Analysis of twenty phenolic compounds in human urine: hydrochloric acid hydrolysis, solid-phase extraction based on K2CO3-treated silica, and gas chromatography tandem mass spectrometry

Associations of prenatal and concurrent exposure to phenols mixture with anthropometric measures and blood pressure during childhood: A time-varying mixture approach

BACKGROUND

Environmental phenols were recognized as endocrine disrupting chemicals (EDCs). However, their impact on childhood anthropometric measures and blood pressure (BP) is still inconclusive. Limited studies have simultaneously considered prenatal and childhood exposures in analyzing mixtures of phenols.

OBJECTIVE

We investigated the relationships between combined prenatal and childhood exposures (two periodic exposures) to phenol mixtures and anthropometric measure and BP, to further identify the vulnerable periods of phenol exposure and to explore the important individual contribution of each phenol.

METHODS

We analyzed 434 mother-child dyads from the Sheyang Mini Birth Cohort Study (SMBCS). The urinary concentrations of 11 phenolic compounds were measured using gas chromatography tandem mass spectrometry. Generalized linear regression models (GLMs) and hierarchical Bayesian Kernel Machine Regression (hBKMR) were used to examine the effects of individual phenolic compounds at each period and of two periodic exposures.

RESULTS

In the single-chemical analysis, prenatal or childhood exposure to specific phenols, especially Benzopheone-3 (BP3), 4-tert-Octylphenol (4-tOP), and Benzyl paraben (BePB) were associated with BMI z-scores (BAZ), Waist-to-height ratio (WHtR), and BP. In the hBKMR models, two periodic exposures to phenol mixtures had a U-shaped association with WHtR, primarily driven by childhood BePB exposure. Moreover, among the phenol mixtures analysis, childhood 4-tOP exposure was identified as the primary contributor to the positive association with diastolic BP. Concurrent exposure to phenol mixtures resulted in greater susceptibility.

CONCLUSIONS

We found that prenatal and childhood exposure to phenol mixtures might influence childhood obesity and elevate blood pressure levels. Concurrent exposure to 4-tOP may be the primary driver of the positive associations with BP.

Identifying childhood pesticide exposure trajectories and critical window associated with behavioral problems at 10 years of age: Findings from SMBCS

BACKGROUND

Pesticides may impact children's neurodevelopment. As children's metabolic function and neural plasticity change throughout their growth and development, the effects of pesticide exposure may also vary.

OBJECTIVES

We aimed to identify the trajectories of combined pesticide exposure during childhood, and to examine the associations of the exposure trajectories with children's neurobehavior at the age of 10.

METHODS

We involved repeated measurements of three pesticide metabolites [Pentachlorophenol (PCP), 3,5,6-Trichloro-2-pyridinol (TCPy), and Carbofuran phenol (CFP)], in urine samples collected from children in a cohort study at ages 1, 2, 3, 6, 7, 8, 9, and 10 years. The group-based multi-trajectory model (GBMT) and latent class analysis (LCA) were separately utilized to describe the distinct trajectories and patterns of pesticide mixture exposure during childhood. Meanwhile, the Strengths and Difficulties Questionnaire (SDQ) and attention deficit hyperactivity disorder (ADHD) Criteria of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) list were applied to assess behavioral disorders in children. The associations between exposure trajectories and behavioral problem scores were then examined.

RESULTS

The GBMT model delineated three distinct trajectories of combined pesticide exposure among children: consistently low, higher levels in early childhood transitioning to lower levels during pre-school age, and lower levels in early childhood followed by higher levels in the middle childhood. The LCA model identified three similar longitudinal exposure patterns. Further, the children in the second trajectory group identified by GBMT, characterized by higher early childhood exposure levels, exhibited significantly elevated hyperactivity/inattention scores of the SDQ compared to the other two groups (β = 0.46, 95 %CI: 0.11, 0.81; β = 0.44, 95 %CI: 0.02, 0.86).

CONCLUSIONS

Our study revealed that exposure to pesticides during early childhood (especially before the age of two), rather than other age periods, was linked to hyperactivity/inattention problems in children aged 10 years. We also provided a novel perspective on characterizing the fluctuation in repeated measurements of multiple environmental chemicals and identifying the potential critical windows.

Application of a PLA/PBAT/Graphite sensor obtained by electrospinning on determination of 2,4,6-trichlorophenol

The widespread use of pesticides requires effective detection and quantification tools to improve monitoring of environmental quality. Electrochemical sensors offer a fast and sensitive response, and can also be optimized by combining several constituents and techniques, including biodegradable materials, being useful in the determination of chemical agents from environmental samples. Here, we produced a polymer-based sensor for 2,4,6-trichlorophenol determination, through electrospinning of poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blend with graphite. The graphite-containing fibres were thermally treated and wetted in mineral oil, thus forming a paste, used as an electrode in the electrochemical sensor. The thermal analysis indicated a disorganization of the polymeric chains between the aromatic carbon chain of the PBAT polymer, resulting in a material with low enthalpy, lower crystallinity and greater thermal degradability after insertion of graphite in polymeric fibres. NIR spectra revealed changes related to the carbonyls of the polymeric ester groups. Cyclic voltammetry and square wave voltammetry techniques were applied to study the electrochemical behaviour of developed sensor. The thermal treatment of graphite-containing fibres increased the adhesion surface in which occurs the adsorption of the analyte on the electrode, which improved the peak current in the electrochemical tests. The PLA/PBAT/Graphite sensor applied to determination of 2,4,6-TCP presented the detection and quantification limits of 7.84 × 10-8 mol L-1 (0.0155 mg L-1) and 2.36 × 10-7 mol L-1 (0.0466 mg L-1) with a linearity response of 1.00 × 10-7 mol L-1 and 2.00 × 10-6 mol L-1 with correlation coefficient of 0.993 (r2).

Ultrasound- and Vortex-Assisted Dispersive Liquid-Liquid Microextraction of Parabens from Personal Care Products and Urine, Followed by High-Performance Liquid Chromatography

Objectives

Parabens, which are p-hydroxybenzoic acid esters, are used as preservatives in personal care products, pharmaceuticals, and food because of their antimicrobial activity. However, they are also classified as suspected endocrine disruptors and carcinogens. In the present study, we aimed to optimize an ultrasound and vortex-assisted dispersive liquid-liquid microextraction (DLLME) procedure for the simultaneous extraction of methyl, ethyl, isopropyl, propyl, isobutyl, and butyl parabens from personal care products and urine.

Materials and Methods

The extraction solvent type, extraction solvent volume, disperser solvent volume, sodium chloride concentration, ultrasonication time, and vortex application time were evaluated to obtain optimum recoveries by ultrasound and vortex-assisted DLLME. Parabens were detected using a validated high performanc-liquid chromatography (HPLC) method with fluorescence detection. Method validation was performed by examining linearity, the limit of detection, limit of quantification, accuracy, and precision.

Results

The limits of detection and quantification of the HPLC method were between 0.09-0.18 μg/mL and 0.28-0.54 μg/mL, respectively. Precision was examined as the relative standard deviation, which was 0.22-1.81% and 1.12-2.03% for intra- and interday studies. Recovery percentages were higher than 96.00%. Samples of two paraben-free personal care products and synthetic urine were spiked with the analyses at 0.02 μg/mL and were successfully analyzed using the developed procedure with recovery values higher than 82.00%.

Conclusion

The proposed procedure provided quantification of selected parabens at 20 ng/mL in analyzed personal care products and urine matrices with good precision and accuracy.

Quantification and stability assessment of urinary phenolic and acidic biomarkers of non-persistent chemicals using the SPE-GC/MS/MS method

Nowadays, people are exposed to numerous man-made chemicals, many of which are ubiquitously present in our daily lives, and some of which can be hazardous to human health. Human biomonitoring plays an important role in exposure assessment, but complex exposure evaluation requires suitable tools. Therefore, routine analytical methods are needed to determine several biomarkers simultaneously. The aim of this study was to develop an analytical method for quantification and stability testing of 26 phenolic and acidic biomarkers of selected environmental pollutants (e.g., bisphenols, parabens, pesticide metabolites) in human urine. For this purpose, a solid-phase extraction coupled with gas chromatography and tandem mass spectrometry (SPE-GC/MS/MS) method was developed and validated. After enzymatic hydrolysis, urine samples were extracted using Bond Elut Plexa sorbent, and prior to GC, the analytes were derivatized with N-trimethylsilyl-N-methyl trifluoroacetamide (MSTFA). Matrix-matched calibration curves were linear in the range of 0.1-1000 ng mL^-1 with R > 0.985. Satisfactory accuracy (78-118%), precision (< 17%), and limits of quantification (0.1-0.5 ng mL^-1) were obtained for 22 biomarkers. The stability of the biomarkers in urine was assayed under different temperature and time conditions that included freezing and thawing cycles. All tested biomarkers were stable at room temperature for 24 h, at 4 °C for 7 days, and at -20 °C for 18 months. The total concentration of 1-naphthol decreased by 25% after the first freeze-thaw cycle. The method was successfully used for the quantification of target biomarkers in 38 urine samples.

Urinary concentration of selected nonpersistent endocrine disrupting chemicals-reproductive outcomes among women from a fertility clinic

Parabens and benzophenones are compounds widely used in cosmetics and personal care products. Although human exposure is widespread there is a limited number of epidemiological studies assessing the relationship between exposure to these chemicals and female reproductive health. The aim of the study is to explore the relationship between paraben and benzophenone concentrations and reproductive outcomes among women attending a fertility center. This prospective cohort included 450 women undergoing in vitro treatment (IVF) at fertility clinic in Poland. The validated gas chromatography ion-tap mass spectrometry to assess concentrations of parabens in urine (methyl (MP), ethyl (EP), propyl (PP), butyl paraben (BP)) and benzophenone-3 (BP-3) was used. To explore the relationship between concentrations of examined chemicals and reproductive outcomes (methaphase II (MII) oocyte yield, total oocyte yield, implantation rate, fertilization rate, clinical pregnancy, live births), multivariable generalized linear mixed model was used for the analysis. Increased exposure to butyl paraben was associated with a significant decrease in MII oocyte count (p = 0.007) when exposure to BP was treated as the continuous variable. Additionally, the exposure to BP in the highest quartile of exposure also decreases MII oocyte count (p = 0.02) compared to the lowest quartile. Urinary concentrations of BP were not related to total oocyte count, fertilization and implantation rate, clinical pregnancy, and live birth when the exposure variable was continuous variable or in the quartiles of exposure. Exposure to MP, EP, PP, the sum of examined parabens, and benzophenone-3 were not related to any of the examined reproductive outcomes. Exposure to butyl paraben was associated with a decrease in MII oocyte count among women attending fertility clinic rinsing concerns that exposure may have a potential adverse impact on embryological outcomes. The results emphasize the importance to reduce chemicals in the environment in order to minimize exposure. As this is the first study showing such an association, further research is needed to confirm these novel results in other populations.

Electrochemical monitoring of 4-chlorophenol as a water pollutant via carbon paste electrode amplified with Fe3O4 incorporated cellulose nanofibers (CNF)

A crucial problem that needs to be resolved is the sensitive and selective monitoring of chlorophenol compounds, especifically 4-chlorophenol (4-CP), one of the most frequently used organic industrial chemicals. In light of this, the goal of this study was to synthesize Fe₃O₄ incorporated cellulose nanofiber composite (Fe₃O₄/CNF) as an amplifier in the development of a modified carbon paste electrode (CPE) for 4-CP detection. Transmission electron microscopy (TEM) was used to evaluate the morphology of the synthesized nanocatalyst, while differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV) techniques were implemented to illuminate the electrochemical characteristics of the fabricated sensor. The ultimate electrochemical sensor (Fe₃O₄/CNF/CPE) was used as a potent electrochemical sensor for monitoring 4-CP in the concentration range of 1.0 nM-170 μM with a limit of detection value of 0.5 nM. As a result of optimization studies, 8.0 mg Fe₃O₄/CNF was found to be the ideal catalyst concentration, whereas pH = 6.0 was chosen as the ideal pH. The 4-CP's oxidation current was found to be over 1.67 times greater at ideal operating conditions than it was at the surface of bare CPE, and its oxidation potential decreased by about 120 mV. By using the standard addition procedure on samples of drinking water and wastewater, the suggested capability of Fe₃O₄/CNF/CPE to detect 4-CP was further investigated. The recovery range was found to be 98.52-103.66%. This study paves the way for the customization of advanced nanostructure for the application in electrochemical sensors resulting in beneficial environmental impact and enhancing human health.

Multiple mediation effects on association between prenatal triclosan exposure and birth outcomes

BACKGROUND

Triclosan is a broad-spectrum antimicrobial, and was thought to affect intrauterine development, but the mechanism remains unclear.

OBJECTIVE

To explore the association between prenatal triclosan exposure and birth outcomes.

METHODS

Based on 726 mother-child pairs from the Sheyang Mini Birth Cohort Study (SMBCS), we used the available (published) data of triclosan in maternal urines, the hormones including thyroid-related hormones, gonadal hormones in cord blood, and adipokines, trimethylamine-N-oxide (TMAO) and its precursors in cord blood to explore possible health effects of triclosan on birth outcomes through assessing different hormones and parameters, using Bayesian mediation analysis.

RESULTS

Maternal triclosan exposure was associated with ponderal index (β = 0.317) and head circumference (β = -0.172) in generalized linear models. In Bayesian mediation analysis of PI model, estradiol (β = 0.806) and trimethylamine (TMA, β = 0.164) showed positive mediation effects, while total thyroxine (TT4, β = -0.302), leptin (β = -2.023) and TMAO (β = -0.110) showed negative mediation effects. As for model of head circumference, positive mediation effects were observed in free thyroxine (FT4, β = 0.493), TMA (β = 0.178), and TMAO (β = 0.683), negative mediation effects were observed in TT4 (β = -0.231), testosterone (β = -0.331), estradiol (β = -1.153), leptin (β = -2.361), choline (β = -0.169), betaine (β = -0.104), acetyl-L-carnitine (β = -0.773).

CONCLUSION

The results indicated triclosan can affect intrauterine growth by interfering thyroid-related hormones, gonadal hormones, adipokines, TMAO and its precursors.

Urinary para-nitrophenol levels of pregnant women and cognitive and motor function of their children aged 2 years: Evidence from the SMBCS (China)

BACKGROUND

Urinary para-nitrophenol (PNP), an exposure biomarker of ethyl parathion (EP) and methyl parathion (MP) pesticides, was still pervasively detected in the general population even after global restriction for years. And the concern whether there is an association of PNP level with child development of the nervous system is increasing. The current study aimed to evaluate the maternal urinary PNP concentrations during late pregnancy and the associations of PNP levels with cognitive and motor function of their children at the age of 2 years.

METHODS

323 mother-child pairs from the Sheyang Mini Birth Cohort Study were included in the current study. Gas chromatography-tandem mass spectrometry was used to measure concentrations of PNP, the specific metabolite of EP and MP, in maternal urine samples during pregnancy. Developmental quotients (DQs) scores measured with Gesell Developmental Scales were employed to evaluate cognitive and motor function of children aged 2 years. Generalized linear models were performed to analyze the associations of PNP concentrations in pregnant women's urine samples with cognitive and motor function of their children.

RESULTS

Maternal PNP was detected in all urine samples with a median of 4.11 μg/L and a range from 0.57 μg/L to 109.13 μg/L, respectively. Maternal urinary PNP concentrations showed a negative trend with DQ of motor area [regression coefficient (β) = - 1.35; 95 % confidence interval (95 %CI): - 2.37, - 0.33; P < 0.01], and the children whose mothers were in the fourth quartile exposure group performed significantly worse compared to the reference group (β = - 1.11; 95 %CI: - 1.80, - 0.42; P < 0.01). As for average DQ score, children with their mothers' urinary PNP concentrations in the third quartile group had higher scores than those in the first quartile group (β = 0.39; 95 %CI: 0.03, 0.75; P = 0.04). In sex-stratified analyses, a negative trend between maternal urinary PNP concentrations and DQ scores in motor area of children was only observed in boys (β = - 1.62; 95 %CI: - 2.80, - 0.43; P < 0.01). Boys in the third quartile group had higher DQ average scores than those in the lowest quartile as reference (β = 0.53; 95 %CI: 0.02, 1.04; P = 0.04).

CONCLUSIONS

The mothers from SMBCS may be widely exposed to EP and/or MP, which were associated with the cognitive and motor function of their children aged 2 years in a sex-specific manner. Our results might provide epidemiology evidence on the potential effects of prenatal exposure to EP and/or MP on children's cognitive and motor function.

Prenatal exposure to parabens in association with cord serum adipokine levels and offspring size at birth

BACKGROUND

Paraben exposure is linked to the release of adipokine such as leptin and adiponectin, and both paraben and adipokine may affect fetal growth. The present study aimed to explore the associations among maternal paraben exposure, adipokine level and offspring size.

METHODS

942 mother-newborn pairs from the Sheyang Mini Birth Cohort Study (SMBCS) were enrolled. Data of birth weight, length, head circumference and ponderal index (PI) were obtained from medical records. Maternal urinary parabens were determined by gas chromatography tandem mass spectrometry. Cord serum leptin and adiponectin were measured using ELISA assay. Generalized linear regression was applied to explore the associations among parabens, adipokines and offspring size.

RESULTS

The median levels of leptin and adiponectin were 13.13 μg/L and 161.82 μg/mL. Benzylparaben level was positively associated with leptin (regression coefficient (β) = 0.06, 95% confidence interval (CI): 0.03-0.09; p < 0.01). Leptin level was positively associated with neonatal weight (β = 84.11, 95% CI: 63.22-105.01; p < 0.01), length (β = 0.25, 95% CI: 0.14-0.37; p < 0.01), head circumference (β = 0.15, 95% CI: 0.07-0.22; p < 0.01) and PI (β = 0.23, 95% CI: 0.08-0.39; p < 0.01). Adiponectin was positively associated with neonatal weight (β = 75.94, 95% CI: 29.65-122.23; p < 0.01) and PI (β = 0.43, 95% CI: 0.09-0.77; p = 0.01). Urinary propylparaben concentration (β = -0.10, 95% CI: -0.17 to -0.02; p = 0.01) was negatively associated with head circumference. Sex-stratified analyses indicated the negative association of propylparaben and head circumference was only remained in male neonates.

CONCLUSIONS

Prenatal paraben exposure might affect cord serum leptin levels. Both paraben and adipokine levels may affect fetal growth, and sex-specific differences may exist.

Comprehensive LC-MS/MS method combined with tandem hybrid hydrolysis for multiple exposure assessment of multiclass environmental pollutants

Environmental pollutants (EPOLs), such as phthalates, volatile organic compounds, phenols, parabens, polycyclic aromatic hydrocarbons, pyrethroids, and environmental tobacco smoke, are highly heterogeneous compounds. Recently, attention has been drawn to the assessment of the combinatory effects of multiple EPs. To correlate multiple exposures with potential health implications, advanced comprehensive analytical methods covering multiclass EPOLs are essential. However, because of several technical problems associated with enzyme hydrolysis, simultaneous extraction, and multiresidue liquid chromatography-tandem mass spectrometry analysis, it is difficult to establish a comprehensive method covering a number of EPOLs in a single sample preparation and analytical run. We developed tandem hybrid hydrolysis, modified direct injection, and a comprehensive mobile phase to overcome these technical problems and established a comprehensive analytical method for simultaneous biomonitoring of multiclass EPOLs. Tandem hybrid hydrolysis using β-glucuronidase and consecutive acid hydrolysis allowed selective hydrolysis of glucuronide- and sulfate-conjugated metabolites without phthalate degradation. The comprehensive mobile phase composed of 0.01% acetic acid and acetonitrile enabled us to simultaneously analyze 86 EPOLs, with good chromatographic behavior and ionization efficiency. Modified direct injection allowed a small amount of sample and simultaneous urinary extraction. The method was validated and applied to 39 urine samples from 19 mother-newborn pairs for multiple exposure assessment. Results showed that BP-3, a general component in sunblock products, and monoethyl phthalate, a metabolite of diethyl phthalate, exhibit a clear positive correlation between mothers and newborns. Therefore, the developed method has potential as a novel analytical tool for long-term, large-scale, and data-rich human biomonitoring of EPOLs.

Carbamate pesticides exposure and delayed physical development at the age of seven: Evidence from the SMBCS study

BACKGROUND

Carbamate pesticides are widely used in agriculture and cause widespread human exposure. The health effect of carbamates on physical development remains unclear. The current study aimed to explore the carbamate's health effect on physical development.

METHODS

Prenatal, 3-year-old, 7-year-old urinary carbofuranphenol concentration was measured by gas chromatography tandem mass spectrometry and adjusted by creatinine. Anthropometric indices were measured by standard method and z-score standardized. Generalized linear models (GLM) were using to assess associations between exposure measurements and anthropometric indices. The generalized estimate equation (GEE) was applied to analyze the association between multiperiod exposure and anthropometric indices, and time-interaction terms were used to exam health effect consistency of exposure in each period. Gender-stratified analysis were conducted according to results of gender-interaction terms to identify gender-specific effects.

RESULTS

The gender-interaction term of prenatal exposure with height z-score was significant (β = -0.057; 95% CI: -0.113, -0.001; p = 0.045). The 3-year-old carbofuranphenol level showed negative associations with weight z-score (β = -0.019; 95% CI: -0.038, -0.000; p = 0.040), height z-score (β = -0.015; 95% CI: -0.028, -0.001; p = 0.026), chest circumference (β = -0.086; 95% CI: -0.171, -0.001; p = 0.046), and waist circumference (β = -0.128; 95% CI: -0.230, -0.026; p = 0.014). No statistically significant trend was found for prenatal and 7-year-old carbofuranphenol levels. In GEEs, carbofuranphenol level was negatively associated with weight z-score (β = -0.103; 95% CI: -0.195, -0.011; p = 0.027), height z-score (β = -0.087; 95% CI: -0.152, -0.022; p = 0.008), and chest circumference (β = -0.472; 95% CI: -0.918, -0.026; p = 0.037). Boy's height z-score was inversely associated with carbamate exposure (β = -0.140; 95% CI: -0.227, -0.053; p = 0.001).

CONCLUSIONS

Prenatal and postnatal carbamate exposure may affect physical developmental process.

Determination of vitamin E and its metabolites in equine urine using liquid chromatography-mass spectrometry

Equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM) is a hereditary, deteriorating central nervous disease in horses. Currently, the only way to confirm eNAD/EDM is through a postmortem histological evaluation of the central nervous system. Vitamin E, specifically the isoform alpha-tocopherol (α-TP), is known to protect eNAD/EDM susceptible horses from developing the clinical phenotype. While vitamin E is an essential nutrient in the diet of horses, there are no diagnostic tests able to quantitate vitamin E and its metabolites in urine. An ultra-performance liquid chromatography-atmospheric-pressure chemical ionization mass spectrometry (UPLC-APCI-MS/MS) method was developed and validated following acidic hydrolysis and solid phase extraction to quantitate vitamin E and its metabolites in equine urine. A blank control horse urine matrix was used and spiked with different concentrations of analytes to form a standard curve using either alpha-tocopherol-d6 or chlorpropamide as the internal standard. Inter-day and intra-day statistics were performed to evaluate the method for accuracy (90% to 116%) and precision (0.75% to 14%). Matrix effects, percent recovery, and stability were also assessed. The method successfully analyzed alpha-carboxyethyl hydroxychroman (α-CEHC), alpha-carboxymethylbutyl hydroxychromans (α-CMBHC), gamma-carboxyethyl hydroxychroman γ-CEHC, and α-TP concentrations in urine to determine a baseline levels of analytes in healthy horses, and can be used to determine concentrations of vitamin E metabolites in equine urine allowing for its evaluation as a diagnostic approach in the treatment of eNAD/EDM.

Prenatal exposure to multiple phenolic compounds, fetal reproductive hormones, and the second to fourth digit ratio of children aged 10 years in a prospective birth cohort

Select phenols are known to possess hormone-disrupting properties, but no previous study has addressed the potential effects of prenatal exposure to phenol mixtures on fetal reproductive hormones and children's second to fourth digit (2D: 4D) ratio, a marker for in utero testosterone (T) exposure. We aimed to explore interrelations of prenatal phenol exposures individually and in mixtures, cord serum reproductive hormones, and 2D: 4D ratio of children aged 10 years. Urinary 11 phenol concentrations were determined from 392 pregnant women participating in a longitudinal birth cohort. We estimated associations of prenatal phenol exposures individually and in mixtures with cord reproductive hormones and children's 2D:4D ratio using three statistical approaches, including generalized linear models (GLMs), elastic net regression (ENR) models and Bayesian kernel machine regression (BKMR) models. In female newborns, the three models showed that maternal triclosan (TCS) concentrations were significantly negatively associated with cord serum T levels [regression coefficient (β) = -0.076, 95% confidence interval (CI): 0.138, -0.013; p = 0.018]. Additionally, maternal urinary bisphenol A (BPA) levels were related to decreases in 2D:4D ratio of the left hand in girls by GLMs (β = -0.003, 95% CI: 0.007, -0.001; p = 0.024) and ENR models, but not BKMR models. We provided evidence that prenatal TCS exposure predicted lower cord serum T levels, and maternal BPA exposure was related to decreased 2D:4D ratio of the left hand in females.

Early-life carbamate exposure and intelligence quotient of seven-year-old children

BACKGROUND

Early-life carbamate exposure during developmental period has been linked with adverse health effects and attracted attention.

METHODS

Three hundred and three children at age of seven were included in the current study. Urinary carbofuranphenol concentrations were measured using gas chromatography-tandem mass spectrometry. Verbal, performance and full-scale intelligence quotients (IQ_V, IQ_P, and IQ_FS) were assessed using Wechsler Intelligence Scale for Children-Chinese Revised. Generalized linear models were used to explore the associations between carbofuranphenol levels and IQs. Generalized estimating equations were used to explore long-term health effect and sensitive time window.

RESULTS

Carbofuranphenol was detected in 96.6% of the seven-year-old urinary samples, the geometric mean, median, and inter quartile range of the carbofuranphenol concentrations were 0.67 μg/L, 0.30 μg/L, and 0.09-3.72 μg/L, respectively, which were similar with the level of three-year-old children from the SMBCS cohort. Seven-year-old carbofuranphenol level was negatively associated with IQ_P [β = -0.044; 95% confidence interval (CI): -0.087, -0.001; p = 0.045]. Three-year-old carbofuranphenol level was negatively associated with IQ_P (β = -0.100; 95% CI: -0.186, -0.014; p = 0.022) and IQ_FS (β = -0.087; 95% CI: -0.173, -0.001; p = 0.047). Carbamate exposure of maternal and children at both three and seven years old had negative associations with IQ_P (β = -0.089; 95% CI: -0.171, -0.007; p = 0.034), and IQ_FS (β = -0.064; 95% CI: -0.127, -0.000; p = 0.049) of children at age of seven.

CONCLUSION

Results of the present study verify that children in an agricultural region of China were widely exposed to carbamate pesticides. Carbamate exposure in utero and at three and seven years may adversely impact children's neurodevelopment.

Maternal and childhood urinary phenol concentrations, neonatal thyroid function, and behavioral problems at 10 years of age: The SMBCS study

BACKGROUND

Environmental phenols, bisphenol A (BPA), triclosan (TCS), and benzophenone-3 (BP-3), are known as emerging endocrine-disrupting chemicals; however, their impacts on thyroid hormones and children's neurobehaviors are still unclear.

OBJECTIVES

We aimed to examine the associations of prenatal and childhood exposure to phenols with neonatal thyroid function and childhood behavioral problems aged 10 years.

METHODS

A total of 386 mother-singleton pairs were included from Sheyang Mini Birth Cohort Study (SMBCS), a longitudinal birth cohort in China. We quantified urinary BPA, TCS and BP-3 concentrations in maternal and 10-year-old children's urine samples using gas chromatography tandem mass spectrometry and thyroid function parameters in cord serum samples. Caregivers completed the Strength and Difficulties Questionnaire (SDQ) for their children at 10 years of age. Multivariable linear regression models and logistic regression models were applied to estimate associations of urinary phenol concentrations with thyroid hormones and risks of children's behavioral problems, respectively.

RESULTS

The median values of urinary BPA, TCS and BP-3 concentrations for pregnant women were 1.75 μg/L, 0.54 μg/L and 0.37 μg/L, while 1.29 μg/L, 6.64 μg/L and 1.39 μg/L for children, respectively. Maternal urinary BPA concentrations were in associations with 1.00% [95% confidence interval (CI): 0.20%, 1.92%] increases in cord serum FT4 concentrations and significantly associated with increased risks of total difficulties [odds ratio (OR): 1.45, 95% CI: 1.07, 1.97], while maternal urinary levels of BP-3 were significantly related to poorer prosocial behaviors (OR: 1.58, 95% CI: 1.04, 2.39) of children at 10 years of age. In sex-stratified analyses, maternal urinary BPA concentrations were related to increased total difficulty subscales only in boys.

CONCLUSIONS

The findings indicated that higher prenatal urinary BPA concentrations were associated with increased risks of total difficulties, especially in boys and maternal urinary BP-3 concentrations were related to poorer prosocial behaviors at 10 years.

Effects of prenatal exposure to five parabens on neonatal thyroid function and birth weight: Evidence from SMBCS study

BACKGROUND

Parabens, suspected as endocrine-disrupting chemicals, are nearly ubiquitous in the human body and exposure to these chemicals during pregnancy may disrupt thyroid hormones homeostasis and even affect fetal growth, although the impacts are still unclear.

OBJECTIVES

We aimed to estimate associations of maternal urinary paraben concentrations with cord serum thyroid hormones and birth weight.

METHODS

A subset of 437 mother-newborn pairs were included from a prospective birth cohort with five parabens quantified in maternal urine and seven thyroid function indicators measured in cord serum samples. Multivariable linear regression models and elastic net regression (ENR) models were applied to explore associations between individual and mixtures of prenatal urinary paraben concentrations and thyroid hormones and birth weight, respectively.

RESULTS

Maternal urinary ethyl-paraben (EtP) concentrations were associated with increased cord serum total triiodothyronine levels (TT3) [percent change: 1.51%; 95% confidence interval (CI): 0.20%, 2.74%; p=0.017]. Urinary propyl-paraben (PrP) levels predicted higher thyroid peroxidase antibodies (percent change: 4.19%, 95%CI: 0.20%, 8.44%; p=0.041). Maternal urinary EtP and butyl-paraben (BuP) concentrations were significantly positively associated with birth weight [regression coefficient, (β)=40.9g, 95%CI: 3.99, 76.6; p=0.030; β=62.1g, 95%CI: 8.70, 115; p=0.023, for EtP and BuP, respectively]. In sex-stratified analyses, positive relationship between EtP levels and birth weight was observed in boys. Urinary EtP concentrations predicted higher TT3 levels in cord serum samples, assessing parabens as a chemical mixture with ENR models.

CONCLUSIONS

Prenatal exposure to parabens may affect thyroid hormone indicators with increased serum TT3 levels and associate with higher birth weight, especially in boys. The underlying biological mechanisms and effects of prenatal paraben exposures on disruption of thyroid function homeostasis and potential impacts of childhood growth and development needed to be further investigated.

Urinary bisphenol A concentrations and adiposity measures at age 7 years in a prospective birth cohort

Bisphenol A (BPA) exposure during early life may increase risk of childhood obesity, however, prospective evidence of birth cohort is limited and inconclusive. We aimed to explore the associations of maternal and childhood BPA exposure with child adiposity measures, including body mass index, waist circumference and skinfold thickness and waist to height ratio of children at 7 years. 430 mother-child pairs were examined from a population-based prospective cohort in a rural area of East China. BPA concentrations of spot urine samples were quantified in mothers and their children aged 3 and 7 years. Maternal urinary BPA concentration was significantly positively associated with waist circumference in children aged 7 years (β = 0.508 cm, 95% CI: 0.067, 0.950). These significant associations were not modified by child sex, but they were only observed among girls in sex-stratified analyses. Risk of central obesity related to prenatal BPA exposure was significantly higher in the second and the third tertile than those in the first tertile (odds ratio, OR = 2.510, 95% CI = 1.146, 5.499; OR = 2.584, 95% CI = 1.186, 5.631, respectively; p for trend = 0.022). The present findings suggested that prenatal exposure to BPA may enhance waist circumference of children and thereby increase risk of central obesity in school-age girls.

Prenatal exposure to mixture of heavy metals, pesticides and phenols and IQ in children at 7 years of age: The SMBCS study

OBJECTIVE

Prenatal exposure to heavy metals, pesticides and phenols has been suggested to interfere with neurodevelopment, but the neurotoxicity of their mixtures is still unclear. We aimed to elucidate the associations of maternal urinary concentrations of selected chemical mixtures with intelligence quotient (IQ) in children.

METHODS

Maternal urinary concentrations of selected heavy metals, pesticide metabolites, and phenols were quantified in pregnant women who participated in the Sheyang Mini Birth Cohort Study (SMBCS) from June 2009 to January 2010. At age 7 years, child's IQ score was assessed using the Chinese version of Wechsler Intelligence Scale for Children (C-WISC) by trained pediatricians. Generalized linear regression models (GLM), Bayesian kernel machine regression (BKMR) models and elastic net regression (ENR) models were used to assess the associations of urinary concentrations individual chemicals and their mixtures with IQ scores of the 7-year-old children.

RESULTS

Of 326 mother-child pairs, single-chemical models indicated that prenatal urinary concentrations of lead (Pb) and bisphenol A (BPA) were significantly negatively associated with full intelligence quotient (FIQ) among children aged 7 years [β = -2.31, 95% confidence interval (CI): -4.13, -0.48; p = 0.013, sex interaction p-value = 0.076; β = -1.18, 95% CI: -2.21, -0.15; p = 0.025; sex interaction p-value = 0.296, for Pb and BPA, respectively]. Stratified analysis by sex indicated that the associations were only statistically significant in boys. In multi-chemical BKMR and ENR models, statistically significant inverse association was found between prenatal urinary Pb level and boy's FIQ scores at 7 years. Furthermore, BKMR analysis indicated that the overall mixture was associated with decreases in boy's IQ when all the chemicals' concentrations were at their 75th percentiles or higher, compared to at their 50th percentiles. ENR models revealed that maternal urinary Pb levels were statistically significantly associated with lower FIQ scores (β = -2.20, 95% CI: -4.20, -0.20; p = 0.031).

CONCLUSIONS

Prenatal exposure to selected chemical mixtures may affect intellectual performance at 7 years of age, particularly in boys. Pb and BPA were suspected as primary chemicals associated with child neurodevelopment.

Parameters of ovarian reserve in relation to urinary concentrations of parabens

BACKGROUND

Parabens are synthetic chemicals commonly used in cosmetics, pharmaceuticals, food and beverage processing as antimicrobial preservatives. In experimental animals, parabens exposure was associated with adverse effects on female reproduction. Despite the widespread use of parabens little is known about their effect on female fecundity. The objective of the current analysis was to evaluate the associations of urinary parabens concentrations with parameters of ovarian reserve among women undergoing treatment in a fertility clinic.

METHODS

Five hundred eleven female aged 25-39 years who attended the infertility clinic in central region of Poland for diagnostic purposes were recruited between September 2014 and February 2019. Urinary concentrations of parabens were measured by a validated gas chromatograohy ion-tap mass spectrometry method. Parameters of ovarian reserve were: antral follicle count (AFC), anti-Müllerian hormone (AMH), follicle-stimulating hormone (FSH) and estradiol (E2) levels.

RESULTS

The geometric mean of specific gravity adjusted urinary concentrations of methyl (MP), ethyl (EP), propyl (PP), butyl (BP) and izobutyl paraben (iBuP) were 107.93 μg/L, 12.9 μg/L, 18.67 μg/L, 5.02 μg/L and 2.80 μg/L. Urinary concentrations of PP in the third quartile of exposure ((50-75] percentyl) were inversely associated with antral follicle count (p = 0.048), estradiol level (p = 0.03) and positively with FSH concentration (p = 0.026). MP, EP, BP and iBuP parabens were not associated any with parameters of ovarian reserve.

CONCLUSIONS

Chronic exposure to PP may potentially contributing to reduced fecundity and impair fertility. As this is one of the first study to investigate the potential effect of parabens on ovarian reserve further epidemiological studies with longer duration of observation are needed.

Exposure to carbamate and neurodevelopment in children: Evidence from the SMBCS cohort in China

BACKGROUND

Carbamate pesticides exposure have been linked with adverse health effects during developmental period. Based on 377 mother-child pairs from Sheyang Mini Birth Cohort Study, the present study aimed to assess carbofuranphenol exposure of three-year-old children and explore the associations between prenatal or postnatal carbofuranphenol exposures and neurodevelopmental indicators.

METHODS

Urinary carbofuranphenol concentrations were measured by gas chromatography-tandem mass spectrometry. Neural developmental quotient (DQ) of children was evaluated using Gesell Developmental Schedules. Generalized linear models were used to examine the associations between carbofuranphenol concentrations and neurodevelopment.

RESULTS

Geometric mean, geometric standard deviation, median, inter quartile range of postnatal urinary carbofuranphenol concentrations were 0.653 μg/L, 9.345 μg/L, 0.413 μg/L, 0.150-1.675 μg/L, respectively. Postnatal carbofuranphenol level showed negatively significant trend in language DQ [beta (β) = -0.121; 95% confidence interval (95% CI): 0.212, -0.031; p value (p) = 0.008] and total average DQ (β = -0.059, 95% CI: 0.115, -0.003; p = 0.035). Prenatal carbofuranphenol level showed negative correlations with children's adaptive DQ (β = -0.755; 95% CI: 1.257, -0.254; p = 0.003), social DQ (β = -0.341; 95% CI: 0.656, -0.027; p = 0.032) and total average DQ (β = -0.349; 95% CI: 0.693, -0.005; p = 0.047).

CONCLUSION

The results of the present study supposed children in agricultural region of China are widely exposed to carbamate pesticides, and both prenatal and postnatal exposure to carbamate pesticides may lead to neurodevelopmental effect.

Anthropometric measures at age 3 years in associations with prenatal and postnatal exposures to chlorophenols

BACKGROUND

Chlorophenols (CPs), suspected as endocrine disrupting chemicals, exposure during early life may contribute to body size. However, limited human data with inconsistent findings have examined the developmental effects of CPs exposure.

OBJECTIVE

To explore associations between prenatal and postnatal CPs exposure and anthropometric parameters in children aged 3 years.

METHODS

A subset of 377 mother-child pairs with urinary five CP concentrations were enrolled from a prospective birth cohort. Generalized linear models were conducted to evaluate associations of CPs exposure with children's anthropometric measures.

RESULTS

Maternal urinary 2,4,6-trichlorophenol (2,4,6-TCP) concentrations were significantly negatively associated with weight z scores [regression coefficient (β) = -0.51, 95% confidence interval (CI): -0.96, -0.05; p = 0.01], weight for height z scores (β = -0.54, 95% CI: -1.02, -0.06; p = 0.01) and body mass index (BMI) z scores (β = -0.53, 95% CI: -1.03, -0.03; p = 0.01) of children aged 3 years, after adjustment for potential confounders and postnatal CPs exposure. In the sex-stratified analyses, these inverse associations remained among boys, while in girls, positive associations of prenatal 2,4,6-TCP exposure with weight for height z scores and BMI z scores were observed. Postnatal exposure to 2,5-diclorophenol (2,5-DCP) was positively associated with weight z scores (β = 0.26, 95% CI: 0.02, 0.50; p = 0.04), after controlling for possible confounders and maternal CPs exposure during pregnancy. Considering potential sex-specific effects, these associations were only observed in girls.

CONCLUSIONS

Our findings indicate that prenatal 2,4,6-TCP exposure and postnatal 2,5-DCP exposure may have adverse and sex-specific effects on children's physical development.

Associations of prenatal and childhood chlorpyrifos exposure with Neurodevelopment of 3-year-old children

Chlorpyrifos (CPF), an organophosphate insecticide, has been linked to adverse neurodevelopmental effects in animal studies. However, little is known about long-term neurotoxicity of early-life CPF exposure in humans. We aimed to evaluate the associations of both prenatal and early childhood CPF exposure with neurodevelopment of children. In this observational study based on Sheyang Mini Birth Cohort, pregnant women were recruited from an agricultural region between June 2009 and January 2010, and their children were followed up from birth to age three. Urinary 3,5,6-Trichloro-2-pyridinol (TCPy), a specific metabolite of CPF, was quantified using large-volume-injection gas chromatography-tandem mass spectrometry. Developmental quotients (DQs) of children in motor, adaptive, language, and social areas were assessed by trained pediatricians. Data from 377 mother-child pairs were used in the current study. Associations between CPF exposure and neurodevelopmental indicators were estimated using generalized linear models with adjustment for potential confounders. The median concentrations of TCPy in maternal and children's urine were 5.39 μg/L and 5.34 μg/L, respectively. No statistically significant association was found between maternal urinary TCPy concentrations and children neurodevelopment. While for postnatal exposure, we found lower motor area DQ score 0.61 [95% confidence interval (CI): -1.13, -0.09; p = 0.02] and social area DQ score 0.55 (95% CI: -1.07, -0.03; p = 0.04) per one-unit increase in the ln-transformed childhood urinary TCPy concentrations. Further stratification by sex indicated that the inverse associations were only observed in boys, but not in girls. Our findings suggest that adverse neurodevelopmental effects were associated with early childhood CPF exposure, but not prenatal exposure. Additional longitudinal studies are needed to replicate these results and to further understand the toxicological mechanisms of CPF.

Simultaneous assessment of phenolic metabolites in human urine for a specific biomonitoring of exposure to organophosphate and carbamate pesticides

Organophosphate pesticides (OPP) and carbamates are still counted among the most prominent agents used for crops protection. Up to date the determination of dialkylphosphates and their thio derivatives in urine is established for the OPP biomonitoring. However, this approach does not provide information on the exposure to specific OPP agents. A lot of OPP as well as some carbamates also provide specific urinary biomarkers indeed. Analytical methods for the determination of phenolic metabolites of OPP and carbamates have already been established by different working groups. However, these approaches only acquire one or few analytes. Therefore, we developed an analytical procedure which enables the simultaneous assessment of a wide spectrum of phenolic metabolites of OPP, carbamates and other pesticides in human urine using GC-MS/MS. The method includes enzymatic hydrolysis, solid phase extraction, derivatization, and subsequent GC-MS/MS analysis. The method showed detection limits between 0.1 and 0.4 μg/l. Variation coefficients ranged from 1 to 9 % for precision in series and 1 % to 13 % for inter-day precision. Furthermore, recovery rates between 87 and 117 % were determined. Compared with other published analytical procedures, the present method enables the simultaneous monitoring of a much broader spectrum of pesticides and biocides whose structures contain aryl moieties with competitive or improved analytical reliability. Furthermore, the suitability of the developed procedure was verified through the successful application to urine samples of pesticide exposed humans.

New approach for the determination of ortho-phenylphenol exposure by measurement of sulfate and glucuronide conjugates in urine using liquid chromatography-tandem mass spectrometry

Ortho-phenylphenol (OPP) has been widely used as a fungicide and preservative. Although low-dose studies have demonstrated its low toxicity in animals and humans, high-dose exposure to this contaminant has toxic effects that range from skin irritation to bladder cancer. Thus far, monitoring of OPP exposure in the general population has been performed by measuring OPP after urine hydrolysis with the β-glucuronidase/arylsulfatase enzyme and sometimes by the use of a mineral acid. We developed a sensitive, accurate, and robust method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) to specifically measure two-phase II OPP metabolites excreted in human urine, OPP sulfate (OPP-S), and OPP glucuronide (OPP-G). Comparative analysis of urine samples from 50 volunteers living in the Quebec City area using a direct method and phosphoric acid hydrolysis method previously developed in our laboratory showed no statistically significant difference (p value for paired t test = 0.701) in OPP concentrations. Moreover, a significant difference showed that underestimation (p value for paired t test = 0.025) occurs when β-glucuronidase/arylsulfatase enzyme deconjugation is used. The LOD achieved by the direct method permits the detection of OPP-S and OPP-G metabolites in urine at the submicrogram per liter level. Graphical abstract ᅟ.

Targeted analysis of microbial-generated phenolic acid metabolites derived from grape flavanols by gas chromatography-triple quadrupole mass spectrometry

Grape-derived products contain a wide array of bioactive phenolic compounds which are of significant interest to consumers and researchers for their multiple health benefits. The majority of bioavailable grape polyphenols, including the most abundant flavan-3-ols, i.e. (+)-catechin and (-)-epicatechin, undergo extensive microbial metabolism in the gut, forming metabolites that can be highly bioavailable and bioactive. To gain a better understanding in microbial metabolism of grape polyphenols and to identify bioactive metabolites, advanced analytical methods are needed to accurately quantitate microbial-derived metabolites, particularly at trace levels, in addition to their precursors. This work describes the development and validation of a high-throughput, sensitive and reproducible GC-QqQ/MS method operated under MRM mode that allowed the identification and quantification of 16 phenolic acid metabolites, along with (+)-catechin and (-)-epicatechin, in flavanol-enriched broth samples anaerobically fermented with human intestinal bacteria. Excellent sensitivity was achieved with low limits of detection and low limits of quantification in the range of 0.24-6.18 ng/mL and 0.480-12.37 ng/mL, respectively. With the exception of hippuric acid, recoveries of most analytes were greater than 85%. The percent accuracies for almost all analytes were within ±23% and precision results were all below 18%. Application of the developed method to in vitro samples fermented with different human gut microbiota revealed distinct variations in the extent of flavanol catabolism, as well as production of bioactive phenolic acid metabolites. These results support that intestinal microbiota have a significant impact on the production of flavanol metabolites. The successful application of the established method demonstrates its applicability and robustness for analysis of grape flavanols and their microbial metabolites in biological samples.

Advances in extraction and analysis of phenolic compounds from plant materials

Phenolic compounds, the most abundant secondary metabolites in plants, have received more and more attention in recent years because of their distinct bioactivities. This review summarizes different types of phenolic compounds and their extraction and analytical methods used in the recent reports, involving 59 phenolic compounds from 52 kinds of plants. The extraction methods include solid-liquid extraction, ultrasound-assisted extractions, microwave-assisted extractions, supercritical fluid extraction, and other methods. The analysis methods include spectrophotometry, gas chromatography, liquid chromatography, thin-layer chromatography, capillary electrophoresis, and near-infrared spectroscopy. After illustrating the specific conditions of the analytical methods, the advantages and disadvantages of each method are also summarized, pointing out their respective suitability. This review provides valuable reference for identification and/or quantification of phenolic compounds from natural products.

Maternal urinary carbofuranphenol levels before delivery and birth outcomes in Sheyang Birth Cohort

Exposure to carbamates has been linked with adverse health effects on developmental period. This study aimed to monitor exposure to carbofuranphenol of pregnant women from Sheyang Birth Cohort and investigate associations between prenatal exposure to carbofuranphenol and birth outcomes. During June 2009 to January 2010, 1100 pregnant women living in Sheyang County participated in our study and donated urine sample. Urinary carbofuranphenol concentration was measured by gas chromatography-tandem mass spectrometry. Associations between urinary carbofuranphenol levels and infant birth outcomes were assessed by generalized linear models. Urinary carbofuranphenol concentrations varied from 0.01 to 395.40μg/L (0.01-303.93μg/g for creatinine adjusted), the geometric mean, median and inter quartile range are 0.81μg/L (1.28μg/g cr), 0.80μg/L (1.23μg/g cr) and 0.27-2.20μg/L (0.47-3.11μg/g cr), respectively. No statistically significant association between maternal urinary carbofuranphenol levels and birth outcomes was found in total infants and female infants. In male neonates, carbofuranphenol level was significantly associated with head circumference (b=-0.226; 95% confidence interval: -0.411, -0.041; P=0.01) and ponderal index (b=0.043, 95% CI: 0.004, 0.083; P=0.03). These findings suggested that the pregnant women were generally exposed to carbofuranphenol and prenatal exposure to carbofuranphenol might have adverse effects on fetal development.

Urinary paraben concentrations and their associations with anthropometric measures of children aged 3 years

Parabens, known as ubiquitous preservatives, have been linked to adverse health outcomes in humans. This study aimed to examine urinary paraben concentrations of children at 3 years of age and evaluate their associations with anthropometric parameters. Urinary parabens including methylparaben (MeP), ethylparaben (EtP), propylparaben (PrP), butylparaben (BuP) and benzylparaben (BeP) were measured among 436 children in a birth cohort using gas chromatography with tandem mass spectrometry. Generalized linear models were performed to evaluate associations of paraben exposures with age- and sex-specific z scores, including weight, height, weight for height and body mass index. MeP, EtP and PrP were the dominant parabens in urinary samples, with the median concentrations of 6.03 μg/L, 3.17 μg/L, 2.40 μg/L, respectively. The median values of estimated daily intake (EDI_urine) of five urinary paraben concentrations were 12.10, 5.68, 4.50, 0.06 and 0.17 μg/kg-body weight/day, respectively. Urinary EtP concentrations were positively associated with weight z scores [regression coefficient β = 0.16, 95% confidence interval (CI): 0.04, 0.29; p = 0.01] and height z scores (β = 0.15, 95% CI: 0.03, 0.27; p = 0.01). Positive associations were found between the sum of molar concentrations of five parabens and height z scores among all children (β = 0.24, 95% CI: 0.04, 0.45; p = 0.02). These significant associations were only observed in boys. Our findings suggest that exposure to parabens may be adversely associated with physical growth in 3-year-old boy children. Further prospective studies are warranted to understand the toxicological mechanisms of paraben exposures and potential risk of children.

Associations of prenatal exposure to five chlorophenols with adverse birth outcomes

Exposures to chlorophenols (CPs) have been linked with adverse health effects on wildlife and humans. This study aimed to evaluate prenatal exposure to five CP compounds using maternal urinary concentrations during pregnancy and the potential associations with birth outcomes of their infants at birth. A total of 1100 mother-newborn pairs were recruited during June 2009 to January 2010 in an agricultural region, China. Urinary concentrations of five CPs from dichlorophenol (DCP) to pentachlorophenol (PCP), namely, 2,5-DCP, 2,4-DCP, 2,4,5-trichlorophenol (2,4,5-TCP), 2,4,6-TCP and PCP, were measured using large-volume-injection gas chromatography-tandem mass spectrometry (LVI-GC-MS-MS), and associations between CP levels and weight, length as well as head circumference at birth were examined. Median urinary creatinine-adjusted concentrations of 2,5-DCP, 2,4-DCP, 2,4,5-TCP, 2,4,6-TCP and PCP were 3.34 μg/g, 1.03 μg/g, < LOD, 1.78 μg/g and 0.39 μg/g creatinine, respectively. We found lower birth weight 30 g [95% confidence interval (CI): -57, -3; p = 0.03] for per SD increase in log10-transformed concentrations of 2,4,6-TCP and lower birth weight 37 g (95% CI: -64, -10; p = 0.04) for PCP, respectively. Similarly, head circumference decrease in associations with creatinine-corrected 2,4,6-TCP and PCP concentrations were also achieved. Considering sex difference, the associations of lower birth weight were only found among male neonates, while head circumference was associated with 2,4-DCP and 2,5-DCP only found among female neonates. This study showed significant negative associations between CPs exposure and reduction in neonatal anthropometric measures. The biological mechanisms concerning CPs exposure on fetal growth deserved further investigations.

Birth outcome measures and prenatal exposure to 4-tert-octylphenol

Exposure to 4-tert-octylphenol (tOP) has been linked with adverse health outcomes in animals and humans, while epidemiological studies about associations between prenatal exposure to tOP and fetal growth are extremely limited. We measured urinary tOP concentrations in 1100 pregnant women before their delivery, and examined whether tOP levels were associated with birth outcomes, including weight, length, head circumference and ponderal index at birth. tOP could be detected in all samples, and the median uncorrected and creatinine-corrected tOP concentrations were 0.90 μg/L (range from 0.25 to 20.05 μg/L) and 1.33 μg/g creatinine (range from 0.15 to 42.49 μg/g creatinine), respectively. Maternal urinary log-transformed tOP concentrations were significantly negatively associated with adjusted birth weight [β (g) = -126; 95% confidence interval (CI): -197, -55], birth length [β (cm) = -0.53; 95% CI:-0.93, -0.14], and head circumference [β (cm) = -0.30; 95% CI: -0.54, -0.07], respectively. Additionally, considering sex difference, these significant negative associations were also found among male neonates, while only higher maternal tOP concentrations were associated with a significant decrease in birth weight among female neonates. This study suggested significant negative associations between maternal urinary tOP concentrations and neonatal sizes at birth, and they differed by neonatal sex. Further epidemiological studies are required to more fully elaborate the associations between prenatal tOP exposure and birth outcomes.