Inflammatory effects of phthalates in neonatal neutrophils

The Impact of Chronic Phthalate Exposure on Rodent Anxiety and Cognition

Background

There is a growing importance for environmental contributions to psychiatric disorders and understanding the impact of the exposome (i.e., pollutants and toxins). For example, increased biomonitoring and epidemiological studies suggest that daily phthalate chemical exposure contributes to neurological and behavioral abnormalities; however, these mechanisms remain poorly understood. Therefore, the current study was aimed at examining the effects of chronic phthalate exposure on rodent anxiety behaviors and cognition and the impact on hypothalamic-pituitary-adrenal axis function.

Methods

Adult male mice (C57BL6/J) were administered MEHP via drinking water (1 mg/mL), and anxiety-like behavior and cognition combined with hypothalamic-pituitary-adrenal axis and inflammatory assays were assessed after 3 weeks of MEHP exposure.

Results

MEHP-treated mice exhibited enhanced generalized anxiety-like behaviors, as demonstrated by reduced time spent in the open-arm of the elevated plus maze and center exploration in the open field. Tests of spatial memory and cognition were unchanged. Following MEHP administration, circulating levels of corticosterone and proinflammatory cytokines were significantly increased, while at the tissue level, there were MEHP-dependent reductions in glucocorticoid metabolism genes Hsd11b1 and Hsd11b2.

Conclusions

These data suggest that chronic MEHP exposure leads to enhanced generalized anxiety behaviors independent of rodent measures of cognition and memory, which may be driven by MEHP-dependent effects on hypothalamic-pituitary-adrenal axis and peripheral glucocorticoid metabolism function.

The effects of industrial chemicals bonded to plastic materials in newborns: A systematic review

BACKGROUND

Phthalates are a family of industrial chemicals noncovalently bonded to plastic materials to enhance flexibility and durability. These compounds are extensively used in a variety of consumer products and even in many medical devices. Newborns present a higher susceptibility to phthalates.

OBJECTIVE

To assess the short- and long-term health consequences of exposure to phthalates during the neonatal period.

METHODS

Systematic review in accordance with the PRISMA statements. Eligible articles in English language were searched in MEDLINE, Scopus, ISI Web of Science, and Ovid databases using the following terms: "phthalate", "newborn", and "neonate". Unpublished data were searched in ClinicalTrials.gov website. All in vivo studies of any design published before May 16th, 2023 and fulfilling the following criteria were included: 1) investigations in which preterm and/or term newborns underwent one or more measurement of concentrations of phthalates on biological samples taken during the neonatal period; 2) studies in which quantitative measurement of phthalates was related to any kind of health outcome. Subgroup analysis was conducted by type of outcome. The quality assessment was performed according to the criteria from the "NIH Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies".

RESULTS

11,895 records were identified; finally, 5 articles were included for review. A mixture of phthalates was associated with improved performance on the NNNS summary scales of Attention, Handling, and Non-optimal reflexes before NICU discharge. At 2 months' corrected age, some phthalates were positively associated with problem-solving and gross motor abilities; increased levels of mono (2-ethylhexyl) phthalate, mono (2-ethyl-5-carboxypentyl) phthalate, and sum of di (2-ethylhexyl) phthalate (DEHP) metabolites (∑3DEHP and ∑4DEHP) were associated with worse fine motor performance. Furthermore, DEHP was associated with transient alteration of gut microbiota and increased IgM production after vaccine. A linear positive association between a mixture of phthalates and slope of the first growth spurt was even reported in preterm newborns. No relationship emerged between phthalates and bronchopulmonary dysplasia. Three studies out of 5 had fair quality.

CONCLUSION

Given some methodological issues and the paucity of related studies, further investigations of flawless quality aimed at clarifying the relationship between early exposure to phthalates and health outcomes are needed.

Exposure to phthalates and their alternatives in relation to biomarkers of inflammation and oxidative stress in adults: evidence from NHANES 2017-2018

Phthalates and their alternatives are considered significant environmental risk factors that potentially influence inflammation and oxidative stress. However, their impact on biomarkers of inflammation and oxidative stress was inconsistent. This study aimed to explore the associations between phthalates and high-sensitivity C-reactive protein (hsCRP), gamma-glutamyl transferase (GGT), and white blood cell (WBC) counts, employing both univariate exposure and multivariate co-exposure models. For this analysis, a total of 1619 individuals aged 18 years and above, sourced from the National Health and Nutrition Examination Survey (NHANES) conducted between 2017 and 2018, were selected as subjects. We explored the associations between hsCRP, GGT, and WBC counts and eighteen different phthalate metabolites. Multiple linear regression analysis revealed significant associations between both MCNP and MEHP and hsCRP. We observed negative correlations of MCOP, MCPP, MHBP, and MONP with GGT. Conversely, MEHHP and MEHHTP exhibited positive correlations with GGT. Furthermore, MECPTP and MEHHTP showed positive correlations with WBC. Notably, we identified a non-linear relationship between phthalates and inflammation and oxidative stress markers. The Bayesian kernel machine regression (BKMR) analysis demonstrated a negative joint effect of the phthalates mixture on GGT, particularly at lower concentrations. The BKMR model also found that MEOHP and MHiBP were negatively associated with GGT. In contrast, MEHHP showed a significant positive association with GGT. Moderating effect analysis suggested that dietary inflammatory index (DII), income-to-poverty ratio (PIR), age, BMI, and physical activity influenced the association between phthalates and inflammation and oxidative stress. These findings contribute to a deeper understanding of the relationships between phthalates and inflammation and oxidative stress.

The Impact of Chronic Phthalate Exposure on Rodent Anxiety and Cognition

There is a growing importance for environmental contributions to psychiatric disorders and understanding the impact of the exposome (i.e., pollutants and toxins). Increased biomonitoring and epidemiological studies, for example, suggest that daily phthalate chemical exposure contribute to neurological and behavioral abnormalities, however these mechanisms remain poorly understood. The current study therefore aimed to examine the effects of chronic phthalate exposure on rodent anxiety behaviors, cognition, and the impact on hypothalamic-pituitary- adrenal (HPA)-axis function. Adult male mice (C57BL6/J) were administered mono-2-ethylhexyl phthalate (MEHP) via drinking water (1 mg/ml), and anxiety-like behavior, cognition combined with HPA- axis and inflammatory assays were assessed after 3 weeks of MEHP exposure. MEHP-treated mice exhibited enhanced generalized anxiety-like behaviors, as demonstrated by reduced time spent in the open-arm of the elevated plus maze (EPM) and center exploration in the open field (OF). Tests of spatial, cognition and memory function were unchanged. Following MEHP administration, circulating levels of corticosterone and pro- inflammatory cytokines were significantly increased, while at the tissue level, MEHP-dependent reductions in glucocorticoid metabolism genes 11β-hydroxysteroid dehydrogenase (11β-HSD) 1 and 2. These data suggest that chronic MEHP exposure leads to enhanced generalized-anxiety behaviors independent of rodent measures of cognition and memory, which maybe driven by MEHP-dependent effects on HPA-axis and peripheral glucocorticoid metabolism function.

Associations of urinary phthalate metabolites and inflammatory biomarkers among pregnant women in Puerto Rico

Phthalates are ubiquitous environmental exposures that may be implicated in inflammatory processes, as demonstrated by previous in vivo and in vitro studies. Few human studies have substantiated these observations. This study sought to examine whether maternal phthalate exposures impact inflammatory processes, as measured by circulating inflammatory biomarkers, in the PROTECT cohort in northern Puerto Rico. Inflammatory biomarkers included matrix metalloproteinases 1, 2, and 9 (MMPs), C-reactive protein (CRP), vascular cell adhesion molecule-1 (VCAM), and intercellular cell adhesion molecule-1 (ICAM). Biomarkers were measured in maternal serum samples collected during pregnancy. 19 phthalate metabolites were assessed in urinary samples collected at three study visits across pregnancy. Phthalates with <50 % of measurements above the limit of detection were excluded from analysis. We utilized linear mixed effect models to estimate associations between interquartile range increases in phthalate metabolite concentrations and percent changes in inflammatory biomarkers. Our results revealed significant associations between mono-n-butyl phthalate (MBP) and higher MMP1 by 7.86 % (95 % CI: 0.49, 15.76) and between mono oxononyl phthalate (MONP) and higher MMP2 by 8.30 % (95 % CI: 2.22, 14.75). We observed negative or null associations between phthalate metabolites and MMP2, MMP9, ICAM, VCAM, and CRP. Many results were significantly modified by fetal sex, particularly those between di-2-ethylhexyl phthalate (DEHP) metabolites and MMP1 (p-interaction: MEHHP = 0.01, MEOHP = 0.04, MECPP = 0.01) and MMP2 (p-interaction: MEHHP = 0.03, MEOHP = 0.01, MECPP = 0.01), for which associations were positive among only women carrying female fetuses. MMPs have been previously associated with preeclampsia and hypertensive pregnancy disorders as mediators of artery remodeling. Hence, our findings suggest a potential role for phthalates in mediating the maternal inflammatory response, as well as significant sexual dimorphism in these relationships, which has implications for several adverse pregnancy outcomes.

Estimated daily intake of phthalates, parabens, and bisphenol A in hospitalised very low birth weight infants

Very low birth weight infants (VLBW, birth weight (BW) < 1500 g) are exposed to phthalates, parabens and bisphenol A (BPA) early in life. We estimated daily intake (EDI) of these excipients in 40 VLBW infants the first and fifth week of life while hospitalised. Based on urinary samples collected in 2010, EDI was calculated and compared to the tolerable daily intake (TDI) with hazard quotients (HQs) evaluated. A HQ > 1 indicates that EDI exceeded TDI with increased risk of adverse health effects. EDI was higher in VLBW infants compared to term-born infants and older children. VLBW infants born at earlier gestational age (GA), or with lower BW, had higher EDI than infants born at later GA or with higher BW. First week median EDI for BPA was higher than TDI in 100% of infants, in 75% for di(2-ethylhexyl) phthalate (DEHP), 90% for the sum of butyl benzyl phthalate (BBzP), di-n-butyl phthalate (DnBP), DEHP and di-iso-nonyl phthalate (DiNP) = ∑BBzP+DnBP+DEHP+DiNP, and in 50% of infants for propylparaben (PrPa), indicating increased risk of adverse effects. Fifth week EDI remained higher than TDI in all infants for BPA, in 75% for DEHP and ∑BBzP+DnBP+DEHP+DiNP, and 25% of infants for PrPa, indicating prolonged risk. Maximum EDI for di-iso-butyl phthalate was higher than TDI suggesting risk of adverse effects at maximum exposure. VLBW infants born earlier than 28 weeks GA had higher EDI, above TDI, for PrPa compared to infants born later than 28 weeks GA. Infants with late-onset septicaemia (LOS) had higher EDI for DEHP, ∑BBzP+DnBP+DEHP+DiNP and BPA, above TDI, compared to infants without LOS. More 75% of the infants' EDI for DEHP and ∑BBzP+DnBP+DEHP+DiNP, 25% for PrPa, and 100% of infants' EDI for BPA, were above TDI resulting in HQs > 1, indicating increased risk of adverse health effects.

Investigating associations between urinary phthalate metabolite concentrations and chronic diarrhea: findings from the National Health and Nutrition Examination Survey, 2005-2010

This study aimed to explore the relationship between chronic diarrhea and urinary phthalate metabolite concentrations in US adults from the 2005-2010 NHANES study. After adjusting for potential confounding factors, logistic regression was used to explore the relationship between phthalates (PAEs) concentrations and chronic diarrhea, Bayesian kernel machine regression (BKMR), and quantile g calculation (quantile-based g calculation, qgcomp) which was used to study the combined and independent effects of PAEs on gastrointestinal infections. In the current study, 4260 adult participants over the age of 20 from the NHANES study were included, of whom 542 (12.72%) were assessed as having chronic diarrhea. In multivariate logistic regression analysis, after adjusting for all relevant covariates, the results showed that urinary phthalate metabolite concentrations were significantly associated with the risk of chronic diarrhea (P<0.001). Various PAEs were risk factors for chronic diarrhea, among which MiBP (OR=1.419, 95% CI: 1.416-1.423) and MCPP (OR=1.237, 95% CI: 1.235-1.239) were more significant. The BKME results showed a significant increase in the risk of chronic diarrhea with increasing total levels of the PAEs mixture. Mixed exposure to PAEs can promote the occurrence of chronic diarrhea, and the effect was more pronounced in obese people. Notably, most PAEs showed some degree of protection in overweight people. The risk effect of PAEs was more significant in the middle-aged and older population than in the younger population.

Role of microRNA in Endocrine Disruptor-Induced Immunomodulation of Metabolic Health

The prevalence of poor metabolic health is growing exponentially worldwide. This condition is associated with complex comorbidities that lead to a compromised quality of life. One of the contributing factors recently gaining attention is exposure to environmental chemicals, such as endocrine-disrupting chemicals (EDCs). Considerable evidence suggests that EDCs can alter the endocrine system through immunomodulation. More concerning, EDC exposure during the fetal development stage has prominent adverse effects later in life, which may pass on to subsequent generations. Although the mechanism of action for this phenomenon is mostly unexplored, recent reports implicate that non-coding RNAs, such as microRNAs (miRs), may play a vital role in this scenario. MiRs are significant contributors in post-transcriptional regulation of gene expression. Studies demonstrating the immunomodulation of EDCs via miRs in metabolic health or towards the Developmental Origins of Health and Disease (DOHaD) Hypothesis are still deficient. The aim of the current review was to focus on studies that demonstrate the impact of EDCs primarily on innate immunity and the potential role of miRs in metabolic health.

Risk Assessment of Phthalates and Their Metabolites in Hospitalized Patients: A Focus on Di- and Mono-(2-ethylhexyl) Phthalates Exposure from Intravenous Plastic Bags

Phthalate esters (PAEs) are plasticizers associated with multiple toxicities; however, no strict regulations have been implemented to restrict their use in medical applications in Lebanon. Our study aimed at assessing the potential risks correlated with phthalate exposure from IV bags manufactured in Lebanon. GC–MS analysis showed that di-(2-ethylhexyl) phthalate (DEHP) is the predominant phthalate found in almost all samples tested with values ranging from 32.8 to 39.7% w/w of plastic. DEHP concentrations in the IV solutions reached up to 148 µg/L, as measured by SPME-GC–MS/MS, thus resulting in hazard quotients greater than 1, specifically in neonates. The toxicity of DEHP is mainly attributed to its metabolites, most importantly mono-(2-ethylhexyl) phthalate (MEHP). The IV bag solution with the highest content in DEHP was therefore used to extrapolate the amounts of urinary MEHP. The highest concentrations were found in neonates having the lowest body weight, which is concerning, knowing the adverse effects of MEHP in infants. Our study suggests that the use of IV bags manufactured in Lebanon could pose a significant risk in hospitalized patients, especially infants in neonatal care. Therefore, Lebanon, as well as other countries, should start imposing laws that restrict the use of phthalates in medical IV bags and substitute them with less toxic plasticizers.

Prenatal exposure to phthalate and decreased body mass index of children: a systematic review and meta-analysis

Phthalates are well-known endocrine-disrupting chemicals. Many detrimental health effects of phthalates were investigated, but studies on the association of phthalates with obesity in children showed inconsistent results. Thus, this systematic review and meta-analysis were performed to clarify whether prenatal and postnatal exposures to phthalates are associated with physical growth disturbances in children. We performed the systematic review and meta-analysis following the PRISMA 2020 statement guidelines, and found 39 studies that met our inclusion criteria, including 22 longitudinal and 17 cross-sectional studies. We observed a significant negative association between the prenatal exposure to DEHP and the body mass index (BMI) z-score of the offspring (β = - 0.05; 95% CI: - 0.10, - 0.001) in the meta-analysis, while no significant association between the prenatal exposure to DEHP and the body fat percentage of the offspring was observed (β = 0.01; 95% CI: - 0.41, 0.44). In the systematic review, studies on the association between phthalates exposure in childhood and obesity were inconsistent. Prenatal exposure to phthalates was found to be associated with decreased BMI z-score in children, but not associated with body fat percentage. Our findings suggest that phthalates disturb the normal muscle growth of children, rather than induce obesity, as previous studies have hypothesized.

Phthalate exposure enhances incidence of urinary incontinence: US NHANES, 2003-2004 and 2005-2006

The aim of this study is to investigate the associations between phthalate exposure and UI in a nationally representative sample of US adults. Cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) database was used for analysis. In total, 2,818 participants with measurements for phthalate metabolites and complete UI questionnaire data were enrolled in our study. Furthermore, seven phthalate metabolites were measured, which were obtained from urine samples and creatinine-standardized in the subsequent analyses. After dividing these phthalate metabolites into three groups, multivariable regression models were performed to evaluate the association between phthalate metabolites and UI rates. Moreover, interaction analyses and subgroup analyses stratified by gender were performed. In these seven phthalate metabolites, high level of mono-carboxynonyl phthalate (MCNP), mono-carboxyoctyl phthalate (MCOP), mono-isobutyl phthalate (MiBP), mono-n-butyl phthalate (MBP), and mono-3-carboxypropyl phthalate (MCPP) showed increased risk of UI (odds ratio (OR) = 1.52, 1.42, 1.43, 1.50, 1.51, respectively, all p value < 0.05). Trend test showed that incidence of UI increased significantly with concentration. A higher incidence of UI among participants was observed in the maximal tertile of phthalate when comparing with the lowest tertile. Subgroup analysis found that different phthalates have varying influence for different types of UI. Moreover, the analyses stratified for sex indicated that the high concentrations of MCNP and median concentrations of MCCP were associated with increase of the odds of UI in women and in men, respectively. Overall, the exposure to phthalates was positively associated with UI among US adults. Notably, different phthalates have varying influence for different types of UI, and male and female exposure to phthalate could result in the different prevalence of UI.

Analysis of 19 urinary biomarkers of oxidative stress, nitrative stress, metabolic disorders, and inflammation using liquid chromatography–tandem mass spectrometry

Environmental chemical exposures have been associated with cancer, diabetes, hormonal and immunological disorders, and cardiovascular diseases. Some direct effects of chemical exposure that are precursors to adverse health outcomes, including oxidative stress, nitrative stress, hormonal imbalance, neutrophilia, and eosinophilia, can be assessed through the analysis of biomarkers in urine. In this study, we describe a novel methodology for the determination of 19 biomarkers of health effects: malondialdehyde (MDA), 8-isoprostaglandin-F_2α (8-PGF_2α), 11-β-prostaglandin-F_2α (11-PGF_2α), 15-prostaglandin-F_2α (15-PGF_2α), 8-iso-15-prostaglandin-F_2α (8,15-PGF_2α), 8-hydroxy-2′-deoxyguanosine (8-OHdG), 8-hydroxyguanosine (8-HdG), 8-hydroxyguanine (8-HG), dityrosine (diY), allantoin (Alla), and two metabolic products of 4-hydroxynonenal (HNE), namely 4-hydroxy-2-nonenal glutathione (HNE-GSH) and 4-hydroxy-2-nonenal mercapturic acid (HNE-MA) (in total, 12 oxidative stress biomarkers, OSBs); 8-nitroguanosine (8-NdG), 8-nitroguanine (8-NG), and 3-nitrotyrosine (NY) (3 nitrative stress biomarkers, NSBs); chlorotyrosine (CY) and bromotyrosine (BY) (2 inflammatory biomarkers); and the advanced glycation end-products (AGEs) N^ε-carboxymethyllysine (CML) and N^ε-carboxyethyllysine (CEL) (2 metabolic disorder biomarkers). Since these biomarkers are trigged by a variety of environmental insults and produced by different biomolecular pathways, their selective and sensitive determination in urine would help broadly elucidate the pathogenesis of diseases mediated by environmental factors.

Lineage-Selective Disturbance of Early Human Hematopoietic Progenitor Cell Differentiation by the Commonly Used Plasticizer Di-2-ethylhexyl Phthalate via Reactive Oxygen Species: Fatty Acid Oxidation Makes the Difference

Exposure to ubiquitous endocrine-disrupting chemicals (EDCs) is a major public health concern. We analyzed the physiological impact of the EDC, di-2-ethylhexyl phthalate (DEHP), and found that its metabolite, mono-2-ethylhexyl phthalate (MEHP), had significant adverse effects on myeloid hematopoiesis at environmentally relevant concentrations. An analysis of the underlying mechanism revealed that MEHP promotes increases in reactive oxygen species (ROS) by reducing the activity of superoxide dismutase in all lineages, possibly via its actions at the aryl hydrocarbon receptor. This leads to a metabolic shift away from glycolysis toward the pentose phosphate pathway and ultimately results in the death of hematopoietic cells that rely on glycolysis for energy production. By contrast, cells that utilize fatty acid oxidation for energy production are not susceptible to this outcome due to their capacity to uncouple ATP production. These responses were also detected in non-hematopoietic cells exposed to alternate inducers of ROS.

Mechanistic insight into toxicity of phthalates, the involved receptors, and the role of Nrf2, NF-κB, and PI3K/AKT signaling pathways

The wide use of phthalates, as phthalates are used in the manufacturing of not only plastics but also many others goods, has become a main concern in the current century because of their potency to induce deleterious effects on organism health. The toxic effects of phthalates such as reproductive toxicity, cardiotoxicity, hepatotoxicity, nephrotoxicity, teratogenicity, and tumor development have been widely indicated by previous experimental studies. Some of the important mechanisms of toxicity by phthalates are the induction and promotion of inflammation, oxidative stress, and apoptosis. Awareness of the involved molecular pathways of these mechanisms will permit the detection of exact molecular targets of phthalates to protect or treat their toxicity. Up to now, various transcription factors and signaling pathways have been associated with phthalate-induced toxicity which by influencing on nuclear surface and the expression of different genes can alter cell hemostasis. In different studies, the role of nuclear factor erythroid 2-related factor 2 (Nrf2), nuclear factor-κB (NF-κB), and phosphatidylinositol-3-kinase (PI3K)/AKT signaling pathways in processes of oxidative stress, inflammation, apoptosis, and cancer has been shown following exposure to phthalates. In the present review, we aim to survey experimental studies (in vitro and in vivo) in order to show firstly the most involved receptors and also the importance and the role of the mentioned signaling pathways in phthalate-induced toxicity, and with considering this point, the future studies can focus on these molecular targets as a strategic method to reduce environmental chemicals-induced toxicity especially phthalates toxic effects.

Exposure to phthalates is associated with grip strength in US adults

The potential association of exposure to phthalates with muscle strength was reported in previous animal experiments. However, their association was rarely directly investigated in general populations. Thus, we aimed to ascertain the association of exposure to phthalates with grip strength using cross-sectional analysis which included 2436 individuals aged ≥ 20 years from the National Health and Nutrition Examination Survey (NHANES) during 2011-2014. The multivariable linear regression models were performed with the adjustment of related covariates. The results suggested that a one-unit increase in log-transformed phthalate metabolites (μg/g creatinine) was inversely associated with grip strength, including Mono-(2-ethyl)-hexyl phthalate (β: -2.727 kg, 95% CI: -3.452, -2.002), Mono-(2-ethyl-5-hydroxyhexyl) phthalate (β: -3.721 kg, 95% CI: -4.836, -2.607), Mono-(2-ethyl-5-oxohexl) phthalate (β: -4.669 kg, 95% CI: -5.761, -3.577), Mono-2-ethyl-5-carboxypentyl phthalate (β: -4.756 kg, 95% CI: -5.957, -3.554), Mono-carboxyoctyl phthalate (β: -1.324 kg, 95% CI: -2.412, -0.235), Mono-carboxynonyl phthalate (β: -2.036 kg, 95% CI: -3.185, -0.886), Mono-benzyl phthalate (β: -2.940 kg, 95% CI: -3.853, -2.026), Mono-n-butyl phthalate (β: -2.100 kg, 95% CI: -3.474, -0.726), Mono-isobutyl phthalate (β: -2.982 kg, 95% CI: -4.331, -1.633), and Mono-ethyl phthalate (β: -1.709 kg, 95% CI: -2.368, -1.050). In subgroup analyses, the associations remained largely unchanged when the samples were stratified by gender and age; However they became ambiguous among underweight subjects when the samples were stratified by BMI status. Overall, exposure to phthalates was inversely associated with grip strength among US adults, regardless of their genders and ages. The suggestive potential BMI status-specific effects of phthalates on grip strength were observed.

Aggravation of autism-like behavior in BTBR T+tf/J mice by environmental pollutant, di-(2-ethylhexyl) phthalate: Role of nuclear factor erythroid 2-related factor 2 and oxidative enzymes in innate immune cells and cerebellum

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder which manifests itself in early childhood and is distinguished by recurring behavioral patterns, and dysfunction in social/communication skills. Ubiquitous environmental pollutant, di-2-ethylhexyl phthalate (DEHP) is one of the most frequently used plasticizers in various industrial products, e.g. vinyl flooring, plastic toys, and medical appliances. DEHP gets easily released into the environment and leads to human exposure through various routes. DEHP has been described to be linked with oxidative stress in various organs in animal/human studies. Increased concentration of DEHP has also been detected in ASD children which indicates an association between phthalates exposure and ASD. However, effect of DEHP on autism-like behavior has not been investigated previously. Therefore, this study probed the effect of DEHP on autism-like behavior (marble burying, self-grooming and sociability) and innate immune cells (dendritic cells/neutrophils)/cerebellar oxidant-antioxidant balance (NFkB, iNOS, NADPH oxidase, nitrotyrosine, lipid peroxides, Nrf2, SOD, GPx) in BTBR and C57 mice. Our data show that DEHP treatment causes worsening of autism-like behavior in BTBR mice which is associated with enhancement of oxidative stress in innate immune cells and cerebellum with concomitant lack of antioxidant protection. DEHP also causes oxidative stress in C57 mice in both innate immune cells and cerebellar compartment, however there is Nrf2-mediated induction of enzymatic antioxidants which protects them from upregulated oxidative stress. This proposes the notion that ubiquitous environmental pollutants such as DEHP may be involved in the pathogenesis/progression of ASD through dysregulation of antioxidant-antioxidant balance in innate immune cells and cerebellum.

Sex-specific difference in placental inflammatory transcriptional biomarkers of maternal phthalate exposure: a prospective cohort study

Previous epidemiologic research has shown that phthalate exposure in pregnant women is related to birth outcomes in a sex-specific manner. These outcomes may be mediated by placental inflammation, which is the proposed biological mechanism. This is the first study to address the relationship between phthalate exposure and gene expression in placental inflammation in a sex-specific manner. We performed quantitative PCR to measure placental inflammatory mRNAs (CRP, TNF-α, IL-1β, IL-6, IL-10, MCP-1, IL-8, CD68, and CD206) in 2469 placentae that were sampled at birth. We estimated the associations between mRNA and urinary phthalate monoesters using multiple linear regression models. Mono-n-butyl phthalate (MBP) was correlated with higher IL-1β, IL-6, and CRP expression in placentae of male fetuses and with higher IL-6, CRP, MCP-1, IL-8, IL-10, and CD68 expression in placentae of female fetuses. Mono benzyl phthalate (MBzP) increased the expression of TNF-α, MCP-1, and CD68 only in placentae of male fetuses. Mono (2-ethyl-5-oxohexyl) phthalate (MEOHP) was negatively correlated with CRP, MCP-1, and CD68 in placentae of female fetuses. Maternal phthalate exposure was associated with inflammatory variations in placental tissues. The associations were stronger in placentae of male than of female fetuses. Compared with the other metabolites, MBP plays a strong role in these associations. The placenta is worth being further investigated as a potential mediator of maternal exposure-induced disease risk in children.

How microplastic components influence the immune system and impact on children health: Focus on cancer

BACKGROUND

As a result of human socioeconomic activity, industrial wastes have increased distressingly. Plastic pollution is globally distributed across the world due to its properties of buoyancy and durability. A big health hazard is the sorption of toxicants to plastic while traveling through the environment. Two broad classes of plastic-related chemicals are of critical concern for human health-bisphenols and phthalates. Bisphenol A (BPA) is an endocrine-disruptor compound (EDC) with estrogenic activity. It is used in the production of materials that are used daily. The endocrine modulating activity of BPA and its effects on reproductive health has been widely studied. BPA also has effects on the immune system; however, they are poorly investigated and the available data are inconclusive. Phthalates are also EDCs used as plasticizers in a wide array of daily-use products. Since these compounds are not covalently bound to the plastic matrix, they easily leach out from it, leading to high human exposure. These compounds exert several cell effects through modulating different endocrine pathways, such as estrogen, androgen, peroxisome proliferator-activated receptor gamma, and arylhydrocarbon receptor pathways. The exposure to both classes of plastic derivatives during critical periods has detrimental effects on human health.

METHODS

In this review, we have compiled the most important of their perinatal effects on the function of the immune system and their relationship to the development of different types of cancer.

RESULTS/CONCLUSION

The administration of bisphenols and phthalates during critical stages of development affects important immune system components, and the immune function; which might be related to the development of different diseases including cancer.

Phthalate exposure alters gut microbiota composition and IgM vaccine response in human newborns

Postnatal exposure to di-(2-ethylhexyl) phthalate (DEHP), a common plasticizer, is associated with allergy development in childhood, suggesting that DEHP exposure may dysregulate immune response in infants. We investigated whether DEHP exposure in newborns through medical treatment affected the gut microbiota pattern and vaccine response, which are both related to immune development. In this prospective cohort study from May 1, 2016 through July 31, 2017, newborns with respiratory distress who were given intravenous infusions (IVs) were enrolled as the DEHP group, and newborns who did not receive IVs were enrolled as the control group. We excluded patients with perinatal maternal probiotics, vaginal delivery, antibiotic treatment, and exclusive human milk or formula feeding. Of 118 infants, urinary phthalate metabolite analysis revealed that the calculated DEHP concentrations of the newborns treated with IVs (n = 15) were higher than those in the control group (n = 10) (p = 0.0001). DEHP exposure altered bacterial communities both in composition and diversity, particularly decreases in Rothia sp. and Bifidobacterium longum in the DEHP group. Furthermore, DEHP exposure significantly enhanced anti-HBsAg-IgM responses in the DEHP group (p = 0.013). Early-life DEHP exposure alter gut microbiota of newborns and may change their immune responses in later life.

Associations of Phthalates and Phthalate Replacements With CRH and Other Hormones Among Pregnant Women in Puerto Rico

CONTEXT

Phthalates are endocrine-disrupting chemicals that may be associated with adverse birth outcomes. Dysregulation of maternal endocrine homeostasis could be a possible biological pathway between phthalates and birth outcomes.

OBJECTIVE

Examine associations between 19 maternal urinary phthalate or phthalate replacement metabolites and 9 serum hormones measured over two time points during pregnancy.

DESIGN

Longitudinal study conducted in the PROTECT pregnancy cohort.

SETTING

Puerto Rico.

PATIENTS

Six hundred seventy-seven women in the first trimester of pregnancy.

MAIN OUTCOME MEASURES SERUM

CRH, estriol, SHBG, progesterone, TSH, total T3, free T4, total T4, and testosterone.

RESULTS

T3 was significantly associated with most metabolites. CRH was inversely associated with mono carboxyisononyl phthalate [MCNP; percent change (%Δ), -4.08; 95% CI, -7.24, -0.804], mono-3-carboxypropyl phthalate (MCPP; %Δ, -5.25; 95% CI, -8.26, -2.14), mono-2-ethyl-5-carboxypentyl phthalate (MECPP; %Δ, -18.4; 95% CI, -30.4, -4.37), mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP; %Δ, -13.4; 95% CI, -22.7, -2.92), and mono-2-ethyl-5-oxohexyl phthalate (MEOHP; %Δ, -12.7; 95% CI, -22.2, -2.20). Positive associations were found between numerous phthalate metabolites and free T4, T4, and the T3/T4 ratio. Testosterone was positively associated with mono hydroxybutyl phthalate (MHBP; %Δ, 4.71; 95% CI, 0.27, 9.35) and inversely associated with monoethyl phthalate (MEP; %Δ, -14.5; 95% CI, -24.3, -3.42), and relationships with MCNP and mono carboxyisooctyl phthalate (MCOP) were significantly modified by study visit. Finally, an inverse association was found between mono-2-ethyl-5-hydrohexyl terephthalate (MEHHTP), a terephthalate metabolite, and progesterone at visit 3 only (%Δ, -13.1; 95% CI, -22.3, -2.75).

CONCLUSIONS

These results indicate that exposure to phthalates may differentially impact the maternal endocrine system at different points during pregnancy, and that exposures to phthalate replacement chemicals may be particularly important to consider in future human health studies.

Urinary phthalate metabolites in relation to childhood asthmatic and allergic symptoms in Shanghai

BACKGROUND

Few studies can be found on phthalate exposure in relation to childhood asthma and allergic symptoms from Mainland China, where a persistent increase in prevalence of childhood asthma and allergic disease has been observed.

OBJECTIVES

This study aimed to assess the exposure levels to phthalates and its relationship with asthmatic and allergic symptoms among children in Shanghai, which has the highest prevalence of childhood asthma in Mainland China.

METHODS

A follow-up study (2013-2014) of 434 children aged 5-10 years was conducted, based on the China, Children, Homes, Health (CCHH) study (2011-2012) in Shanghai, China. Information on asthmatic and allergic symptoms (wheeze, rhinitis, and eczema) were collected using validated questionnaires. Ten phthalate metabolites in morning urine samples were analyzed by high-performance liquid chromatography with triple quadrupole tandem mass spectrometry (HPLC-MS/MS). Multivariable logistic regression was used to estimate the associations between symptoms and urinary phthalate metabolites controlling for demographics, family history of allergic diseases and other covariates.

RESULTS

Nine out of 10 phthalate metabolites were detected in all subjects (average detection rate of 93.2%). By multivariable logistic regression analyses, the 4th quartile of Mono‑n‑butyl phthalate (MnBP) (reference: 1st quartile) had adjusted prevalence odds ratios (aPOR_S) and 95% confidence intervals (95%CIs) of 2.27(1.06-4.88), 2.14(1.02-4.46) and 2.98(1.19-7.50) for wheeze, rhinitis and eczema, respectively, while those of Mono‑isobutyl phthalate (MiBP) were 2.23(1.08-4.62) and 2.96(1.02-8.60) for rhinitis and eczema, respectively. The highest quartile of mono‑2‑ethyl‑5‑hydroxyhexyl phthalate(MEHHP) and mono‑2‑ethyl‑5‑oxohexyl phthalate(MEOHP) had aPOR_S and 95%CIs of 3.10(1.10-8.74) and 2.63(1.02-6.80) for eczema, respectively. By summing up the 4 low molecular weight metabolites (∑₄LMWP) and all 9 metabolites (∑₉Total), the highest quartiles of ∑₄LMWP and∑₉Total were significantly associated with all symptoms. In most of the above associations, a significantly increasing trend from the 1st to the 4th quartile was observed. Subjects with 2 or 3 concomitant symptoms (reference: no symptoms) had significant positive associations with a higher level (the 4th quartile) of phthalate metabolites.

CONCLUSIONS

Low MW metabolites such as MnBP and MiBP, high MW DEHP and the total amount of phthalate metabolites might have adverse health effects on asthma and allergic symptoms in Chinese children.

Metabolomic Markers of Phthalate Exposure in Plasma and Urine of Pregnant Women

Phthalates are known endocrine disruptors and found in almost all people with several associated adverse health outcomes reported in humans and animal models. Limited data are available on the relationship between exposure to endocrine disrupting chemicals and the human metabolome. We examined the relationship of metabolomic profiles in plasma and urine of 115 pregnant women with eleven urine phthalate metabolites measured at 26 weeks of gestation to identify potential biomarkers and relevant pathways. Targeted metabolomics was performed by selected reaction monitoring liquid chromatography and triple quadrupole mass spectrometry to measure 415 metabolites in plasma and 151 metabolites in urine samples. We have chosen metabolites with the best defined peaks for more detailed analysis (138 in plasma and 40 in urine). Relationship between urine phthalate metabolites and concurrent metabolomic markers in plasma and urine suggested potential involvement of diverse pathways including lipid, steroid, and nucleic acid metabolism and enhanced inflammatory response. Most of the correlations were positive for both urine and plasma, and further confirmed by regression and PCA analysis. However, after the FDR adjustment for multiple comparisons, only 9 urine associations remained statistically significant (q-values 0.0001–0.0451), including Nicotinamide mononucleotide, Cysteine T2, Cystine, and L-Aspartic acid. Additionally, we found negative associations of maternal pre-pregnancy body mass index (BMI) with more than 20 metabolomic markers related to lipid and amino-acid metabolism and inflammation pathways in plasma (p = 0.01–0.0004), while Mevalonic acid was positively associated (p = 0.009). Nicotinic acid, the only significant metabolite in urine, had a positive association with maternal BMI (p = 0.002). In summary, when evaluated in the context of metabolic pathways, the findings suggest enhanced lipid biogenesis, inflammation and altered nucleic acid metabolism in association with higher phthalate levels. These results provide new insights into the relationship between phthalates, common in most human populations, and metabolomics, a novel approach to exposure and health biomonitoring.

Immune failure reveals vulnerability of populations exposed to pollution in the bioindicator species Hediste diversicolor

Human activities on the shoreline generate a growing pollution, creating deleterious habitats in coastal zones. Some species nevertheless succeed in such harsh milieus, raising the question of their tolerance to environmental stress. The annelid Hediste diversicolor lives buried in the sediments, directly exposed to contaminants trapped in the mud. After verifying the similarity of their genetic contexts, we compared reproductive output and individual immune resistance measures of populations living in polluted vs. 'clean' sediments, and related these assessments with measures of phthalates and metal pollution, and associated toxicity indices. Chemical analyses predicted no toxicity to the local infauna, and phenological studies evidenced no direct cost of living in noxious habitats. However, populations exposed to pollutants showed a significantly reduced survival upon infection with a local pathogen. Surprisingly, physiological studies evidenced a basal overinflammatory state in the most exposed populations. This over-activated baseline immune phenotype likely generates self-damage leading to enhanced immune cell death rate and immune failure. Monitoring the immune status of individual worms living in anthropic areas could thus be used as a reliable source of information regarding the actual health of wild populations.

Peroxisome proliferator activated receptor gamma in human placenta may mediate the adverse effects of phthalates exposure in pregnancy

Peroxisome-proliferator activated receptor gamma (PPARG) in placenta play an important role in pregnancy. Our previous study showed that it mediated the effects of phthalates on placental mRNA expression of estrogen synthetases in rats. To assess the effects of phthalate exposure on PPARG placental expression, and the contribution of PPARG to the effects of phthalates in human. 207 healthy pregnant women were recruited and their cord blood and placenta were collected upon delivery. Three phthalates, estrogens in cord blood and protein expression of PPARG in placenta were measured. Linear regression were used to analyze the relationship between phthalates exposure, PPARG expression and hormones. Phthalate levels in cord blood were positively associated with PPARG protein expression in placenta (p<0.05), whereas estrogens in cord blood were negatively associated with phthalate levels and PPARG expression (p<0.05). This study shows that PPARG in placenta may mediate the adverse effects of phthalates on pregnancy in human.

The chemical disruption of human metabolism

BACKGROUND

Recent evidence highlights the reality of unprecedented human exposure to toxic chemical agents found throughout our environment - in our food and water supply, in the air we breathe, in the products we apply to our skin, in the medical and dental materials placed into our bodies, and even within the confines of the womb. With biomonitoring confirming the widespread bioaccumulation of myriad toxicants among population groups, expanding research continues to explore the pathobiological impact of these agents on human metabolism.

METHODS

This review was prepared by assessing available medical and scientific literature from Medline as well as by reviewing several books, toxicology journals, government publications, and conference proceedings. The format of a traditional integrated review was chosen.

RESULTS

Toxicant exposure and accrual has been linked to numerous biochemical and pathophysiological mechanisms of harm. Some toxicants effect metabolic disruption via multiple mechanisms.

CONCLUSIONS

As a primary causative determinant of chronic disease, toxicant exposures induce metabolic disruption in myriad ways, which consequently result in varied clinical manifestations, which are then categorized by health providers into innumerable diagnoses. Chemical disruption of human metabolism has become an etiological determinant of much illness throughout the lifecycle, from neurodevelopmental abnormalities in-utero to dementia in the elderly.

Maternal exposure to di-2-ethylhexylphthalate and adverse delivery outcomes: A systematic review

Adverse pregnancy outcomes, including preterm delivery, short gestational age, and abnormal birth weight, remain a public health concern. The evidence on the association of the most common phthalate, di-2-ethylhexyl phthalate (DEHP) with adverse pregnancy outcomes remains equivocal. This systematic review summarizes published studies that investigated the association of DEHP with preterm delivery, gestational age, and birthweight. A comprehensive literature search found 15 relevant studies, most of which evaluated more than one outcome (four studies for preterm delivery, nine studies for gestational age, and ten studies for birthweight). Studies varied greatly with respect to study design, exposure assessment, analytical methods, and direction of the associations. We identified important methodological concerns which could have resulted in selection bias and exposure misclassification and contributed to null findings and biased associations. Given limitations of the previous studies discussed in this review, more thorough investigation of these associations is warranted to advance our scientific knowledge.

Increased levels of phthalates in very low birth weight infants with septicemia and bronchopulmonary dysplasia

Very low birth weight infants (VLBW; birth weight<1500g) are exposed to potentially harmful phthalates from medical devices during their hospital stay. We measured urinary phthalate concentrations among hospitalized VLBW infants participating in a nutritional study. Possible associations between different phthalates and birth weight (BW), septicemia and bronchopulmonary dysplasia (BPD) were evaluated. Forty-six VLBW infants were enrolled in this randomized controlled nutritional study. The intervention group (n=24) received increased quantities of energy, protein, fat, essential fatty acids and vitamin A, as compared to the control group (n=22). The concentrations of 12 urinary phthalate metabolites were measured, using high-performance liquid chromatography coupled to tandem mass spectrometry, at 3 time points during the first 5weeks of life. During this study, the levels of di (2-ethylhexyl) phthalate (DEHP) metabolites decreased, whereas an increasing trend was seen regarding metabolites of di-iso-nonyl phthalate (DiNP). Significantly higher levels of phthalate metabolites were seen in infants with lower BW and those diagnosed with late onset septicemia or BPD. A significant positive correlation between the duration of respiratory support and DEHP metabolites was observed (p≤0.01) at 2.9weeks of age. Birth weight was negatively associated with urinary phthalate metabolite concentrations. Infants with lower BW and those diagnosed with septicemia or BPD experienced prolonged exposure from medical equipment containing phthalates, with subsequent higher levels of phthalate metabolites detected. Clinical Trial Registration no.: NCT01103219.

Mono-(2-Ethylhexyl) Phthalate Promotes Pro-Labor Gene Expression in the Human Placenta

Women exposed to phthalates during pregnancy are at increased risk for delivering preterm, but the mechanism behind this relationship is unknown. Placental corticotropin-releasing hormone (CRH) and cyclooxygenase-2 (COX-2) are key mediators of parturition and are regulated by the non-canonical NF-kB (RelB/p52) signaling pathway. In this study, we demonstrate that one of the major phthalate metabolites, mono-(2-ethylhexyl)-phthalate (MEHP), increased CRH and COX-2 mRNA and protein abundance in a dose-dependent manner in primary cultures of cytotrophoblast. This was coupled with an increase in nuclear import of RelB/p52 and its association with the CRH and COX-2 promoters. Silencing of NF-kB inducing kinase, a central signaling component of the non-canonical NF-kB pathway, blocked MEHP-induced upregulation of CRH and COX-2. These results suggest a potential mechanism mediated by RelB/p52 by which phthalates could prematurely induce pro-labor gene activity and lead to preterm birth.

Association of Urinary Phthalates with Self-Reported Eye Affliction/Retinopathy in Individuals with Diabetes: National Health and Nutrition Examination Survey, 2001-2010

Background. An epidemiological association between exposure to phthalates and type 2 diabetes (T2D) is known. However, the potential role of environmental phthalates in the complications of T2D is unknown. Methods. Using data from the National Health and Nutrition Examination Survey (NHANES) 2001-2010, we studied the association of 12 urinary phthalate metabolites with self-reported eye affliction/retinopathy in 1,004 participants with diabetes. Data from retinal imaging was used to validate this outcome. Independence of the phthalates→T2D association was studied by adjusting for age, sex, race, marital status, educational attainment, poverty income ratio, physical activity, glycated hemoglobin levels, total serum cholesterol, serum high-density lipoprotein cholesterol, serum triglycerides, blood pressure, duration of diabetes, total calorie intake, and obesity. Results. Self-reported eye affliction/retinopathy had 82% accuracy with Cohen's kappa of 0.31 (p < 0.001). Urinary mono-n-octyl phthalate (MOP) was independently associated with the likelihood of self-reported eye affliction/retinopathy in subjects with T2D after accounting for all the confounders. This significance of this association was robust to the potential misclassification in cases and controls of retinopathy. Further, a significant dose-response relationship between MOP and self-reported eye affliction/retinopathy was demonstrable. Conclusions. We show a novel epidemiological link between the environment and diabetic complications in NHANES 2001-2010 participants.

Environmental immune disruptors, inflammation and cancer risk

An emerging area in environmental toxicology is the role that chemicals and chemical mixtures have on the cells of the human immune system. This is an important area of research that has been most widely pursued in relation to autoimmune diseases and allergy/asthma as opposed to cancer causation. This is despite the well-recognized role that innate and adaptive immunity play as essential factors in tumorigenesis. Here, we review the role that the innate immune cells of inflammatory responses play in tumorigenesis. Focus is placed on the molecules and pathways that have been mechanistically linked with tumor-associated inflammation. Within the context of chemically induced disturbances in immune function as co-factors in carcinogenesis, the evidence linking environmental toxicant exposures with perturbation in the balance between pro- and anti-inflammatory responses is reviewed. Reported effects of bisphenol A, atrazine, phthalates and other common toxicants on molecular and cellular targets involved in tumor-associated inflammation (e.g. cyclooxygenase/prostaglandin E2, nuclear factor kappa B, nitric oxide synthesis, cytokines and chemokines) are presented as example chemically mediated target molecule perturbations relevant to cancer. Commentary on areas of additional research including the need for innovation and integration of systems biology approaches to the study of environmental exposures and cancer causation are presented.

Associations between Maternal Biomarkers of Phthalate Exposure and Inflammation Using Repeated Measurements across Pregnancy

Phthalate exposure is prevalent in populations worldwide, including pregnant women. Maternal urinary metabolite concentrations have been associated with adverse reproductive outcomes, but underlying mechanisms remain unclear. Here we investigate inflammation as a possible pathway by examining phthalates in association with inflammation biomarkers, including C-reactive protein (CRP) and a panel of cytokines (IL-1β, IL-6, IL-10, and TNF-α) in a repeated measures analysis of pregnant women (N = 480). Urinary phthalate metabolites and plasma inflammation biomarkers were measured from samples collected at up to four visits per subject during gestation (median 10, 18, 26, and 35 weeks). Associations were examined using mixed models to account for within-individual correlation of measures. Few statistically significant associations or clear trends were observed, although in full models mono-carboxypropyl phthalate (MCPP) was significantly (percent change with interquartile range increase in exposure [%Δ] = 8.89, 95% confidence interval [CI] = 3.28, 14.8), and mono-benzyl phthalate (MBzP) was suggestively (%Δ = 6.79, 95%CI = -1.21, 15.4) associated with IL-6. Overall these findings show little evidence of an association between phthalate exposure and peripheral inflammation in pregnant women. To investigate inflammation as a mechanism of phthalate effects in humans, biomarkers from target tissues or fluids, though difficult to measure in large-scale studies, may be necessary to detect effects.

Mono-ethylhexyl phthalate stimulates prostaglandin secretion in human placental macrophages and THP-1 cells

BACKGROUND

Diethylhexyl phthalate (DEHP) is widely used as a plasticizer in polyvinyl chloride products. DEHP exposure, which is widespread in the US, increases preterm birth risk; however, the mechanisms driving this relationship are unclear. Because cyclooxygenase-2 (COX-2) dependent prostaglandin synthesis is implicated in preterm birth, we evaluated effects of mono-2-ethylhexyl phthalate (MEHP), the active metabolite of DEHP, on prostaglandin E2 (PGE2) synthesis and COX expression in human placental macrophages (PM). In addition, responses in PM were compared to those in a human macrophage-like cell line, THP-1.

METHODS

PM and THP-1 cells were treated for 2, 4, 8, or 24 h with MEHP concentrations ranging from 10 to 180 micromolar. PGE2 concentrations were assessed in culture medium using ELISA, and COX expression was determined by western blot.

RESULTS

Treatment of PM and THP-1 cells with 180 micromolar MEHP for 24 h significantly increased PGE2 release. Co-treatment of PMs or THP-1 cells with 180 micromolar MEHP and the non-selective COX inhibitor indomethacin reduced MEHP-stimulated PGE2 production. Similarly, co-treatment of PM and THP-1 cells with the COX-2 selective inhibitor NS-398 resulted in a significant decrease in PGE2, suggesting that MEHP-stimulated PGE2 is dependent specifically on increased COX-2 expression. Western blot analysis revealed a significant increase in COX-2 expression in PM and THP-1 cells treated with 180 micromolar MEHP, and no changes in COX-1 expression, supporting the role of COX-2 in MEHP-stimulated PGE2 synthesis.

CONCLUSIONS

The findings from this study are the first to demonstrate phthalate-stimulated PGE2 synthesis in PM and warrant future studies into COX-2-dependent prostaglandin synthesis as a mechanism of toxicant-associated preterm birth.

Phthalate metabolites and bisphenol-A in association with circulating angiogenic biomarkers across pregnancy

INTRODUCTION

Phthalates and bisphenol-a (BPA) are endocrine disrupting compounds with widespread exposure that have been linked to adverse birth outcomes and developmental effects. We hypothesized that these associations may be mediated in part through altered placental development and function consequent to exposure. To investigate this question, we examined associations between plasma biomarkers of angiogenesis and urinary biomarkers of exposure to phthalates and bisphenol-a (BPA) measured at repeated time points across pregnancy.

METHODS

We utilized a nested case-control population of 130 mothers who delivered preterm and 352 who delivered term from a prospective birth cohort. Placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) were measured in plasma samples collected from up to four visits during pregnancy (median 10, 18, 26, and 35 weeks). Phthalate metabolites and BPA were measured in urine samples collected at the same visits as indices of exposure.

RESULTS

In linear mixed effects models adjusted for urine dilution and gestational age at sample collection, oxidized di-2-ethylhexyl phthalate (DEHP) metabolites were associated with decreases in PlGF as well as increases in the sFlt-1 to PlGF ratio. These results were slightly attenuated in fully adjusted models. Other phthalate metabolites did not show consistent relationships with either sFlt-1 or PlGF. BPA, however, was associated with increased sFlt-1 as well as the sFlt-1 to PlGF ratio in both crude and adjusted models.

DISCUSSION

We observed associations between urinary DEHP metabolites and BPA and biomarkers of angiogenesis during pregnancy that may be indicative of disrupted placental development and/or function during gestation.

Can exposure to environmental chemicals increase the risk of diabetes type 1 development?

Type 1 diabetes mellitus (T1DM) is an autoimmune disease, where destruction of beta-cells causes insulin deficiency. The incidence of T1DM has increased in the last decades and cannot entirely be explained by genetic predisposition. Several environmental factors are suggested to promote T1DM, like early childhood enteroviral infections and nutritional factors, but the evidence is inconclusive. Prenatal and early life exposure to environmental pollutants like phthalates, bisphenol A, perfluorinated compounds, PCBs, dioxins, toxicants, and air pollutants can have negative effects on the developing immune system, resulting in asthma-like symptoms and increased susceptibility to childhood infections. In this review the associations between environmental chemical exposure and T1DM development is summarized. Although information on environmental chemicals as possible triggers for T1DM is sparse, we conclude that it is plausible that environmental chemicals can contribute to T1DM development via impaired pancreatic beta-cell and immune-cell functions and immunomodulation. Several environmental factors and chemicals could act together to trigger T1DM development in genetically susceptible individuals, possibly via hormonal or epigenetic alterations. Further observational T1DM cohort studies and animal exposure experiments are encouraged.

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

BACKGROUND

Phthalate exposure occurs readily in the environment and has been associated with an array of health end points, including adverse birth outcomes. Some of these may be mediated by oxidative stress, a proposed mechanism for phthalate action.

OBJECTIVES

In the present study, we explored the associations between phthalate metabolites and biomarkers of oxidative stress measured in urine samples from multiple time points during pregnancy.

METHODS

Women were participants in a nested case-control study of preterm birth (n = 130 cases, n = 352 controls). Each was recruited early in pregnancy and followed until delivery, providing urine samples at up to four visits. Nine phthalate metabolites were measured to assess exposure, and 8-hydroxydeoxyguanosine and 8-isoprostane were also measured in urine as markers of oxidative stress. Associations were assessed using linear mixed models to account for intraindividual correlation, with inverse selection probability weightings based on case status to allow for greater generalizability.

RESULTS

Interquartile range increases in phthalate metabolites were associated with significantly higher concentrations of both biomarkers. Estimated differences were greater in association with monobenzyl phthalate (MBzP), mono-n-butyl phthalate (MBP), and monoisobutyl phthalate (MiBP), compared with di(2-ethylhexyl) phthalate (DEHP) metabolites.

CONCLUSIONS

Urinary phthalate metabolites were associated with increased oxidative stress biomarkers in our study population of pregnant women. These relationships may be particularly relevant to the study of birth outcomes linked to phthalate exposure. Although replication is necessary in other populations, these results may also be of great importance for a range of other health outcomes associated with phthalates.

Phthalates and critically ill neonates: device-related exposures and non-endocrine toxic risks

OBJECTIVE

To assess the types and magnitudes of non-endocrine toxic risks to neonates associated with medical device-related exposures to di(2-ethylhexyl)phthalate (DEHP).

STUDY DESIGN

Dose-response thresholds for DEHP toxicities were determined from published data, as were the magnitudes of DEHP exposures resulting from neonatal contact with polyvinyl chloride (PVC) devices. Standard methods of risk assessment were used to determine safe levels of DEHP exposure in neonates, and hazard quotients were calculated for devices individually and in aggregate.

RESULT

Daily intake of DEHP for critically ill preterm infants can reach 16 mg/kg per day, which is on the order of 4000 and 160,000 times higher than desired to avoid reproductive and hepatic toxicities, respectively. The non-endocrine toxicities of DEHP are similar to complications experienced by preterm neonates.

CONCLUSION

DEHP exposures in neonatal intensive care are much higher than estimated safe limits, and might contribute to common early and chronic complications of prematurity. Concerns about phthalates should be expanded beyond endocrine disruption.

Effects of phthalates on the development and expression of allergic disease and asthma

OBJECTIVE

To review recent evidence relating phthalate exposures to allergies and asthma and to provide an overview for clinicians interested in the relevance of environmental health research to allergy and who may encounter patients with concerns about phthalates from media reports.

DATA SOURCES

PubMed, TOXLINE, and Web of Science were searched using the term phthalate(s) combined with the keywords allergy, asthma, atopy, and inflammation.

STUDY SELECTIONS

Articles were selected based on relevance to the goals of this review. Studies that involved humans were prioritized, including routes and levels of exposure, developmental and early-life exposures, immunotoxicity, and the development of allergic disease.

RESULTS

The general public and those with allergy are exposed to significant levels of phthalates via diet, pharmaceuticals, phthalate-containing products, and ambient indoor environment via air and dust. Intravenous exposures occur through medical equipment. Phthalates are metabolized and excreted quickly in the body with metabolites measured in urine. Phthalates, which are known endocrine disrupting compounds, have been associated with oxidative stress and alterations in cytokine expression. Metabolites in human urine, particularly of the higher-molecular-weight phthalates, have been associated with allergies and asthma in multiple studies.

CONCLUSION

Despite mounting evidence implicating phthalates, causation of allergic disease by these compounds cannot currently be established. In utero and early-life exposures and possible transgenerational effects are not well understood. However, considering the current evidence, reducing exposures to phthalates by avoiding processed and foods packaged and stored in plastics, personal care products with phthalates, polyvinyl chloride materials indoors, and reducing home dust is advised. Further longitudinal, molecular, and intervention studies are needed to understand the association between phthalates and allergic disease.

Mono-2-ethylhexyl phthalate induces oxidative stress responses in human placental cells in vitro

Di-2-ethylhexyl phthalate (DEHP) is an environmental contaminant commonly used as a plasticizer in polyvinyl chloride products. Exposure to DEHP has been linked to adverse pregnancy outcomes in humans including preterm birth, low birth-weight, and pregnancy loss. Although oxidative stress is linked to the pathology of adverse pregnancy outcomes, effects of DEHP metabolites, including the active metabolite, mono-2-ethylhexyl phthalate (MEHP), on oxidative stress responses in placental cells have not been previously evaluated. The objective of the current study is to identify MEHP-stimulated oxidative stress responses in human placental cells. We treated a human placental cell line, HTR-8/SVneo, with MEHP and then measured reactive oxygen species (ROS) generation using the dichlorofluorescein assay, oxidized thymine with mass-spectrometry, redox-sensitive gene expression with qRT-PCR, and apoptosis using a luminescence assay for caspase 3/7 activity. Treatment of HTR-8 cells with 180μM MEHP increased ROS generation, oxidative DNA damage, and caspase 3/7 activity, and resulted in differential expression of redox-sensitive genes. Notably, 90 and 180μM MEHP significantly induced mRNA expression of prostaglandin-endoperoxide synthase 2 (PTGS2), an enzyme important for synthesis of prostaglandins implicated in initiation of labor. The results from the present study are the first to demonstrate that MEHP stimulates oxidative stress responses in placental cells. Furthermore, the MEHP concentrations used were within an order of magnitude of the highest concentrations measured previously in human umbilical cord or maternal serum. The findings from the current study warrant future mechanistic studies of oxidative stress, apoptosis, and prostaglandins as molecular mediators of DEHP/MEHP-associated adverse pregnancy outcomes.

Mono-2-ethylhexylphthalate (MEHP) induces TNF-α release and macrophage differentiation through different signalling pathways in RAW264.7 cells

Epidemiological studies have associated indoor phthalate exposure with increased incidences and severity of asthma in children and adults, and inflammatory effects have been suggested as a possible mechanism. Recent studies report that phthalates may activate mitogen-activated protein (MAP) kinase p38 and various peroxisome proliferator-activated receptor (PPAR) isoforms. Here we confirm and extend these findings by investigating possible signalling pathways activated in the murine monocyte-macrophage cell line RAW264.7, using mono-2-ethylhexylphthalate (MEHP) as a model compound. MEHP exposure (0.3-1.0 mM) for 3h increased tumour necrosis factor (TNF)-α release and changed the cellular morphology into elongated spindle-like appearance, resembling more differentiated anti-inflammatory macrophages (M2). This was accompanied by increased expression of the macrophage differentiation marker CD163. Western analysis showed phosphorylation of p38 and Akt after 30 min exposure. Experiments using specific inhibitors suggested that MEHP-induced activation of both p38 and the phosphoinositide-3 (PI3) kinase/Akt pathway were involved in the release of TNF-α; whereas only PI3kinase seemed to be involved in differentiation. In contrast, inhibitors of PPARα and γ reduced differentiation, but did not affect TNF-α release. In conclusion, MEHP induced cytokine release and triggered differentiation of RAW264.7 cells, possibly into M2-like macrophages, but different signalling pathways appear to be involved in these responses.

Expression status of ribonucleotide reductase small subunits hRRM2/p53R2 as prognostic biomarkers in stage I and II non-small cell lung cancer

Overexpression of ribonucleotide reductase M2 (hRRM2) and p53-dependent RR small subunit (p53R2) has been correlated with tumor malignancy and progression in several types of cancer. The aim of this study was to determine the association of p53R2/hRRM2 expression with clinicopathological characteristics of stage I and II non-small cell lung cancer (NSCLC). Immunohistochemistry was conducted on a tissue array that included 92 samples. Correlations between hRRM2 and p53R2 expression and clinicopathological factors, recurrence/metastasis, and outcomes were analyzed. The analyses revealed that there was no correlation between p53R2 expression and clinicopathological factors; hRRM2 was only positively related to poor tumor differentiation (p=0.006). Regarding overall survival during the follow-up period, patients with p53R2+/hRRM2- tumors had the best outcomes (p<0.01). Multivariant Cox analysis revealed that p53R2 (risk=0.232, 95% CI=0.086-0.626, p=0.004) not only served as a prognostic biomarker to predict survival, but also as an independent biomarker to predict disease-free survival (risk=0.545, 95% CI=0.301-0.987, p=0.045) of patients with NSCLC. Therefore, we consider that the expression of p53R2 can be used not only as a biomarker for overall survival, but also as an indicator for tumor recurrence. Based on our finding, p53R2 expression seems more important than that of hRRM2 in prognosis of early-stage lung cancer.