Glucocorticoid-like activity of propylparaben, butylparaben, diethylhexyl phthalate and tetramethrin mixtures studied in the MDA-kb2 cell line

Assessment of immunomodulatory effects of five commonly used parabens on human THP-1 derived macrophages: Implications for ecological and human health impacts

Parabens are widely used as broad-spectrum anti-microbials and preservatives in food, cosmetics, pharmaceuticals, and personal care products. Studies suggest that the utilization of parabens has substantially increased over the past years, particularly during the global pandemic of coronavirus disease 2019 (COVID-19). Although parabens are generally recognized as safe by the U.S. FDA, some concerns have been raised regarding the potential health effects of parabens associated with immunotoxicity. Herein, we comprehensively investigated several key characteristics of immunotoxicants of five commonly used parabens (methyl-, ethyl-, propyl-, butyl-, and benzyl parabens) in human THP-1 derived macrophages, which are effector cells serving as a first line of host defense against pathogens and tumor immunosurveillance. The results indicate parabens, at concentrations found in humans and biota, significantly dampened macrophage chemotaxis and secretion of major pro-inflammatory cytokines (TNF-α and IL-6) and anti-inflammatory cytokine (IL-10), corroborating the mRNA expression profile. Furthermore, some parabens were found to markedly alter macrophage adhesion and cell surface expression of costimulatory molecules, CD80+ and CD86+, and significantly increase macrophage phagocytosis. Collectively, these findings heighten awareness of potential immunotoxicity posed by paraben exposure at biologically relevant concentrations, providing implications for human health and ecological risks associated with immune dysfunctions.

Transcriptional analysis in peripheral blood cells of individuals with elevated phthalate exposure - Results of the EuroMix study

Exposure to phthalates is widespread in Europe. Phthalates are considered endocrine disrupting compounds and are classified as toxic for reproduction. However how phthalates affect the transcriptome in humans remains largely unknown. To investigate the effects of phthalate exposure on the transcriptomic profile we conducted RNA sequencing on peripheral blood samples from the Norwegian EuroMix cohort. We compared gene expression changes between participants with high, medium, and low exposure of six phthalates and 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH). Comparing high and low exposure groups, DINCH was the compound that showed the highest number of differentially expressed genes (126 genes) followed by mono-n-butyl phthalate (MnBP; 89 genes) and mono-iso-nonyl phthalate (MiBP; 70 genes). Distributions between up- or down-regulated genes were similar across the different phthalates and DINCH. All phthalates including DINCH shared common differentially expressed genes ranging from 3 to 37 overlaps. Enriched Gene Ontology (GO) and biological pathway analysis revealed that most of the differentially expressed genes were associated with general cellular metabolism GO terms. MnBP and DINCH, particularly, showed a marked enrichment in various immunological function pathways including neutrophil degranulation, adaptive immune system and signaling by interleukins. Furthermore, the association between genes involved in the peroxisome proliferator activated receptor (PPAR) signaling pathway and phthalates, including DINCH, was evaluated. In total, 15 genes showed positive or negative associations across 5 phthalates and DINCH. MnBP and MiBP were the phthalate metabolites with the highest number of associations: 8 and 4 PPAR signaling pathway genes, respectively. Overall, we have performed an association study between phthalate exposure levels and modulation of transcriptomic profiles in human peripheral blood cells. DINCH, which is often mentioned as a substitute for phthalates, had comparable effects on differential gene expression in peripheral blood cells as phthalates.

Halogenated ingredients of household and personal care products as emerging endocrine disruptors

The everyday use of household and personal care products (HPCPs) generates an enormous amount of chemicals, of which several groups warrant additional attention, including: (i) parabens, which are widely used as preservatives; (ii) bisphenols, which are used in the manufacture of plastics; (iii) UV filters, which are essential components of many cosmetic products; and (iv) alkylphenol ethoxylates, which are used extensively as non-ionic surfactants. These chemicals are released continuously into the environment, thus contaminating soil, water, plants and animals. Wastewater treatment and water disinfection procedures can convert these chemicals into halogenated transformation products, which end up in the environment and pose a potential threat to humans and wildlife. Indeed, while certain parent HPCP ingredients have been confirmed as endocrine disruptors, less is known about the endocrine activities of their halogenated derivatives. The aim of this review is first to examine the sources and occurrence of halogenated transformation products in the environment, and second to compare their endocrine-disrupting properties to those of their parent compounds (i.e., parabens, bisphenols, UV filters, alkylphenol ethoxylates). Albeit previous reports have focused individually on selected classes of such substances, none have considered the problem of their halogenated transformation products. This review therefore summarizes the available research on these halogenated compounds, highlights the potential exposure pathways, and underlines the existing knowledge gaps within their toxicological profiles.

Concentrations and endocrine disruptive potential of phthalates in marine mammals from the Norwegian Arctic

This study investigated concentrations of phthalates (diesters of phthalic acids) in blubber/adipose tissue of blue whales (Balaenoptera musculus), fin whales (Balaenoptera physalus), bowhead whales (Balaena mysticetus) and polar bears (Ursus maritimus) sampled in the Svalbard Archipelago (extending westward in the case of bowhead whales). Additionally, total concentrations (free and conjugated forms) of eight phthalate monoester metabolites were analysed in plasma of polar bears. Bis(2-ethylhexyl) phthalate (DEHP) was the only phthalate quantified among the 12 phthalates investigated. This compound was present in 6/7 fin whale samples, 4/7 blue whale samples, 2/5 bowhead whale samples and 1/12 polar bear samples. DEHP concentrations ranged from <20-398 ng/g wet weight. Phthalate metabolites, mono-n-butyl phthalate and monoisobutyl phthalate, were found in low concentrations (<1.2 ng/mL) in some of the polar bear samples. In vitro reporter gene assays were used to assess transcriptional activity of fin whale peroxisome proliferator-activated receptor gamma (PPARG), glucocorticoid receptor (GR) and the thyroid hormone receptor beta (THRB) by DEHP and diisononyl phthalate (DiNP). Due to the high degree of similarity of the ligand binding domain in the THRB and PPARG among whales, polar bears and humans, the transactivation results also apply for these species. DEHP showed both agonistic and antagonistic effects towards whale THRB at considerably higher concentrations than measured in the study animals; DiNP was a weak agonist of whale THRB. No significant agonistic or antagonistic effects were detected for DEHP or DiNP for whale PPARG, whereas DEHP and DiNP decreased basal luciferase activity mediated by whale GR at several test concentrations. In conclusion, DEHP was detected in the blubber of marine mammals from the Norwegian Arctic and it appears to have potential to modulate the transcriptional activity of whale THRB, but current DEHP concentrations do not modulate the function of the studied nuclear receptors in adipose tissue of blue whales, fin whales, bowhead whales or polar bears sampled from the Norwegian Arctic.

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.

Hormonal activity in commonly used Black hair care products: evaluating hormone disruption as a plausible contribution to health disparities

BACKGROUND

Certain types of hair products are more commonly used by Black women. Studies show hair products contain several endocrine-disrupting chemicals that are associated with adverse health outcomes. As chemical mixtures of endocrine disruptors, hair products may be hormonally active, but this remains unclear.

OBJECTIVE

To assess the hormonal activity of commonly used Black hair products.

METHODS

We identified six commonly used hair products (used by >10% of the population) from the Greater New York Hair Products Study. We used reporter gene assays (RGAs) incorporating natural steroid receptors to evaluate estrogenic, androgenic, progestogenic, and glucocorticoid hormonal bioactivity employing an extraction method using bond elution prior to RGA assessment at dilutions from 50 to 500.

RESULTS

All products displayed hormonal activity, varying in the amount and effect. Three samples showed estrogen agonist properties at levels from 12.5 to 20 ng/g estradiol equivalent concentrations All but one sample showed androgen antagonist properties at levels from 20 to 25 ng/g androgen equivalent concentrations. Four samples showed antagonistic and agonistic properties to progesterone and glucocorticoid.

SIGNIFICANCE

Hair products commonly used by Black women showed hormonal activity. Given their frequent use, exposure to hormonally active products could have implications for health outcomes and contribute to reproductive and metabolic health disparities.

Assessment of the endocrine-disrupting potential of halogenated parabens: An in silico approach

Parabens are endocrine-disrupting chemicals present in a variety of pharmaceutical and personal care products. Due to their wide-spread use, significant amounts are also released into the aquatic domain of the environment. During water disinfection, parabens give rise to halogenated transformation products. As opposed to parabens, there is considerable lack of knowledge with regard to the endocrine-disrupting potential of their halogenated counterparts, which presents a challenge for regulatory decision making. We aimed to fill this knowledge gap by using the Endocrine Disruptome and VirtualToxLab™ to predict their endocrine-disrupting potential on the basis of calculated affinities for different nuclear receptors. The applied computational approach indicates a high probability of halogenated parabens binding to glucocorticoid, thyroid and aryl hydrocarbon receptors and suggests that disinfection is likely to form transformation products with more pronounced endocrine-disrupting activities than those of parent parabens. The obtained results not only highlight the need for additional in vitro/in vivo investigations of these chemicals as endocrine disruptors but also provide a means of guiding and prioritizing these future studies, in order to assess fully their hazard to human health.

Phthalate esters and dexamethasone synergistically activate glucocorticoid receptor

This study was conducted to determine the endocrine-disrupting effects of phthalate esters (PAEs) on the glucocorticoid receptor (GR) signaling. Potential (anti)glucocorticoid activities of six typical PAEs including di (2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DINP), dibutyl phthalate (DBP), diisobutyl phthalate (DIBP), diethyl phthalate (DEP) and dimethyl phthalate (DMP) were evaluated on human GR using cell viability assessment, reporter gene expression analysis, mRNA analysis, and molecular docking and simulation. For all tested chemicals, co-treatment of DEHP and DINP with dexamethasone (DEX) exhibited a synergistic effect on GR transactivity in the reporter assays. Such co-treatment also synergistically enhanced DEX-induced upregulation of GR mediated gene (PEPCK, FAS and MKP-1) mRNA expression in HepG2 cells and A549 cells. Molecular docking and dynamics simulations showed that hydrophobic interactions may stabilize the binding between molecules and GR. In summary, DEHP and DINP may be involved in synergistic effects via human GR, which highlight the potential endocrine-disrupting activities of PAEs as contaminants.

Application of generalized concentration addition to predict mixture effects of glucocorticoid receptor ligands

Environmental exposures often occur in complex mixtures and at low concentrations. Generalized concentration addition (GCA) is a method used to estimate the joint effect of receptor ligands that vary in efficacy. GCA models have been successfully applied to mixtures of aryl hydrocarbon receptor (AhR) and peroxisome proliferator-activated receptor gamma (PPARγ) ligands, each of which can be modeled as a receptor with a single binding site. Here, we evaluated whether GCA could be applied to homodimer nuclear receptors, which have two binding sites, to predict the combined effect of full glucocorticoid receptor (GR) agonists with partial agonists. We measured transcriptional activation of GR using a cell-based bioassay. Individual concentration-response curves for dexamethasone (full agonist), prednisolone (full agonist), and medroxyprogesterone 17-acetate (partial agonist) were generated and applied in three additivity models, GCA, effect summation (ES), and relative potency factor (RPF), to generate response surfaces. GCA and RPF yielded adequate predictions of the experimental data for two full agonists. However, GCA fit experimental data significantly better than ES and RPF for all other binary mixtures. This work extends the application of GCA to homodimer nuclear receptors and improves prediction accuracy of mixture effects of GR agonists.

Amended Safety Assessment of Parabens as Used in Cosmetics

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of 21 parabens as preservatives in cosmetic products. All of these ingredients are reported to function in cosmetics as preservatives; however, 5 are reported to also function as fragrance ingredients. The Panel reviewed relevant data relating to the safety of these ingredients under the reported conditions of use in cosmetic formulations. The Panel concluded that 20 of the 21 parabens included in this report are safe in cosmetics in the present practices of use and concentration described in this safety assessment when the sum of the total parabens in any given formulation does not exceed 0.8%. However, the available data are insufficient to support a conclusion of safety for benzylparaben in cosmetics.

Glucocorticoid and mineralocorticoid receptors and corticosteroid homeostasis are potential targets for endocrine-disrupting chemicals

Endocrine-disrupting chemicals (EDCs) have received significant concern, since they ubiquitously exist in the environment and are able to induce adverse health effects on human and wildlife. Increasing evidence shows that the glucocorticoid receptor (GR) and the mineralocorticoid receptor (MR), members of the steroid receptor subfamily, are potential targets for EDCs. GR and MR mediate the actions of glucocorticoids and mineralocorticoids, respectively, which are two main classes of corticosteroids involved in many physiological processes. The effects of EDCs on the homeostasis of these two classes of corticosteroids have also gained more attention recently. This review summarized the effects of environmental GR/MR ligands on receptor activity, and disruption of corticosteroid homeostasis. More than 130 chemicals classified into 7 main categories were reviewed, including metals, metalloids, pesticides, bisphenol analogues, flame retardants, other industrial chemicals and pharmaceuticals. The mechanisms by which EDCs interfere with GR/MR activity are primarily involved in ligand-receptor binding, nuclear translocation of the receptor complex, DNA-receptor binding, and changes in the expression of endogenous GR/MR genes. Besides directly interfering with receptors, enzyme-catalyzed synthesis and prereceptor regulation pathways of corticosteroids are also important targets for EDCs. The collected evidence suggests that corticosteroids and their receptors should be considered as potential targets for safety assessment of EDCs. The recognition of relevant xenobiotics and their underlying mechanisms of action is still a challenge in this emerging field of research.

Urinary concentrations of parabens mixture and pregnancy glucose levels among women from a fertility clinic

BACKGROUND

A number of endocrine disrupting chemicals (EDC) have been associated with gestational diabetes (GDM) risk factors. However, no human study has investigated the association between pregnancy exposure to parabens, a class of EDCs, and pregnancy glucose levels, a risk factor for GDM. Furthermore, little is known about this association in subfertile women-a group at high risk of GDM.

METHODS

A total of 241 women from the Environment and Reproductive Health Study had data available on 1st and/or 2nd trimester urinary methylparaben, propylparaben, and butylparaben concentrations, and blood glucose levels after the glucose loading test (GLT), a non-fasting 50 g glucose loading test taken at late 2nd trimester. Trimester-specific associations between specific gravity adjusted methylparaben, butylparaben, and propylparaben with adjusted mean of pregnancy glucose levels were evaluated in linear regression models, using quartiles of each paraben's distribution, and as a paraben mixture, using mutual adjustment and Bayesian kernel machine regression (BKMR), a recently proposed method for investigating chemical mixtures that flexibly models the joint effect of chemicals.

RESULTS

Investigating parabens one at the time did not provide any significant results. When investigating parabens as a chemical mixture with both multiple regression and BKMR, we observed positive associations of butylparaben (e.g comparing the 4th and 1st quartiles) with glucose levels, for both the 1st trimester (adjusted difference=12.5 mg/dL; 95% CI: 0.9, 24.2) and 2nd trimester (adjusted difference=11.2 mg/dL; 95% CI: 0.2, 22.3), and a negative association between 1st trimester propylparaben and glucose (adjusted difference=-22.3 mg/dL; 95% CI: -43.2, -1.4).

CONCLUSIONS

We found 1st trimester butylparaben and propylparaben urinary concentrations to be associated with glucose levels in a pregnancy cohort of women at high risk of GDM, even after adjusting for potential confounders. Because exposure to parabens is widespread, these findings may suggest further investigating the effects of this chemical class on pregnancy health.

Frontiers in endocrine disruption: Impacts of organotin on the hypothalamus-pituitary-thyroid axis

Endocrine disruptors (EDs), chemical substances widely used in industry and ubiquitously distributed in the environment, are able to interfere with the synthesis, release, transport, metabolism, receptor binding, action, or elimination of endogenous hormones. EDs affect homeostasis mainly by acting on nuclear and nonnuclear steroid receptors but also on serotonin, dopamine, norepinephrine and orphan receptors in addition to thyroid hormone receptors. Tributyltin (TBT), an ED widely used as a pesticide and biocide in antifouling paints, has well-documented actions that include inhibiting aromatase and affecting the nuclear receptors PPARγ and RXR. TBT exposure in humans and experimental models has been shown to mainly affect reproductive function and adipocyte differentiation. Since thyroid hormones play a fundamental role in regulating the basal metabolic rate and energy homeostasis, it is crucial to clarify the effects of TBT on the hypothalamus-pituitary-thyroid axis. Therefore, we review herein the main effects of TBT on important metabolic pathways, with emphasis on disruption of the thyroid axis that could contribute to the development of endocrine and metabolic disorders, such as insulin resistance and obesity.

State of the evidence 2017: an update on the connection between breast cancer and the environment

BACKGROUND

In this review, we examine the continually expanding and increasingly compelling data linking radiation and various chemicals in our environment to the current high incidence of breast cancer. Singly and in combination, these toxicants may have contributed significantly to the increasing rates of breast cancer observed over the past several decades. Exposures early in development from gestation through adolescence and early adulthood are particularly of concern as they re-shape the program of genetic, epigenetic and physiological processes in the developing mammary system, leading to an increased risk for developing breast cancer. In the 8 years since we last published a comprehensive review of the relevant literature, hundreds of new papers have appeared supporting this link, and in this update, the evidence on this topic is more extensive and of better quality than that previously available.

CONCLUSION

Increasing evidence from epidemiological studies, as well as a better understanding of mechanisms linking toxicants with development of breast cancer, all reinforce the conclusion that exposures to these substances - many of which are found in common, everyday products and byproducts - may lead to increased risk of developing breast cancer. Moving forward, attention to methodological limitations, especially in relevant epidemiological and animal models, will need to be addressed to allow clearer and more direct connections to be evaluated.

Methylparaben and butylparaben alter multipotent mesenchymal stem cell fates towards adipocyte lineage

Paraben esters and their salts are widely used as preservatives in cosmetics, personal care products, pharmaceuticals, and foods. We previously reported that parabens promoted adipocyte differentiation in vitro and increased adiposity but suppressed serum marker of bone formation in vivo. Here, we investigated the effects of parabens (methylparaben and butylparaben) on modulating cell fate of multipotent stem cell line C3H10T1/2. Both parabens modulated adipogenic, osteogenic, and chondrogenic differentiation of C3H10T1/2 cells in vitro. Butylparaben markedly promoted adipogenic differentiation, but suppressed osteogenic and chondrogenic differentiation whereas methylparaben showed similar but less pronounced effects. Moreover, butylparaben, but not methylparaben, was shown to activate peroxisome proliferator-activated receptor (PPAR) γ whereas neither of the paraben was shown to activate glucocorticoid receptor (GR) responsive reporter in C3H10T1/2 cells. The adipogenic effects of butylparaben were significantly attenuated by PPARγ knockdown, but not by GR knockdown. In contrast, paraben's effects on osteoblast differentiation were affected by both knockdowns. Collectively, the results demonstrate opposing effects of parabens on adipogenic and osteoblastogenic/chondrogenic differentiation of multipotent stem cells. In light of the recent findings that parabens are detected in human placenta and milk, our studies provide rationales to study paraben exposure during early development of life in the future.

The insect repellents: A silent environmental chemical toxicant to the health

In recent years, a large number of insect repellents have been developed with the idea of consumer benefits. In addition to already known advantageous application of insect repellents, there is increasing concern about the potential toxicity in environment leading to health caused by random use of these compounds. An increasing number of evidence suggests that insect repellents may trigger undesirable hazardous interactions with biological systems with a potential to generate harmful effects including intermediate metabolites. Biotransformation followed by bioaccumulation (vice e versa) may be an important phenomenon for toxic response of this chemicals. In this review, we have summarized the current state of knowledge on the insect repellent toxicity, including biochemical pathway alteration under in vitro and in vivo conditions considering different classes of organisms, from lower to higher vertebrate. Furthermore, we have tried to incorporate the effects of insect repellent in light of some clinical reports. We hope this review would provide useful information on potential side effects of uncontrolled use of insect repellents.