Estrogenic potency of food-packaging-associated plasticizers and antioxidants as detected in ERalpha and ERbeta reporter gene cell lines

Antimicrobial, Preservative, and Hazard Assessments from Eight Chemical Classes

Preservatives, such as isothiazolinones and formaldehyde-releasing compounds, provide safety and stability in consumer products by preventing microbial contamination. Yet these ingredients present human and environmental hazards, including allergic contact dermatitis and aquatic toxicity. The development of safer alternatives has been stymied by trade-offs between safety and efficacy. To enable the identification of safer preservatives, substances from eight functional classes were assessed for antimicrobial efficacy and human and environmental hazards. First, 130 substances were evaluated for microbial inhibitory activity against two relevant model microorganisms, Aspergillus brasiliensis (filamentous fungi) and Pseudomonas aeruginosa (Gram-negative bacteria). High-performing compounds within each class were assessed for hazards across a broad suite of human and environmental health end points. Four promising compounds were selected for further testing based on microbial inhibition, hazard profiles, and commercial availability. These ingredients were tested for biocidal activity in model home care formulations using methods adapted from industrial preservative challenge guidelines (USP-51). Two substances were identified, caprylhydroxamic acid and caprylyl glycol, that provided adequate preservation and improved toxicity profiles compared to isothiazolinone and formaldehyde-releasing preservatives. This study highlights trade-offs between antimicrobial activity and hazards across a broad spectrum of chemical classes relevant to safer preservative development.

Safety Assessment of Trialkyl Trimellitates as Used in Cosmetics

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of 5 trialkyl trimellitates. These ingredients, which are all structurally related as alkyl esters of trimellitic acid, are reported to function in cosmetics as skin conditioning agents; 2 of the ingredients are also reported to function in cosmetics as plasticizers. The Panel reviewed the available data to determine the safety of these ingredients, and concluded that the trialkyl trimellitates are safe in the current practices of use and concentration when formulated to be non-irritating.

A review of the occurrence, metabolites and health risks of butylated hydroxyanisole (BHA)

Butylated hydroxyanisole (BHA) is mainly used as a food additive due to its antioxidant properties, which prevent or delay oxidation reactions and extend the storage life of products. The widespread use of BHA has led to its extensive presence in various environmental matrices and human tissues. Food intake is the main route of human exposure to BHA. Under different conditions, BHA can produce different metabolites, with tert-butyl hydroquinone (TBHQ) being one of the major products. Several studies have shown that BHA could cause thyroid system damage, metabolic and growth disorders, neurotoxicity, and carcinogenesis. Mechanisms such as endocrine disruption, genotoxicity, disturbances of energy metabolism, reactive oxygen species (ROS) production, signaling pathways, and imbalances in calcium homeostasis appear to be associated with the toxic effects of BHA. Avoiding the toxic effects of BHA to the maximum extent possible is a top priority. Finding safe, non-toxic and environmentally friendly alternatives to BHA should be the focus of subsequent research. In all, this review summarized the current situation related to BHA and might make recommendations for future research directions. © 2023 Society of Chemical Industry.

Tailoring Oligomeric Plasticizers for Polylactide through Structural Control

Structural variations (oligolactide segments, functionalized end groups, and different plasticizer cores) were utilized to tailor the performances of biobased plasticizers for polylactide (PLA). Six plasticizers were developed starting from 1,4-butanediol and isosorbide as cores: two monomeric (1,4-butanediol levulinate and isosorbide levulinate) and four oligomeric plasticizers with hydroxyl or levulinate ester end groups (1,4-butanediol-based oligolactide, isosorbide-based oligolactide, 1,4-butanediol-based oligomeric levulinate, and isosorbide-based oligomeric levulinate). Structural variations in plasticizer design were reflected in the thermal stability, plasticizing efficiency, and migration resistance. The monomeric plasticizer 1,4-butanediol levulinate decreased the glass-transition temperature of PLA from 59 to 16 °C and increased the strain at break substantially from 6 to 227% with 20 wt % addition. 1,4-Butanediol-based oligomeric levulinate exhibited better thermal stability and migration resistance, though the plasticizing efficiency was slightly lower (glass-transition temperature = 28 °C; strain at break = 202%). Compared to PLA films plasticized by plasticizers with flexible butanediol cores, those plasticized by plasticizers with rigid isosorbide cores exhibited higher Young's modulus and thermal stability and lower plasticizing efficiency. Furthermore, plasticizers with levulinate ester end groups had improved thermal stability, plasticizing efficiency, and migration resistance compared to the corresponding plasticizers with hydroxyl end groups. Hence, a set of controlled structural variations in plasticizer design were successfully demonstrated as a potent route to tailor the plasticizer performances.

Lipase-catalyzed one-step regioselective synthesis of 1,2-dioctanoylgalloylglycerol in a solvent-free system: Optimization of reaction conditions and structural elucidation

A multi-functional galloylated structured lipid, 1,2-dioctanoylgalloylglycerol (DOGG), was synthesized enzymatically via a regioselective transesterification of propyl gallate and trioctanoate using an immobilized food-grade Candida antarctica lipase B (Lipozyme® 435) as the biocatalyst under solvent-free condition. The variables that affect the reaction, including reaction temperature, substrate ratio, reaction time, and enzyme load, were evaluated and optimized using Taguchi method and response surface methodology. Both methods predicted the same optimal reaction condition, resulting in a 68.8 ± 1.3% DOGG yield with reaction selectivity of 82.9 ± 0.6% at 90 °C, 25/1 trioctanoate/PG (mol/mol), 72 h reaction, and 25% enzyme load relative to the total substrate weight. The structure of the reaction product was elucidated using NMR spectroscopy and ESI-HRMS, confirming the regioselectivity of the reaction. Enzyme retained 50% of its activity after 5 cycles of reuse. It is feasible to synthesize DOGG as a potential antioxidant and nutraceutical using Lipozyme® 435.

In Vivo Study of The Oestrogenic Activity of Milk

Introduction

Milk has been suggested to be a possible source of oestrogenically active compounds. In order to assess the health risk for milk consumers and ensure the safety of this staple part of the human diet, it is important to study the effect of xenooestrogen mixtures present in milk. This investigation used the available in vivo model to learn to what extent such compounds may be endocrine disruptors.

Material and Methods

The recommended immature golden hamster uterotrophic bioassay was chosen. A total of 132 animals were divided into nine groups of experimental animals and positive and negative control groups, each of 12 animals. The experimental females received ad libitum either one of five samples of raw cow’s milk from individual animals or one of four samples of pasteurised or ultra-high temperature treated cow’s milk as retail products. After 7 days, the animals were sacrificed and necropsied. Uterine weight increases were measured as the endpoint of oestrogenic activity in milk.

Results

The milk samples from individual cows and the retail milk samples did not show oestrogenic activity. However, in three groups, decreased uterine weights were observed.

Conclusion

Considering that milk supplies are beneficial to health, contamination in this food should be avoided. There is a need for further animal experiments and epidemiological studies are warranted to evaluate any causative role of milk in human endocrinological disorders.

A prominent environmental endocrine disruptor, 4-nonylphenol, promotes endometriosis development via plasmacytoid dendritic cells

Endometriosis is an estrogen-dependent chronic inflammatory disease and is associated etiologically with environmental endocrine disruptor (EED) exposure. 4-nonylphenol (NP), a widely found EED, has weak estrogenic activity and modulates plasmacytoid dendritic cell (pDC) function in vitro and in vivo. We aimed to elucidate the immunomodulatory effect of NP on the development of endometriosis, particularly focusing on pDCs. This study established a surgically induced endometriosis murine model (C57BL/6) under conditions of NP treatment that are relevant to the level and route of human exposure. Multi-parametric flow cytometry was used for analysis of infiltrated immune cell subsets in lesions. The results showed that NP exposure significantly promoted endometriotic lesion growth, survival and angiogenesis development of lesions as well as pDC accumulation in the lesions in mice. Adoptive transfer of NP-conditioned pDCs into mice significantly enhanced lesion development and local pDC infiltration, whereas NP-conditioned conventional dendritic cells did not affect lesion growth. In vitro functional analysis showed that NP-conditioned pDCs in lesions expressed high levels of CD36, a scavenger receptor and NP-conditioned splenic pDCs secreted an enhanced level of IL-10 in response to apoptotic cell recognition in a CD36-dependent manner. Furthermore, we observed that local treatment with blocking antibodies against IL-10 and CD36 on the day of surgery significantly inhibited lesion development. NP exposure also altered the estrous cycle in mice. The results suggest that chronic and low-dose exposure to NP enhances endometriotic lesion growth by altering pDC homeostasis and function. This study has important implications for understanding the environment-innate immunity interaction in human endometriosis.

Development of a Web-Based Toolbox to Support Quantitative In-Vitro-to-In-Vivo Extrapolations (QIVIVE) within Nonanimal Testing Strategies

The goal of the present study was to develop an online web-based toolbox that contains generic physiologically based kinetic (PBK) models for rats and humans, including underlying calculation tools to predict plasma protein binding and tissue:plasma distribution, to be used for quantitative in-vitro-to-in-vivo extrapolations (QIVIVE). The PBK models within the toolbox allow first estimations of internal plasma and tissue concentrations of chemicals to be made, based on the logP and pKa of the chemicals and values for intestinal uptake and intrinsic hepatic clearance. As a case study, the toolbox was used to predict oral equivalent doses of in vitro ToxCast bioactivity data for the food additives methylparaben, propyl gallate, octyl gallate, and dodecyl gallate. These oral equivalent doses were subsequently compared with human exposure estimates, as a low tier assessment allowing prioritization for further assessment. The results revealed that daily intake levels of especially propyl gallate can lead to internal plasma concentrations that are close to in vitro biological effect concentrations, particularly with respect to the inhibition of human thyroid peroxidase (TPO). Estrogenic effects were not considered likely to be induced by the food additives, as daily exposure levels of the different compounds remained 2 orders of magnitude below the oral equivalent doses for in vitro estrogen receptor activation. Overall, the results of the study show how the toolbox, which is freely accessible through www.qivivetools.wur.nl, can be used to obtain initial internal dose estimates of chemicals and to prioritize chemicals for further assessment, based on the comparison of oral equivalent doses of in vitro biological activity data with human exposure levels.

Thyroid Receptor Antagonism of Chemicals Extracted from Personal Silicone Wristbands within a Papillary Thyroid Cancer Pilot Study

Research suggests that thyroid cancer incidence rates are increasing, and environmental exposures have been postulated to be playing a role. To explore this possibility, we conducted a pilot study to investigate the thyroid disrupting bioactivity of chemical mixtures isolated from personal silicone wristband samplers within a thyroid cancer cohort. Specifically, we evaluated TRβ antagonism of chemical mixtures extracted from wristbands (n = 72) worn by adults in central North Carolina participating in a case-control study on papillary thyroid cancer. Sections of wristbands were solvent-extracted and analyzed via mass spectrometry to quantify a suite of semivolatile chemicals. A second extract from each wristband was used in a bioassay to quantify TRβ antagonism in human embryonic kidney cells (HEK293/17) at concentrations ranging from 0.1 to 10% of the original extract (by volume). Approximately 70% of the sample extracts tested at a 1% extract concentration exhibited significant TRβ antagonism, with a mean of 30% and a range of 0-100%. Inhibited cell viability was noted in >20% of samples that were tested at 5 and 10% concentrations. Antagonism was positively associated with wristband concentrations of several phthalates, organophosphate esters, and brominated flame retardants. These results suggest that personal passive samplers may be useful in evaluating the bioactivities of mixtures that people contact on a daily basis. We also report tentative associations between thyroid receptor antagonism, chemical concentrations, and papillary thyroid cancer case status. Future research utilizing larger sample sizes, prospective data collection, and measurement of serum thyroid hormone levels (which were not possible in this study) should be utilized to more comprehensively evaluate these associations.

Exploring the Potential of ToxCast Data in Supporting Read-Across for Evaluation of Food Chemical Safety

The intention of this study was to determine the utility of high-throughput screening (HTS) data, as exemplified by ToxCast and Tox21, for application in toxicological read-across in food-relevant chemicals. Key questions were addressed on the extent to which the HTS data could provide information enabling (1) the elucidation of underlying bioactivities associated with apical toxicological outcomes, (2) the closing of existing toxicological data gaps, and (3) the definition of the boundaries of chemical space across which bioactivity could reliably be extrapolated. Results revealed that many biological targets apparently activated within the chemical groupings lack, at this time, validated toxicity pathway associations. Therefore, as means of providing proof-of-principle, a comparatively well-characterized end point-estrogenicity-was selected for evaluation. This was facilitated through the preparation of two exploratory case studies, focusing upon groupings of paraben-gallates and pyranone-type compounds (notably flavonoids). Within both, the HTS data were seen to reflect estrogenic potencies in a manner which broadly corresponded to established structure-activity group relationships, with parabens and flavonoids displaying greater estrogen receptor affinity than benzoate esters and alternative pyranone-containing molecules, respectively. As such, utility in the identification of out-of-domain compounds was demonstrated, indicating potential for application in addressing point (3) as detailed above.

Safety and efficacy of propyl gallate for all animal species

Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of propyl gallate as feed additive for all animal species. Propyl gallate is neither genotoxic nor carcinogenic. Propyl gallate a is safe for veal calves, cattle for fattening, dairy cows, sheep, goats, sows, horses and salmonids at the proposed maximum use level of 40 mg/kg and for ornamental fish at the proposed maximum use level of 100 mg/kg. The following concentrations (mg/kg complete feed) are considered safe for the other target species: 15 for chickens for fattening; 20 for turkeys for fattening, laying hens and rabbits; 27 for piglets and pigs for fattening and 71 for dogs. The Panel cannot conclude on a safe level for cats. The exposure of the consumer to propyl gallate and its metabolites cannot be estimated owing to the absence of reliable data on residues of propyl gallate and its metabolites in edible tissues and products. Therefore, the FEEDAP Panel is not in the position to conclude on the safety for the consumer of propyl gallate, when used as a feed additive for all food-producing animal species. Propyl gallate is irritant to skin and eyes and a dermal sensitiser. Exposure via inhalation is possible and it is considered a hazard. The use of the additive in animal nutrition does not pose a risk for the environment. The FEEDAP Panel concludes that propyl gallate has the potential to act as an antioxidant in feedingstuffs. The Panel did not see a reason for the use of propyl gallate as an antioxidant in water for drinking.

Fish and Seabird Gut Conditions Enhance Desorption of Estrogenic Chemicals from Commonly-Ingested Plastic Items

Plastic is ingested by over 100 bird species and 40 fish species. Once ingested, plastic may release endocrine-disrupting plastic additives in the animal; however, amounts transferred are poorly characterized. We exposed 16 commonly ingested plastic items to fish and seabird laboratory gut mimic models using the digestive enzyme pepsin at pH 2 and shook them for 16 h at either 28 °C (in saltwater) for fish or 40 °C (in freshwater) for seabirds. Gut liquid was then evaluated for estrogen receptor activity using an in vitro cell line, and plastic-additive concentrations were quantified using ultrahigh-performance liquid chromatography/tandem mass spectrometry. Both seabird ( p < 0.0001) and fish gut conditions ( p < 0.0001) significantly enhanced the biological estrogenicity of expanded polystyrene, polyethylene shopping bag, and polypropylene string relative to controls, resulting in up to a 10.6-fold increase in estrogenicity. Out of 12 plastic additives analyzed, bisphenol A (BPA) (204 ± 129%) and diethylhexyl phthalate (DEHP) (175 ± 97%) concentrations were significantly increased in seabird gut conditions relative to control and butylbenzyl phthalate (BBP) (132 ± 68%) was significantly increased in fish gut conditions relative to control. BPA, DEHP, and BBP did not adequately account for the increase in biological estrogenicity, suggesting that uncharacterized plastic additives may have been enhanced by gut conditions.

Nonylphenol can aggravate allergic rhinitis in a murine model by regulating important Th cell subtypes and their associated cytokines

Nonylphenol (NP) is a widely distributed, toxic endocrine-disrupting chemical exhibiting estrogenic activity. However, its effect on allergic rhinitis (AR) remains unclear. In this study, the effects of NP on a murine model of AR were investigated. Mice were divided into ovalbumin (OVA), NP, and control groups. OVA was used for sensitization and challenge. Mice in the NP group were administered NP during the sensitization period. Allergic nasal symptoms and eosinophil counts in nasal mucosa were measured. Serum levels of OVA-specific IgE were determined by enzyme-linked immunosorbent assay. The mRNA levels of transcription factors of Th cells were determined with real-time polymerase chain reaction. Th cell subtypes and Treg numbers were counted with the aid of multi-color flow cytometry. Cytokine concentrations in nasal mucosa were determined using the cytometric bead array method. Subcutaneous injection of NP into mice exhibiting AR enhanced not only the nasal allergic symptoms, but also eosinophil infiltration and OVA-specific IgE. Moreover, NP upregulated IL-4, IL-5, IL-13, IL-9, IL-6 and IL-17, and downregulated IL-10, in the AR mouse model; IFN-γ and IL-23 were not affected. Transcription factors and Th cell percentages were evaluated to determine whether NP regulates Th cell subtypes in an AR mouse model. GATA3, PU.1, and RORγt levels were significantly increased, but FoxP3 and Helios were decreased. In addition, Th2, Th9, and Th17 subtype percentages significantly increased, and Treg cell percentages decreased, in NP administration groups; the percentage of Th1 subtypes was not affected. NP enhanced allergic inflammation in the AR mouse model through upregulation of Th2, Th9, and Th17 responses and negative regulation of Treg responses. These results suggest that NP may be trigger AR.

Simulated digestion of polystyrene foam enhances desorption of diethylhexyl phthalate (DEHP) and In vitro estrogenic activity in a size-dependent manner

Marine polychaetes and fish are known to ingest polystyrene microparticles in the environment. Laboratory microplastic feeding experiments have demonstrated that plastic may release endocrine-disrupting compounds such as diethylhexyl phthalate (DEHP), which can cause adverse effects in both vertebrates and invertebrates. In order to determine the influence of size and digestive conditions on the desorption of DEHP and other plasticizers to polychaetes and fish, we exposed polystyrene particles of various sizes under invertebrate and vertebrate digestive conditions (vertebrate mimic; pepsin, pH = 2.0, 24 °C, invertebrate mimic; Na taurocholate pH = 7, 18 °C). Estrogen receptor activation and concentrations of 12 plasticizers were measured in the extracts. DEHP, bisphenol S and 4-tert-octylphenol were the only compounds detected. Simulated vertebrate gut digestion did not significantly enhance the release of chemicals nor estrogenic activity. However, a 6.3 ± 2.0-fold increase in the concentration of DEHP was observed in extracts from invertebrate gut conditions (Mean ± SD; N = 24, p < 0.0001). Additionally, estimated particle surface area was positively correlated with estrogenic activity across all treatment types (r = 0.85, p < 0.0001). Overall, these data indicate an elevated bioaccessibility of DEHP may occur in invertebrates, and size-dependent desorption of uncharacterized estrogenic compounds from plastic suggest additional complexity when considering the risks of MP to aquatic organisms.

Antioxidant responses and DNA damage in primary hepatocytes of Van fish (Alburnus tarichi, Güldenstadt 1814) exposed to nonylphenol or octylphenol

Alkylphenols, a nonionic surface-active agent group, such as nonylphenol (NP) and octylphenol (OP) are important endocrine-disrupting chemicals (EDC). In this study, the dose- and time-dependent effects of NP and OP were investigated in the primary hepatocyte culture of Van Fish. In this study, samples were taken at different times and biochemical parameters were studied separately. The effects of the chemicals used on SOD, CAT, GSH-Px, MDA, and 8-OHdG were investigated in hepatocyte culture. The antioxidants SOD and CAT were observed to increase in all groups in the primary hepatocyte cultures at the 24th hour after NP and OP administration, whereas the GSH-Px level was observed to increase with OP at the 24th hour and with NP at the 48th hour. The MDA level was observed to reach its highest value for both chemicals in the 24th hour, and the 8-OHdG level was observed to increase toward the end of the follow-up time, compared to the control group (p < 0.05). In conclusion, different doses of NP and OP were found to induce an increase in the levels of antioxidants and the MDA level in Van Fish primary hepatocyte culture. DNA damage, on the other hand, may be considered to appear after longer-term exposure to NP and OP.

Synthetic Phenolic Antioxidants Cause Perturbation in Steroidogenesis in Vitro and in Vivo

Synthetic phenolic antioxidants (SPAs) are closely correlated with human life due to their extensive usages, and increasing concerns have been raised on their biosafety. The previous controversial findings caused continuous debates on their potential endocrine disrupting effects. In the present study, four commonly used SPAs, including butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ) and 2,2'-methylenebis(6-tert-butyl-4-methylphenol) (AO2246), were investigated for their estrogenic effects, and the results from in vitro screening assays showed SPAs themselves had negligible estrogen receptor binding affinities. Nevertheless, significant increase in E₂ secretion was observed in H295R cells treated with SPAs, especially for BHA. The transcriptional levels of steroidogenic enzymes, including StAR, 3βHSD, CYP11B1, and CYP11B2 were up-regulated via the mediation of protein kinase A (PKA) signaling pathway. In vivo experiment confirmed that waterborne exposure to BHA disturbed E₂ and testosterone (T) levels in zebrafish gonad, thus causing potential estrogenic effects through the regulation of hypothalamic-pituitary-gonadal-liver axis (HPGL-axis). Accordingly, this study has provided new insights for SPA-induced endocrine disrupting effects. Considering the allowable maximum level of individual BHA or in combination with TBHQ and BHT in foodstuffs (200 mg kg^-1), the perturbation in steroidogenesis observed for relatively low concentrations of SPAs would need more public attention.

Risks and benefits related to alimentary exposure to xenoestrogens

Xenoestrogens are widely diffused in the environment and in food, thus a large portion of human population worldwide is exposed to them. Among alimentary xenoestrogens, phytoestrogens (PhyEs) are increasingly being consumed because of their potential health benefits, although there are also important risks associated to their ingestion. Furthermore, other xenoestrogens that may be present in food are represented by other chemicals possessing estrogenic activities, that are commonly defined as endocrine disrupting chemicals (EDCs). EDCs pose a serious health concern since they may cause a wide range of health problems, starting from pre-birth till adult lifelong exposure. We herein provide an overview of the main classes of xenoestrogens, which are classified on the basis of their origin, their structures and their occurrence in the food chain. Furthermore, their either beneficial or toxic effects on human health are discussed in this review.

Exposure of hospitalised pregnant women to plasticizers contained in medical devices

Background

Medical devices (MDs) in polyvinyl chloride (PVC) are not a well-known source of exposure to plasticizers, in particular during pregnancy. Because of its toxicity, the di-(2-ethylhexyl) phthalate (DEHP) has been replaced by other plasticizers such as di (isononyl)-cyclohexane-1,2-dicarboxilic acid (DINCH), tri-octyltrimellitate (TOTM) and di-(isononyl) phthalate (DiNP). Our study aimed to quantify the plasticizers (DEHP and alternative plasticizers) contained in PVC medical devices used for hospitalised pregnant women and to describe which these MDs had been used (type, number, duration of exposure).

Methods

The plasticizers contained in the MDs used for daily care in the Obstetrics Department of a French University Hospital were extracted from PVC (after contact with a chloroform solution), identified and quantified by gas-chromatography-mass-spectrometry analysis. A total of 168 pregnant women hospitalised in the Obstetrics Department with at least one catheter were included in the observational study. The median number of MDs containing plasticizers used and the daily duration of exposure to the MDs were compared in three groups of pregnant women: “Pathology group” (women hospitalised for an obstetric disorder who did not give birth during this hospitalisation; n = 52), “Pathology and delivery group” (hospitalised for an obstetric disorder and who gave birth during this stay; n = 23) and “Delivery group” (admitted for planned or spontaneous delivery without obstetric disorder; n = 93).

Results

DiNP, TOTM and DINCH were the predominant plasticizers contained in the MDs at an amount of 29 to 36 g per 100 g of PVC. Women in the “Pathology group” (preterm labour or other pathology) were exposed to a median number of two MDs containing TOTM and one MD containing DiNP, fewer than those in the “Pathology and delivery group” (p < 0.05). Women in the “Pathology group” had a median exposure of 3.4 h/day to MDs containing DiNP and 8.2 h/day to MDs containing TOTM, longer than those in the “Delivery group” (p < 0.01).

Conclusions

Our study shows that the medical management of pregnant women in a hospital setting entails exposure to MDs containing alternative plasticizers (DiNP, TOTM and DINCH).

Electronic supplementary material

The online version of this article (doi:10.1186/s12905-017-0398-7) contains supplementary material, which is available to authorized users.

The potential health effects of dietary phytoestrogens

Phytoestrogens are plant-derived dietary compounds with structural similarity to 17-β-oestradiol (E2), the primary female sex hormone. This structural similarity to E2 enables phytoestrogens to cause (anti)oestrogenic effects by binding to the oestrogen receptors. The aim of the present review is to present a state-of-the-art overview of the potential health effects of dietary phytoestrogens. Various beneficial health effects have been ascribed to phytoestrogens, such as a lowered risk of menopausal symptoms like hot flushes and osteoporosis, lowered risks of cardiovascular disease, obesity, metabolic syndrome and type 2 diabetes, brain function disorders, breast cancer, prostate cancer, bowel cancer and other cancers. In contrast to these beneficial health claims, the (anti)oestrogenic properties of phytoestrogens have also raised concerns since they might act as endocrine disruptors, indicating a potential to cause adverse health effects. The literature overview presented in this paper illustrates that several potential health benefits of phytoestrogens have been reported but that, given the data on potential adverse health effects, the current evidence on these beneficial health effects is not so obvious that they clearly outweigh the possible health risks. Furthermore, the data currently available are not sufficient to support a more refined (semi) quantitative risk-benefit analysis. This implies that a definite conclusion on possible beneficial health effects of phytoestrogens cannot be made.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Human sex hormone-binding globulin as a potential target of alternate plasticizers: an in silico study

BACKGROUND

Currently, alternate plasticizers are used to replace phthalate plasticizers in children's toys, medical equipments and food packaging, due to the adverse effects of phthalate compounds on human health and laws prohibiting their use. Current information regarding the safety and potential adverse effects of alternate plasticizers is limited and recent studies have found alternate plasticizers to display similar characteristics to those observed in phthalate plasticizers. This study was undertaken to evaluate and predict the potential endocrine disrupting activity of the three most commonly used alternate plasticizers: di(2-ethylhexyl)terephthalate (DEHT), tris(2-ethylhexyl)trimellitate (TOTM), and diisononyl hexahydrophthalate (DINCH) against human sex hormone-binding globulin (SHBG) using in silico approaches.

MATERIALS AND METHODS

The crystal structure of human SHBG (Id: 1D2S) was retrieved from Protein Data Bank. PubChem database was searched for the structures of alternate plasticizers, DEHT, TOTM, and DINCH. Docking was performed using Glide (Schrodinger) Induced Fit Docking module.

RESULTS

Induced Fit Docking of three alternate plasticizer compounds indicated that each of the three compounds fitted well into the steroid binding pocket of SHBG. Docking displays showed interactions of alternate plasticizers with 25-30 amino-acid residues of SHBG; 18-20 amino residues overlapped between the natural ligand, DHT, and the three compounds (commonality of 82-91 %). The hydrogen-bonding interaction of the amino-acid residue, Asn-82, of SHBG was also present in displays of DHT and all the three alternate phthalates. The binding affinity of all the three alternate phthalates was higher than DHT; maximum in DINCH followed by TOTM and DEHT.

CONCLUSION

Our results suggested that the three alternate plasticizers have potential to engage the important interacting residues of SHBG and thus interfere in its steroid homeostatic function.

The metabolite 3,4,3',4'-tetrachloroazobenzene (TCAB) exerts a higher ecotoxicity than the parent compounds 3,4-dichloroaniline (3,4-DCA) and propanil

3,4,3',4'-tetrachloroazobenzene (TCAB) is not commercially manufactured but formed as an unwanted by-product in the manufacturing of 3,4-dichloroaniline (3,4-DCA) or metabolized from the degradation of chloranilide herbicides, like propanil. While a considerable amount of research has been done concerning the toxicological and ecotoxicological effects of propanil and 3,4-DCA, limited information is available on TCAB. Our study examined the toxicity of TCAB in comparison to its parent compounds propanil and 3,4-DCA, using a battery of bioassays including in vitro with aryl hydrocarbon receptor (AhR) mediated activity by the 7-ethoxyresorufin-O-deethylase (EROD) assay and micro-EROD, endocrine-disrupting activity with chemically activated luciferase gene expression (CALUX) as well as in vivo with fish embryo toxicity (FET) assays with Danio rerio. Moreover, the quantitative structure activity response (QSAR) concepts were applied to simulate the binding affinity of TCAB to certain human receptors. It was shown that TCAB has a strong binding affinity to the AhR in EROD and micro-EROD induction assay, with the toxic equivalency factor (TEF) of 8.7×10(-4) and 1.2×10(-5), respectively. TCAB presented to be a weak endocrine disrupting compound with a value of estradiol equivalence factor (EEF) of 6.4×10(-9) and dihydrotestosterone equivalency factor (DEF) of 1.1×10(-10). No acute lethal effects of TCAB were discovered in FET test after 96h of exposure. Major sub-lethal effects detected were heart oedema, yolk malformation, as well as absence of blood flow and tail deformation. QSAR modelling suggested an elevated risk to environment, particularly with respect to binding to the AhR. An adverse effect potentially triggering ERβ, mineralocorticoid, glucocorticoid and progesterone receptor activities might be expected. Altogether, the results obtained suggest that TCAB exerts a higher toxicity than both propanil and 3,4-DCA. This should be considered when assessing the impact of these compounds for the environment and also for regulatory decisions.

Estrogenic effects in the influents and effluents of the drinking water treatment plants

Estrogen-like endocrine disrupting compounds (EEDC) such as bisphenol A, nonylphenol, and phthalic acid esters are toxic compounds that may occur in both raw- and drinking water. The aim of this study was to combine chemical- and bioassay to evaluate the risk of EEDCs in the drinking water treatment plants (DWTPs). Fifty-six samples were collected from seven DWTPs located in northern-, central-, and southern Taiwan from 2011 to 2012 and subjected to chemical analyses and two bioassay methods for total estrogenic activity (E-Screen and T47D-KBluc assay). Among of the considered EEDCs, only dibutyl phthalate (DBP) and di (2-ethylhexyl) phthalate (DEHP) were detected in both drinking and raw water samples. DBP levels in drinking water ranged from <MDL to 0.840 μg/L and from <MDL to 0.760 μg/L in raw water. DEHP had higher detection rate (82.1 %) than other compounds and was present in both drinking water and raw water from all the DWTPs. The highest daily drinking water intake calculated for male and female were 0.0823 and 0.115 μg/kg per day. The two selected bioassays were conducted for the first batch of 56 samples and a detection rate of 23 % for estradiol equivalent (EEQ) lower than the LOQ to 1.3 and 15 % for EEQ lower than LOQ to 0.757 for the second 53 samples. Our results showed a good correlation between E-screen and chemical assay which indicates that a combination of both can be used in detecting EEDCs in environmental samples.

Transcriptome profiling and pathway analysis of hepatotoxicity induced by tris (2-ethylhexyl) trimellitate (TOTM) in mice

Tris (2-ethylhexyl) trimellitate (TOTM) is commonly used as an alternative plasticizer for medical devices. But very little information was available on its biological effects. In this study, we investigated toxicity effects of TOTM on hepatic differential gene expression analyzed by using high-throughput sequencing analysis for over-represented functions and phenotypically anchored to complementary histopathologic, and biochemical data in the liver of mice. Among 1668 candidate genes, 694 genes were up-regulated and 974 genes were down-regulated after TOTM exposure. Using Gene Ontology analysis, TOTM affected three processes: the cell cycle, metabolic process and oxidative activity. Furthermore, 11 key genes involved in the above processes were validated by real time PCR. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that these genes were involved in the cell cycle pathway, lipid metabolism and oxidative process. It revealed the transcriptome gene expression response to TOTM exposure in mouse, and these data could contribute to provide a clearer understanding of the molecular mechanisms of TOTM-induced hepatotoxicity in human.

Impact of the nature and concentration of plasticizers on the ability of PVC to sorb drug

The sorption of a drug by an infusion set may dramatically reduce the drug delivery efficiency. In this paper, we investigated how the drug sorption, in static conditions, is affected by the plasticizer's nature and ratio in the case of plasticized PVC, one of the most common material for infusion set tubing. Within the study, the drug concentration in diazepam solutions was studied after contact with PVC films containing different amounts of DEHP, DEHT, TOTM and DINCH® plasticizers. Moreover the partition coefficients between material and water were calculated. The drug sorption levels were equivalent for the different plasticizers and there was a plasticizer ratio for which the drug uptake was enhanced. As a consequence, the amount of sorbed drug might not be only linked to the amount of plasticizer in the film and to the solubility of the drug in the plasticizer alone: it must probably depend on specific interactions between plasticizer and PVC.

Estrogenic endocrine disruptors: Molecular mechanisms of action

A comprehensive summary of more than 450 estrogenic chemicals including estrogenic endocrine disruptors is provided here to understand the complex and profound impact of estrogen action. First, estrogenic chemicals are categorized by structure as well as their applications, usage and effects. Second, estrogenic signaling is examined by the molecular mechanism based on the receptors, signaling pathways, crosstalk/bypassing and autocrine/paracrine/homeostatic networks involved in the signaling. Third, evaluation of estrogen action is discussed by focusing on the technologies and protocols of the assays for assessing estrogenicity. Understanding the molecular mechanisms of estrogen action is important to assess the action of endocrine disruptors and will be used for risk management based on pathway-based toxicity testing.

Estrogenic activity of wastewater, bottled waters and tap water in Finland as assessed by a yeast bio-reporter assay

Aims: Environmental pollutants appearing in wastewater, bottled mineral water, tap water, and bottled drinking water are potential, but yet poorly characterized, sources of human exposure to endocrine disrupting chemicals globally. Here, we investigated the current situation in the most densely populated region in Finland. Methods: Influent and effluent bi-monthly samples from a major wastewater treatment plant in Helsinki were obtained over a preceding 2-year period at two time-points (in 2011 and 2014). Equivalent samples from a household water purification plant (located in the same region) were also analyzed, together with various brands of bottled still and mineral water as well as tap water from residential buildings. Samples were obtained in one liter sterile containers, extracted by solid-phase extraction method, and their estrogenic potential determined by a yeast bioluminescent assay. Results: The estrogenic activities of influent samples from the wastewater treatment plant in Helsinki were generally low (from less than limit of detection to 0.7 ng/L estrogen equivalent quantities (EEQ)), except in March and August 2011, when relatively high levels (14.0 and 7.8 ng/L EEQ, respectively) were obtained. Meanwhile, no estrogenic activity was recorded in any of the treated effluent samples from the wastewater treatment plant, influent and effluent samples from the drinking water plant, as well as tap water, bottled still, and mineral waters. Conclusions: These findings indicate that the purification method applied in Helsinki wastewater treatment plant, activated sludge with mechanical, chemical and biological purification steps, is effective in reducing estrogenic activity, and that tap or bottled waters are not a significant source of these compounds to the population in this region.

Deconjugation of soy isoflavone glucuronides needed for estrogenic activity

Soy isoflavones (SIF) are present in the systemic circulation as conjugated forms of which the estrogenic potency is not yet clear. The present study provides evidence that the major SIF glucuronide metabolites in blood, genistein-7-O-glucuronide (GG) and daidzein-7-O-glucuronide (DG), only become estrogenic after deconjugation. The estrogenic potencies of genistein (Ge), daidzein (Da), GG and DG were determined using stably transfected U2OS-ERα, U2OS-ERβ reporter gene cells and proliferation was tested in T47D-ERβ cells mimicking the ERα/ERβ ratio of healthy breast cells and inT47D breast cancer cells. In all assays applied, the estrogenic potency of the aglycones was significantly higher than that of their corresponding glucuronides. UPLC analysis revealed that in U2OS and T47D cells, 0.2-1.6% of the glucuronides were deconjugated to their corresponding aglycones. The resulting aglycone concentrations can account for the estrogenicity observed upon glucuronide exposure. Interestingly, under similar experimental conditions, rat breast tissue S9 fraction was about 30 times more potent in deconjugating these glucuronides than human breast tissue S9 fraction. Our study confirms that SIF glucuronides are not estrogenic as such, and that the small % of deconjugation in the cell is enough to explain the slight bioactivity observed for the SIF-glucuronides. Species differences in deconjugation capacity should be taken into account when basing risk-benefit assessment of these SIF for the human population on animal data.

Lactational exposure of phthalate causes long-term disruption in testicular architecture by altering tight junctional and apoptotic protein expression in Sertoli cells of first filial generation pubertal Wistar rats

Di(2-ethylhexyl) phthalate (DEHP) is a ubiquitous environmental contaminant and a well-known endocrine disruptor (ED) that interferes with the reproductive function in both humans and animals. This study aimed to find out the impact of lactational exposure of DEHP in testes of first filial generation (F1) progeny male rat postnatal day (PND)-60. Lactating dams were orally treated with DEHP (0, 1, 10 and 100 mg/kg body weight/day, respectively) from the PND-1 to PND-21. Rats were killed at PND 60. Testes were removed and used for histological analysis and for isolation of Sertoli cells (SCs). The histoarchitecture of DEHP-treated rats showed disturbed testicular structure. DEHP-treated rats also showed increased oxidative stress by decreasing antioxidant levels in the SCs; it disrupted SC tight junctional proteins occludin, claudin, junctional adhesion molecule, zona occludens protein-1 (ZO-1), zona occludens protein-2 (ZO-2), and afadin-6 (AF-6), increased apoptosis by altering the apoptotic genes Bax, cytochrome c, caspase-8, -9, -3 and antiapoptotic gene Bcl-2. It is concluded that early postnatal exposure to DEHP disturbs histoarchitecture of testis and SC function in pubertal Wistar rats.

Cell proliferation and modulation of interaction of estrogen receptors with coregulators induced by ERα and ERβ agonists

The aim of the present study was to investigate modulation of the interaction of the ERα and ERβ with coregulators in the ligand responses induced by estrogenic compounds. To this end, selective ERα and ERβ agonists were characterized for intrinsic relative potency reflected by EC50 and maximal efficacy towards ERα and ERβ mediated response in ER selective reporter gene assays, and subsequently tested for induction of cell proliferation in T47D-ERβ cells with variable ERα/ERβ ratio, and finally for ligand dependent modulation of the interaction of ERα and ERβ with coregulators using the MARCoNI assay, with 154 unique nuclear receptor coregulator peptides derived from 66 different coregulators. Results obtained reveal an important influence of the ERα/ERβ ratio and receptor selectivity of the compounds tested on induction of cell proliferation. ERα agonists activate cell proliferation whereas ERβ suppresses ERα mediated cell proliferation. The responses in the MARCoNI assay reveal that upon ERα or ERβ activation by a specific agonist, the modulation of the interaction of the ERs with coregulators is very similar indicating only a limited number of differences upon ERα or ERβ activation by a specific ligand. Differences in the modulation of the interaction of the ERs with coregulators between the different agonists were more pronounced. Based on ligand dependent differences in the modulation of the interaction of the ERs with coregulators, the MARCoNI assay was shown to be able to classify the ER agonists discriminating between different agonists for the same receptor, a characteristic not defined by the ER selective reporter gene or proliferation assays. It is concluded that the ultimate effect of the model compounds on proliferation of estrogen responsive cells depends on the intrinsic relative potency of the agonist towards ERα and ERβ and the cellular ERα/ERβ ratio whereas differences in the modulation of the interaction of the ERα and ERβ with coregulators contribute to the ligand dependent responses induced by estrogenic compounds.

Dietary exposure of Nigerians to mutagens and estrogen-like chemicals

Food and drinking water are poorly delineated sources of human exposure to chemical food mutagens and endocrine-disrupting chemicals. In this study, we investigated the presence of mutagens and chemicals exhibiting estrogenic activity in the daily diet of Nigerians, using in vitro assays. Commercially processed foods or snacks and various brands of pure water sachets were extracted by solid-phase extraction and liquid-liquid extraction, respectively. Mutagenicity was determined by the conventional Ames test and two complementary assays on two strains of Salmonella (TA 100 and TA 98), while the estrogenic activity was assessed by a yeast bioluminescent assay, using two recombinant yeast strains (Saccharomyces cerevisiae BMAEREluc/ERα and S. cerevisiae BMA64/luc). A third of the food varieties investigated (chin-chin, hamburger, suya and bean cake) were mutagenic in all three assays, either in the presence or absence of S9 mix. Of the packed water samples, five out of the sixteen investigated (31%), were found to be estrogenic, with estradiol and bisphenol A equivalents ranging from 0.79 to 44.0 ng/L and 124.2 to 1,000.8 ng/L, respectively. Hence, although the current situation in Nigeria does not appear to be substantially worse than, e.g., in Europe, regular monitoring is warranted in the future.

Identification of coregulators influenced by estrogen receptor subtype specific binding of the ER antagonists 4-hydroxytamoxifen and fulvestrant

The aim of the present study was to investigate modulation of the interaction of ERα and ERβ with coregulators in the ligand dependent responses induced by the ER antagonistic compounds 4OHT and fulvestrant. Comparison with the modulation index (MI) profiles for the ER agonist estradiol (E2) will elucidate whether differences in the (ant)agonist dependent interaction of ERα and ERβ with coregulators expressed in MI profiles contribute to the differences in (ant)agonist responses. To this end, the selected ER antagonistic compounds were first characterized for intrinsic relative potency and efficacy towards ERα and ERβ using ER selective U2OS reporter gene assays, and subsequently tested for ligand dependent modulation of the interaction of ERα and ERβ with coregulators using the MARCoNI assay. Results obtained indicate a preference of 4OHT to antagonize ERβ and find fulvestrant to be less ER specific. MARCoNI assay responses reveal that ERα and ERβ mediated interaction with coregulators expressed in MI profiles are similar for 4OHT and fulvestrant and generally opposite to the MI profile of the ER agonist E2. Hierarchical clustering based on the MI profiles appeared able to clearly discriminate the two compounds with ER antagonistic properties from the ER agonist E2. Taken together the data reveal that modulation of the interaction of ERs with coregulators discriminates ER agonists from antagonists but does not discriminate between the less specific ER antagonist fulvestrant and the preferential ERβ antagonistic compound 4OHT. It is concluded that differences in modulation of the interaction of ERα and ERβ with coregulators contribute to the differences in ligand dependent responses induced by ER agonists and ER antagonists but the importance of the subtle differences in modulation of the interaction of ERs with coregulators between the ER antagonistic compounds 4OHT and fulvestrant for the ultimate biological effect remains to be established.

An integrated approach combining chemical analysis and an in vivo bioassay to assess the estrogenic potency of a municipal solid waste landfill leachate in Qingdao

Various adverse effects related to landfill leachate have made leachates an important issue in past decades, and it has been demonstrated that landfill leachate is an important source of environmental estrogens. In this study, we employed chemical analysis of some already evaluated estrogenic substances, in combination with a bioassay using several specific biomarkers (e.g., plasma vitellogenin and sex steroids, enzyme activity of gonad gamma-glutamyl transpeptidase, and gonadosomatic index) to evaluate the estrogenic activities in outlets from different stages of the leachate treatment process. The results indicated that 5 environmental estrogens (4-t-octylphenol, bisphenol A, di-ethyl phthalate, di-n-butyl phthalate, and diethylhexyl phthalate) were detected by a gas chromatography-mass spectrometry, and the concentrations in leachate samples were 6153 ng/L, 3642 ng/L, 2139 ng/L, 5900 ng/L, and 9422 ng/L, respectively. Leachate (1∶200 diluted) induced the synthesis of plasma vitellogenin and led to decreased enzyme activity of gonad gamma-glutamyl transpeptidase and gonadosomatic index in male goldfish (Carassius auratus) after a 28-day exposure, while increased circulating 17β-estradiol level was also observed in males exposed to treated effluent. Although the target EEs were partially removed with removal rates varying from 87.2% to 99.77% by the “membrane bioreactor+reverse osmosis+aeration zeolite biofilter” treatment process, the treated effluent is still estrogenic to fish. The method combined chemical techniques with the responses of test organisms allowing us to identify the group of estrogen-like chemicals so that we were able to evaluate the overall estrogenic effects of a complex mixture, avoiding false negative assessments.

Isolation and characterization of new phenolic compounds with estrogen biosynthesis-inhibiting and antioxidation activities from Broussonetia papyrifera leaves

Broussonetia papyrifera leaves (BPL) as a traditional Chinese medicine are also used in livestock feed for stimulating reproduction, adipose tissue and muscle development; however, the mechanism of their action is still unknown. Through estrogen biosynthesis-guided fractionation in human ovarian granulosa-like KGN cells, five new phenolic glycosides, broussoside A–E(1–5), along with fifteen known dietary phenolic compounds, were isolated from the n-butanol extract of BPL, and their structures were elucidated on the basis of NMR spectra analysis and chemical evidence. New compounds 3, 4, 5 and the known compounds 9 and 10 were found to potently inhibit estrogen biosynthesis in KGN cells. In addition, compounds 9, 17, 18, and 20 showed strong antioxidant activity against ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) and DPPH (1, 1′-diphenyl -2-picryl-hydrazyl radical) assays. These findings suggest that BPL may improve meat quality through the regulation of estrogen biosynthesis. Furthermore, they may be useful for the discovery of potential aromatase modulators from natural products. Finally, they could be considered as a new source for natural antioxidants.

A common environmental pollutant, 4-nonylphenol, promotes allergic lung inflammation in a murine model of asthma

BACKGROUND

Exposure to environmental hormones, such as alkylphenols, has been suggested to be associated with the development of asthma, but the mechanism of action remains unclear.

OBJECTIVE

This study examined the effect of 4-nonylphenol (NP), one of the most important alkylphenols, on conventional dendritic cells (cDCs) and adaptive T-cell responses. It also explored the role of aryl hydrocarbon receptor (AhR) in NP's effect.

METHODS

NP-conditioned bone marrow-derived DCs (BM-DCs) and splenic CD11c(+) cDCs were assessed regarding function in a murine model under conditions relevant to route and level of exposure in humans.

RESULTS

Our results showed that splenic cDCs from NP-exposed mice have potent Th2-skewing ability and secrete increased levels of IL-6 and TNF-α, but not IL-10 and IL-12, at baseline and after stimulation with LPS. Further, bone marrow-derived DCs were cultured in the presence of NP and showed similar cytokine pattern and influenced the antigen-specific T cells secreting significantly less IFN-γ. Importantly, NP-exposed mice developed more severe OVA-induced allergic lung inflammation compared with control group. Interestingly, in a congenic strain of mice carrying low-affinity, ligand-binding mutant AhR (AhR(d) ), NP's effect on DC functions and lung inflammation was not observed in vitro and in vivo.

CONCLUSION

These results suggested that NP may disturb physiologic function of DCs through, in part, AhR-dependent mechanisms, supporting the importance of NP exposure on the regulation of DC functions and allergic inflammation.

Trigger values for investigation of hormonal activity in drinking water and its sources using CALUX bioassays

To screen for hormonal activity in water samples, highly sensitive in vitro CALUX bioassays are available which allow detection of estrogenic (ERα), androgenic (AR), progestagenic (PR), and glucocorticoid (GR) activities. This paper presents trigger values for the ERα, AR, PR, and GR CALUX bioassays for agonistic hormonal activities in (drinking) water, which define a level above which human health risk cannot be waived a priori and additional examination of specific endocrine activity may be warranted. The trigger values are based on 1) acceptable or tolerable daily intake (ADI/TDI) values of specific compounds, 2) pharmacokinetic factors defining their bioavailability, 3) estimations of the bioavailability of unknown compounds with equivalent hormonal activity, 4) relative endocrine potencies, and 5) physiological, and drinking water allocation factors. As a result, trigger values of 3.8ng 17β-estradiol (E2)-equivalents (eq)/L, 11ng dihydrotestosterone (DHT)-eq/L, 21ng dexamethasone (DEX)-eq/L, and 333ng Org2058-eq/L were derived. Benchmark Quotient (BQ) values were derived by dividing hormonal activity in water samples by the derived trigger using the highest concentrations detected in a recent, limited screening of Dutch water samples, and were in the order of (value) AR (0.41)>ERα (0.13)>GR (0.06)>PR (0.04). The application of trigger values derived in the present study can help to judge measured agonistic hormonal activities in water samples using the CALUX bioassays and help to decide whether further examination of specific endocrine activity followed by a subsequent safety evaluation may be warranted, or whether concentrations of such activity are of low priority with respect to health concerns in the human population. For instance, at one specific drinking water production site ERα and AR (but no GR and PR) activities were detected in drinking water, however, these levels are at least a factor 83 smaller than the respective trigger values, and therefore no human health risks are to be expected from hormonal activity in Dutch drinking water from this site.

Plastics additives and green chemistry

The plastics enterprise depends on a small number of commodity polymers to perform in diverse applications, requiring additives to produce desired properties and performance. Toxic effects and environmental persistence of certain additive chemicals impact the sustainability of the industry. Green chemistry has been and will continue to be applied to find solutions to these issues. This review focuses on alternatives to phthalate plasticizers and halogenated flame retardants, two categories that together account for a significant portion of the global additives market and the global dispersion of endocrine-disrupting chemicals. Small-molecule alternatives that exist in various stages of research and commercialization will be discussed, with emphasis on the use of renewable resources. The rise of biorefineries and new bio-based monomers may help overcome existing economic barriers to adoption of alternatives. Increasing the molecular weight of additives or covalently linking them to polymer backbones are two promising strategies for reducing both mobility and toxicity that will also be discussed. Finally, the design of new polymers that show desirable properties without the use of additives will be considered. The substances put forward as “green” alternatives have yet to receive the same level of scrutiny as diethylhexyl phthalate (DEHP, also known as dioctyl phthalate) or polybrominated diphenyl ethers (PBDEs). Cooperation between chemists, engineers, and the environmental health community will be critical to ensure the safety and sustainability of new technologies.

Alkylphenols--potential modulators of the allergic response

The prevalence of allergic diseases has increased in recent decades. Allergic diseases, particularly asthma, are complex diseases with strong gene-environment interactions. Epidemiological studies have identified a variety of risk factors for the development of allergic diseases. Among them, endocrine-disrupting chemicals (EDCs) play an important role in triggering or exacerbating these diseases. 4-Nonylphenol (NP) and 4-octylphenol (OP)--two major alkylphenols--have been recognized as common toxic and xenobiotic endocrine disrupters. Due to their low solubility, high hydrophobicity, and low estrogenic activity, they tend to accumulate in the human body and may be associated with the adverse effects of allergic diseases. Recently, new evidence has supported the importance of alkylphenols in the in vitro allergic response. This review focuses on the effects of alkylphenols on several key cell types in the context of allergic inflammation.

Anti-inflammatory activity of n-propyl gallate through down-regulation of NF-κB and JNK pathways

The present study aimed to assess anti-inflammatory activity and underlying mechanism of n-propyl gallate, the n-propyl ester of gallic acid. n-Propyl gallate was shown to contain anti-inflammatory activity using two experimental animal models, acetic acid-induced permeability model in mice, and air pouch model in rats. It suppressed production of nitric oxide and induction of inducible nitric oxide synthase and cyclooxygenase-2 in the lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells. It was able to diminish reactive oxygen species level elevated in the LPS-stimulated RAW264.7 macrophage cells. It also suppressed gelatinolytic activity of matrix metalloproteinase-9 enhanced in the LPS-stimulated RAW264.7 macrophage cells. It inhibited inhibitory κB-α degradation and enhanced NF-κB promoter activity in the stimulated macrophage cells. It was able to suppress phosphorylation of c-Jun NH(2)-terminal kinase 1/2 (JNK1/2) and activation of c-Jun promoter activity in the stimulated macrophage cells. In brief, n-propyl gallate possesses anti-inflammatory activity via down-regulation of NF-κB and JNK pathways.

Prenatal and lactational exposure to low-doses of bisphenol A alters adult mice behavior

Bisphenol A (BPA) is an endocrine-disrupting chemical, widely used in dentistry and various industries. We previously reported that BPA affected murine neocortical development by accelerating neuronal differentiation/migration, resulting in abnormal neocortical architecture as well as aberrant thalamocortical connections in the brains of adult mice. The aim of this study was to investigate whether prenatal and lactational BPA exposure affected behavior in adult mice. Pregnant mice were injected subcutaneously with 20μg/kg of BPA daily from embryonic day 0 (E0) until postnatal day 21 (P21). Control animals received a vehicle alone. Behavioral tests (n=15-20) were conducted at postnatal 3weeks (P3W) and P10-15W. After an open-field test, an elevated plus maze and Morris water maze tests were performed. The total distance in the elevated plus maze test at P3W and in the open-field test at P10W was significantly decreased in the BPA-exposed group, compared with the control group. Significant sex differences were observed in the time spent in the central area in the open-field test at P3W and in the total distance in the elevated plus maze test at P11W. These results indicated that prenatal and lactational BPA exposure disturbed the murine behavior in the postnatal development period and the adult mice.

Specific in vitro toxicity of crude and refined petroleum products: 3. Estrogenic responses in mammalian assays

Current petroleum risk assessment considers only narcosis as the mode of action, but several studies have demonstrated that oils contain compounds with dioxin-like, estrogenic or antiestrogenic, and androgenic or antiandrogenic activities. The present study is the third in a series investigating the specific toxic effects of 11 crude oils and refined products. By employing recombinant mammalian cells stably transfected with the human estrogen receptor alpha (ERα) or beta (ERβ), and expressing the luciferase protein (ERα-U2OS-Luc and ERβ-U2OS-Luc assay), the estrogenicity or antiestrogenicity of oils was studied. All oils, except for two refined oils and one crude oil, induced estrogenic responses. The calculated estrogenic potencies of the oils were six to nine orders of magnitude lower than the potency of 17β-estradiol (E2). Upon coexposure to a fixed concentration of E2 and increasing concentrations of oils, additive, antagonistic, and synergistic effects were revealed. One nautical fuel oil was tested in the human breast carcinoma cell line MCF-7, in which it induced cell proliferation up to 70% relative to the maximal induction by E2. At its minimum effect concentration of 25 mg/L, the oil was also capable of inducing mRNA expression of the estrogen-dependent protein pS2 by a factor of two. The present results indicate that oils naturally contain potentially endocrine-disrupting compounds that are able to influence the estrogenicity of other compounds and may cause biological responses beyond receptor binding.