCs tended to be higher for metabolites for which exposure sources are personal care products or indoor residential materials than those for which diet is an important exposure source. ICCs tended to increase and FMV/pool ratios tended to decrease with an increasing number of composite samples in the pools. Conclusions: Our study helped determine the number of samples needed to capture moderate to high reproducibility of individual's average exposure to phthalates and the average exposure can be differently characterized depending on the number of samples in the pools. Keywords: First morning void, Intraclass coefficient, Phthalate exposure, Pooled sample, Variability

Background: Understanding important sources and pathways of exposure to common chemicals known or suspected to impact human health is critical to eliminate or reduce the exposure. This is particularly important in areas such as Puerto Rico, where residents have higher exposures to numerous chemicals, as well as higher rates of many adverse health outcomes, compared to the mainland US. Objective: The aim of this study was to assess distributions, time trends, and predictors of urinary triclocarban, phenol, and paraben biomarkers measured at multiple times during pregnancy among women living in Northern Puerto Rico. Methods: We recruited 1003 pregnant women between years 2010 and 2016 from prenatal clinics and collected urine samples and questionnaire data on personal care product use at up to three separate visits, between 16 and 28 weeks gestation. Urine samples were analyzed for triclocarban, seven phenols and four parabens: 2,4-dichlorophenol, 2,5-dichlorophenol, benzophenone-3, bisphenol A (BPA), bisphenol S (BPS), bisphenol F, triclosan, butylparaben, ethylparaben, methylparaben, and propylparaben. Results: Detectable triclocarban, phenol and paraben concentrations among pregnant women were prevalent and tended to be higher than levels measured in women of reproductive age from the general US population, especially triclocarban, which had a median concentration 37 times higher in Puerto Rico participants (2.6 vs 0.07 ng/mL). A decreasing temporal trend was statistically significant for urine concentrations of BPA during the study period, while the BPA substitute BPS showed an increasing temporal trend. Significant and positive associations were found between biomarker concentrations with the products use in the past 48-h (soap, sunscreen, lotion, cosmetics). There was an increasing trend of triclocarban/triclosan urinary concentrations with increased concentrations of triclocarban/triclosan listed as the active ingredient in the bar soap/liquid soap products reported being used. Conclusion: Our results suggest several potential exposure sources to triclocarban, phenols, and parabens in this population and may help inform targeted approaches to reduce exposure. Keywords: Human biomonitoring, Exposure assessment, Pregnancy, Endocrine disruptors, Antimicrobials, Personal care products

Background: During puberty, mammary tissue undergoes rapid development, which provides a window of heightened susceptibility of breast composition to the influence of endogenous and exogenous hormones. Exposure to endocrine-disrupting chemicals (EDC) may affect breast development and composition and the risk of developing breast cancer in adulthood. Methods: We evaluated the associations between breast density and urinary concentrations of phenols and phthalates collected at Tanner 1 (B1) and Tanner 4 (B4) in 200 Chilean girls. Total breast volume (BV), fibroglandular volume (FGV), and percent dense breast (%FGV) were evaluated at B4 using dual X-ray absorptiometry. Generalized estimating equations were used to analyze the association between concentrations of EDC biomarkers across puberty and breast density. Results: The geometric mean %FGV was 7% higher among girls in the highest relative to the lowest tertile of monocarboxyisooctyl phthalate [1.07; 95% confidence interval (CI), 1.01–1.14]. Monoethyl phthalate concentrations at B4 were positively associated with FGV (highest vs. lowest tertile: 1.22; 95% CI, 1.06–1.40). Bisphenol A displayed a U-shaped association with FGV; girls in the middle tertile had at least 10% lower FGV than girls in the lowest or highest tertiles. Monocarboxyisononyl phthalate showed a nonlinear association with BV. No other statistically significant associations were observed. Conclusions: Our results suggest that the developing breast tissue is susceptible to select EDCs during childhood and adolescence. Impact: This study may spur further investigations into environmental influences on breast development during puberty and how shifts in pubertal breast density track through the life course to modify breast cancer risk.

Background Environmental phenols, such as parabens, bisphenol A, and triclosan, are ubiquitous in indoor environments because of their use in packaging, plastics, personal care products, and as anti-microbials. The primary pathways of exposure, as well as habits and behaviors that may lead to greater exposure, are still unclear. Objectives Herein, we investigate the relationships between phenols found in residential environments by comparing levels in paired samples of house dust and hand wipes with children’s urine. In addition, phenols were analyzed in a novel exposure tool, the silicone wristbands, to investigate which external matrix best correlates with individual exposure based on urinary phenol biomarkers. Methods Children aged 3–6 years in central North Carolina, United States, provided paired hand wipe (n = 202), wristband (n = 76), and spot urine samples (n = 180), while legal guardians completed questionnaires on habits and behaviors. House dust samples (n = 186) were collected from the main living area during home visits completed between 2014 and 2016. Results Environmental phenols were detected frequently in all matrices investigated. Ethyl, methyl, and propylparaben levels observed in hand wipes, dust, and on wristbands were significantly correlated to their associated urinary biomarkers. In addition, intra-paraben correlations were noted, with biomarkers of ethyl, methyl, and propylparabens generally positively and significantly correlated, which suggests co-application of parabens in products. Triclosan levels in dust were positive and significantly correlated with levels in hand wipes and wristbands and with urinary concentrations, suggesting non-personal care product sources may be important in children’s overall triclosan exposure. Generally, chemicals on wristbands were more highly correlated with urinary biomarkers than with chemicals in hand wipes or house dust. In addition, more frequent lotion use was positively associated with urinary concentrations of paraben biomarkers. Conclusions Our results suggest that the home environment is an important source of exposure which has been under-investigated for some environmental phenols (e.g., triclosan in house dust). Associations between wristbands and biomarkers of exposure, which were stronger than for hand wipes and house dust, suggest that silicone wristbands may provide a suitable exposure assessment tool for some phenols.

Background Toxicological studies highlight the potential neurotoxicity of perfluoroalkyl substances (PFAS) during fetal development. However, few epidemiological studies have examined the impact of childhood PFAS on neurodevelopment. Methods We employed data from 208 children in the Health Outcomes and Measures of the Environment Study, a birth cohort (Cincinnati, OH), to examine associations of six serum PFAS concentrations measured at 3 and 8 years with executive function assessed at 8 years using the validated parent-completed Behavior Rating Inventory of Executive Function survey. We used multiple informant models to identify susceptible windows of neurotoxicity to PFAS and executive function. We investigated trajectories of PFAS concentrations and whether sex modified these associations. Results Each ln-increase in perfluorononanoate (PFNA) at 8 years was associated with a 3.4-point increase (95% CI 0.4, 6.3) in metacognition score, indicating poorer function. Children with PFNA above the median at 8 years had poorer global executive functioning compared to children with concentrations consistently below median levels (β = 6.5, 95% CI 0.2, 12.9). Higher concurrent PFNA was associated with poorer behavior regulation among males, while associations among females were null (pPFNA×sex = 0.018). Children with higher concurrent perfluorooctanoate (PFOA) had increased odds of being at risk of having clinical impairments in metacognition (OR = 3.18, 95% CI 1.17, 8.60). There were no associations between perfluorooctane sulfonate and perfluorohexane sulfonate and executive function. Conclusions PFNA and PFOA at 8 years, but not 3 years, may be related to poorer executive function at 8 years. Results need to be confirmed in cohort studies with larger sample sizes.

In epidemiologic studies, classifying episodic exposures to chemicals with short half-lives, such as phthalates and phenols, is challenging. We assessed whether accounting for sources of variability unrelated to exposure pathways would improve the reproducibility of urine concentrations of select phthalate metabolites and phenols. In 2011, a subset of pregnant women (n = 19) enrolled in a prospective study provided first morning urine samples every 3-4 weeks between 16 and 36 weeks gestation. At the time of collection, we identified potential contributors to variations in urinary concentrations: weight gain, gestational age, time slept, time since awoke, time since last food/drink, and time since last void. We estimated intraclass correlation coefficients (ICCs) among repeat urine concentrations with and without adjustment for sources of variability using a random intercept linear mixed model. Concentrations of monoethyl phthalate, butyl, and propyl parabens were the most reproducible (ICCs: 0.68, 0.56, and 0.56, respectively). However, adjustment for potential sources of variability unrelated to exposure pathways did not materially improve reproducibility nor the ability of a single sample to predict exposure based on average biomarker concentrations across pregnancy. Future studies should carefully consider the exposure timeframe and the reliability of using biomarker concentrations from a single time point to represent exposures over pregnancy.

Design of inexpensive and highly efficient bifunctional electrocatalyst is paramount for overall water splitting. In this study, amorphous Ni–Fe–P alloy was successfully synthesized by one-step direct-current electrodeposition method. The performance of Ni–Fe–P alloy as a bifunctional electrocatalyst toward both hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) was evaluated in 30 wt% KOH solution. It was found that Ni–Fe–P alloy exhibits excellent HER and OER performances, which delivers a current density of 10 mA cm−2 at overpotential of ∼335 mV for HER and ∼309 mV for OER with Tafel slopes of 63.7 and 79.4 mV dec−1, respectively. Moreover, the electrolyzer only needs a cell voltage of ∼1.62 V to achieve 10 mA cm−2 for overall water splitting. The excellent electrocatalytic performance of Ni–Fe–P alloy is attributed to its electrochemically active constituents, amorphous structure, and the conductive Cu Foil.

Background Subfertile women are at increased risk of glucose intolerance in pregnancy. Based on epidemiologic studies, exposure to certain phthalates is associated with diabetes, elevated glucose, and increased insulin resistance. Objectives To evaluate the association between urinary phthalate metabolites and pregnancy glucose levels in women seeking medically assisted reproduction. Methods We evaluated 245 women participating in a prospective cohort study based at a large fertility clinic who delivered live births and had data on pregnancy urinary phthalate metabolite concentrations and blood glucose levels. Urinary phthalate metabolite concentrations were from single spot urine samples collected in 1st and 2nd trimesters. Blood glucose data was abstracted from medical records for non-fasting 50-g glucose challenge tests at 24–28 weeks gestation. Multivariable linear regression models were used to evaluate associations between 7 urinary phthalate metabolites in quartiles and mean glucose adjusted for potential confounders. Results Eighteen percent of women had glucose levels ≥ 140 mg/dL. Second trimester monoethyl phthalate (MEP) concentrations were positively associated with glucose levels, with adjusted mean (95%CI) glucose levels of 121 mg/dl (114, 128) vs. 109 mg/dL (103, 116) for women in highest and lowest quartiles, respectively. Women in the highest quartile of second trimester mono-isobutyl phthalate (MiBP) concentrations had a mean glucose level 14 mg/dL lower compared to women in the lowest quartile. No other urinary phthalate metabolites were associated with glucose levels. Conclusions MEP and MiBP—metabolites of diethyl phthalate and dibutyl phthalate, respectively—were associated with higher pregnancy glucose in subfertile women—a population at high risk of glucose intolerance in pregnancy. Electronic supplementary material The online version of this article (10.1186/s12940-018-0399-5) contains supplementary material, which is available to authorized users.

Human exposure to consumer and personal care products chemicals such as phenols, including parabens and other antimicrobial agents, can be assessed through biomonitoring by quantifying urinary concentrations of the parent chemical or its metabolites, often after hydrolysis of phase II conjugates. Developing suitable analytical methods for the concurrent quantification of multiple exposure biomarkers is challenging because optimal conditions for the hydrolysis of such conjugates (e.g., O-glucuronides, N-glucuronides, sulfates) may differ depending on the biomarker. We evaluated the effectiveness of seven commercial hydrolytic enzymes to simultaneously hydrolyze N-glucuronides (using the antibacterial triclocarban as example compound) and other conjugates (using select phenols and parabens as examples) by using on-line solid phase extraction–high performance liquid chromatography-isotope dilution-tandem mass spectrometry. Incubation (30 min, 55 °C) with a genetically engineered β-glucuronidase (IMCS, ≥ 15 units/μL urine) hydrolyzed N-glucuronide triclocarban, but did not fully hydrolyze the conjugates of phenols and parabens. By contrast, incubation (4 h, 37 °C) with solid β-glucuronidase (Helix pomatia, Type H-1, ≥ 30 units/μL urine) or liquid β-glucuronidase/arylsulfatase (Helix pomatia, 30 units/μL urine [i.e., 30 μL/100 μL urine]) in the presence of 100 μL methanol for 100 μL urine completely hydrolyzed N-glucuronide triclocarban and the conjugates of several phenols and parabens, without cleaving the ester bond of the parabens to form p-hydroxybenzoic acid. These results highlight the relevance of method validation procedures that include optimizing the hydrolysis of phase II urinary conjugates (e.g., enzyme type and amount used, reaction time, temperature) to quantify accurately and concurrently multiple exposure biomarkers for biomonitoring purposes.

BACKGROUND: Phthalates and phenols are suspected endocrine disrupting chemicals that may adversely impact fetal outcomes following in utero exposure. Understanding predictors of exposure to phthalates and phenols during the prenatal period is important. METHODS: We measured urinary concentrations of 15 phthalate metabolites and 11 phenols in 446 pregnant women enrolled in the Healthy Start pre-birth cohort. Creatinine-adjusted geometric means (GM) for each urinary biomarker were compared across categories of potential sociodemographic and dietary predictors. To assess the independent relationship between each significant food group predictor and biomarker we used multivariable models, adjusted for sociodemographic predictors. RESULTS: The phthalate metabolites with the highest concentrations were monoethyl phthalate (GM: 41.1 μg/g creatinine) and monocarboxyisooctyl phthalate (GM: 20.5 μg/g creatinine). Benzophenone-3 (GM: 124.6 μg/g creatinine) and methyl paraben (GM: 119.9 μg/g creatinine) were the phenols with the highest concentrations. Concentrations of the metabolites of di-n-butyl phthalate and di(2-ethylhexyl) phthalate were significantly higher in younger, unmarried or unemployed mothers, those who were overweight or obese, those with lower educational attainment, or those of minority race/ethnicity (p-values

Background: Exposure to perfluoroalkyl substances (PFASs) may impact children's neurodevelopment. Objective: To examine the association of prenatal and early childhood serum PFAS concentrations with children's reading skills at ages 5 and 8years. Methods: We used data from 167 mother-child pairs recruited during pregnancy (2003–2006) in Cincinnati, OH, quantified prenatal serum PFAS concentrations at 16±3weeks of gestation and childhood sera at ages 3 and 8years. We assessed children's reading skills using Woodcock-Johnson Tests of Achievement III at age 5years and Wide Range Achievement Test-4 at age 8years. We used general linear regression to quantify the covariate-adjusted associations between natural log-transformed PFAS concentrations and reading skills, and used multiple informant model to identify the potential windows of susceptibility. Results: Median serum PFASs concentrations were PFOS>PFOA>PFHxS>PFNA in prenatal, 3-year, and 8-year children. The covariate-adjusted general linear regression identified positive associations between serum PFOA, PFOS and PFNA concentrations and children's reading scores at ages 5 and 8years, but no association between any PFHxS concentration and reading skills. The multiple informant model showed: a) Prenatal PFOA was positively associated with higher children's scores in Reading Composite (β: 4.0, 95% CI: 0.6, 7.4 per a natural log unit increase in exposure) and Sentence Comprehension (β: 4.2, 95% CI: 0.5, 8.0) at age 8years; b) 3-year PFOA was positively associated with higher children's scores in Brief Reading (β: 7.3, 95% CI: 0.9, 13.8), Letter Word Identification (β: 6.6, 95% CI: 1.1, 12.0), and Passage Comprehension (β: 5.9, 95% CI: 1.5, 10.2) at age 5years; c) 8-year PFOA was positively associated with higher children's Word Reading scores (β: 5.8, 95% CI: 0.8, 10.7) at age 8years. Prenatal PFOS and PFNA were positively associated with children's reading abilities at age 5years, but not at age 8years; 3-year PFOS and PFNA were positively associated with reading scores at age 5years. But PFHxS concentrations, at any exposure windows, were not associated with reading skills. Conclusion: Prenatal and childhood serum PFOA, PFOS and PFNA concentrations were positively associated with better children's reading skills at ages 5 and 8years, but no association was found between serum PFHxS and reading skills. Keywords: Prenatal, Childhood, Perfluoroalkyl substances (PFASs), Reading skills

Background: Growing evidence suggests that exposure to per- and polyfluoroalkyl substances (PFASs) may disrupt lipid homeostasis and liver function, but data in children are limited. Objective: We examined the association of prenatal and mid-childhood PFAS exposure with lipids and alanine aminotransferase (ALT) levels in children. Methods: We studied 682 mother-child pairs from a Boston-area pre-birth cohort. We quantified PFASs in maternal plasma collected in pregnancy (median 9.7weeks gestation, 1999–2002) and in child plasma collected in mid-childhood (median age 7.7years, 2007–2010). In mid-childhood we also measured fasting total (TC), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), and ALT. We then derived low-density lipoprotein cholesterol (LDL-C) from TC, HDL-C, and TG using the Friedewald formula. Results: Median (interquartile range, IQR) perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and perfluorodecanoate (PFDeA) concentrations in child plasma were 6.2 (5.5), 4.3 (3.0), and 0.3 (0.3) ng/mL, respectively. Among girls, higher child PFOS, PFOA, and PFDeA concentrations were associated with detrimental changes in the lipid profile, including higher TC and/or LDL-C [e.g., β per IQR increment in PFOS=4.0mg/dL (95% CI: 0.3, 7.8) for TC and 2.6mg/dL (−0.5, 5.8) for LDL-C]. However, among both boys and girls, higher plasma concentrations of these child PFASs were also associated with higher HDL-C, which predicts better cardiovascular health, and slightly lower ALT, which may indicate better liver function. Prenatal PFAS concentrations were also modestly associated with improved childhood lipid and ALT levels. Conclusions: Our data suggest that prenatal and mid-childhood PFAS exposure may be associated with modest, but somewhat conflicting changes in the lipid profile and ALT levels in children. Keywords: Per- and polyfluoroalkyl substances, Lipids, Liver function, Pregnancy, Childhood

Background: Per- and polyfluoroalkyl substances (PFAS) are considered chemicals of emerging concern, in part due to their environmental and biological persistence and the potential for widespread human exposure. In 2007, a PFAS manufacturer near Decatur, Alabama notified the United States Environmental Protection Agency (EPA) it had discharged PFAS into a wastewater treatment plant, resulting in environmental contamination and potential exposures to the local community. Objectives: To characterize PFAS exposure over time, the Agency for Toxic Substances and Disease Registry (ATSDR) collected blood and urine samples from local residents. Methods: Eight PFAS were measured in serum in 2010 (n=153). Eleven PFAS were measured in serum, and five PFAS were measured in urine (n=45) from some of the same residents in 2016. Serum concentrations were compared to nationally representative data and change in serum concentration over time was evaluated. Biological half-lives were estimated for perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and perfluorohexane sulfonic acid (PFHxS) using a one-compartment pharmacokinetic model. Results: In 2010 and 2016, geometric mean PFOA and PFOS serum concentrations were elevated in participants compared to the general U.S. population. In 2016, the geometric mean PFHxS serum concentration was elevated compared to the general U.S. population. Geometric mean serum concentrations of PFOA, PFOS, and perfluorononanoic acid (PFNA) were significantly (p≤0.0001) lower (49%, 53%, and 58%, respectively) in 2016 compared to 2010. Half-lives for PFOA, PFOS, and PFHxS were estimated to be 3.9, 3.3, and 15.5years, respectively. Concentrations of PFOA in serum and urine were highly correlated (r=0.75) in males. Conclusions: Serum concentrations of some PFAS are decreasing in this residentially exposed community, but remain elevated compared to the U.S. general population. Keywords: PFAS, PFOA, PFOS, Biomonitoring, Half-life

Objective To investigate the association between urinary triclosan concentrations and antral follicle count (AFC), a well-accepted marker of ovarian reserve, among women from a fertility center. Design Prospective cohort study. Setting Hospital fertility center. Patient(s) A total of 109 women. Intervention(s) Urinary triclosan concentrations quantified by online solid phase extraction-high performance liquid chromatography-isotope dilution tandem mass spectrometry. Main Outcome Measure(s) AFC through transvaginal ultrasonography on the third day of an unstimulated menstrual cycle or on the third day of a progesterone withdrawal bleed. Result(s) The geometric mean of the specific gravity–adjusted urinary triclosan concentrations for the 225 samples provided by the 109 women was 13.0 μg/L (95% confidence interval [CI], 8.9, 19.1). Women had median (with interquartile range) AFC of 13 (8, 18). The specific gravity–adjusted urinary triclosan concentrations were inversely associated with AFC (−4%; 95% CI, −7%, −1%). Women with triclosan concentrations above the median had lower AFC compared with those whose triclosan concentrations were equal to or below the median, with an adjusted difference of −3.2 (95% CI, −3.9, −1.6) among those with a body mass index 2 and −1.8 (95% CI, −3.2, −0.3) among those who were Conclusion(s) Specific gravity–adjusted urinary triclosan concentrations were inversely associated with AFC in women seeking care at a fertility center. This association was modified by age and body mass index, with the younger and leaner women showing larger decreases in AFC.

Tin oxide nanostructured arrays with different morphologies were grown on stainless-steel mesh substrates by a simple thermal evaporation process. It was found that the SnO 2 nanostructures could be easily changed from nanobelts to nanocones, nanoneedles, micro-rods, ultra-long nanowires, and slim nanorods by controlling the parameters of growth temperature and N 2 /O 2 flow. A model combining vapor-liquid-solid (VLS)-base growth and vapor-solid (VS)-tip growth was proposed to explain the growth of SnO 2 nanostructures with manifold morphologies. Field-emission (FE) studies revealed that the morphologies of these patterned SnO 2 nanostructures had considerable effects on the FE properties. Among these nanostructures, ultra-long nanowire arrays had the lowest turn-on field (~0.47 V/um) and the highest field enhancement factor (~8848). More importantly, the ultra-long nanowire emitters showed excellent FE stability with fluctuations within 2.7%. The enhanced FE properties may be attributed to synergic effects arising from the aligned structures of the ultra-long nanowire emitters, their smaller areal density and their highest aspect ratio (~12000).

Di-2-ethylhexyl terephthalate (DEHTP), a structural isomer of di-2-ethylhexyl phthalate (DEHP), is a plasticizer used in a variety of commercial applications, but data on Americans’ exposure to DEHTP do not exist. We investigated the exposure to DEHTP in a convenience group of U.S. adults by analyzing urine collected anonymously in 2000 (N = 44), 2009 (N = 61), 2011 (N = 81), 2013 (N = 92), and 2016 (N = 149) for two major DEHTP oxidative metabolites: mono-2-ethyl-5-carboxypentyl terephthalate (MECPTP) and mono-2-ethyl-5-hydroxyhexyl terephthalate (MEHHTP). For comparison, we also quantified the analogous DEHP metabolites mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP) and mono-2-ethyl-5-carboxypentyl phthalate (MECPP). We detected MECPTP, MEHHP, and MECPP in all samples collected in 2016 with geometric means of 13.1, 4.1, and 6.7 ng/mL, respectively; we detected MEHHTP in 91% of the samples (geometric mean = 3.1 ng/mL). Concentrations of MECPTP correlated well with those of MEHHTP (R 2 = 0.8, p 0.05) suggesting different sources of exposure to DEHP and DEHTP. We also evaluated the fraction of the metabolites eliminated in their free (i.e., unconjugated) form. The median percent of unconjugated species was lower for the DEHP metabolites (MECPP [45.5%], MEHHP [1.9%]) compared to the DEHTP metabolites (MECPTP [98.8%], MEHHTP [21.2%]). Contrary to the downward trend from 2000 to 2016 in urinary concentrations of MEHHP and MECPP, we observed an upward trend for MEHHTP and MECPTP. These preliminary data suggest that exposure to DEHTP may be on the rise. Nevertheless, general population exposure data using MEHHTP and MECPTP as exposure biomarkers would increase our understanding of exposure to DEHTP, one of the known DEHP alternatives.

Background General population human biomonitoring programs such as the National Health and Nutrition Examination Survey (NHANES) in the United States suggest that chemical exposures are common. Exposures during childhood may affect health later in life, but biomonitoring data in NHANES among pre-school aged children are limited. Methods A convenience group of 122 3–5 year old American boys and girls were recruited in 2013 for a pilot study to assess the feasibility of collecting urine from young children and analyzing it for select chemical exposure biomarkers for future NHANES. Children were primarily Hispanic (64.8%); the remainder was divided between non-Hispanic black, and non-Hispanic white and “other.” We measured 52 urinary biomarkers: 13 phthalates and one non-phthalate plasticizer, five phenols and four parabens, 10 polycyclic aromatic hydrocarbons (PAHs), and 19 pesticides. For each biomarker, we calculated descriptive statistics. We also calculated the number of biomarkers detected within each child, and performed principal components analysis (PCA). Results NHANES staff obtained permission to attempt collection of 60 mL urine from 3 to 5 year olds who participated in the 2013 NHANES health examination; 83% of children successfully provided the target volume. We detected 24 individual biomarkers of pesticides, phenols and parabens, phthalates/non-phthalate plasticizers, and PAHs in 95–100% of children. The median number of biomarkers detected was 37: nine pesticides, five phenols and parabens, 13 phthalates and non-phthalate plasticizers, and 10 PAHs. Biomarkers concentrations appear to be similar to national estimates among 6–11 year old children from previous NHANES. PCA suggested high within-class correlations among biomarkers. Conclusions These young children successfully adhered to the collection protocol and produced enough urine for the quantification of environmental biomarkers currently being measured in NHANES participants 6 years of age and older. Using the same analytical methods employed for the analysis of samples collected from older NHANES participants, in this sample of pre-school aged children we detected multiple chemicals including plasticizers, combustion products, personal-care product chemicals, and pesticides. Starting with NHANES 2015–2016, the NHANES biomonitoring program will include urinary biomarkers for 3–5 year old children to provide exposure data to select chemicals at the national level among this age group.

Background: Few studies have examined whether prenatal exposure to perfluoroalkyl substances (PFASs) is associated with childhood adiposity. Objective: We examined associations of prenatal exposure to PFASs with adiposity in early and mid-childhood. Methods: We measured plasma PFAS concentrations in 1,645 pregnant women (median, 9.6 weeks gestation) enrolled in Project Viva, a prospective pre-birth cohort study in Massachusetts (USA), between 1999 and 2002. We assessed overall and central adiposity in 1,006 children in early childhood (median, 3.2 years) and 876 in mid-childhood (median, 7.7 years) using anthropometric and dual X-ray absorptiometry (DXA) measurements. We fitted multivariable linear regression models to estimate exposure-outcome associations and evaluated effect modification by child sex. Results: Median (25–75th percentiles) prenatal plasma perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorononanoate (PFNA) concentrations in children assessed in early childhood were 5.6 (4.1–7.7), 24.8 (18.4–33.9), 2.4 (1.6–3.8), and 0.6 (0.5–0.9) ng/mL, respectively. Among girls, each interquartile range increment of prenatal PFOA concentrations was associated with 0.21 kg/m 2 (95% CI: –0.05, 0.48) higher body mass index, 0.76 mm (95% CI: –0.17, 1.70) higher sum of subscapular and triceps skinfold thickness, and 0.17 kg/m 2 (95% CI: –0.02, 0.36) higher DXA total fat mass index in mid-childhood. Similar associations were observed for PFOS, PFHxS, and PFNA. We observed null associations for boys and early-childhood adiposity measures. Conclusions: In this cohort, prenatal exposure to PFASs was associated with small increases in adiposity measurements in mid-childhood, but only among girls. Antecedentes: pocos estudios han examinado si la exposición prenatal a sustancias perfluoroalquilo (PFAS) está asociada con la adiposidad infantil. Objetivo: Examinamos las asociaciones de la exposición prenatal a los PFAS con la adiposidad en la niñez temprana y media. Métodos: medimos las concentraciones plasmáticas de PFAS en 1.645 mujeres embarazadas (mediana, 9,6 semanas de gestación) inscritas en Project Viva, un estudio prospectivo de cohortes prenatal en Massachusetts (EE. UU.), Entre 1999 y 2002. Evaluamos la adiposidad general y central en 1.006 niños en la primera infancia (mediana, 3,2 años) y 876 en la infancia media (mediana, 7,7 años) mediante mediciones antropométricas y de absorciometría de rayos X duales (DXA). Ajustamos modelos de regresión lineal multivariable para estimar las asociaciones exposición-resultado y evaluamos la modificación del efecto por sexo del niño. Resultados: La mediana (percentiles 25-75) de perfluorooctanoato plasmático prenatal (PFOA), sulfonato de perfluorooctano (PFOS), sulfonato de perfluorohexano (PFHxS) y perfluorononanoato (PFNA) en niños evaluados en la primera infancia fue de 5,6 (4,1-7,7), 24,8 ( 18,4 a 33,9), 2,4 (1,6 a 3,8) y 0,6 (0,5 a 0,9) ng / ml, respectivamente. Entre las niñas, cada incremento del rango intercuartílico de las concentraciones prenatales de PFOA se asoció con 0,21 kg / m 2 (IC del 95%: –0,05, 0,48) mayor índice de masa corporal, 0,76 mm (IC del 95%: –0,17, 1,70) mayor suma de subescapular y espesor del pliegue cutáneo del tríceps, y 0,17 kg / m 2 (IC del 95%: –0,02, 0,36) índice de masa grasa total DXA más alto en la infancia media. Se observaron asociaciones similares para PFOS, PFHxS y PFNA. Observamos asociaciones nulas para los niños y las medidas de adiposidad en la primera infancia. Conclusiones: En esta cohorte, la exposición prenatal a los PFAS se asoció con pequeños aumentos en las mediciones de adiposidad en la infancia media, pero solo entre las niñas. Antecedentes: Poucos estudos examinaram se a exposição pré-natal a substâncias perfluoroalquil (PFASs) está associada à adiposidade infantil. Objetivo: Nós examinamos associações de exposição pré-natal a PFASs com adiposidade na primeira e na metade da infância. Métodos: Medimos as concentrações plasmáticas de PFAS em 1.645 mulheres grávidas (mediana, 9,6 semanas de gestação) inscritas no Projeto Viva, um estudo de coorte prospectivo pré-nascimento em Massachusetts (EUA), entre 1999 e 2002. Avaliamos a adiposidade geral e central em 1.006 crianças na primeira infância (mediana, 3,2 anos) e 876 na meia-infância (mediana, 7,7 anos) usando medidas antropométricas e absortometria de raio-X duplo (DXA). Ajustamos modelos de regressão linear multivariável para estimar as associações de exposição-desfecho e avaliamos a modificação do efeito por sexo da criança. Resultados: As concentrações de perfluorooctanoato plasmático pré-natal (PFOA), perfluorooctano sulfonato (PFOS), perfluorohexano sulfonato (PFHxS) e perfluorononanoato (PFNA) em crianças avaliadas na primeira infância foram 5,6 (4,1-7,7), 24,8 ( 18,4–33,9), 2,4 (1,6–3,8) e 0,6 (0,5–0,9) ng / mL, respectivamente. Entre as meninas, cada incremento do intervalo interquartil das concentrações pré-natais de PFOA foi associado a 0,21 kg / m 2 (IC 95%: -0,05, 0,48) índice de massa corporal mais alto, 0,76 mm (IC 95%: -0,17, 1,70) maior soma do subescapular e espessura da dobra cutânea tricipital, e 0,17 kg / m 2 (IC 95%: –0,02, 0,36) índice de massa gorda total DXA mais alto no meio da infância. Associações semelhantes foram observadas para PFOS, PFHxS e PFNA. Observamos associações nulas para meninos e medidas de adiposidade na primeira infância. Conclusões: Nesta coorte, a exposição pré-natal a PFASs foi associada a pequenos aumentos nas medidas de adiposidade no meio da infância, mas apenas entre as meninas. Boston University School of Public Health, United States Universidad Nacional, Costa Rica Harvard Medical School and Harvard Pilgrim Health Care Institute, United States Harvard T.H. Chan School of Public Health, United States National Center for Environmental Health, United States University of California, United States Instituto Regional de Estudios en Sustancias Tóxicas

Background: Perfluoroalkyl substances (PFASs) are synthetic chemicals that may persist in the environment and in humans. There is a possible association between early-life PFAS exposure and metabolic dysfunction in later life, but data are limited. Methods: We studied 665 mother–child pairs in Project Viva, a Boston, Massachusetts-area cohort recruited 1999–2002. We quantified concentrations of PFASs [perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoate (PFNA), perfluorohexane sulfonate (PFHxS), and perfluorodecanoate (PFDeA)] in maternal plasma collected at the first prenatal visit (median, 9.6 weeks gestation) and in child plasma from the mid-childhood research visit (median, 7.7 years). We assessed leptin, adiponectin, and homeostatic model assessment of insulin resistance (HOMA-IR) in mid-childhood. We fit covariate-adjusted linear regression models and conducted stratified analyses by child sex. Results: Children with higher PFAS concentrations had lower HOMA-IR [e.g., –10.1% (95% CI: –17.3, –2.3) per interquartile range increment in PFOA]. This inverse association between child PFAS and HOMA-IR was more pronounced in females [e.g., PFOA: –15.6% (95% CI: –25.4, –4.6) vs. –6.1% (95% CI: –16.2, 5.2) for males]. Child PFAS plasma concentrations were not associated with leptin or adiponectin. Prenatal PFAS plasma concentrations were not associated with leptin, adiponectin, or HOMA-IR in offspring. Conclusions: We found no evidence for an adverse effect of early-life PFAS exposure on metabolic function in mid-childhood. In fact, children with higher PFAS concentrations had lower insulin resistance. Antecedentes: las sustancias perfluoroalquilo (PFAS) son sustancias químicas sintéticas que pueden persistir en el medio ambiente y en los seres humanos. Existe una posible asociación entre la exposición temprana al PFAS y la disfunción metabólica en la edad adulta, pero los datos son limitados. Métodos: Estudiamos 665 parejas de madre e hijo en el Proyecto Viva, una cohorte del área de Boston, Massachusetts, reclutada en 1999-2002. Se cuantificaron las concentraciones de PFAS [perfluorooctanoato (PFOA), sulfonato de perfluorooctano (PFOS), perfluorononanoato (PFNA), sulfonato de perfluorohexano (PFHxS) y perfluorodecanoato (PFDeA)] en el plasma materno recolectado en la primera visita prenatal (mediana de 9,6 semanas), y en el plasma infantil de la visita de investigación de la niñez media (mediana, 7,7 años). Evaluamos la leptina, la adiponectina y la evaluación del modelo homeostático de la resistencia a la insulina (HOMA-IR) en la infancia media. Ajustamos modelos de regresión lineal ajustados por covariables y realizamos análisis estratificados por sexo del niño. Resultados: Los niños con concentraciones más altas de PFAS tenían HOMA-IR más bajo [por ejemplo, –10,1% (IC del 95%: –17,3, –2,3) por incremento de rango intercuartílico en PFOA]. Esta asociación inversa entre PFAS infantil y HOMA-IR fue más pronunciada en las mujeres [p. Ej., PFOA: –15,6% (IC del 95%: –25,4, –4,6) frente a –6,1% (IC del 95%: –16,2, 5,2) para machos]. Las concentraciones plasmáticas de PFAS en niños no se asociaron con leptina o adiponectina. Las concentraciones plasmáticas prenatales de PFAS no se asociaron con leptina, adiponectina o HOMA-IR en la descendencia. Conclusiones: No encontramos evidencia de un efecto adverso de la exposición temprana al PFAS sobre la función metabólica en la niñez media. De hecho, los niños con concentraciones más altas de PFAS tenían menor resistencia a la insulina. Antecedentes: As substâncias perfluoroalquílicas (PFASs) são produtos químicos sintéticos que podem persistir no meio ambiente e nos seres humanos. Há uma possível associação entre a exposição precoce ao PFAS e disfunção metabólica na vida adulta, mas os dados são limitados. Métodos: Estudamos 665 pares de mãe e filho no Projeto Viva, uma coorte da área de Boston, Massachusetts, recrutada em 1999–2002. Quantificamos as concentrações de PFASs [perfluorooctanoato (PFOA), perfluorooctano sulfonato (PFOS), perfluorononanoato (PFNA), sulfonato de perfluorohexano (PFHxS) e perfluorodecanoato (PFDeA)] no plasma materno coletado na primeira visita pré-natal (mediana). e no plasma infantil da visita de pesquisa do meio da infância (mediana, 7,7 anos). Avaliamos a leptina, a adiponectina e a avaliação do modelo homeostático de resistência à insulina (HOMA-IR) no meio da infância. Ajustamos modelos de regressão linear ajustados por covariável e conduzimos análises estratificadas por sexo da criança. Resultados: Crianças com concentrações mais altas de PFAS tiveram menor HOMA-IR [por exemplo, –10,1% (IC 95%: –17,3, –2,3) por incremento do intervalo interquartil no PFOA]. Esta associação inversa entre crianças PFAS e HOMA-IR foi mais pronunciada em mulheres [por exemplo, PFOA: –15,6% (IC 95%: –25,4, –4,6) vs. –6,1% (IC 95%: –16,2, 5,2) para machos]. As concentrações plasmáticas de crianças PFAS não foram associadas à leptina ou adiponectina. As concentrações plasmáticas de PFAS pré-natal não foram associadas à leptina, adiponectina ou HOMA-IR na prole. Conclusões: Não encontramos evidências de um efeito adverso da exposição precoce ao PFAS sobre a função metabólica na metade da infância. Na verdade, crianças com concentrações mais altas de PFAS apresentaram menor resistência à insulina. Boston Children’s Hospital, United States Harvard Medical School, United States Harvard Pilgrim Health Care Institute, United States Boston University School of Public Health, United States Universidad Nacional, Costa Rica National Center for Environmental Health, United States Harvard School of Public Health, United States University of California, United States Instituto Regional de Estudios en Sustancias Tóxicas

To study potential environmental influences on puberty in girls, we investigated urinary biomarkers in relation to age at menarche. Phenols and phthalates were measured at baseline (6–8 years of age). Menarche was ascertained over 11 years for 1051 girls with menarche and biomarkers. Hazards ratios were estimated from Cox models adjusted for race/ethnicity and caregiver education (aHR, 95% confidence intervals [CI] for 5th vs 1st quintile urinary biomarker concentrations). 2,5-Dichlorophenol was associated with earlier menarche (aHR 1.34 [1.06–1.71]); enterolactone was associated with later menarche (aHR 0.82 [0.66–1.03]), as was mono-3-carboxypropyl phthalate (MCPP) (aHR 0.73 [0.59–0.91]); the three p-trends were

Background Bisphenol A (BPA) toxicity and exposure risk to humans has been the subject of considerable scientific debate; however, published occupational exposure data for BPA are limited. Methods In 2013-2014, 77 workers at six US companies making BPA, BPA-based resins, or BPA-filled wax provided seven urine samples over two consecutive work days (151 worker-days, 525 samples). Participant information included industry, job, tasks, personal protective equipment used, hygiene behaviors, and canned food/beverage consumption. Total (free plus conjugated) BPA, quantified in urine by mass spectrometry, was detected in all samples. Results The geometric mean (GM) creatinine-adjusted total BPA (total BPACR) concentration was 88.0 µg g-1 (range 0.78-18900 µg g-1), ~70 times higher than in US adults in 2013-2014 (1.27 µg g-1). GM total BPACR increased during Day 1 (26.6-127 µg g-1), decreased by pre-shift Day 2 (84.4 µg g-1) then increased during Day 2 to 178 µg g-1. By industry, baseline and post-baseline total BPACR was highest in BPA-filled wax manufacturing/reclaim (GM = 111 µg g-1) and lowest in phenolic resin manufacturing (GM = 6.56 µg g-1). By job, total BPACR was highest at baseline in maintenance workers (GM = 157 µg g-1) and post-baseline in those working with molten BPA-filled wax (GM = 441 µg g-1). Workers in the job of flaking a BPA-based resin had the lowest concentrations at baseline (GM = 4.81 µg g-1) and post-baseline (GM = 23.2 µg g-1). In multiple regression models, at baseline, industry significantly predicted increased total BPACR (P = 0.0248); post-baseline, handling BPA containers (P = 0.0035), taking ≥3 process/bulk samples with BPA (P = 0.0002) and wearing a Tyvek® coverall (P = 0.0042) significantly predicted increased total BPACR (after adjusting for total BPACR at baseline, time point, and body mass index). Conclusion Several work-related factors, including industry, job, and certain tasks performed, were associated with increased urinary total BPACR concentrations in this group of manufacturing workers. The potential for BPA-related health effects among these workers is unknown.

Di(isononyl)cyclohexane-1,2-dicarboxylate (DINCH), a non-phthalate plasticizer, was introduced commercially in 2002 as an alternative to ortho-phthalate esters because of its favorable toxicological profile. However, the potential health effects from DINCH exposure remain largely unknown. We explored the associations between urinary concentrations of metabolites of DINCH on markers of ovarian response among women undergoing in vitro fertilization (IVF) treatments. Between 2011 and 2015, 113 women enrolled a prospective cohort study at the Massachusetts General Hospital Fertility Center and provided up to two urine samples prior to oocyte retrieval. The urinary concentrations of two DINCH metabolites, cyclohexane-1,2-dicarboxylic acid monohydroxy isononyl ester (MHiNCH) and cyclohexane-1,2-dicarboxylic acid monocarboxyisooctyl ester (MCOCH), were quantified by isotope dilution tandem mass spectrometry. We used generalized linear mixed models to evaluate the association between urinary metabolite concentrations and markers of ovarian response, accounting for multiple IVF cycles per woman via random intercepts. On average, women with detectable urinary MHiNCH concentrations, as compared to those below LOD, had a lower estradiol levels (-325 pmol/l, p=0.09) and number of retrieved oocytes (-1.8, p=0.08), with a stronger association among older women. However, urinary MHiNCH concentrations were unrelated to mature oocyte yield and endometrial wall thickness. In conclusion, we found suggestive negative associations between urinary MHiNCH concentrations and peak estradiol levels and number of total oocyte yields. This is the first study evaluating the effect of DINCH exposure on human reproductive health and raises the need for further experimental and epidemiological studies to better understand the potential effects of this chemical on health.

Background: Identifying factors that impair bone accrual during childhood is a critical step toward osteoporosis prevention. Exposure to per- and polyfluoroalkyl substances (PFASs) has been associa...

Background Bisphenol A (BPA) has been linked with pediatric asthma development and allergic airway inflammation in animal models. Whether exposure to BPA or its structural analogs bisphenol S (BPS) and bisphenol F (BPF) is associated with asthma morbidity remains unknown. Objective We examined associations between bisphenols and morbidity due to pediatric asthma. Methods We quantified concentrations of BPA, BPS, and BPF in 660 urine samples from 148 predominantly low-income, African American children (aged 5-17 years) with established asthma. We used biobanked biospecimens and data on symptoms, health care utilization, and pulmonary function and inflammation that were collected every 3 months over the course of a year. We used generalized estimating equations to examine associations between concentrations or detection of urinary bisphenols and morbidity outcomes and assessed heterogeneity of associations by sex. Results We observed consistent positive associations between BPA exposure and measures of asthma morbidity. For example, we observed increased odds of general symptom days (adjusted odds ratio [aOR] = 1.40 [95% C = 1.02-1.92]), maximal symptom days (aOR = 1.36 [95% CI = 1.00-1.83]), and emergency department visits (aOR = 2.12 [95% CI =1.28-3.51]) per 10-fold increase in BPA concentration. We also observed evidence of sexually dimorphic effects; BPA concentrations were associated with increased odds of symptom days and health care utilization only among boys. Findings regarding BPS and BPF did not consistently point to associations with asthma symptoms or health care utilization. Conclusion We found evidence to suggest that BPA exposure in a predominantly low-income, minority pediatric cohort is associated with asthma morbidity and that associations may differ by sex. Our findings support additional studies, given the high pediatric asthma burden and widespread exposure to BPA in the United States.

The ZnO/Ag composite photocatalysts were prepared via the deposition of Ag on the surface of the grassy ZnO by a simple immersion reduction method. The dosage of Ag in the composites was adjusted by the concentration of Ag ions, immersion time and the content of the reducing agent. The grassy ZnO substrate presented a hexagonal wurtzite structure and a uniform dispersion. The band gap of the ZnO/Ag composites was decreased than that of grassy ZnO due to the surface plasma resonance (SPR) effect caused by Ag modification. The photocurrent response of the composites with proper amount of Ag loading was greatly improved by the SPR effect of Ag and subsequently enhanced light absorption, which resulted in the separation of electron-hole pairs in the near-surface region of the neighboring semiconductor. The ZnO/Ag composites had excellent photocatalytic efficiency in decolorization of RhB under UV irradiation.

Perfluoroalkyl substances (PFAS) were shown to be immunotoxic in laboratory animals. There is some epidemiological evidence that PFAS exposure is inversely associated with vaccine-induced antibody concentration. We examined immune response to vaccination with FluMist intranasal live attenuated influenza vaccine in relation to four PFAS (perfluorooctanoate, perfluorononanoate, perfluorooctane sulfonate, perfluorohexane sulfonate) serum concentrations among 78 healthy adults vaccinated during the 2010 – 2011 influenza season. We measured anti-A H1N1 antibody response and cytokine and chemokine concentrations in serum pre-vaccination, 3 days post-vaccination, and 30 days post-vaccination. We measured cytokine, chemokine, and mucosal IgA concentration in nasal secretions 3 days post-vaccination and 30 days post-vaccination. Adults with higher PFAS concentrations were more likely to seroconvert after FluMist vaccination as compared to adults with lower PFAS concentrations. The associations, however, were imprecise and few participants seroconverted as measured either by hemagglutination inhibition (9%) or immunohistochemical staining (25%). We observed no readily discernable or consistent pattern between PFAS concentration and baseline cytokine, chemokine, or mucosal IgA concentration, or between PFAS concentration and change in these immune markers between baseline and FluMist-response states. The resuts of this study do not support a reduced immune response to FluMist vaccination among healthy adults in relation to serum PFAS concentration. Given the study’s many limitations, however, it does not rule out impaired vaccine response to other vaccines or vaccine components in either children or adults.

Single crystal Zn-doped SnO 2 (Zn–SnO 2 ) nanorods with cone-shaped tips (~25 nm) on copper foil were synthesized by an organic-free hydrothermal method. The effects of the Zn doping on the morphology, microstructure and field-emission (FE) properties of Zn–SnO 2 were investigated. It is found that the Zn doping play an important role in tuning the morphology and size of the SnO 2 nanorods. The turn-on fields of SnO 2 and Zn–SnO 2 nanorods were 3.16 and 2.37 V/μm, and field enhancement factors (β) were 960 and 3352, respectively. The enhanced FE property is due to the tapered structures of nanorods with sharp tips and the weak screening effect, and the better electrical contact between conductive copper substrate and field emitters.

Ultra-long gold nanowires (NWs) were prepared and characterized. The gold NWs were predominantly formed from gold nanorods. The ultraviolet–visible absorption spectrum of the gold NWs contained two absorption bands. One corresponded to transverse surface plasmon absorption in the gold NWs, and the other to absorption by residual organic groups. The nonlinear optical and optical limiting (OL) properties of the gold NWs were characterized by the open aperture Z-scan technique, using 532-nm laser pulses with pulse duration of ~7 ns. The NWs exhibited strong OL effects for nanosecond laser pulses at 532 nm, and their OL performance was superior to that of carbon nanotubes; a benchmark OL material. Thus, the gold NWs could potentially replace carbon nanotubes in OL applications. Nonlinear scattering played an important role in the OL activity of the ultra-long gold NWs at 532 nm. The nonlinear behavior of the gold NWs altered from saturable absorption to reverse saturable absorption, with increasing excitation energy. This property can be exploited in optical pulse compressors, optical switching, and laser pulse narrowing.

The paper was retracted as the authors have submitted the same manuscript to two completely different journals, which is seriously academic fraud and against academic ethics.

In this study, the variations in compressive mechanical properties of a variety of Zr-based bulk metallic glasses (BMGs) were analyzed. Systematic changes in composition were employed to modify the compressive malleability of the Zr-based BMGs. The enhancement on the malleability of investigated Zr-based BMGs could be correlated with the variations in Poisson's ratio. Two-parameter Weibull statistical analysis was performed on their compressive strengths over a statistically significant number of specimens. High compressive strength reliability demonstrated by its high uniformity in strength was found on the Zr-based BMGs. Malleable Z4 (Zr 66 Al 9 Ni 8.3 Cu 16.7 ) BMG showed a higher Weibull modulus ( m = 71) as compared with the less malleable Z1 (Zr 53 Al 16 Co 23.25 Ag 7.75 ) BMG ( m = 38), implying a more uniform distribution of compressive failure strength and a higher reliability. The correlation of m with the intrinsic malleability of Zr-based BMGs was discussed by the variations in the Poisson's ratio, the shear modulus or the glass transition temperature.

The mechanical, electrochemical, wear, and corrosive-wear behaviors of a TiZrCuPd bulk glassy alloy were investigated. The Ti-based glassy alloy demonstrates a high yield strength of 2.3 GPa, low Young's modulus of 95 GPa, and Vickers microhardness of 7.2 GPa, which are superior to those of the Ti-6Al-4V biomedical alloy. The TiZrCuPd glassy alloy shows a good corrosion resistance in the phosphate buffer saline (PBS) solution, owing to the formation the Ti- and Zr-enriched passivation film on the alloy surface. The TiZrCuPd alloy displays the lowdry-wear rate of 6.1 × 10−8 mm3 mm N−1and wet-wear rate of 8.0 × 10−8 mm3 mm N−1. The triobocorrosionresults illustrate that the TiZrCuPd alloyshows a high pitting corrosion resistance during the wet sliding, which render its good corrosive wear performance. The good combination of mechanical, corrosion, and wear properties of the Ti-based glassy alloy make it promising for biomedical applications.

Wear behaviors of the FeCoCrMoCBY bulk metallic glass (BMG), 316 L stainless steel (SS), and CoCrMo alloy under wet sliding in the phosphate buffered saline (PBS) solution were studied and compared with those under dry sliding. The Fe-based BMG exhibited an excellent corrosive wear resistance with a low wear rate of 1.84 × 10−8 mm3 mm−1•N − 1. On the contrary, the CoCrMo alloy and 316 L SS suffered from the synergistic effect of corrosion and wear in the PBS solution. The electrochemical results revealed that the Fe-based BMG possessed the greatest corrosion performance in the PBS solution among three alloys. The excellent corrosion behavior of the Fe-based BMG was attributed to the highly-protective surface passivation film enriched in Cr and Mo elements. The triobocorrosion results manifested that the great anti-corrosive-wear capacity of the Fe-based BMG can be ascribed to the high stable passivation process during wet sliding.

BackgroundAnimal studies suggest that phthalates and bisphenol A (BPA), endocrine-disrupting chemicals found in many consumer products, may impact the timing of puberty.ObjectivesWe aimed to determine the association of prenatal exposure to high-molecular-weight phthalates and BPA with pubertal timing in boys and girls participating in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) longitudinal cohort study.MethodsWe quantified urinary concentrations of eight phthalate metabolites and BPA at two time points during pregnancy among participating mothers ([Formula: see text]) and conducted clinical Tanner staging of puberty on their children every 9 months between 9 and 13 y of age. We conducted accelerated failure time models and examined the role of child overweight/obese status in this association.ResultsThe sum of urinary metabolites of di(2-ethylhexyl) phthalate [Formula: see text], monobenzyl phthalate (MBzP), and BPA were associated with later onset of at least one of the three outcomes assessed in girls (thelarche, pubarche, or menarche) and with earlier onset of at least one of the two outcomes assessed in boys (gondarche and pubarche). We found that monocarboxynonyl phthalate, monocarboxyoctyl phthalate, mono(3-carboxypropyl) phthalate, and BPA were associated with later pubarche and menarche mostly among normal-weight girls but not overweight/obese girls. MBzP was associated with later thelarche in all girls, and [Formula: see text] was associated with later thelarche and menarche in all girls. BPA and all phthalate biomarkers were associated with earlier gonadarche and pubarche in all boys as well as in overweight/obese boys when stratified by weight. Among normal-weight boys, associations with BPA were also inverse, whereas associations with phthalate metabolites were close to the null or positive.ConclusionsSeveral high-molecular-weight phthalates and BPA were associated with later puberty in girls and earlier puberty in boys included in the CHAMACOS cohort study. Childhood overweight/obesity may modify these associations. https://doi.org/10.1289/EHP3424.

In this study, titania (TiO2) nanosheets were composited onto reduced graphene oxide (rGO) by an in situ hydrothermal synthesis method using tetrabutyl titanate and hydrofluoric acid. The photocatalytic activities of the TiO2 nanosheet/rGO nanocomposites were investigated after the application of various amounts of GO. The nanocomposites were characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, Brunauer-Emmett-Teller (BET) analysis, and UV–vis spectroscopy (UV–vis). The photocatalytic properties of the composites were examined. The results indicated that the TiO2 nanosheets with anatase uniformly combined with the GO. The composites exhibited higher specific surface areas after the addition of GO compared to the TiO2 nanosheets. Methyl orange (MO) exhibited the highest first-order degradation efficiency at a GO dosage of 6 wt%. The TiO2 nanosheet/rGO with 3 wt% GO exhibited a high performance after four cycles. Improvements in the photocatalytic performance depended significantly upon the composite specific surface area and the electron-storage ability of the GO. The results suggest that the TiO2 nanosheet/rGO composites are applicable for the photocatalytic treatment of various organic dyes. The synthesis method may also be applied for other composite materials with similar structures.

Environmental phenols and parabens are commonly used in personal care products and other consumer products and human exposure to these chemicals is widespread. Although human and animal studies suggest an association between exposure to phenols and parabens and thyroid hormone levels, few studies have investigated the association of in utero exposure to these chemicals and thyroid hormones in pregnant women and their neonates. We measured four environmental phenols (triclosan, benzophenone-3, and 2,4- and 2,5-dichlorophenol), and three parabens (methyl-, propyl-, and butyl paraben) in urine collected from mothers at two time points during pregnancy as part of the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study. We measured free thyroxine (T4), total T4, and thyroid-stimulating hormone (TSH) in serum of the pregnant women (N = 454) and TSH in their neonates (N = 365). We examined potential confounding by a large number of additional chemical exposures and used Bayesian Model Averaging (BMA) to select the most influential chemicals to include in regression models. We observed negative associations of prenatal urinary concentrations of propyl paraben and maternal TSH (β for two-fold increase = −3.26%, 95% CI: −5.55, −0.90) and negative associations of 2,4-dichlorophenol and maternal free T4 (β for two-fold increase = −0.05, 95% CI: −0.08, −0.02), after controlling for other chemical exposures. We observed negative associations of triclosan with maternal total T4 after controlling for demographic variables, but this association became non-significant after controlling for other chemicals (β for two-fold increase = −0.05, 95% CI: −0.11, 0.00). We found evidence that environmental phenols and parabens are associated with lower TSH and free T4 in pregnant women after controlling for related chemical exposures.

A kind of novel ternary polyurethane (PU)/silver (Ag)/zinc oxide (ZnO) array composite coatings was fabricated by the growth of ZnO arrays onto the stainless steel substrates, the modification of Ag nanoparticles and following PU spinning. The structure, morphologies, wettability and mechanical properties of the PU/Ag/ZnO array composite coatings were measured by SEM, TEM, XRD, UV-vis, surface contact angle (CA) and nano indentation technology. The infrared emissivity values of the composites (8–14 μm) were estimated. The results showed that hexagonal wurtzite ZnO arrays and face-centered cubic Ag nanoparticles were in the composite coatings with good dispersion. The content and the density of the Ag and ZnO arrays can be varied by controlling the deposition time of the Ag and the concentration of the ZnO crystal growth solution, which remarkably had effect on the surface roughness properties of the coatings. By comparison with PU, the mechanical properties of PU/Ag/ZnO array coatings were obviously improved. The PU/Ag/ZnO coatings exhibited improved infrared emissivity property than that of pure PU and PU/ZnO due to the introduction of component Ag with high reflectivity.

BACKGROUND: A number of endocrine disrupting chemicals (EDC) have been associated with gestational diabetes (GDM) risk factors. However, no human study has investigated the association between pregnancy exposure to parabens, a class of EDCs, and pregnancy glucose levels, a risk factor for GDM. Furthermore, little is known about this association in subfertile women—a group at high risk of GDM. METHODS: A total of 241 women from the Environment and Reproductive Health Study had data available on 1(st) and/or 2(nd) trimester urinary methylparaben, propylparaben, and butylparaben concentrations, and blood glucose levels after the glucose loading test (GLT), a non-fasting 50 gram glucose loading test taken at late 2(nd) trimester. Trimester-specific associations between specific gravity adjusted methylparaben, butylparaben, and propylparaben with adjusted mean of pregnancy glucose levels were evaluated in linear regression models, using quartiles of each paraben’s distribution, and as a paraben mixture, using mutual adjustment and Bayesian kernel machine regression (BKMR), a recently proposed method for investigating chemical mixtures that flexibly models the joint effect of chemicals. RESULTS: Investigating parabens one at the time did not provide any significant results. When investigating parabens as a chemical mixture with both multiple regression and BKMR, we observed positive associations of butylparaben (e.g comparing the 4(th) and 1(st) quartiles) with glucose levels, for both the 1(st) trimester (adjusted difference=12.5 mg/dL; 95% CI: 0.9, 24.2) and 2(nd) trimester (adjusted difference=11.2 mg/dL; 95% CI: 0.2, 22.3), and a negative association between 1(st) trimester propylparaben and glucose (adjusted difference=−22.3 mg/dL; 95% CI: −43.2, −1.4). CONCLUSIONS: We found 1(st) trimester butylparaben and propylparaben urinary concentrations to be associated with glucose levels in a pregnancy cohort of women at high risk of GDM, even after adjusting for potential confounders. Because exposure to parabens is widespread, these findings may suggest further investigating the effects of this chemical class on pregnancy health.

Per- and polyfluoroalkyl substances (PFAS), man-made chemicals with variable length carbon chains containing the perfluoroalkyl moiety (CnF2n+1–), are used in many commercial applications. Since 1999–2000, several long-chain PFAS, including perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), have been detected at trace levels in the blood of most participants of the National Health and Nutrition Examination Survey (NHANES)—representative samples of the U.S. general population—while short-chain PFAS have not. Lower detection frequencies and concentration ranges may reflect lower exposure to short-chain PFAS than to PFOS or PFOA or that, in humans, short-chain PFAS efficiently eliminate in urine. We developed on-line solid phase extraction–HPLC–isotope dilution–MS/MS methods for the quantification in 50 μL of urine or serum of 15 C3-C11 PFAS (C3 only in urine), and three fluorinated alternatives used as PFOA or PFOS replacements: GenX (ammonium salt of 2,3,3,3,-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoate, also known as HFPO-DA), ADONA (ammonium salt of 4,8-dioxa-3H-perfluorononanoate), and 9Cl-PF3ONS (9-chlorohexadecafluoro-3-oxanonane-1-sulfonate), main component of F53-B. Limit of detection for all analytes was 0.1 ng/mL. To validate the method, we analyzed 50 commercial urine/serum paired samples collected in 2016 from U.S. volunteers with no known exposure to the chemicals. In serum, detection frequency and concentration patterns agreed well with those from NHANES. By contrast, except for perfluorobutanoate, we did not detect long-chain or short-chain PFAS in urine. Also, we did not detect fluorinated alternatives in either urine or serum. Together, these results suggest limited exposure to both short-chain PFAS and select fluorinated alternatives in this convenience population.

Background The age of menarche has been associated with metabolic and cardiovascular disease, as well as cancer risk. The decline in menarcheal age over the past century may be partially attributable to increased exposure to endocrine disrupting chemicals (EDCs). Methods We assessed the influence of 26 phenol and phthalate biomarkers on the timing of menarche in a longitudinal cohort of Chilean girls. These EDCs were quantified in urine collected prior to the onset of breast development (Tanner 1; B1), and during adolescence (Tanner 4; B4). Multivariable accelerated failure time (AFT) models were used to analyze associations between biomarker concentrations and the age of menarche adjusting for body mass index (BMI) Z-score and maternal education, accounting for within-subject correlation. Results Several biomarkers were significantly associated with the age at menarche; however, these associations were dependent on the timing of biomarker assessment. A log(ng/ml) increase in B1 concentrations of di(2-ethylhexyl) phthalate biomarkers was associated with later menarche (hazard ratio (HR): 0.77; 95% CI: 0.60, 0.98), whereas higher B1 concentrations of 2,5-dichlorophenol and benzophenone-3 were associated with earlier menarche (HR: 1.13; 95% CI: 1.01, 1.27; HR: 1.17; 95% CI: 1.06, 1.29, respectively). Elevated B4 concentrations of monomethyl phthalate were similarly associated with earlier menarche (HR: 1.30; 95% CI: 1.10, 1.53). The impact of monoethyl phthalate and triclosan concentrations on pubertal timing were significantly modified by BMI Z-score. Higher monoethyl phthalate and triclosan concentrations were associated with earlier menarche among overweight or obese girls, but not among those that were normal weight. Conclusions This study identifies modulation of sexual maturation by specific EDC biomarkers in Latina girls. Electronic supplementary material The online version of this article (10.1186/s12940-018-0376-z) contains supplementary material, which is available to authorized users.

Background Despite evidence from toxicological studies describing the potential neurotoxicity of perfluoroalkyl substances (PFAS), their role in neurodevelopment remains uncertain amid inconsistent findings from epidemiological studies. Methods Using data from 218 mother-child dyads from the Health Outcomes and Measures of the Environment Study, we examined prenatal and childhood (3 and 8 years) serum concentrations of four PFAS and inattention, impulsivity, and visual spatial abilities. At 8 years, we used the Conners' Continuous Performance Test-II to assess attention and impulse control and the Virtual Morris Water Maze (VMWM) to measure visual spatial abilities. Results In multiple informant models, there was no evidence to indicate that prenatal or childhood PFAS are associated with attention. However, there was an inverse association between prenatal ln-perfluorooctanoate (PFOA) and errors of commission (β = −2.0, 95% Confidence Interval [CI] −3.8, −0.3). Ln-perfluorononanoate (PFNA) at 3 years was associated with longer (poorer) VMWM completion times of 3.6 seconds (CI 1.6, 5.6). However, higher concurrent concentrations of ln-perfluorohexane sulfonate (PFHxS) (β = −2.4 s, 95% CI −4.4, −0.3) were associated with shorter (better) times. Higher prenatal PFHxS was positively associated with percentage of traveling distance in the correct quadrant (β = 4.2%, 95% CI 0.8, 7.7), indicating better performance. Conclusion Findings were mixed for prenatal and childhood PFAS concentrations and visual spatial abilities. There is not enough evidence to support that PFAS are associated with visual spatial abilities as assessed by the VMWM or CPT-II measures of inattention or impulsivity in children at age 8 years.

Semi-volatile organic compounds (SVOCs) are used extensively in consumer and personal care products; electronics; furniture; and building materials and are detected in most indoor environments. As a result, human exposure to mixtures of SVOCs is wide-spread. However, very few studies have measured biomarkers of exposure to multiple SVOC classes, and exposure determinants have not been thoroughly explored, particularly for young children. In this study, we investigated biomarkers of exposure to SVOCs among children (age 3–6 years), who may experience higher exposures and be more susceptible to adverse health outcomes than other age groups. We enrolled 203 participants in the Toddlers Exposure to SVOCs in Indoor Environments (TESIE) study (181 provided urine samples and 90 provided serum samples).We quantified 44 biomarkers of exposure to phthalates, organophosphate esters (OPEs), parabens, phenols, antibacterial agents and per- and polyfluoroalkyl substances (PFASs); we detected 29 of the 44 biomarkers in >95% of samples, and many biomarkers were detected at higher median concentrations than those previously reported in the U.S. general population. Demographic characteristics were associated with differences in concentrations. In general, non-Hispanic white race and higher maternal education were associated with lower concentrations, even after adjusting for other potential confounding variables. Our results suggest that outdoor temperature at the time of biospecimen collection may be a particularly important and under-evaluated predictor of biomarker concentrations; statistically significant relationships were observed between 10 biomarkers and outdoor temperature at the time of collection. A complex correlation structure was also observed among the biomarkers assessed. By and large, statistically significant correlations between biomarkers of exposure to phthalates, parabens, phenols, and OPEs were positive. Conversely, although PFASs were positively correlated with one another, they tended to be negatively correlated with other biomarkers where significant associations were observed. Taken together, our results provide evidence that the assessments of SVOC-associated health impacts should focus on chemical mixtures.