Urinary phthalate metabolites and biomarkers of oxidative stress in pregnant women: a repeated measures analysis

Blood and urinary biomarkers of prenatal exposure to disinfection byproducts and oxidative stress: A repeated measurement analysis

BACKGROUND

Toxicological studies have demonstrated that disinfection by-products (DBPs) can induce oxidative stress, a proposed mechanism that is relevant to adverse birth outcomes.

OBJECTIVE

To examine the associations of blood trihalomethanes (THMs) and urinary haloacetic acids (HAAs) with urinary biomarkers of oxidative stress among pregnant women.

METHODS

From 2015 to 2017, a total of 4150 blood and 4232 urine samples were collected from 1748 Chinese women during pregnancy. We determined concentrations of 4 blood THMs [chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)] and 2 urinary HAAs [dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA)]. The summary measures of exposure for brominated THMs (Br-THMs; a molar sum of BDCM, DBCM, and TBM) and total THMs (TTHMs; a molar sum of TCM and Br-THMs) were also calculated. Associations of categorical (i.e., tertiles) and continuous measures of DBPs with urinary concentrations of oxidative stress (OS) biomarkers, 8-hydroxy-2-deoxyguanosine (8-OHdG), 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA), and 8-iso-prostaglandin F_2α (8-isoPGF_2α), were assessed using linear mixed regression models.

RESULTS

After adjusting for relevant confounding factors, we observed positive dose-response relationships between blood Br-THM tertiles and urinary HNE-MA (P for trend < 0.001). We also found positive associations between tertiles of blood TCM and TTHMs and urinary 8-OHdG and HNE-MA (all P for trend < 0.05). Urinary HAAs were also positively associated with 8-OHdG, HNE-MA, and 8-isoPGF_2α in a dose-response manner (all P for trend < 0.001). These associations were further confirmed when we modeled DBP exposures as continuous variables in linear mixed regression models, as well as in penalized regression splines based on generalized additive mixed models.

CONCLUSIONS

Exposure to DBPs during pregnancy may increase maternal OS status.

Associations of urinary di-(2-ethylhexyl) phthalate metabolites with the residential characteristics of pregnant women

Epidemiological evidence on the associations between urinary di-(2-ethylhexyl) phthalate (DEHP) metabolites and residential characteristics is limited. Therefore, we investigated the associations of urinary DEHP metabolites with the residential characteristics of pregnant women. We collected completed questionnaires and maternal spot urine samples from 616 random pregnant women in Shengjing Hospital of China Medical University in Shenyang. Urinary DEHP metabolites concentrations, including mono-(2-ethylhexyl) phthalate (MEHP) and mono (2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), were measured and analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). Multivariable linear regression models were performed to obtain regression estimates (β) and 95% confidence intervals (CIs) after adjustment for sociodemographic characteristics. In all participants, the geometric mean of MEHP and MEHHP concentrations were 4.25 ± 4.34 and 5.72 ± 2.65 μg/L, respectively. In multivariable analyses after adjusting for sociodemographic characteristics, distance from residence to motor vehicle traffic (≥150 m versus <20 m) was negatively associated with MEHP (β = -0.241, 95% CI: -0.448, -0.033) and MEHHP (β = -0.279, 95% CI: -0.418, -0.140) concentrations. Compared with the one that had not recently been renovated, a renovated home was associated with higher MEHP (β = 0.194, 95% CI: 0.064, 0.324) and MEHHP (β = 0.111, 95% CI: 0.024, 0.197) concentrations. Air freshener use was associated with higher MEHP (β = 0.322, 95% CI: 0.007, 0.636) concentrations. Moldy walls were positively associated with MEHP (β = 0.299, 95% CI: 0.115, 0.482) and MEHHP (β = 0.172, 95% CI: 0.050, 0.294) concentrations. In contrast, humidifier use was associated with a lower MEHP concentration (β = -0.167, 95% CI: -0.302, -0.032). Residential characteristics were probably associated with the DEHP exposure of pregnant women in Shenyang. Living near the motor vehicle traffic, residential renovation, air freshener use, and moldy walls are likely risk factors for increased DEHP exposure, whereas using household humidifier could be considered a protective measure to reduce DEHP exposure.

High frequency discharge plasma induced plasticizer elimination in water: Removal performance and residual toxicity

Plasticizers are widely present in water and soil environment, and they can bring enormous threats to environmental safety and human health. A discharge plasma system driven by a high-frequency electric source was used to remove the plasticizer from wastewater; and dimethyl phthalate (DMP) was chosen as the representative of plasticizer. DMP elimination performance at various operating parameters, roles of active species in DMP degradation, DMP decomposition process, and its residual toxicity after decomposition were systematically investigated. The experimental results demonstrated that almost all of the DMP and 80.4% of the total organic carbon (TOC) were removed after 30 min of treatment. The DMP decomposition process fitted well with the first-order kinetic model. Relatively higher applied voltage, lower initial concentration, and alkaline conditions favored its decomposition. •OH was the decisive species for DMP decomposition, in addition to •O₂^- and ¹O₂; while the role of hydrated electrons was negligible. The analysis of DMP decomposition process showed that the molecular structures of the DMP were destroyed, and 3-hydroxy-dimethyl phthalate, monomethyl phthalate, and phthalic acid were detected. Furthermore, the residual toxicity after DMP decomposition was analyzed via seed germination and photobacterium bioassay.

Latent classes for chemical mixtures analyses in epidemiology: an example using phthalate and phenol exposure biomarkers in pregnant women

Latent class analysis (LCA), although minimally applied to the statistical analysis of mixtures, may serve as a useful tool for identifying individuals with shared real-life profiles of chemical exposures. Knowledge of these groupings and their risk of adverse outcomes has the potential to inform targeted public health prevention strategies. This example applies LCA to identify clusters of pregnant women from a case-control study within the LIFECODES birth cohort with shared exposure patterns across a panel of urinary phthalate metabolites and parabens, and to evaluate the association between cluster membership and urinary oxidative stress biomarkers. LCA identified individuals with: "low exposure," "low phthalates, high parabens," "high phthalates, low parabens," and "high exposure." Class membership was associated with several demographic characteristics. Compared with "low exposure," women classified as having "high exposure" had elevated urinary concentrations of the oxidative stress biomarkers 8-hydroxydeoxyguanosine (19% higher, 95% confidence interval [CI] = 7, 32%) and 8-isoprostane (31% higher, 95% CI = -5, 64%). However, contrast examinations indicated that associations between oxidative stress biomarkers and "high exposure" were not statistically different from those with "high phthalates, low parabens" suggesting a minimal effect of higher paraben exposure in the presence of high phthalates. The presented example offers verification of latent class assignments through application to an additional data set as well as a comparison to another unsupervised clustering approach, k-means clustering. LCA may be more easily implemented, more consistent, and more able to provide interpretable output.

Exposures to chemical mixtures during pregnancy and neonatal outcomes: The HOME study

INTRODUCTION

Exposure to mixtures of environmental chemicals are prevalent among pregnant women and may be associated with altered fetal growth and gestational age. To date, most research regarding environmental chemicals and neonatal outcomes has focused on the effect of individual agents.

METHODS

In a prospective cohort of 380 pregnant women from Cincinnati, OH (enrolled 2003-2006), we used biomarkers to estimate exposure to 43 phenols, phthalates, metals, organophosphate/pyrethroid/organochlorine pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers, perfluoroalkyl substances (PFAS), and environmental tobacco smoke. Using three approaches, we estimated covariate-adjusted associations of chemical mixtures or individual chemicals with gestational-age-specific birth weight z-scores, birth length, head circumference, and gestational age: k-means clustering, principal components (PC), and one-chemical-at-a-time regression.

RESULTS

We identified three chemical mixture profiles using k-means clustering. Women in cluster 1 had higher concentrations of most phenols, three phthalate metabolites, several metals, organophosphate/organochlorine pesticides, polychlorinated biphenyls, and several PFAS than women in clusters 2 and 3. On average, infants born to women in clusters 1 (-1.2 cm; 95% CI: -1.9, -0.5) and 2 (-0.5 cm; 95% CI: -1.1, 0.1) had lower birth length than infants in cluster 3. Six PCs explained 50% of the variance in biomarker concentrations and biomarkers with similar chemical structures or from shared commercial/industrial settings loaded onto commons PCs. Each standard deviation increase in PC 1 (organochlorine pesticides, some phenols) and PC 6 (cadmium, bisphenol A) was associated with 0.2 cm (95% CI: -0.4, 0.0) and 0.1 cm (95% CI: -0.4, 0.1) lower birth length, respectively. Organochlorine compounds, parabens, and cadmium were inversely associated with birth length in the one-chemical-at-a-time analysis. Cluster membership, PC scores, and individual chemicals were not associated with other birth outcomes.

CONCLUSION

All three methods of characterizing multiple chemical exposures in this cohort identified inverse associations of select organochlorine compounds, phenols, and cadmium with birth length, but not other neonatal outcomes.

Experience Gained from Ecotoxicological Studies in the Seine River and Its Drainage Basin Over the Last Decade: Applicative Examples and Research Perspectives

The Seine River and its drainage basin are recognised as one of the most urbanised water systems in France. This chapter gathers typical applications of complementary ecotoxicological tools that were used in PIREN-Seine programmes for a decade to reflect the Seine River contamination as well as its biological repercussions on organisms. Ecotoxicological studies focused on both (1) specific bioassays and (2) (sub)-individual biological responses (i.e. biomarkers) measured in diverse taxa (i.e. crustaceans, mussels and fishes) representative of the trophic network. Experience gained from these studies made it possible to establish reference and threshold values for numerous biological endpoints. They now can be combined with chemical measurements within integrated models (i.e. the Weight of Evidence [WOE] approach) generating a global index of waterbody pollution. These biological endpoints today appear sufficiently relevant and mature to be proposed to water stakeholders as efficient tools to support environmental management strategies.

Mediation of the relationship between phthalate exposure and semen quality by oxidative stress among 1034 reproductive-aged Chinese men

BACKGROUND

Emerging evidence from animals indicates that oxidative stress plays a crucial role in the effects of phthalate exposure on male reproductive dysfunctions, which has never been thoroughly explored in humans.

OBJECTIVE

To explore the potential mediating role of oxidative stress in the association of phthalate exposure with semen quality among 1034 Chinese men.

METHOD

Repeated urine samples gathered from the male partners of sub-fertile couples were analyzed for 3 oxidative stress markers [8-hydroxy-2-deoxyguanosine (8-OHdG), 8-iso-prostaglandin F_2α (8-isoPGF_2α) and 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA)], using a liquid chromatography-tandem mass spectrometry. Multivariate regression models were constructed to evaluate the associations of urinary oxidative stress markers with urinary phthalate metabolites and semen quality. We also explored the potential mediation effects by oxidative stress markers.

RESULTS

Significantly positive dose-dependent relationships were observed between each individual phthalate metabolite and all analyzed oxidative stress markers (all p for trend<0.05), except for monoethyl phthalate (MEP) in relation to HNE-MA. Additionally, significantly or suggestively inverse dose-dependent relationships were exhibited between urinary 8-isoPGF_2α and sperm concentration (p for trend = 0.05), and between urinary 8-OHdG and percent of normal sperm morphology (p for trend = 0.01). Mediation analysis showed that urinary 8-isoPGF_2α suggestively mediated 12% of the inverse association between monobutyl phthalate (MBP) and sperm concentration, and that urinary 8-OHdG suggestively mediated 32% of the inverse association of MEP with percent of normal sperm morphology (both p < 0.10).

CONCLUSIONS

Although further investigations are required, our results suggest that oxidative stress may play a mediating role in the effects of phthalate exposure on impaired semen quality.

Effect of exposure to phthalates on association of polycyclic aromatic hydrocarbons with 8-hydroxy-2'-deoxyguanosine

BACKGROUND

Although polycyclic aromatic hydrocarbons (PAHs) and phthalates separately related to oxidative DNA damage have been reported, the joint effect of them on oxidative DNA damage need to be evaluated.

METHODS

In this pilot study, 106 participants were recruited from the community-dwelling residents (n=1240) of Wuhan city, China. Each individual provided three continuous days of spot urine samples for measuring the urinary monohydroxylated PAHs (OH-PAHs), phthalates metabolites and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in the two seasons. Linear mixed effect model and Bayesian Kernel Machine Regression (BKMR) were used to analyze joint effect of urinary PAHs and phthalates metabolites on urinary 8-OHdG levels. We measured cellular and mitochondrial reactive oxygen species (ROS), malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) levels as well as IL-6 and IL-8 secretions by the corresponding commercial kits in HepG2 cells treated with di (2-ethylhexyl) phthalate (DEHP, 62.5, 125.00, 250.00, 500.00 or 1000.00μM) alone, benzo[a]pyrene (BaP, 50.00μM) alone or both DEHP and BaP.

RESULTS

Linear mixed effect model showed that each of urinary PAHs metabolite was positively associated with urinary 8-OHdG levels; urinary level of mono (2-ethylhexyl) phthalate or monoisononyl phthalate was positively associated with urinary 8-OHdG levels; BKMR model indicated that a positive association of eight OH-PAHs with urinary 8-OHdG levels, nine urinary phthalates metabolites enhanced the association. We found that DEHP at the indicated concentration plus 50.00μM BaP increased cellular and mitochondrial ROS levels, IL-6 and IL-8 secretions at 24 and 48h as well as MDA levels and GSH-Px activities at 48h, compared to the solvent control.

CONCLUSIONS

Exposure to certain dose phthalates may attenuate the positive association of PAHs exposure with oxidative DNA damage in the body. DEHP at the certain concentrations enhanced BaP-induced mitochondrial ROS, pro-inflammatory response and the activation of the antioxidant defense system in HepG2 cells.

Associations between socioeconomic status, psychosocial stress, and urinary levels of 8-iso-prostaglandin-F2α during pregnancy in Puerto Rico

BACKGROUND

Lower socioeconomic status (SES) and psychosocial stress during pregnancy have been associated with adverse birth outcomes. While hypothalamic-pituitary-axis activation is thought to be the primary driver, oxidative stress may also be involved mechanistically. We used data from the Puerto Rico Testsite for Exploring Contamination Threats (PROTECT) cohort (N=476) to examine associations between self-reported psychosocial stress measures, SES indicators, and urinary oxidative stress biomarker concentrations, hypothesizing that women with lower SES and increased psychosocial stress would have elevated oxidative stress biomarkers.

METHODS

Maternal age, education, marital status, insurance status, alcohol use and smoking status were obtained via self-reported questionnaires and were used as indicators of SES. Perceived stress, depression, negative life experiences, neighborhood perceptions, and social support were self-reported in questionnaires administered during pregnancy. Responses were grouped into tertiles for analysis, where the highest tertile corresponded to highest level of psychosocial stress. Urinary concentrations of 8-iso-prostaglandin F2α (8-iso-PGF2α) and its primary metabolite were measured at three study visits (median 18, 24, 28 weeks gestation) and averaged to reflect oxidative stress across pregnancy. Linear models were used to examine associations between SES indicators, tertiles of psychosocial stress and oxidative stress biomarkers.

RESULTS

Average levels of 8-iso-PGF2α and the 8-iso-PGF2α metabolite were higher among pregnant women who were younger, who had public compared to private insurance, and who were unemployed compared to employed. However, no associations were observed between psychosocial stress measures and biomarker concentrations in adjusted analyses.

CONCLUSIONS

Psychosocial stress during pregnancy, as indicated by self-reported questionnaire measures, was not associated with biomarkers of oxidative stress in the PROTECT study. However, results suggest that these biomarkers are elevated among women of lower SES, which is typically associated with stress. Notably, compared to other populations, self-reported psychosocial stress measures were lower in PROTECT compared to other populations.

Urinary bisphenol analogues concentrations and biomarkers of oxidative DNA and RNA damage in Chinese school children in East China: A repeated measures study

The associations between bisphenol analogues (BPs) exposure and oxidative damage was explored in this 3-year longitudinal study of 275 school children in East China. Nine BPs in first morning urine samples were measured to assess BPs exposure, and 8-hydroxydeoxyguanosine (8-OHdG) and 8-oxo-7,8-dihydroguanosine (8-OHG) were measured as biomarkers of oxidative DNA and RNA damage. Linear mixed model (LMM) was used for repeated measures analysis. School children were mainly exposed to BPA, BPS, BPF, and BPAF (detection frequencies: 97.9%, 42.2%, 13.3%, and 12.8%) with median concentrations of 1.55, 0.355, 0.236 and 0.238 μg g^-1_Cre, respectively. An interquartile range (IQR) increase in urinary BPA was significantly associated with 12.9% (95% CI: 6.1%, 19.6%) increase in 8-OHdG and 19.4% (95% CI: 11.7%, 27.1%) increase in 8-OHG, and for total of BPs (the sum of BPA, BPS, BPF, and BPAF), they were 17.4% (95% CI: 8.9%, 26.0%) for 8-OHdG and 25.9% (95% CI: 16.1%, 35.7%) for 8-OHG, respectively. BPS was positively associated with 8-OHG, but not with 8-OHdG. The study found positive associations of urinary levels of BPA and total BPs with 8-OHdG and 8-OHG and indicated that BPs exposure might cause oxidative RNA damage.

Environmental pollutant induced cellular injury is reflected in exosomes from placental explants

INTRODUCTION

Exosomes are intercellular signaling vesicles whose cargo reflects the physiological status of the cell of their origin and can regulate gene expression in other tissues. Polybrominated diphenyl ethers (PBDEs) and bisphenols (A [BPA], Tetrabromobisphenol A [TBBPA], and 2,4,6-Tribromophenol [TBP]) are common environmental pollutants known to increase the risk for spontaneous preterm birth (PTB). We hypothesized that placental exposure to these environmental pollutants causes exosome cargo changes that reflect exposure associated placental response.

METHODS

Full-term, C-section placenta explants were treated with PBDE congeners (47, 100, 153, 209), TBBPA, TBP or BPA for 24 h. Exosomes were isolated from media by sequential ultracentrifugation and purified by size exclusion chromatography. Exosomes were characterized by electron microscopy, nanoparticle tracking analysis and Western blot. Proteomics identified differentially expressed exosomal proteins and Ingenuity pathway analysis (IPA) determined biological functions and pathways represented by identified proteins.

RESULTS

Regardless of treatment, placental expressed exosomes markers (PLAP, CD9, CD63, 81 and ALIX), had a size distribution between 50 and 175 nm and were present in the conditioned medium at 5-8 x 10¹¹ exosomes/mL. Proteomic analysis identified 2598 proteins which demonstrated that specific pollutants caused differential expression of specific proteins, including alarmin, High Mobility Group Box 1 (HMGB1), MAPK14 (p38 MAPK) and GSK3β. IPA revealed an inhibition of pathways associated with cell survival, tissue repair and proliferation, as well as activation of cell death pathways (e.g. necrosis).

CONCLUSION

Environmental exposure of placental explants did not change the quantity of exosomes or their characteristics. However, exosome cargo composition exposed to some environment pollutants may be involved in placental nuclear and cellular injury and inflammation.

Urinary concentrations of phenols in association with biomarkers of oxidative stress in pregnancy: Assessment of effects independent of phthalates

BACKGROUND

Maternal exposure to environmental phenols is common in pregnancy and has been linked to preterm birth, preeclampsia, and reduced fetal growth. One potential mechanism may be through increased maternal oxidative stress.

OBJECTIVE

We examined the associations between a panel of 10 urinary phenols, including dichlorophenols, benzophenone-3, parabens, triclosan and triclocarban, and bisphenol-S, and two urinary oxidative stress biomarkers, 8-hydroxydeoxyguanosine (8-OHdG) and 8-isoprostane. All exposure and outcome biomarkers were measured at 4 time points in pregnancy.

METHODS

We used repeated measures models to examine the association between repeated exposure and outcome biomarkers. Additionally, we used adaptive elastic net (AENET) to identify non-null associations accounting for the correlation structure of exposures, both for phenols and urinary phthalate metabolites that were previously associated with the oxidative stress biomarkers in our study population.

RESULTS

In adjusted repeated measures models, we observed that dichlorophenols, benzophenone-3, triclosan, and some parabens were associated with increases in both oxidative stress biomarkers. The greatest effect estimates were observed for 2,5-dichlorophenol; an interquartile range (IQR) increase in this compound was associated with a 15.2% (95% confidence interval [CI] = 11.0, 19.6) increase in 8-OHdG and a 16.7% (95% CI = 9.66, 24.2) increase in 8-isoprostane. Bisphenol-S detection was associated with a clear increase in 8-isoprostane (18.5%, 95% CI = 7.68, 30.5) but a more modest increase in 8-OHdG (6.18%, 95% CI = -0.27, 13.1). However, AENET models did not consistently select any of the phenols as predictors of 8-OHdG or 8-isoprostane when phthalate metabolites were included in the model.

CONCLUSION

Overall, urinary phenols were associated with increases in biomarkers of oxidative stress in pregnancy but either to a lesser extent, or due to correlation with, urinary phthalate metabolites.

Inverse associations of bisphenol A and phthalate metabolites with serum bilirubin levels in Korean population

Bisphenol A (BPA) and phthalates are endocrine disruptors that can induce oxidative stress. Serum bilirubin has antioxidant properties and may serve as a biomarker of oxidative stress. The objective of this study was to explore the relationship of BPA and phthalates with serum bilirubin levels in a Korean population. Urinary concentrations of BPA and six phthalate [mono-n-butyl phthalate (MnBP), mono-iso-butyl phthalate (MiBP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-(2-ethyl-5- hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), and mono-benzyl phthalate (MBzP)] were measured in 709 participants. Serum concentrations of BPA and three phthalate metabolites [MnBP, MiBP, and mono-(2-ethylhexyl) phthalate (MEHP)] were measured in 752 participants. After excluding missing variables, associations between above chemicals and serum bilirubin levels were analyzed using multivariate linear regression with age, sex, BMI, GGT, GOT, GPT, and alcohol intake adjustment. Participants were further stratified by sex. Among the urinary chemicals, BPA and four phthalate metabolites (MnBP, MEOHP, MEHHP and MECPP) were inversely associated with serum bilirubin levels (BPA: β = - 0.071, P < 0.0001; MnBP: β = - 0.055, P = 0.025; MEOHP: β = - 0.101, P < 0.0001; MEHHP: β = - 0.106, P < 0.0001; MECPP: β = - 0.052, P = 0.003). In a case of serum chemicals, only MiBP showed significantly positive association (β = 0.036, P = 0.016). After stratification by sex, the associations of urinary BPA remained both in male and female, of which urinary phthalates disappeared in female. The association of serum MiBP was disappeared after stratification. Urinary BPA and phthalate metabolites were inversely associated with serum bilirubin levels, whereas serum MiBP showed positive association with bilirubin. These results could provide clues for understanding the mechanisms of endocrine disruptor from oxidative stress to excretion from our body.

Prenatal phthalate exposure in relation to gestational age and preterm birth in a prospective cohort study

This study enrolled 3266 pregnant women, to explore the relationship of prenatal phthalate exposure with the risk of preterm birth and gestational age. All participants filled questionnaires and provided with up to three urine samples during three trimesters. Seven phthalate metabolites in urines were measured. The incidences of very preterm, late preterm, early-term, late-term and postterm births were 0.58%, 3.52%, 24.22%, 10.53%, and 0.34%, respectively. Non-linear relationships were shown between phthalate metabolites and gestational age. Except for monomethyl phthalate (OR = 1.65, 95%CI = 1.17-2.34), the average concentrations of phthalate metabolites were associated with a slightly and insignificantly increased risk of overall preterm birth (<37⁺⁰ gestational weeks). Through a restricted cubic spline regression, phthalate metabolites were found to be related to the risk of overall preterm birth in a linear manner (p-value >0.05) or a non-linear manner (p-value <0.05). All curves indicated the overall preterm birth risk rose with the increase of phthalate metabolite concentrations. Finally, compared with full-term birth (39⁺⁰ to 40⁺⁶ gestational weeks), phthalate metabolites were associated with the elevated risks of very preterm, late preterm and postterm births, although some relationships were not statistically significant. In conclusion, these findings suggested non-linear associations between phthalate metabolites and gestational age. Exposure to some phthalate metabolites was associated with increased risks of overall preterm birth and postterm birth.

Association of urinary concentrations of early pregnancy phthalate metabolites and bisphenol A with length of gestation

BACKGROUND

Environmental exposure to phthalates and bisphenol A (BPA) may have endocrine disrupting effects that alter length of gestation. We assessed the association between the urinary concentrations of 11 phthalate metabolites and BPA with length of gestation in a cohort of women followed from before conception with daily 1st-morning urinary hormone measures that identified day of implantation.

METHODS

Pre-implantation and post-implantation urinary phthalate metabolites and BPA concentrations were measured in pooled urine samples designed to limit single-measure variability due to the likely episodic nature of these exposures and the short half-life of these compounds. We estimated associations between these exposure biomarkers early in pregnancy with length of gestation from implantation to spontaneous birth. Cox proportional hazards models were used to estimate the hazard of birth among 125 naturally-conceived, singleton live births with censoring for medical interventions that artificially shortened pregnancy.

RESULTS

Higher concentrations of mono (2-ethyl-5-hydroxyhexyl) phthalate (a metabolite of di (2-ethylhexyl) phthalate (DEHP)) during the pre-implantation window were associated with reduced probability of birth, i.e., longer gestations (hazard ratio (HR): 0.55, 95% CI: 0.35, 0.86; p = 0.01). The HR for the molar sum of the four DEHP metabolites measured showed a similar association (HR: 0.67, 95% CI: 0.43, 1.05). Higher concentrations of mono (3-carboxypropyl) phthalate (MCPP), a non-specific metabolite of several high molecular-weight phthalates, measured post-implantation were associated with increased risk of earlier birth, i.e. shorter length of gestation, HR: 1.59, CI: 1.02, 2.49.

CONCLUSIONS

Early gestational exposure to DEHP and possibly other high-molecular weight phthalates, (as reflected by urinary MCPP concentrations) may influence the length of pregnancy. Such effects could have consequences for neonatal and maternal health.

Prenatal Exposure to Phthalates and Newborn Telomere Length: A Birth Cohort Study in Wuhan, China

BACKGROUND

Telomere length (TL) is a marker of biological aging and is inversely related to aging-related diseases. The setting of TL at birth may have important implications for lifelong telomere dynamics; however, its determinants remain poorly understood.

OBJECTIVES

The purpose of our study was to explore the relationships between prenatal exposure to phthalates and umbilical cord blood TL.

METHODS

A total of 762 mother–newborn pairs were recruited from a birth cohort study performed between November 2013 and March 2015 in Wuhan, China. Relative cord blood TL was measured using quantitative real-time polymerase chain reaction. Six phthalate metabolites were measured in urine samples acquired from pregnant women during the three trimesters. Multiple informant models were applied to estimate the associations between prenatal exposure to phthalates and cord blood TL and to evaluate potential windows of vulnerability.

RESULTS

Exposure to mono-ethyl phthalate (MEP), mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-butyl phthalate (MBP), and di(2-ethylhexyl) phthalate ([Formula: see text]) during the first trimester were inversely related to cord blood TL. In addition, we observed a female-specific association between maternal exposure to MEP during the first trimester and cord blood TL ([Formula: see text]). The associations between maternal exposure to MECPP, MEHHP, MEOHP, and [Formula: see text] during the first trimester and cord blood TL were consistent between males and females (all [Formula: see text]).

CONCLUSION

This prospective study demonstrated that prenatal exposure to some phthalate metabolites were associated with shorter cord blood TL. Our results, if confirmed in other populations, may provide more evidence of adverse health outcomes of phthalate exposure and support the hypothesis that the intrauterine environment may be one of the major determinants for newborn TL. https://doi.org/10.1289/EHP4492.

Phthalate Exposures, DNA Methylation and Adiposity in Mexican Children Through Adolescence

Phthalates are a class of endocrine disrupting chemicals with near ubiquitous exposure to populations around the world. Phthalates have been associated with children's adiposity in previous studies, though discrepancies exist across studies that may be due to timing of exposure or outcome assessment and population differences (i.e., genetics, other confounders). DNA methylation, an epigenetic modification involved in gene regulation, may mediate the effects of early life phthalate exposures on health outcomes. This study aims to evaluate the mediating effect of DNA methylation at growth-related genes on the association between phthalate exposure and repeat measures of adiposity (BMI-for-age z-score, waist circumference, and skinfolds thickness) in Mexican children. Urinary phthalate metabolite concentrations were quantified in mothers at each of the three trimesters of pregnancy and in children at the first peri-adolescent study visit. Blood leukocyte DNA methylation at H19 and HSD11B2 was quantified during the first peri-adolescent visit, and adiposity was measured at the first visit and again ~3 years later among participants (n = 109 boys, 114 girls) from the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) project. Associations between phthalates or DNA methylation and repeat outcome measures were assessed separately in boys and girls using generalized estimating equation models including covariates (urinary specific gravity, maternal education, and child's age). Sobel tests were used to assess DNA methylation as a mediator in models adjusting for the same covariates. Associations between phthalates and adiposity varied by phthalate and timing of exposure. Early gestation MBP, MIBP, and MBzP were associated with adiposity among girls. For example, among girls first trimester maternal urine concentrations of MIBP were associated with increases in skinfold thickness, BMI-for-age, and waist circumference (p < 0.01). Second trimester and adolescent MBzP were associated with adiposity among boys in opposite directions. In girls, H19 methylation was positively associated with skinfold thickness. No significant mediation of phthalate exposure on adiposity by DNA methylation of H19 or HSD11B2 was observed (Sobel p > 0.05). However, the mediation analysis was underpowered to detect small to medium effect sizes, and the role of DNA methylation as a mediator between phthalates and outcomes merits further study.

Classification and Temporal Variability in Urinary 8-oxodG and 8-oxoGuo: Analysis by UHPLC-MS/MS

Oxidative stress damage has been found to be associated with exposure of children to environmental pollutants, but there are few data on the variability of urinary oxidative stress biomarkers and the accuracy of biomarker concentration classification. We performed a longitudinal study in Chinese school-aged children to investigate the variability of urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo) concentrations and the ability of a single first morning urine sample to assess accuracy and sensitivity of biomarkers concentration classification. After adjusting for both creatinine and specific gravity, we characterized the distribution and reproducibility of repeated measurement of 8-oxodG and 8-oxoGuo by using intraclass correlation coefficients (ICCs) derived from linear mixed model and performed surrogate category analyses to determine whether a single spot sample could accurately classify 8-oxodG and 8-oxoGuo levels. Results indicated that the geometric mean (GM) concentrations of 8-oxodG and 8-oxoGuo were 3.865 ng/mL and 5.725 ng/mL, respectively. High variability of 8-oxodG and 8-oxoGuo was observed in the single spot first morning urine sample (ICC = 0.25 and 0.18, respectively). Three repeated urinary specimens achieved sensitivity of 0.87 for 8-oxodG and 0.83 for 8-oxoGuo in low tertile and sensitivity of 0.78 in high tertile. But classification in medium tertile was less accurate for both 8-oxodG and 8-oxoGuo. In conclusion, high variability of urinary 8-oxodG and 8-oxoGuo levels results in repeated samplings needed for accurate classification.

Racial disparity in maternal phthalates exposure; Association with racial disparity in fetal growth and birth outcomes

Experimental and observational data implicate phthalates as developmental toxicants. However, few data are available to assess the maternal risks of gestational exposure by race and infant sex. To begin to address this data gap, we characterized associations between maternal urinary phthalate metabolites and birth outcomes among African American and white mothers from a southeastern U.S. population. We enrolled pregnant African American (n = 152) and white (n = 158) women with singleton live births between 18 and 22 weeks gestation. We measured phthalate metabolites (mono-n-butyl phthalate (MBP), monoisobutyl phthalate (MiBP), monobenzyl phthalate (MBzP), mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP), monoethyl phthalate (MEP), monomethyl phthalate (MMP), and the sums of DEHP (ΣDEHP) and DBP (ΣDBP) metabolites) in up to two gestational urine specimens from mothers, and evaluated confounder-adjusted associations per natural log unit greater concentration with birth weight for gestational age z-score, small for gestational age (SGA; <10th %tile), preterm birth (PTB; <37 weeks gestation), and low birth weight (LBW; <2500 g). We also tested for interactions by maternal race and infant sex. We found that lower z-scores were associated with greater MiBP (β = -0.28; 95% CI: -0.54, -0.02) and MMP (β = -0.30; 95% CI: -0.52, -0.09) concentrations, while MEP interacted with race (p = 0.04), indicating an association among whites (β = -0.14; 95% CI: -0.28, 0.001) but not among African Americans (β = 0.05; 95% CI = -0.09, 0.19). Greater MiBP (OR = 2.82; 95% CI: 1.21, 6.56) and MEOHP (OR = 2.80; 95% CI: 1.05, 7.42) were associated with an overall higher SGA risk, greater MEHP was associated with higher SGA risk (p = 0.10) in whites (OR = 3.26 95% CI: 0.64, 16.56) but not in African Americans (OR = 0.71 95% CI: 0.07, 7.17), and the associations for MiBP (p = 0.02) and ΣDBP (p = 0.02) varied by infant sex. We detected interactions for PTB in which African Americans were at higher risk than whites for greater MiBP (p = 0.08) and MEP (p = 0.02) although lower risk for greater MEHP (p = 0.09). Greater MEP was associated with an overall higher LBW risk (OR = 1.33; 95% CI: 0.95, 1.86), and males were at higher risk than females with greater MBP (p = 0.002), MiBP (p = 0.02), MBzP (p = 0.01), MEP (p = 0.002), MMP (p = 0.09), and ΣDBP (p = 0.01) concentrations. Overall, our results suggest that gestational phthalate exposure is associated with adverse maternal birth outcomes, and that the effects vary by maternal race and infant sex.

Fetal growth in environmental epidemiology: mechanisms, limitations, and a review of associations with biomarkers of non-persistent chemical exposures during pregnancy

BACKGROUND

Non-persistent chemicals, such as phthalates, environmental phenols, organophosphate pesticides, and others, are challenging to study because of their ubiquity in the environment, diverse exposure routes, and high temporal variability of biomarkers. Nonetheless, there is interest in understanding how gestational exposure to these chemicals may affect fetal growth, as perturbations to normal fetal growth are related to a plethora of adverse health outcomes in childhood and adulthood.

METHODS

The purpose of this review is to describe the state of the science on this topic. We searched PubMed for studies that included both 1) biomarkers of non-persistent chemicals collected during pregnancy and 2) fetal growth outcomes measured at birth (e.g., birth weight) or by ultrasound in utero (e.g., estimated fetal weight).

RESULTS

The bulk of the literature we found uses biomarkers measured at a single time point in pregnancy and birth weight as the primary measure of fetal growth. There is a small, but growing, body of research that uses ultrasound measures to assess fetal growth during pregnancy. In addition to summarizing the findings of the publications we identified, we describe inconsistencies in methodology, areas for improvement, and gaps in existing knowledge that can be targeted for improvement in future work. This literature is characterized by variability in methodology, likely contributing to the inconsistency of results reported. We further discuss maternal, placental, and fetal pathways by which these classes of chemicals may affect fetal growth.

CONCLUSIONS

To improve understanding of how everyday chemical exposures affect fetal growth, and ultimately lifelong health outcomes, mechanisms of toxicant action should be considered alongside improved study designs for future hypothesis-driven research.

Mediation analysis for the relationship between urinary phthalate metabolites and type 2 diabetes via oxidative stress in a population in Jeddah, Saudi Arabia

Human exposure to phthalates is ubiquitous and has received considerable attention due to their association with adverse health outcomes, including type 2 diabetes mellitus (T2DM). Nevertheless, earlier studies that link phthalate exposure to T2DM yielded ambiguous results. Furthermore, studies that associate phthalate exposure with oxidative stress and then with T2DM are scant. In this diabetic case-control study, urine samples collected from 101 individuals aged 28-68 years from Jeddah, Saudi Arabia, were analyzed to determine 20 phthalate metabolites (PhMs) and seven oxidative stress biomarkers (OSBs). Unconditional logistic regression was used to estimate odds ratios for the association between diabetes and urinary PhMs and OSBs in participants, stratified by age, gender, nationality, smoking status, occupation, and urinary creatinine. Twelve PhMs and five OSBs were found at detection rates above 50%, with geometric mean concentrations of 0.61-100 and 0.35-10.7 ng/mL (1.04-171 and 0.61-18.6 μg/g creatinine), respectively. Almost all exposures were significantly higher in diabetic cases than in controls. The 12 PhMs were positively associated with higher urinary concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-iso-prostaglandin F_2α (8-PGF_2α). Individuals in the 3rd and/or 4th quartile(s) for urinary concentrations of PhMs and OSBs showed 3.7- and 7.3-fold increase, respectively, in the odds of having diabetes compared with those in the 1st quartile. The rank order of association of PhMs/OSBs with diabetes followed the order of: mEP ≈ mBP > mEHP > mCPP > mECPP ≈ mEOHP ≈ mEHHP ≈ mIBP ≈ mMP > mCMHP ≈ mBzP and 8-OHdG > 8-PGF_2α ≈ 15-PGF_2α. The relationship between phthalate exposure and risk of developing T2DM was mediated in part by phthalate-induced oxidative stress, especially 8-OHdG. Our study suggests that human exposure to phthalates is associated with increased oxidative stress which mediates the development of T2DM.

The extent and predictors of phthalate exposure among couples undergoing in vitro fertilization treatment

Phthalates are chemicals used as plasticizers and solvents in many consumer products but are suspected of disrupting the endocrine system and are known for their reproductive/developmental health risks. This study examined the extent and predictors of phthalate exposure among 599 couples undergoing in vitro fertilization. A questionnaire was administered to obtain sociodemographic, health, and lifestyle data, and two spot urine samples were collected from the couples to analyze eight phthalate metabolites, cotinine (COT) as a smoking index, and creatinine to adjust for urine dilution. Seven phthalate metabolites were detected in > 94% of the urine samples, and monobenzyl phthalate (MBzP) was found in 24% of the women and 26% of their male partners. Median phthalate levels were highest for monoethyl phthalate (MEP), at 333.26 μg/l in women and 290 μg/l in male partners, and lowest for MBzP, at 1.17 μg/l in women and 1.14 μg/l in male partners. Correlation coefficients of ≥ 0.4 between the women and their male partners for the eight urinary phthalate metabolites may indicate a shared source of exposure. A multivariate regression model was used to assess the association between predictors and each urinary phthalate metabolite. Several potential predictors for the variations in specific urinary phthalate metabolites were identified, including the body mass index, age, socioeconomic status, and regional distribution for both women and their male partners but with slightly different patterns. Women with a history of breastfeeding, using bottled water for cooking and storing food in plastic bags had lower MEP (8.7%), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP) (9.2%), and both mono-iso-butyl phthalate and MECPP (8.2 and 8.1%). A history of contraceptive use was associated with an increase in MECPP (8.7%), mono-(2-ethyl-5-hydroxyhexyl) phthalate (11.4%), mono-(2-ethyl-5-oxohexyl) phthalate (7.6%), and the molar sum of bis (2-ethylhexyl) phthalate metabolites (8.9%). Urinary COT levels were associated with an increase of 10-16% in all urinary metabolites in women but of only 10.5% in mono-(2-ethylhexyl) phthalate in male partners. More than 95% of the couples reported the use of cosmetics, perfumes, and personal-care products, but we were not able to find associations with urinary phthalate metabolites, perhaps due to their short half-lives. MEP levels associated with the use of household cleaning products were 11.2% higher in male partners. Our levels were generally higher than those reported elsewhere, perhaps due to different lifestyles, cultural practices, dietary habits, use of personal-care products, and governmental legislation.

A Review of Biomonitoring of Phthalate Exposures

Phthalates (diesters of phthalic acid) are widely used as plasticizers and additives in many consumer products. Laboratory animal studies have reported the endocrine-disrupting and reproductive effects of phthalates, and human exposure to this class of chemicals is a concern. Several phthalates have been recognized as substances of high concern. Human exposure to phthalates occurs mainly via dietary sources, dermal absorption, and air inhalation. Phthalates are excreted as conjugated monoesters in urine, and some phthalates, such as di-2-ethylhexyl phthalate (DEHP), undergo secondary metabolism, including oxidative transformation, prior to urinary excretion. The occurrence of phthalates and their metabolites in urine, serum, breast milk, and semen has been widely reported. Urine has been the preferred matrix in human biomonitoring studies, and concentrations on the order of several tens to hundreds of nanograms per milliliter have been reported for several phthalate metabolites. Metabolites of diethyl phthalate (DEP), dibutyl- (DBP) and diisobutyl- (DiBP) phthalates, and DEHP were the most abundant compounds measured in urine. Temporal trends in phthalate exposures varied among countries. In the United States (US), DEHP exposure has declined since 2005, whereas DiNP exposure has increased. In China, DEHP exposure has increased since 2000. For many phthalates, exposures in children are higher than those in adults. Human epidemiological studies have shown a significant association between phthalate exposures and adverse reproductive outcomes in women and men, type II diabetes and insulin resistance, overweight/obesity, allergy, and asthma. This review compiles biomonitoring studies of phthalates and exposure doses to assess health risks from phthalate exposures in populations across the globe.

Association of antenatal depression with oxidative stress and impact on spontaneous preterm birth

OBJECTIVE

To determine whether antenatal depression is associated with oxidative stress and inflammation, and secondarily, whether the association between antenatal depression and spontaneous preterm birth (SPTB) is mediated by these biomarkers.

STUDY DESIGN

The primary outcome included urine oxidative stress biomarkers 8-hydroxydeoxyguanosine (8-OHdG) and 8-isoprostane and plasma inflammatory biomarkers measured at 10, 18, and 26 weeks and averaged within individual. Linear and logistic regression models were used, adjusting for age, race, parity, and pre-pregnancy body mass index.

RESULTS

Among 462 women, 8-isoprostane was higher among depressed women (geometric mean: 299.96 pg/mL vs. 237.01 pg/mL; p = 0.001). In multivariable analyses, antenatal depression was significantly associated with an increase in average 8-isoprostane (β: 0.25; 95% CI: 0.05-0.44; p = 0.01). The association of antenatal depression with SPTB was partially mediated by 8-isoprostane. Antenatal depression was not associated with 8-OHdG or inflammatory biomarkers.

CONCLUSIONS

Antenatal depression was associated with higher oxidative stress across pregnancy, namely 8-isoprostane, and may impact SPTB via oxidative stress.

Environmental ototoxicants, a potential new class of chemical stressors

Hearing loss is an injury that can develop over time, and people may not even be aware of it until it becomes a severe disability. Ototoxicants are substances that may damage the inner ear by either affecting the structures in the ear itself or by affecting the nervous system. We have examined the possibility that ototoxicants may present a health hazard in association with environmental exposures, adding to existing knowledge of their proven hazards under medical therapeutic conditions or occupational activities. In addition to the already described human environmental ototoxicants, mainly organochlorines such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE), hexachlorocyclohexane (HCH) and hexachlorobenzene (HCB), we have examined the ubiquitous chemical stressors phthalates, bisphenol A/S/F/, PFCs, flame retardants (FRs) and cadmium for potential ototoxic properties, both as single substances or as chemical mixtures. Our literature review confirmed that these chemicals may disturb thyroid hormones homeostasis, activate aryl hydrocarbon receptor (AhR), and induce oxidative stress, which in turn may initiate a chain of events resulting in impairment of cochlea and hearing loss. With regard to auditory plasticity, diagnostics of a mixture of effects of ototoxicants, potential interactions of chemical and physical agents with effects on hearing, parallel deterioration of hearing due to chemical exposures and ageing, metabolic diseases or obesity, even using specific methods as brainstem auditory evoked potentials (BAEP) or otoacoustic emissions (OAEs) registration, may be difficult, and establishment of concentration-response relationships problematic. This paper suggests the establishment of a class of environmental oxotoxicants next to the established classes of occupational and drug ototoxicants. This will help to properly manage risks associated with human exposure to chemical stressors with ototoxic properties and adequate regulatory measures.

Environmental Exposures and Depression: Biological Mechanisms and Epidemiological Evidence

Mental health and well-being are consistently influenced—directly or indirectly—by multiple environmental exposures. In this review, we have attempted to address some of the most common exposures of the biophysical environment, with a goal of demonstrating how those factors interact with central structures and functions of the brain and thus influence the neurobiology of depression. We emphasize biochemical mechanisms, observational evidence, and areas for future research. Finally, we include aspects of contextual environments—city living, nature, natural disasters, and climate change—and call for improved integration of environmental issues in public health science, policies, and activities. This integration is necessary for reducing the global pandemic of depression.

Phthalates and Phthalate Alternatives Have Diverse Associations with Oxidative Stress and Inflammation in Pregnant Women

Exposure to environmental chemicals such as phthalates has been linked to numerous adverse pregnancy outcomes, potentially through an oxidative stress mediated mechanism. Most research examined urinary 8-iso-prostaglandin F2α (8-iso-PGF2α) as the oxidative stress biomarker. However, 8-iso-PGF2α also originates from enzymatic sources linked to inflammation. Therefore, associations between phthalates and 8-iso-PGF2α could have been misinterpreted. To clarify this, the 8-iso-PGF2α/prostaglandin F2α ratio approach was used to quantitatively distinguish between inflammation or oxidative stress derived 8-iso-PGF2α and estimate their associations with phthalate metabolites in a cohort of 758 pregnant women from The Infant Development and Environment Study (TIDES). Most urinary phthalate metabolites were associated with a significant increase in 8-iso-PGF2α. For example, a 22.4% higher 8-iso-PGF2α concentration (95% confidence interval = 14.4, 30.9) was observed with an interquartile range increase in mono- n-butyl phthalate. For most metabolites, associations were observed solely with oxidative stress derived 8-iso-PGF2α. In contrast, monocarboxy-isononyl phthalate and monoisononyl phthalate (MNP) were associated with both sources of 8-iso-PGF2α. Metabolites of the phthalate alternative 1,2-cyclohexane dicarboxylic acid, diisononyl ester (DINCH), were only associated with inflammation-derived 8-iso-PGF2α, which is interesting because DINCH metabolites and MNP have structural similarities.In conclusion, phthalates metabolites are not exclusively associated with oxidative stress derived 8-iso-PGF2α. Depending on the metabolite structure, some are also associated with inflammation derived sources, which provides interesting insights in the toxicology of phthalates.

Human exposure to phthalate esters associated with e-waste dismantling: Exposure levels, sources, and risk assessment

Phthalate esters (PAEs) can be released into the environment during the dismantling of electronic waste (e-waste), but urinary levels of PAE metabolites (mPAEs) in humans living in e-waste sites have not been documented. In this study, 11 mPAEs were determined in urine samples collected from participants living in e-waste dismantling sites and a reference area in Southern China. The total urinary concentrations of the 11 mPAEs (∑mPAEs) in the e-waste sites (range: 11.1 ng/mL to 3380 ng/mL) were dominated by mono-(2-isobutyl) phthalate and mono-n-butyl phthalate. Participants living in the e-waste sites had significantly higher (p < 0.05) urinary concentrations of ∑mPAEs (and 5 individual mPAEs) than those in the reference area. Hence, e-waste dismantling activities contributed to human exposure to PAEs. The exposure doses of di-n-butyl phthalate, di(2-ethylhexyl)phthalate, di-iso-butyl phthalate, dimethyl phthalate, and diethyl phthalate were 3.41, 3.04, 1.37, 0.25, and 0.20 μg/kg bw/day, respectively. Furthermore, the health risk assessment in terms of hazard quotient and hazard index showed that approximately 22% of the participants living in the e-waste sites had HI values exceeding 1; importantly, 68% of them were non-adults (i.e., 0-18 years old). In the e-waste sites, 8 of the 11 mPAEs in urine samples had significantly positively associations (r = 0.185-0.358, p < 0.05) with the urinary concentration of 8-hydroxy-2'-deoxyguanosine, a marker of DNA oxidative stress. Therefore, people living in e-waste dismantling areas may have a potential health risk caused by PAE exposure. To the best of our knowledge, this study is the first to measure urinary mPAE levels in people living in e-waste dismantling areas.

Urinary phthalate metabolites among children in Saudi Arabia: Occurrences, risks, and their association with oxidative stress markers

Phthalates have been used as plasticizers in numerous consumer applications and therefore, their metabolites have been detected in human urine worldwide. Despite concerns regarding their potential adverse health effects, few exposure assessments have been conducted among young populations in Middle Eastern countries. In this study, children (n = 109, aged 3-9 years) were recruited from four elementary schools in Riyadh, Saudi Arabia, in 2017, and major phthalate metabolites were measured in their urine. Their parents were asked to complete a questionnaire on their behalf to assess potential exposure sources of phthalates. In addition to 18 phthalate metabolites, malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) were measured in urine samples by LC/MS/MS. Among the children of Saudi Arabia, urinary levels of monoisobutyl phthalate (MiBP) and monobutyl phthalate (MnBP) were higher than those reported previously in children worldwide. Monoethyl phthalate (MEP) was also detected at high levels. Several phthalate metabolites showed significant associations with the levels of MDA or 8-OHdG. Hazard quotients (HQs) derived for certain phthalates were greater than one. In particular, the HQs for di(2-ethylhexyl) phthalate (DEHP) were greater than one in 34% of the participating children. Levels of monocyclohexyl phthalate (MCHP), monoisodecyl phthalate (MiDP), mono(2-ethylhexyl) phthalate (MEHP), and mono[2-(carboxymethyl)hexyl] phthalate (MCMHP) in the urine samples were positively associated with the consumption frequency of certain foods. Very high levels of exposure to phthalates, along with positive associations with oxidative stress markers, outline the importance of follow-up investigations for identification of phthalate exposure sources and potential health implications among the young population of Saudi Arabia.

Tampon use, environmental chemicals and oxidative stress in the BioCycle study

BACKGROUND

Tampons are used by up to 86% of US women and are a rarely considered potential source of pesticide and metal exposure. Tampons may be of particular concern given the likely higher absorption that occurs in the vagina. Our objective was to examine the potential associations between tampon use and metal concentrations, and biomarkers of inflammation and oxidative stress among healthy women.

METHODS

We used information from a prospective cohort of 259 regularly menstruating women, aged 18-44, followed for two menstrual cycles. Tampon use was assessed using information provided in participant study diaries. Metal concentrations were measured from a blood sample collected at enrollment. Oxidative stress and inflammation biomarker concentrations were determined from blood samples collected at up to 8 clinic visits for each cycle. Linear regression models were used to estimate associations of tampon use with metal exposure, and linear mixed models to estimate associations of tampon use with inflammation and oxidative stress biomarkers at different times during the menstrual cycle.

RESULTS

We observed non-significantly higher mean levels of mercury for tampon users compared to non-tampon users (exp(β) = 1.25, 95% CI = 0.93, 1.68). We found no evidence of an association between tampon use and inflammation biomarkers. We observed consistently higher isoprostane levels, an oxidative stress biomarker, among tampon users compared to non-tampon users (e.g. exp.(β) = 1.05, 95%CI = 0.96, 1.16, for the average isoprostane during the menstruating week); however, these results were not statistically significant.

CONCLUSIONS

While our results are not statistically significant, we observed suggestive associations between tampon use and elevated levels of mercury and oxidative stress biomarkers. Although our finding should be interpreted in light of our limitations, they indicate that tampons may be a source of exposure to metals and chemicals that have been largely ignored, and any related health effects are an important public health concern.

The negative impact of the environment on methylation/epigenetic marking in gametes and embryos: A plea for action to protect the fertility of future generations

Life expectancy has increased since World War II, and this may be attributed to several aspects of modern lifestyles. However, now we are faced with a downturn, which seems to be the result of environmental issues. This paradigm is paralleled with reduced human fertility, decreased sperm quality, increased premature ovarian failure, and diminished ovarian reserve syndromes. Endocrine disruptor chemicals and other toxic chemicals, herbicides, pesticides, plasticizers, to mention a few, are a rising concern in today's environment. Some of these are commonly used in the domestic setting: cleaning material and cosmetics and they have a known impact on epigenesis and imprinting via perturbation of methylation processes. Pollution from polyaromatic hydrocarbons, particulate matter <10 and <2.5 μm, and ozone released into the air, all affect fertility. Poor food processing management is a source of DNA adduct formation, which impairs the quality of gametes. An important concern is the nanoparticles that are present in food and are thought to induce oxidative stress. Now is the time to take a step backward. Global management of the environment and food production is required urgently to protect the fertility of future generations.

Exposure to phthalates in couples undergoing in vitro fertilization treatment and its association with oxidative stress and DNA damage

This prospective study of 599 couples seeking fertility treatment and who were recruited between 2015 and 2017 was conducted to (a) explore the associations between phthalate exposure and in vitro fertilization (IVF) outcomes; and (b) examine the implication of oxidative stress as a mediator of these. We measured eight phthalate metabolites in two spot urine samples; oxidative stress biomarkers such as malondialdehyde, 8-hydroxy-2-deoxyguanosine, hydrogen peroxide, catalase (CAT), and total antioxidant capacity in follicular fluid and seminal plasma. We also examined DNA damage in sperm and granulosa cells. Couples were exposed to a broad range of phthalate compounds and seven metabolites were detected in over 94% of the urine samples, whereas monobenzyl phthalate was found in only 24% of women and 26% of men. Our results showed high levels of seven urinary phthalate metabolites (except monobenzyl phthalate) and a notable increase in many oxidative stress markers in both follicular fluid and seminal plasma. However, their associations with exposure were rather limited. Multivariate binomial regression modeling showed higher levels of follicular CAT levels reduced the probability of fertilization rate (≤ 50%) [Adjusted relative risk (RR_adj) = 0.52, p = 0.005] and unsuccessful live birth (RR_adj = 0.592, p = 0.023). We observed a 46% decrease in the probability of clinical pregnancy in association with an elevated percentage of DNA in the tail (RR_adj = 0.536, p = 0.04). There was a 32% and 22% increase in the probability of clinical pregnancy and unsuccessful live birth associated with higher levels of mono-(2-ethylhexyl) phthalate (RR_adj = 1.32, p = 0.049) and monoethyl phthalate (RR_adj = 1.22, p = 0.032) in women, respectively. In contrast, the probability of clinical pregnancy reduced by 20% with higher levels of mono-(2-ethyl-5-carboxypentyl) phthalate (RR_adj = 0.797, p = 0.037) and 19.6% with mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) (RR_adj = 0.804, p = 0.041) in men. Other oxidative stress biomarkers or urinary phthalate metabolites showed suggestive relationships with certain IVF outcomes. Lastly, our results demonstrated that elevated levels of CAT in follicular fluid might have a positive impact on fertilization rate ≥ 50% and successful live birth. CAT seems to play a potential role in mediating the relationship between the risk of poor fertilization rate and MEOHP and mono-isobutyl phthalate. Additional data are required to understand the clinical implications of oxidative stress and its contribution to the reproductive toxicity of phthalate exposure.

Urinary levels of bisphenol A, F and S and markers of oxidative stress among healthy adult men: Variability and association analysis

BACKGROUND

Bisphenol F (BPF) and bisphenol S (BPS) are increasingly used as alternatives to endocrine disrupting chemical bisphenol A (BPA). Evidence from in vitro and animal studies demonstrates that BPA, BPF and BPS induce oxidative stress, a proposed mechanism that is relevant to various adverse health effects. Evaluation in humans is hampered by the potentially high within-subject variability of urinary measurements.

OBJECTIVE

To evaluate the variability and associations of levels of BPA, BPS, BPF and 3 oxidative stress markers [i.e., 8-hydroxy-2-deoxyguanosine (8-OHdG), 8-iso-prostaglandin F_2α (8-isoPGF_2α) and 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA)] in urine collected on multiple occasions over 3 months.

METHOD

A total of 529 spot urine samples, including 88 first morning voids (FMVs) and 24-h specimens, were gathered from 11 adult men on days 0, 1, 2, 3, 4, 30, 60 and 90 and analyzed for BPA, BPF, BPS, 8-OHdG, 8-isoPGF_2α and HNE-MA. Intraclass correlation coefficients (ICCs) were estimated to characterize the reproducibility of urinary bisphenols and oxidative stress markers, and linear mixed models were applied to assess the associations between markers of exposure and response.

RESULTS

BPA and BPF were detected in ≥85% of the spot samples, while BPS in 13% of the samples. High degrees of within-subject variability were found for BPA, BPF, 8-OHdG, 8-isoPGF_2α and HNE-MA in spot samples, FMVs and 24-h specimens (creatinine-corrected ICCs ≤ 0.37). The sensitivities were low-to-moderate (0.30-0.63) when using single spot samples or FMVs to predict high (>27th, or 36th percentile) 3-month average urinary levels of BPA, BPF, 8-OHdG, 8-isoPGF_2α and HNE-MA. Collecting repeated specimens at different time points improved the accuracy of classification for markers of exposure and response. Elevated urinary BPA and BPF were associated with significantly higher levels of oxidative stress markers.

CONCLUSIONS

Repeated urinary specimens are required to characterize bisphenol exposure levels and the oxidative stress status of individuals. Exposure to BPA and BPF may partly contribute to the elevated urinary levels of oxidative stress makers in adult men.

Epigenetic and Neurological Impairments Associated with Early Life Exposure to Persistent Organic Pollutants

The incidence of neurodevelopmental and neurodegenerative diseases worldwide has dramatically increased over the last decades. Although the aetiology remains uncertain, evidence is now growing that exposure to persistent organic pollutants during sensitive neurodevelopmental periods such as early life may be a strong risk factor, predisposing the individual to disease development later in life. Epidemiological studies have associated environmentally persistent organic pollutant exposure to brain disorders including neuropathies, cognitive, motor, and sensory impairments; neurodevelopmental disorders such as autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD); and neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS). In many ways, this expands the classical “Developmental Origins of Health and Disease” paradigm to include exposure to pollutants. This model has been refined over the years to give the current “three-hit” model that considers the individual's genetic factors as a first “hit.” It has an immediate interaction with the early-life exposome (including persistent organic pollutants) that can be considered to be a second “hit.” Together, these first two “hits” produce a quiescent or latent phenotype, most probably encoded in the epigenome, which has become susceptible to a third environmental “hit” in later life. It is only after the third “hit” that the increased risk of disease symptoms is crystallised. However, if the individual is exposed to a different environment in later life, they would be expected to remain healthy. In this review, we examine the effect of exposure to persistent organic pollutants and particulate matters in early life and the relationship to subsequent neurodevelopmental and neurodegenerative disorders. The roles of those environmental factors which may affect epigenetic DNA methylation and therefore influence normal neurodevelopment are then evaluated.

Urinary oxidative stress biomarkers and accelerated time to spontaneous delivery

BACKGROUND

Oxidative stress has been implicated in numerous birth outcomes, including spontaneous preterm birth. However, the relationship with presentation at delivery has been less well studied. We assessed the relationship between oxidative stress biomarkers and gestational duration with a focus on spontaneous presentation for delivery.

METHODS

Our sample included 740 women from a multi-center prospective cohort study, recruited from 2010 to 2012. Resultant measures of oxidative stress in pregnancy prostaglandin F_2α (PGF_2α), 8-iso-prostaglandin F_2α (8-iso-PGF_2α), and the primary 8-iso-PGF_2α metabolite were measured in third trimester urine samples. Information on presentation for delivery was abstracted from medical records. We examined associations with preterm birth using adjusted logistic models. Time to event (overall delivery and spontaneous delivery) was examined using adjusted accelerated failure time models.

RESULTS

The 8-iso-PGF_2α metabolite was associated with increased odds of overall preterm birth (OR: 1.44 [95% CI: 1.00, 2.06]), and the association with spontaneous preterm birth was similar in magnitude but not statistically significant (OR: 1.45 [95% CI: 0.96, 2.20]). We did not detect associations between other biomarkers and preterm birth, or between biomarkers and timing of overall or spontaneous delivery in accelerated failure time models.

CONCLUSIONS

Our data suggest that increased oxidative stress, as indicated by the 8-iso-PGF_2α metabolite, may be associated with preterm birth. In contrast to previous studies, associations were similar among individuals with spontaneous versus non-spontaneous presentation for delivery.

Dimethyl phthalate elimination from micro-polluted source water by surface discharge plasma: Performance, active species roles and mechanisms

Plasticizer pollution brought huge risks to ecological environment and human health. Surface discharge plasma (SDP) was employed to eliminate plasticizer in natural water, with dimethyl phthalate (DMP) as a typical plasticizer. Experimental results showed that DMP degradation efficiency reached 82.8% within 60 min's SDP treatment, and the elimination process fitted well the first-order kinetic model. Low initial DMP concentration, alkaline condition, and low natural organic matter content were all conducive for DMP degradation. The contributions of OH radical and O₂^- to DMP elimination were 91.9% and 78.1%, respectively. Total organic carbon (TOC), UV-vis spectroscopy, and atomic force microscopy analysis demonstrated that DMP molecular structure was destroyed after the SDP treatment, and some small molecular fractions were generated. Approximately 47.8% of TOC and 73.5% of COD were eliminated after 60 min's SDP treatment. Phthalic acid monomethyl ester, phthalic acid, o-phthalic anhydride, acetic acid, formic acid, and oxalic acid were detected as the byproducts. Carbon balance analysis among these intermediates showed that total carbon content was approximately 4.64 × 10^-2 mmol before treatment, and it was 4.578 × 10^-2 mmol after treatment, suggesting that some C-containing intermediates still existed but not detected. DMP degradation pathways in the SDP system were proposed.

Food Additives and Child Health

Increasing scientific evidence suggests potential adverse effects on children's health from synthetic chemicals used as food additives, both those deliberately added to food during processing (direct) and those used in materials that may contaminate food as part of packaging or manufacturing (indirect). Concern regarding food additives has increased in the past 2 decades in part because of studies that increasingly document endocrine disruption and other adverse health effects. In some cases, exposure to these chemicals is disproportionate among minority and low-income populations. This report focuses on those food additives with the strongest scientific evidence for concern. Further research is needed to study effects of exposure over various points in the life course, and toxicity testing must be advanced to be able to better identify health concerns prior to widespread population exposure. The accompanying policy statement describes approaches policy makers and pediatricians can take to prevent the disease and disability that are increasingly being identified in relation to chemicals used as food additives, among other uses.

Food Additives and Child Health

Our purposes with this policy statement and its accompanying technical report are to review and highlight emerging child health concerns related to the use of colorings, flavorings, and chemicals deliberately added to food during processing (direct food additives) as well as substances in food contact materials, including adhesives, dyes, coatings, paper, paperboard, plastic, and other polymers, which may contaminate food as part of packaging or manufacturing equipment (indirect food additives); to make reasonable recommendations that the pediatrician might be able to adopt into the guidance provided during pediatric visits; and to propose urgently needed reforms to the current regulatory process at the US Food and Drug Administration (FDA) for food additives. Concern regarding food additives has increased in the past 2 decades, in part because of studies in which authors document endocrine disruption and other adverse health effects. In some cases, exposure to these chemicals is disproportionate among minority and low-income populations. Regulation and oversight of many food additives is inadequate because of several key problems in the Federal Food, Drug, and Cosmetic Act. Current requirements for a "generally recognized as safe" (GRAS) designation are insufficient to ensure the safety of food additives and do not contain sufficient protections against conflict of interest. Additionally, the FDA does not have adequate authority to acquire data on chemicals on the market or reassess their safety for human health. These are critical weaknesses in the current regulatory system for food additives. Data about health effects of food additives on infants and children are limited or missing; however, in general, infants and children are more vulnerable to chemical exposures. Substantial improvements to the food additives regulatory system are urgently needed, including greatly strengthening or replacing the "generally recognized as safe" (GRAS) determination process, updating the scientific foundation of the FDA's safety assessment program, retesting all previously approved chemicals, and labeling direct additives with limited or no toxicity data.

Association of phthalate exposures with urinary free cortisol and 8-hydroxy-2'-deoxyguanosine in early childhood

Several studies suggested potential links of phthalates to stress-related outcomes. However, limited evidence has been available for the relationships between phthalate metabolites and free cortisol and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in perinatal and postnatal environments. Therefore, we evaluated the relationships between phthalate metabolites and free cortisol and 8-OHdG in mother-child pairs. We repeatedly collected urine samples of 287 mother-child pairs from just before delivery to 15 months of age to measure the levels of four phthalate metabolites - mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-isobutyl phthalate (MiBP), and mono-n-butyl phthalate (MnBP) - and free cortisol and 8-OHdG. We used linear mixed effect models and generalized additive mixed models to estimate the relationship between the phthalate metabolites and free cortisol and 8-OHdG after adjusting for the child's gender, urine collection time, and maternal smoking status. The four phthalate metabolite levels were strongly correlated each other (all, p < .0001), and intra-class correlation for each metabolite in children ranged from 0.18 to 0.96. All four phthalate metabolites were positively associated with both free cortisol (MEHHP, β = 0.18 and p < .0001; MEOHP, β = 0.17 and p < .0001; MiBP, β = 0.13 and p = .0001; MnBP, β = 0.21 and p < .0001; and molar sum of metabolites, β = 0.21 and p < .0001) and 8-OHdG (MEHHP, β = 0.20 and p < .0001; MEOHP, β = 0.18 and p < .0001; MiBP, β = 0.23 and p < .0001; MnBP, β = 0.28 and p < .0001; and molar sum of metabolites, β = 0.29 and p < .0001) in childhood. Our findings suggest that phthalate exposures increase free cortisol and 8-OHdG levels in early childhood.

Trimester-specific phthalate concentrations and glucose levels among women from a fertility clinic

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.

Temporal Variability of Cumulative Risk Assessment on Phthalates in Chinese Pregnant Women: Repeated Measurement Analysis

The assessment of the combined effects of multiple phthalate exposures at low levels is a newly developed concept to avoid underestimating their actual cumulative health risk. A previous study included 3455 Chinese pregnant women. Each woman provided up to three urine samples (in total 9529). This previous study characterized the concentrations of phthalate metabolites. In the present study, the data from 9529 samples was reanalyzed to examine the cumulative risk assessment (CRA) with two models: (1) the creatinine-based and (2) the volume-based. Hazard index (HI) values for three phthalates, dibutyl phthalate, butyl benzyl phthalate, and di(2-ethylhexyl) phthalate, in the first, second, and third trimesters of pregnancy, were calculated, respectively. In creatinine-based model, 3.43%, 14.63%, and 17.28% of women showed HI based on the European Food Safety Authority tolerable daily intake exceeding 1 in the first, second, and third trimester of pregnancy, respectively. The intraclass correlation coefficient of HI was 0.49 (95% confidence interval: 0.46-0.53). Spearman correlations between HI of the creatinine model and ∑androgen disruptor (a developed potency weighted approach) ranged from 0.824 to 0.984. In summary, this study suggested a considerable risk of cumulative exposure to phthalates during the whole gestation in Chinese pregnant women. In addition, moderate temporal reproducibility indicated that single HI, estimated by the phthalate concentration in single spot of urine, seemed representative to describe the throughout pregnancy CRA. Finally, strong correlation between HI of the creatinine model and ∑androgen disruptor revealed that the creatinine-based model was more appropriate to evaluate the CRA.

Urinary phthalate metabolites concentrations and symptoms of depression in an elderly population

BACKGROUND

Animal studies have reported an association between phthalates and depression, although there is limited evidence from epidemiological studies. We investigated the association between phthalate exposure and symptoms of depression in an elderly population.

METHODS

Repeated measures surveys up to three times were conducted during the study period (2012-2014) in the 535 elderly subjects. We measured the following urinary phthalate metabolite levels: mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono-n-butyl phthalate (MnBP), and mono-benzyl phthalate (MBzP). MEHHP, MEOHP, and MECPP are metabolites of diethylhexyl phthalates (DEHP). MnBP and MBzP are metabolites of dibutyl phthalate and butyl benzyl phthalate, respectively. The phthalate metabolite concentrations were evaluated to identify associations with the symptoms of depression using the Korean version of the Geriatric Depression Scale-Short Form (SGDS-K). After factor analysis of the components of SGDS-K, we evaluated the association between phthalate exposure and SGDS-K subgroups to determine which symptoms of depression were affected by phthalate exposure.

RESULTS

Concentrations of DEHP metabolites were positively associated with the risk of depressive symptoms in the elderly population (Odds ratio (95% confidence interval); 1.92 (1.17-3.13) for sum of three DEHP metabolites), while we found no significant association between depressive symptoms and either MnBP or MBzP. When we evaluated the associations between phthalate metabolite concentrations and the SDGS-K subgroup, we found that affective and spiritual symptoms were significantly associated with DEHP metabolite concentrations.

CONCLUSIONS

Our study suggests that DEHP exposure is associated with depressive symptoms, particularly, the affective and spiritual symptoms, among the elderly population.

DEP and DBP induce cytotoxicity in mouse embryonic stem cells and abnormally enhance neural ectoderm development

Diethyl phthalate (DEP) and dibutyl phthalate (DBP) are two typical small phthalate esters, extensively used in personal care and consumer products. Although previous studies have linked phthalate esters to several health issues, it is still unclear whether they can affects the early stages of embryonic development. In this study, we evaluated the early developmental neurotoxicity as well as the cytotoxicity of DEP and DBP, using mouse embryonic stem cells (mESCs). Our results showed that both DEP and DBP could decrease mESC viability in a dose-dependent manner. Moreover, while DBP could activate the caspase-3/7 enzymes and cause cell membrane damage as well as intracellular ROS accumulation, interestingly DEP treatment only showed stimulation of ROS production. In addition, DEP and DBP treatment at non-cytotoxic concentrations, abnormally altered the expression levels of several vitally important regulators of embryo development. For instance, neural ectoderm markers, such as Pax6, Nestin, Sox1 and Sox3, were significantly up-regulated upon DEP and DBP exposure. In conclusion, our work suggests a potential developmental toxicity of DEP and DBP on mammals, especially for neural ectoderm specification. Our findings help better understand the association between health problems and DEP/DBP exposure and most significantly remind us of the importance of additional health risk tests for these two largely used chemicals.

Associations between maternal phenol and paraben urinary biomarkers and maternal hormones during pregnancy: A repeated measures study

BACKGROUND

A number of phenols and parabens are added to consumer products for a variety of functions, and have been found at detectable levels in the majority of the U.S.

POPULATION

Among other functions, thyroid hormones are essential in fetal neurodevelopment, and could be impacted by the endocrine disrupting effects of phenols and parabens. The present study investigated the association between ten maternal urinary phenol and paraben biomarkers (bisphenol S, triclosan, triclocarban, benzophenone-3, 2,4-dichlorophenol, 2,5-dichlorophenol, and ethyl, butyl, methyl and propyl paraben) and four plasma thyroid hormones in 439 pregnant women in a case-control sample nested within a cohort study based in Boston, MA.

METHODS

Urine and blood samples were collected from up to four visits during pregnancy (median weeks of gestation at each visit: Visit 1: 9.64, Visit 2: 17.9, Visit 3: 26.0, Visit 4: 35.1). Linear mixed models were constructed to take into account the repeated measures jointly, followed by multivariate linear regression models stratified by gestational age to explore potential windows of susceptibility.

RESULTS

We observed decreased total triiodothyronine (T3) in relation to an IQR increase in benzophenone-3 (percent change [%Δ] = -2.07; 95% confidence interval [CI] = -4.16, 0.01), butyl paraben (%Δ = -2.76; 95% CI = -5.25, -0.26) and triclosan (%Δ = -2.53; 95% CI = -4.75, -0.30), and triclocarban at levels above the LOD (%Δ = -5.71; 95% CI = -10.45, -0.97). A 2.41% increase in T3 was associated with an IQR increase in methyl paraben (95% CI = 0.58, 4.24). We also detected a negative association between free thyroxine (FT4) and propyl paraben (%Δ = -3.14; 95% CI = -6.12, -0.06), and a suggestive positive association between total thyroxine (T4) and methyl paraben (%Δ = 1.19; 95% CI = -0.10, 2.47). Gestational age-specific multivariate regression analyses showed that the magnitude and direction of some of the observed associations were dependent on the timing of exposure.

CONCLUSION

Certain phenols and parabens were associated with altered thyroid hormone levels during pregnancy, and the timing of exposure influenced the association between phenol and paraben, and hormone concentrations. These changes may contribute to downstream maternal and fetal health outcomes. Additional research is required to replicate the associations, and determine the potential biological mechanisms underlying the observed associations.

The associations between phthalate exposure and insulin resistance, β-cell function and blood glucose control in a population-based sample

In developed countries, phthalate exposure is ubiquitous. Previous studies have shown an association between phthalate levels and health effects. To test associations between phthalate exposures, estimated from urinary phthalate metabolites, and insulin resistance, β-cell function and glucose control. Data were obtained from a cross-sectional, nationally representative study; the Canadian Health Measures Survey (CHMS, 2009-2011). Participants under the age of 12, those with diabetes, who were pregnant or who had not fasted overnight were excluded. Fasting blood glucose, insulin, and glycosylated hemoglobin (HbA_1C) levels were measured in a subset of participants, and urine was collected for creatinine and phthalate metabolites. We tested associations between these variables using linear regression analysis. Of 4437 participants (12-79years old), 2119 had fasting glucose measurements and at least one phthalate metabolite above detection limits. MBzP, MCPP, MEHP, MEHHP, MiBP, and the sum of DEHP metabolites were positively associated with increased HbA_1C (p<0.05). DEHP metabolites were positively associated with increased fasting glucose, insulin, HOMA-IR and HOMA-β. An interquartile increase in the sum of log transformed DEHP metabolites was associated with increases in HOMA-IR and HOMA-β of 0.15 (95% CI 0.04, 0.26) and 10.24 (95% CI 3.71, 16.77) respectively. Increased concentrations of all measured phthalate metabolites were associated with reduced blood glucose control. DEHP metabolites were also associated with increased glucose concentrations, and indicators of β-cell function and insulin resistance. Our results suggest that exposure to phthalates may possibly impair control of blood glucose and thereby predispose to pre-diabetes.

Associations of phthalates exposure with attention deficits hyperactivity disorder: A case-control study among Chinese children

Researches on associations between phthalates exposure and child attention deficit hyperactivity disorder (ADHD) are inconsistent. This study aimed to evaluate the associations of urinary phthalates with ADHD, co-occurring oppositional defiant disorder (ODD), related symptoms and behavior problems among Chinese children. We enrolled 225 ADHD cases and 225 healthy controls aged 6-13 years old in Liuzhou, China. Each child provided repeated urine samples at 4 visits. Eight phthalate metabolites were measured by high-performance liquid chromatography and tandem mass spectrometry. Child ADHD symptoms and related behaviors were assessed using Swanson, Nolan, and Pelham Version IV scale and child behavior checklist. Higher urinary concentrations of mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-(2-ethyl)-hexyl phthalate (MEHP) were dose-dependently associated with ADHD [odds ratios (ORs) ranged from 2.35 to 3.04 for the highest vs. the lowest tertile] and co-occurring ODD (ORs ranged from 3.27 to 4.44 for the highest vs. the lowest tertile) in the multivariable logistic regression models (all p for trend ≤ 0.01), which were consistent with positive trends of increased scores of inattention domain, hyperactive domain and ODD symptoms (all p for trend ≤ 0.01). Besides, the monomethyl phthalate (MMP) concentration was associated with higher scores of inattention domain and ODD symptoms (both p < 0.05). Additionally, the MEHHP, MEOHP and MEHP concentrations were related to child attention problems, aggressive behaviors and externalizing behaviors (all p < 0.05). We also observed positive associations of the MEHP concentration with depressed behaviors and internalizing behaviors (all p < 0.05). Our results indicate that child exposure to phthalates may contribute to ADHD, ODD and externalizing and internalizing behavior problems.

Birth outcome racial disparities: A result of intersecting social and environmental factors

Adverse birth outcomes such as preterm birth, low-birth weight, and infant mortality continue to disproportionately affect black and poor infants in the United States. Improvements in healthcare quality and access have not eliminated these disparities. The objective of this review was to consider societal factors, including suboptimal education, income inequality, and residential segregation, that together lead to toxic environmental exposures and psychosocial stress. Many toxic chemicals, as well as psychosocial stress, contribute to the risk of adverse birth outcomes and black women often are more highly exposed than white women. The extent to which environmental exposures combine with stress and culminate in racial disparities in birth outcomes has not been quantified but is likely substantial. Primary prevention of adverse birth outcomes and elimination of disparities will require a societal approach to improve education quality, income equity, and neighborhoods.