Biomarkers of phthalates and inflammation: Findings from a subgroup of Women's Health Initiative participants

Impact of phthalate metabolites on vitamin D levels and subclinical inflammation: national health and nutrition examination survey, 2013-2018

This study explores the association between phthalates and total vitamin D levels and the link between phthalates exposure and subclinical inflammation using monocyte percentage to high-density lipoprotein cholesterol ratio (MHR), utilizing three National Health and Nutrition Examination Survey (NHANES) survey cycles 2013-2018. This study is cross-sectional, utilizing one-time urine samples from randomly selected NHANES participants to assess phthalate metabolites. An inverse association between vitamin D and all Di(2-ethylhexyl) phthalate (DEHP) metabolites was found. The molar sum of DEHP metabolites was inversely associated with vitamin D (β -2.329; 95% CI -3.937,-0.720). An inverse association was observed between monocarboxynonyl phthalate and vitamin D (β -0.0278; 95% CI -0.0527,-0.00298). A similar relationship was found between monocarboxyoctyl phthalate and vitamin D (β -0.0160; 95% CI -0.0242,-0.00775). There was no association between phthalate metabolites and MHR. Stratified analysis showed that the association between phthalate metabolites and MHR may vary according to vitamin D status.

Prenatal Exposure to Chemical Mixtures and Metabolic Syndrome Risk in Children

Importance

Prenatal exposure to ubiquitous endocrine-disrupting chemicals (EDCs) may increase the risk of metabolic syndrome (MetS) in children, but few studies have studied chemical mixtures or explored underlying protein and metabolic signatures.

Objective

To investigate associations of prenatal exposure to EDC mixtures with MetS risk score in children and identify associated proteins and metabolites.

Design, Setting, and Participants

This population-based, birth cohort study used data collected between April 1, 2003, and February 26, 2016, from the Human Early Life Exposome cohort based in France, Greece, Lithuania, Norway, Spain, and the UK. Eligible participants included mother-child pairs with measured prenatal EDC exposures and complete data on childhood MetS risk factors, proteins, and metabolites. Data were analyzed between October 2022 and July 2023.

Exposures

Nine metals, 3 organochlorine pesticides, 5 polychlorinated biphenyls, 2 polybrominated diphenyl ethers (PBDEs), 5 perfluoroalkyl substances (PFAS), 10 phthalate metabolites, 3 phenols, 4 parabens, and 4 organophosphate pesticide metabolites measured in urine and blood samples collected during pregnancy.

Main Outcomes and Measures

At 6 to 11 years of age, a composite MetS risk score was constructed using z scores of waist circumference, systolic and diastolic blood pressures, triglycerides, high-density lipoprotein cholesterol, and insulin levels. Childhood levels of 44 urinary metabolites, 177 serum metabolites, and 35 plasma proteins were quantified using targeted methods. Associations were assessed using bayesian weighted quantile sum regressions applied to mixtures for each chemical group.

Results

The study included 1134 mothers (mean [SD] age at birth, 30.7 [4.9] years) and their children (mean [SD] age, 7.8 [1.5] years; 617 male children [54.4%] and 517 female children [45.6%]; mean [SD] MetS risk score, -0.1 [2.3]). MetS score increased per 1-quartile increase of the mixture for metals (β = 0.44; 95% credible interval [CrI], 0.30 to 0.59), organochlorine pesticides (β = 0.22; 95% CrI, 0.15 to 0.29), PBDEs (β = 0.17; 95% CrI, 0.06 to 0.27), and PFAS (β = 0.19; 95% CrI, 0.14 to 0.24). High-molecular weight phthalate mixtures (β = -0.07; 95% CrI, -0.10 to -0.04) and low-molecular weight phthalate mixtures (β = -0.13; 95% CrI, -0.18 to -0.08) were associated with a decreased MetS score. Most EDC mixtures were associated with elevated proinflammatory proteins, amino acids, and altered glycerophospholipids, which in turn were associated with increased MetS score.

Conclusions and Relevance

This cohort study suggests that prenatal exposure to EDC mixtures may be associated with adverse metabolic health in children. Given the pervasive nature of EDCs and the increase in MetS, these findings hold substantial public health implications.

Cardiovascular disrupting effects of bisphenols, phthalates, and parabens related to endothelial dysfunction: Review of toxicological and pharmacological mechanisms

Cardiovascular diseases (CVDs) are the leading cause of death worldwide. CVDs are promoted by the accumulation of lipids and immune cells in the endothelial space resulting in endothelial dysfunction. Endothelial cells are important components of the vascular endothelium, that regulate the vascular flow. The imbalance in the production of vasoactive substances results in the loss of vascular homeostasis, leading the endothelial dysfunction. Thus, endothelial dysfunction plays an essential role in the development of atherosclerosis and can be triggered by different cardiovascular risk factors. On the other hand, the 17β-estradiol (E2) hormone has been related to the regulation of vascular tone through different mechanisms. Several compounds can elicit estrogenic actions similar to those of E2. For these reasons, they have been called endocrine-disrupting compounds (EDCs). This review aims to provide up-to-date information about how different EDCs affect endothelial function and their mechanistic roles in the context of CVDs.

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.

BMI-specific inflammatory response to phthalate exposure in early pregnancy: findings from the TMCHESC study

Studies that have evaluated associations between phthalate metabolites and inflammation have reported inconsistent results among pregnant women, and it is unclear how body mass index (BMI) affects such relationships. Therefore, the present study aimed to examine the association between urinary phthalate metabolite concentrations and the levels of inflammatory biomarkers in the general circulation among 394 pregnant women selected from the Tianjin Maternal and Child Health Education and Service Cohort (TMCHESC) and to determine the role that BMI plays in the relationship. The concentrations of eight inflammatory biomarkers and three phthalate metabolites were measured in serum and urine samples, respectively. Multivariable linear modeling was conducted to examine the association between each phthalate and inflammatory biomarker while controlling for potential confounding factors in BMI-stratified subgroups. Restricted cubic splines were also utilised to explore potential non-linear relationships. In the high-BMI group, positive associations were observed between the levels of mono-n-butyl phthalate (MBP) and interleukin 1 beta (IL-1β) (β = 0.192; 95% CI: 0.033, 0.351), monoethyl phthalate (MEP), and C-reaction protein (CRP) (β = 0.129; 95% CI 0.024, 0.233), and mono-ethylhexyl phthalate (MEHP) and interleukin 6 (IL-6) (β = 0.146; 95% CI 0.016, 0.277). Restricted cubic spline models also revealed non-linear associations between the levels of MBP and interleukins 10 and 17A (IL-10 and IL-17A) and between MEP and interleukin 8 (IL-8) and tumor necrosis factor alpha (TNF-α) in pregnant women. These results suggest that phthalate exposure plays a potential role in promoting inflammation in the high-BMI group. While the precise mechanisms underlying the proinflammatory effects of phthalates are not fully understood, these findings suggest that BMI may play a role.

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.

Associations of Urinary Phthalate Metabolites with Thyroid Function and the Mediated Role of Cytokines: A Panel Study of Healthy Children

Evidence on joint association of a phthalate mixture with thyroid function among children and its underlying mechanism is largely unknown. We aimed to explore the associations of 10 urinary phthalate metabolites (mPAEs), either as individuals or as a mixture, with thyroid function indicators [free thyroxine, free triiodothyronine (FT3), and thyroid-stimulating hormone (TSH)] in 144 children aged 4-12 years with up to 3 repeated visits across 3 seasons. Significant and positive associations were observed for mono-(2-ethylhexyl) phthalate (MEHP), mono-iso-butyl phthalate (MiBP), and mono-n-butyl phthalate (MnBP) with TSH, as well as monobenzyl phthalate (MBzP) with FT3 in dose-response manners. The relationship between MEHP and TSH remained robust in multiple-phthalate models. Bayesian kernel machine regression (BKMR) models revealed overall linear associations of the 10 mPAE mixture with higher TSH and FT3 levels, and MEHP and MBzP were major contributors. Meanwhile, MEHP, MiBP, and MnBP were linked to the elevation of multiple cytokines including CCL 27, CCL3, CXCL1, and IL-16. Among them, IL-16 mediated the relationships of MEHP and MiBP with TSH, and the mediated proportions were 24.16% and 24.27%, respectively. Our findings suggested that mPAEs dominated by MEHP were dose-responsively associated with elevated TSH among healthy children and mediated by IL-16.

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.

Associations of circulating levels of phthalate metabolites with cytokines and acute phase reactants in a Spanish human cohort

The associations between human phthalate exposure and the onset of chronic diseases with an immunological component (e.g., metabolic syndrome, cancer) remain unclear, partly due to the uncertainties in the underlying mechanisms. This study investigates cross-sectional associations of the concentrations of 10 phthalate metabolites with 19 cytokines and acute phase proteins in 213 serum samples of Spanish adults. The associations were explored by Spearman's correlation, multivariable linear regression, and weighted quantile sum regression analyses. In the multivariable analyses, levels of plasminogen activator inhibitor (PAI)-1 were positively associated with mono-n-butyl phthalate (fold-change per one IQR increase in phthalate levels, 95% Confidence Interval: 1.65, 1.45-1.88) and mono-iso-butyl phthalate (3.07, 2.39-3.95), mono-ethyl phthalate (2.05, 1.62-2.61), as well as categorized mono-iso-decyl and mono-benzyl phthalates. The same phthalates also were significantly associated with leptin, interleukin (IL)-18 and monocyte chemoattractant protein-1. Moreover, the proinflammatory markers IL-1β, IL-17, IL-8, IL-6, IL-12, tumor necrosis factor, and lipopolysaccharide-binding protein showed positive and negative associations with, respectively, mono-(2-ethyl-hexyl) and mono-methyl phthalates. Finally, phthalate mixtures were positively associated with PAI-1, leptin, IL-18, IL-12, IL-8 and IL-1β. Despite the cross-sectional design limitation, these associations point to relevant subclinical immuno-inflammatory actions of these pollutants, warranting confirmation in future studies.

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.

The associations between endocrine disrupting chemicals and markers of inflammation and immune responses: A systematic review and meta-analysis

Exposure to endocrine disrupting chemicals (EDCs) may lead to dysregulated inflammatory responses, however, the detailed relationship between different EDCs and inflammation remains unclear. A systematic review and meta-analysis was conducted to evaluate the associations between four types of EDCs (bisphenol A (BPA), phthalates (PAEs), organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs)) and markers of inflammation and immune responses in humans. Three databases were searched, and 36 studies with a total of 22055 participants were included. The associations between EDCs and 26 inflammation-related acute phase proteins and cytokines were analyzed. The results demonstrated that exposure to BPA was positively associated with circulating levels of C-reactive protein (CRP) and interleukin (IL)-6. Exposure to PAEs was associated with elevated levels of CRP, IL-6 and IL-10. Subgroup analysis found that three PAE metabolites mono-benzyl phthalate (MBzP), mono-isobutyl phthalate (MiBP), and mono-n-butyl phthalate (MnBP) were directly associated with a higher level of CRP, and two other PAE metabolites mono-carboxyisononyl phthalate (MCNP) and mono-3-carboxypropyl phthalate (MCPP) were positively associated with IL-6. The positive associations between PAEs and CRP, IL-6 and IL-10 were significant in the high-molecular-weight phthalate (HMWP) exposure group, not the low-molecular-weight phthalate (LMWP) exposure group. Exposure to OCPs was positively associated with CRP, IL-1β, IL-2, and IL-10. No significant association was found between PCBs and inflammatory markers. These findings demonstrate that exposure to EDCs is closely linked to dysregulated inflammatory responses. More studies should be conducted in the future to get a comprehensive view of the associations between different EDCs and inflammation, and investigations on the underlying mechanisms are needed.