Screening of endocrine activity of compounds migrating from plastic baby bottles using a multi-receptor panel of in vitro bioassays

Aqueous distillate of mature leaves of Vernonia zeylanica (L.) Less. and Mallotus repandus (Rottler) Müll. Arg. cued from traditional medicine exhibits rapid wound healing properties

ETHNOPHARMACOLOGICAL RELEVANCE

Sri Lankan traditional medicine uses Vernonia zeylanica and Mallotus repandus broadly for the treatment of a multitude of disease conditions, including wound healing.

AIM OF THE STUDY

We aimed to scientifically validate the safety and efficacy of wound healing of an aqueous distillate of Vernonia zeylanica and Mallotus repandus (ADVM) mature leaves, tested on primary human dermal fibroblasts.

MATERIALS AND METHODS

Human dermal fibroblasts isolated from clinical waste from circumcision surgery were characterized by flowcytometry and trilineage differentiation. The MTT dye reduction assay, and the ex vivo wound healing scratch assay established wound healing properties of ADVM using the primary human dermal fibroblast cell line. Upregulation of genes associated with wound healing (MMP3, COL3A1, TGFB1, FGF2) were confirmed by RT qPCR. GC-MS chromatography evaluated the phytochemical composition of ADVM.

RESULTS

Compared to the synthetic stimulant, β fibroblast growth factor, ADVM at 0.25% concentration on the primary dermal fibroblast cell line exhibited significant ex vivo, (i) 1.7-fold % cell viability (178.7% vs 304.3 %, p < 0.001), (ii) twofold greater % wound closure (%WC) potential (47.74% vs 80.11%, p < 0.001), and (iii) higher rate of % WC (3.251 vs 3.456 % WC/h, p < 0.05), sans cyto-genotoxicity. Up regulated expression of FGF2, TGFB1, COL3A1 and MMP3, genes associated with wound healing, confirmed effective stimulation of pathways of the three overlapping phases of wound healing (P < 0.05). GC-MS profile of ADVM characterized four methyl esters, which may be posited as wound healing phytochemicals.

CONCLUSIONS

Exceeding traditional medicine claims, the exvivo demonstration of rapid skin regeneration, reiterated by upregulated expression of genes related to wound healing pathways, sans cytotoxicity, propounds ADVM, cued from traditional medicine, as a potential safe and effective natural stimulant for rapid wound-healing. Additionally, it may serve as an effective proliferative stimulant of dermal fibroblasts for cell therapy, with potential in reparative and regenerative therapy of skin disorders.

Migration Studies and Endocrine Disrupting Activities: Chemical Safety of Cosmetic Plastic Packaging

The endocrine activity and endocrine disruptor (ED) chemical profiles of eleven plastic packaging materials covering five major polymer types (3PET, 1HDPE, 4LDPE, 2 PP, and 1SAN) were investigated using in vitro cell-based reporter-gene assays and a non-targeted chemical analysis using gas chromatography coupled to mass spectrometry (GC-MS). To mimic cosmetic contact, six simulants (acidic, alkaline, neutral water, ethanol 30%, glycerin, and paraffin) were used in migration assays performed by filling the packaging with simulant. After 1 month at 50 °C, simulants were concentrated by Solid Phase Extraction (SPE) or Liquid-Liquid Extraction (LLE). The migration profiles of seven major endocrine disrupting chemicals detected from GC-MS in the different materials and simulants were compared with Estrogen Receptor (ER) and Androgen Receptor (AR) activities. With low extraction of ED chemicals in aqueous simulants, no endocrine activities were recorded in the leachates. Paraffin was shown to be the most extracting simulant of antiandrogenic chemicals, while glycerin has estrogenic activities. Overall, ED chemical migration in paraffin was correlated with hormonal activity. The NIAS 2,4-di-tert-butyl phenol and 7,9-di-tert-butyl1-oxaspiro (4,5) deca-6,9-diene-2,8-dione were two major ED chemicals present in all polymers (principally in PP and PE) and in the highest quantity in paraffin simulant. The use of glycerin and liquid paraffin as cosmetic product simulants was demonstrated to be relevant and complementary for the safety assessment of released compounds with endocrine activities in this integrated strategy combining bioassays and analytical chemistry approaches.

Ethylene oxide derived glycol ethers: A review of the alkyl glycol ethers potential to cause endocrine disruption

The 'ethylene glycol ethers' (EGE) are a broad family of solvents and hydraulic fluids produced through the reaction of ethylene oxide and a monoalcohol. Certain EGE derived from methanol and ethanol are well known to cause toxicity to the testes and fetotoxicity and that this is caused by the common metabolites methoxy and ethoxyacetic acid, respectively. There have been numerous published claims that EGE fall into the category of 'endocrine disruptors' often without substantiated evidence. This review systematically evaluates all of the available and relevant in vitro and in vivo data across this family of substances using an approach based around the EFSA/ECHA 2018 guidance for the identification of endocrine disruptors. The conclusion reached is that there is no significant evidence to show that EGE target any endocrine organs or perturb endocrine pathways and that any toxicity that is seen occurs by non-endocrine modes of action.

Assessing the estrogenic activity of chemicals present in resin based dental composites and in leachates of commercially available composites using the ERα-CALUX bioassay

OBJECTIVE

The biocompatibility of resin based dental composites has not yet been fully characterized even though certain monomers used in these composites are synthesized from Bisphenol A (BPA), a well-known estrogenic endocrine disruptor. As a result, they show structural relationship to BPA and can contain it as an impurity. Therefore, the estrogenic activity of 9 monomers, 2 photoinitiators, one photostabilizer and leachates of 4 commercially available composites was determined.

METHODS

The ERα-CALUX bioassay was used to determine both agonistic and antagonistic estrogenic activities of the pure compounds (BPA, BisDMA, BisGMA, BisEMA(3), BisEMA(6), BisEMA(10), TEGDMA, TCD-DI-HEA, BADGE, UDMA, HMBP, DMPA, CQ) and the leachates of cured composite disks. The leachates of 4 commercially available composites (Solitaire 2, Ceram.x Spectra ST, G-ænial Posterior and Filtek Supreme XTE) in water and 0.1 M NaOH (pH = 13, 'worst-case scenario') were tested for estrogenic activity (pooled leachates from 10 cured composite disks).

RESULTS

Agonistic estrogenic activity was found for the monomer BisDMA, the photostabilizer HMBP and photoinitiator DMPA. All leachates from the 4 tested composites showed significant agonistic estrogenic activity higher than the DMSO control, and the highest activity (potency and efficacy) was found for Solitaire 2, followed by Ceram.x Spectra ST. Furthermore, antagonistic estrogenic activity was found in the leachates from G-ænial Posterior.

SIGNIFICANCE

These results show that significant estrogenic activity was found in all leachates of the cured composite disks, and that this estrogenicity is most likely due to a mixture effect of multiple estrogenic compounds (including BPA, HMBP and DMPA). This indicates that further research into the endocrine activity of all the compounds that are present in these composites (even at low quantities) and their possible mixture effect is warranted to guarantee their safe use.

An integrative toxicogenomic analysis of plastic additives

In developed countries, contact with plastics is constant. Plastics contain a vast number of additives such as plasticisers, stabilisers, antioxidants, flame retardants, etc., that can impact human health. Most of them have been studied separately; however, an integrative approach to identify genes, biological processes, molecular functions, and diseases linked to exposure to these compounds has not been addressed until now. The genes most commonly affected by plastic additives are related to apoptosis, cell death, proliferation and differentiation, immunity and insulin-related processes, and are mainly associated with cancer, mental disorders, diabetes mellitus type II and obesity. The most commonly affected molecular functions included steroid hormone receptor activity implicated in cancer, mental disorders, immune signalling and gonadotropin-releasing hormones. These processes and functions affected by plastic additives are related to the diseases of the developed world, most of which are linked to the endocrine system, such as cancer, diabetes, infertility and obesity. The strong interconnection among the top 50 genes modulated by plastic additives shows that the pathways affected are strongly interrelated. Therefore, studying the effects of plastic additives through a single-compound approach cannot be sufficient and a holistic approach is more appropriate for evaluating the potential effects of plastics in human health.

Chlorine Solutions for a Safe Method of Decontamination of Breast Pump Milk Collection Kits Before and After the Coronavirus Disease 2019 Pandemic

To promote breast feeding and breast pumping is essential for the most vulnerable infants even if the current coronavirus disease 2019 (COVID-19) pandemic sanitary crisis imposes more stringent hygienic measures. As recommended by the Centers for Disease Control and Prevention, World Health Organization, and Milk Bank Association, "after each pumping session, all pump part that come into contact with breast milk should be appropriately disinfected." The present study proposed different methods than can be used and focus on the safety analysis of chlorine solution (CS) in terms of residual hypochlorous acid (HCA) and total trihalomethanes (THM). We also performed an efficacy testing of the CS approach to decontaminate the devices used to collect the milk (breast pumps and bottles). The bacteriologic results of 1,982 breast pump milk samples collected in three different settings showed a major decrease of the microbial contamination using either sterile device or decontamination with CS compared to a simple soap washing. The main messages from our study are to propose a guideline for the safe use of CS and to define situations when breast pump decontamination might be necessary: vulnerable babies for which sterile device is recommended; special circumstances, for example the current COVID-19 pandemic; special situations, for example women living in precarious conditions; or women pumping their milk at work but that would have low or no access to boiled water. Overall, cold decontamination reduced losses of milk for bacteriological reasons in human milk banks and may also be interesting to prevent horizontal contamination by virus like COVID-19.

Multivariate optimization of low-temperature cleanup followed by dispersive solid-phase extraction for detection of Bisphenol A and benzophenones in infant formula

A simple and effective analytical method to determine six contaminants, including five benzophenones (BP, BP-1, BP-3, BP-8, and BP-12) and bisphenol A (BPA) in infant formulas was developed in this study. For this, a sequential experimental design was used to optimize the extraction and cleanup method using low temperature partition (LTP) combined with dispersive solid phase extraction (dSPE). The effect of primary secondary amine (PSA), sodium chloride (NaCl), graphitized carbon black (GCB), octadecyl (C18), strong anion exchanger (SAX), water, acetonitrile (ACN) and, ultrasound (US) time were evaluated using a sequential design of experiments including a Plackett-Burman, a central composite rotatable design, and the Derringer and Suich's tool. The method was validated, and it showed a limit of quantification varying from 0.06 to 2 mg.kg^-1, good precision (< 20% RSD), and recovery (52-106%). The method proposed was applied to twenty-five samples of commercial infant formulas.

In vitro profiling of the potential endocrine disrupting activities affecting steroid and aryl hydrocarbon receptors of compounds and mixtures prevalent in human drinking water resources

Prioritizing chemicals posing threats to drinking water resources is crucial for legislation considering the cost of water treatment, remediation, and monitoring. We profiled in vitro potential endocrine disrupting activities (both agonistic and antagonistic) of 18 contaminants most prevalent in Walloon raw water resources intended for drinking water production, including several compound groups: pesticides, perfluorinated compounds, polycyclic aromatic hydrocarbons, a corrosion inhibitor, and bisphenol A. Mixtures thereof relevant for human realistic exposure were also investigated. Seven luciferase reporter gene cell lines were used i.e. three (human and rat) responsive to dioxins through the aryl hydrocarbon receptor (AhR) and four (human) responsive to steroids through the estrogen (ER), androgen (AR), progesterone (PR), and glucocorticoid (GR) receptors. Among the 18 compounds, ten caused at least one response in at least one receptor. Specifically, chlorpyrifos, bisphenol A, fluoranthene, phenanthrene, and benzo [a]pyrene displayed significant activities on several receptors. Bisphenol A agonized ER, but abolished the cells' response to androgen and progesterone. While fluoranthene and phenanthrene strongly reduced human AhR and AR transactivation, benzo [a]pyrene strongly activated AhR and ER, but inhibited GR and AR. In human breast cancer cells, benzo [a]pyrene dramatically activated AhR, inducing a 10-fold higher response than 2,3,7,8-tetrachlorodibenzodioxin (TCDD) at concentrations possibly found realistically in human blood. The mixture of the 18 compounds exerted both ER and rat AhR agonism, with the main contribution being from benzo [a]pyrene or its combination with bisphenol A. Moreover, the mixture significantly inhibited TCDD-induced CYP1A activity (detected only by EROD assays) in human hepatoma cells.

Effects and Mechanisms of Phthalates' Action on Reproductive Processes and Reproductive Health: A Literature Review

The production of plastic products, which requires phthalate plasticizers, has resulted in the problems for human health, especially that of reproductive health. Phthalate exposure can induce reproductive disorders at various regulatory levels. The aim of this review was to compile the evidence concerning the association between phthalates and reproductive diseases, phthalates-induced reproductive disorders, and their possible endocrine and intracellular mechanisms. Phthalates may induce alterations in puberty, the development of testicular dysgenesis syndrome, cancer, and fertility disorders in both males and females. At the hormonal level, phthalates can modify the release of hypothalamic, pituitary, and peripheral hormones. At the intracellular level, phthalates can interfere with nuclear receptors, membrane receptors, intracellular signaling pathways, and modulate gene expression associated with reproduction. To understand and to treat the adverse effects of phthalates on human health, it is essential to expand the current knowledge concerning their mechanism of action in the organism.

Estrogenic activity of food contact materials-evaluation of 20 chemicals using a yeast estrogen screen on HPTLC or 96-well plates

Food contact materials (FCM) may contain complex mixtures of estrogenic chemicals. A yeast estrogen screen performed on high performance thin-layer chromatography plates (planar-YES, P-YES) is promising for analysis of such mixtures, as it could allow for better elucidation of effects compared with established methods in microtiter plates. However, the P-YES has not been directly compared with established methods. We compared the performance of a microtiter plate YES (lyticase-YES, L-YES) to P-YES on silica gel HPTLC plates using 17β-estradiol (E2), 20 chemicals representative of migrants from plastic FCM, and three migrates of coated metal food cans. Effective doses (ED10, ED50) and estradiol equivalencies were calculated for each chemical. Thirteen chemicals had calculable EDs in the L-YES or P-YES, with average EDs 13-fold (range 0.63-36) more potent in P-YES than in the L-YES. Normalized to E2, the median estrogenicity was within 1.5-fold (0.43-8.8) between the assays. Therefore, P-YES was as or more sensitive than L-YES but potencies relative to E2 were comparable between assays. With chromatography, the P-YES detected estrogenicity in coated metal cans, effects that were unmeasurable in L-YES. With the sample preparation methods used in this study, both YES assays are sufficiently sensitive to detect bisphenol A below the specific migration limit for plastic packaging (0.05 mg/kg food). This study demonstrates that P-YES outperforms L-YES because it is more sensitive, provides comparable estradiol equivalents, and circumvents confounding mixture effects. The P-YES will be useful for routine monitoring of FCM and toxicant identification in problematic materials. Graphical abstract.

Environmental Pollutants Modulate Transcriptional Activity of Nuclear Receptors of Whales In Vitro

This study reports the transcriptional activity of fin (Balaenoptera physalus) and blue whale (Balaenoptera musculus) peroxisome proliferator-activated receptor γ (PPARG), glucocorticoid receptor (GR), and thyroid hormone receptor β (THRB), when exposed to 14 persistent organic pollutants (so-called "legacy" persistent organic pollutants (POPs)) and a synthetic mixture of POPs, using GAL4-UAS-based in vitro luciferase reporter gene assays. Polychlorinated biphenyls (PCBs) had both agonistic and antagonistic effects on PPARG and GR, and mainly antagonistic, except for PCB153, effects on THRB. 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites had mainly antagonistic effects on all of the receptors, except for o,p'-DDT. Given that the ligand-binding domain (LBD) of PPARG is the same in killer whales, white whales, polar bears, and humans, and that GR-LBD is identical in killer whales and minke whales and that the LBD of THRB is the same in killer whales, white whales, and humans, it is likely that the results of this study are representative for these other species as well. It is important to note that several environmental pollutants modulated the transcriptional activity of tested nuclear receptors at environmentally relevant concentrations for whales.

GC-MS Screening for the Identification of Potential Migrants Present in Polymeric Coatings of Food Cans

The coatings used in cans can release complex chemical mixtures into foodstuffs. Therefore, it is important to develop analytical methods for the identification of these potential migrant compounds in packaged food to guarantee the compliance with European food packaging legislation and ensure consumer safety. In the present work, the type of coating in a total of twelve cans collected in Santiago de Compostela (Spain) were evaluated using an ATR (attenuated total reflectance)-FTIR spectrometer. These samples were analysed after extraction with acetonitrile in order to identify potential migrants through a screening method by gas chromatography coupled to mass spectrometry (GC-MS). A total of forty-seven volatile and semi-volatile compounds were identified in these samples, including plasticizers, photoinitiators, antioxidants, lubricants, etc. Then, in a second step, a targeted analysis was carried out for the simultaneous determination of 13 compounds, including bisphenols (BPA, BPB, BPC, BPE, BPF, BPG) and BADGEs (BADGE, BADGE.H₂O, BADGE.2H₂O, BADGE.HCl, BADGE.2HCl, BADGE.H₂O.HCl, cyclo-di-BADGE) by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) with atmospheric pressure chemical ionisation (APCI) source. Among all the bisphenols analysed, only the bisphenol A was detected in four samples; while cyclo-di-BADGE was the predominant compound detected in all the samples analysed.

Ontogenetic expression of thyroid hormone signaling genes: An in vitro and in vivo species comparison

Thyroid hormone (TH) is essential for brain development. While disruption of TH signaling by environmental chemicals has been discussed as a mechanism of developmental neurotoxicity (DNT) for more than a decade, there remains a paucity of information linking specific TH disrupting chemicals to adverse neurodevelopmental outcomes. This data gap reflects, in part, the fact that the molecular machinery of TH signaling is complex and varies according to cell type and developmental time. Thus, establishing a baseline of the ontogenetic profile of expression of TH signaling molecules in relevant cell types is critical for developing in vitro and alternative systems-based models for screening TH disrupting chemicals for DNT. Here, we characterize the transcriptomic profile of molecules critical to TH signaling across three species-human, rat, and zebrafish-in vitro and in vivo across different stages of neurodevelopment. Our data indicate that while cultured human and rat neural progenitor cells, primary cultures of rat cortical cells, and larval zebrafish all express a fairly comprehensive transcriptome of TH signaling molecules, the spatiotemporal expression profiles as well as the responses to TH vary across species and developmental stages. The data presented here provides a roadmap for identifying appropriate in vitro and in simpler systems-based models for mechanistic studies and screening of chemicals that alter neurodevelopment via interference with TH action.

Overview of known plastic packaging-associated chemicals and their hazards

Global plastics production has reached 380 million metric tons in 2015, with around 40% used for packaging. Plastic packaging is diverse and made of multiple polymers and numerous additives, along with other components, such as adhesives or coatings. Further, packaging can contain residues from substances used during manufacturing, such as solvents, along with non-intentionally added substances (NIAS), such as impurities, oligomers, or degradation products. To characterize risks from chemicals potentially released during manufacturing, use, disposal, and/or recycling of packaging, comprehensive information on all chemicals involved is needed. Here, we present a database of Chemicals associated with Plastic Packaging (CPPdb), which includes chemicals used during manufacturing and/or present in final packaging articles. The CPPdb lists 906 chemicals likely associated with plastic packaging and 3377 substances that are possibly associated. Of the 906 chemicals likely associated with plastic packaging, 63 rank highest for human health hazards and 68 for environmental hazards according to the harmonized hazard classifications assigned by the European Chemicals Agency within the Classification, Labeling and Packaging (CLP) regulation implementing the United Nations' Globally Harmonized System (GHS). Further, 7 of the 906 substances are classified in the European Union as persistent, bioaccumulative, and toxic (PBT), or very persistent, very bioaccumulative (vPvB), and 15 as endocrine disrupting chemicals (EDC). Thirty-four of the 906 chemicals are also recognized as EDC or potential EDC in the recent EDC report by the United Nations Environment Programme. The identified hazardous chemicals are used in plastics as monomers, intermediates, solvents, surfactants, plasticizers, stabilizers, biocides, flame retardants, accelerators, and colorants, among other functions. Our work was challenged by a lack of transparency and incompleteness of publicly available information on both the use and toxicity of numerous substances. The most hazardous chemicals identified here should be assessed in detail as potential candidates for substitution.

Effects of Flavored Nonalcoholic Beverages on Transcriptional Activities of Nuclear and Steroid Hormone Receptors: Proof of Concept for Novel Reporter Cell Line PAZ-PPARg

We developed and characterized a novel human luciferase reporter cell line for the assessment of peroxisome proliferator-activated receptor γ (PPARγ) transcriptional activity, PAZ-PPARg. The luciferase activity induced by PPARγ endogenous agonist 15d-PGJ2 and prostaglandin PGD2 reached mean values of (87.9 ± 14.0)-fold and (89.6 ± 19.7)-fold after 24 h of exposure to 40 μM 15d-PGJ2 and 70 μM PGD2, respectively. A concentration-dependent inhibition of 15d-PGJ2- and PGD2-induced luciferase activity was observed after the application of T0070907, a selective antagonist of PPARγ, which confirms the specificity of response to both agonists. The PAZ-PPARg cell line, along with the reporter cell lines for the assessment of transcriptional activities of thyroid receptor (TR), vitamin D3 receptor (VDR), androgen receptor (AR), and glucocorticoid receptor (GR), were used for the screening of 27 commonly marketed flavored nonalcoholic beverages for their possible disrupting effects. Our findings indicate that some of the examined beverages have the potential to modulate the transcriptional activities of PPARγ, VDR, and AR.

In Vitro Toxicity Testing of Food Contact Materials: State-of-the-Art and Future Challenges

Currently, toxicological testing of food contact materials (FCMs) is focused on single substances and their genotoxicity. However, people are exposed to mixtures of chemicals migrating from food contact articles (FCAs) into food, and toxic effects other than genotoxic damage may also be relevant. Since FCMs can be made of more than 8 thousand substances, assessing them one-by-one is very resource-consuming. Moreover, finished FCAs usually contain non-intentionally added substances (NIAS). NIAS toxicity can only be tested if a substance's chemical identity is known and if it is available as a pure chemical. Often, this is not the case. Nonetheless, regulations require safety assessments for all substances migrating from FCAs, including NIAS, hence new approaches to meet this legal obligation are needed. Testing the overall migrate or extract from an FCM/FCA is an option. Ideally, such an assessment would be performed by means of in vitro bioassays, as they are rapid and cost-effective. Here, we review the studies using in vitro bioassays to test toxicity of FCMs/FCAs. Three main categories of in vitro assays that have been applied include assays for cytotoxicity, genotoxicity, and endocrine disruption potential. In addition, we reviewed studies with small multicellular animal-based bioassays. Our overview shows that in vitro testing of FCMs is in principle feasible. We discuss future research needs and FCM-specific challenges. Sample preparation procedures need to be optimized and standardized. Further, the array of in vitro tests should be expanded to include those of highest relevance for the most prevalent human diseases of concern.