Bisphenol A Alternatives Research Articles

The Caenorhabditis elegans cuticle plays an important role against toxicity to bisphenol A and bisphenol S.

Caenorhabditis elegans represents a favorite non-mammalian animal model, which is often used to study the effect of foreign substances on living organisms. Its epidermal barrier is a primary biological barrier that protects nematodes from the toxicity of chemicals. In this study, we investigated the effect of Bisphenol A (BPA), an endocrine disrupting chemical, and its structural analog Bisphenol S (BPS), which is often used as a substitute for BPA in some products, on the behavior of C. elegans wild type (N2) and C. elegans bli-1 mutant strain, which is characterized by the production of abnormal cuticle blisters. We found that exposure of C. elegans wild type (N2), as well as its mutant strain bli-1, to selected concentrations of BPA (0.1, 0.5, 1 and 5µM) and BPS (0.1, 0.5, 1 and 5µM) resulted in significant changes in reproduction, habituation behavior, and body length of nematodes. Based on our findings, we can conclude that BPS, which was supposed to be a safer alternative to BPA, caused almost identical detrimental effects on C. elegans behavior. Furthermore, compared to the wild type of C. elegans, these effects were more pronounced in the bli-1 strain, which is characterized by a mutation in an individual collagen gene responsible for proper cuticle formation, underlying the role of the epidermal barrier in bisphenol toxicity. Taken together, our data indicate the potential risks of using BPS as a BPA alternative.

Bisphenol A alternatives continuously contribute to the endocrine disruption in cetaceans

The bans on bisphenol A (BPA) have facilitated the widespread use of BPA alternatives and shifted environmental contamination profiles of bisphenols (BPs). However, the continued reports of toxicities of emerging BPA alternatives have raised questions about whether the shifting profiles are contributed to mitigate BPs-mediated endocrine-disruption effects (EDEs). Cetaceans are commonly used as the ideal sentinel species for monitoring marine pollutants of concern and determining potential health effects, but far less is known about BP loads and BPs-mediated EDEs in cetaceans. Here we measured the hepatic concentrations of six BPs in eight stranded cetacean species (n = 41) in the South China Sea, between 2007 and 2020. The large-bodied whales generally showed higher ∑BPs concentrations than the small-bodied dolphins. In Indo-Pacific finless porpoises (Neophocaena phocaenoides) (n = 33), BPA concentrations first increased (2007–2014) and then decreased (2014–2020), while ∑BPAlternatives concentrations increased from 2007 to 2020. It appears that the alternatives gradually replaced BPA, probably due to the BPA-related bans in China. In order to examine the hormone disruption of BPA and its alternatives in finless porpoises, five blubber hormones (cortisol, progesterone, testosterone, triiodothyronine and tetraiodothyronine), which are proven to be validated endocrine biomarkers, were measured in 21 samples. Tetraiodothyronine, testosterone, and cortisol were significantly and positively correlated with BPA and its alternatives, suggesting that the interference of endocrine hormone homeostasis may continue to occur despite the changes of BP profiles in finless porpoises. This is the first investigation of the relationship between hormone and BP concentrations in cetaceans and represents a substantial advance in understanding BPs-mediated endocrine effects on cetaceans.

Synthesis and reproductive toxicity of bisphenol A analogs with cyclic side chains in Caenorhabditis elegans.

Accumulating evidence has shown that bisphenol A (BPA) affects not only the growth and development of reproductive tissues but also disrupts meiosis. Meiotic disturbances lead to the formation of aneuploid gametes, resulting in the inability to conceive, pregnancy loss, and developmental disabilities in offspring. In recent years, increasing health concerns led manufacturers to seek BPA alternatives. In response, BPA analogs have been prepared and investigated in a variety of toxicity-related studies. Despite hopes that these analogs would prove less harmful than BPA, published data show that these alternatives continue to pose a significant risk to human health. In this study, we synthesized two less investigated BPA analogs with cyclic side chains, bisphenol Y (BPY) and bisphenol Z (BPZ), and evaluated their reprotoxic potential using Caenorhabditis elegans. C. elegans were cultured on nematode growth medium plates containing a 1mM concentration of the dimethyl sulfoxide-dissolved bisphenols. The uptake of the chemicals was via two major routes: ingestion and cuticle diffusion. Following exposure, we evaluated fertilized egg count, germline apoptosis, and embryonic lethality-three parameters previously shown to reliably predict the reprotoxic potential of bisphenols in mammals. Our results indicated that both BPY and BPZ had a significant impact on fertility, resulting in increased germline apoptosis and a reduced number of progeny, without affecting the embryonic viability. After comparison with commercially relevant BPA and bisphenol S, our findings imply that BPA analogs with cyclic side chains, BPY and BPZ, adversely affect meiotic fidelity, resulting in diminished reproductive capacity.

Abstract 2687: The estrogenic activities of endocrine disruptors alter the extracellular matrix and tissue stiffness in the mammary gland

Abstract In utero exposure to estrogenic endocrine disrupting compounds (EDCs) increases a woman’s lifetime risk of breast cancer. Similarly, mice exposed in utero to the estrogenic EDC bisphenol A (BPA) have increased susceptibility to mammary gland tumors. It is unclear which BPA-induced alterations predispose the mammary gland to cancer transformation. There is a critical need to understand the mechanisms that drive increased cancer risk in order to assess the impact of BPA and BPA alternatives that retain estrogenic activity. We have utilized in utero BPA exposure as a model system for in utero estrogenic endocrine disruption to study the long-term consequences to the mouse mammary stroma. We found that BPA exposed fibroblasts showed significant transcriptional deregulation, with the extracellular matrix being the most altered cellular component and multiple collagen genes being more highly expressed. The fibroblasts from the BPA exposed mice decreased fluid permeability of the extracellular matrix, indicative of an increased density in the extracellular matrix. Also, in utero BPA exposure increased mammary gland stiffness. Changes to breast density, stiffness, and collagen deposition are all associated with breast cancer risk. Further, we test BPA alternative compounds with varying affinities for the estrogen receptor in our in utero model to assess the phenotypes in the mouse mammary stroma which are associated with breast cancer risk. Additionally, we use a mesenchymal estrogen receptor alpha (ERα) knockout mouse model to dissect the in utero cellular target of EDCs. Citation Format: Clarissa Wormsbaecher, Andrea R. Hindman, Alex Avendano, Marcos Cortes-Medina, Jonathan W. Song, Craig J. Burd. The estrogenic activities of endocrine disruptors alter the extracellular matrix and tissue stiffness in the mammary gland [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2687.

Assessing the toxicity of bisphenol A and its six alternatives on zebrafish embryo/larvae.

Bisphenol A (BPA) analogues are gradually replacing BPA in the plastics industry. Whether these alternatives are indeed safer than BPA itself, however, remains unclear. Here, we studied the toxicity of BPA and six of its alternatives-BPB, BPC, BPE, BPF, BPAF, and BPAP-using zebrafish embryos/larvae. According to their half lethal concentration (LC50) values, the acute toxicity of BPA and six alternative bisphenols to zebrafish embryos, from highest to lowest, was BPAP ≈ BPAF > BPC > BPB > BPA > BPE > BPF. Under nonlethal concentrations, the tested bisphenols had different toxic effects on development in terms of reducing the hatching rate, frequency of spontaneous movements, and heart rate in the embryo, as well as inducing yolk sac edema, pericardial edema, and spinal deformation in the larvae. The estrogenic activity of BPE, BPF, and BPAF was higher than that of BPA, as shown by vtg1 expression assays. Moreover, BPA and its alternatives increased SOD activity and cell apoptosis in embryos/larvae under nonlethal concentrations. Our findings indicate that BPA alternatives may not be safer than BPA in zebrafish, and that these BPA alternatives should be applied with caution.

Bisphenols impact hormone levels in animals: A meta-analysis

Bisphenols are used in the manufacture of plastics and are endocrine disrupting compounds detectable in free living organisms and environments globally. The original bisphenol, bisphenol A (BPA), is best known as a xenoestrogen, but it also disrupts other steroid hormones and other classes of hormones including thyroid and pituitary hormones. When its toxicity became better known, BPA was replaced by presumably less toxic alternatives, including bisphenols S, F, and AF. However, recent data suggest that all bisphenols can have endocrine disrupting effects, although their impacts remain unresolved particularly in non-human animals. Our aim was to establish the current state-of-knowledge of the effects of different bisphenols on circulating hormone levels in non-human animals. Our meta-analysis showed that a diverse range of hormones (including thyroid hormones, corticosterone, follicle stimulating hormone, luteinizing hormone, and estradiol) are strongly impacted by exposure to any bisphenol type, and that in laboratory rats (Rattus norvegicus) the effect was modified by life-stage. Although there were qualitative differences, BPA alternatives had as great or greater effects on hormone levels as BPA. However, data coverage across hormones was uneven, and most studies measured the effects of BPA on vertebrate reproductive hormones. Similarly, taxonomic coverage was poor. Over 80% of data originated from laboratory rats and zebrafish (Danio rerio) and there are no data for whole classes of invertebrates and vertebrates (e.g., amphibians). Our results show that all bisphenols alter circulating levels of a broad range of hormones. However, the current state-of-knowledge is incomplete so that the ecological impacts of bisphenols are difficult to gauge, although based on the available data bisphenols are likely to be detrimental to a broad range of taxa and ecosystems.

Urinary bisphenol concentrations and its association with metabolic disorders in the US and Korean populations

Bisphenol A (BPA) is a representative endocrine disrupting compound used in a vast array of consumer products, and are being frequently substituted by its analogues, bisphenol S (BPS) and bisphenol F (BPF). We aimed to examine the association between urinary bisphenol levels with obesity and lipid profiles in the general population to comprehensively evaluate its potential of metabolic disturbance. A representative sample of 1046 US adults from the National Health and Nutrition Examination Survey (2013–2016) and 3268 Korean adults from the Korean National Environmental Health Survey (2015–2017) was analyzed. We examined the exposure levels of bisphenols and determined their associations with obesity, high-density lipoprotein cholesterol (HDL-C) and triglyceride (TG) levels, and hypercholesterolemia prevalence through multiple linear, and binary/ordinal logistic regression models. In both populations, high BPA levels (lowest tertile vs. 2nd, 3rd tertiles) showed corresponding associations with lipid profile and obesity. BPA levels were associated with decreased HDL-C levels (Q3: β = −0.053, p = 0.08 (US); Q2: β = −0.030, p-0.03), increased TG levels (Q3: β = 0.121, p = 0.029 (US); Q3: β = 0.089, p = 0.021, and higher odds for obesity (Q3: OR = 1.58, 95% CI: 1.06, 2.35 (US); Q3: OR = 1.41, 95% CI: 1.11, 1.78). Higher BPS levels were positively associated with obesity status, especially in US men (Q2: OR = 1.84, 95% CI: 1.15, 2.96) and Korean women (Q3: OR = 1.27, 95% CI: 0.99, 1.64). A significant decrease in HDL-C (Q3: β = −0.088, p = 0.01) and elevated odds for obesity at higher BPF levels (Q3: OR = 1.60, 95% CI: 1.00, 2.56) was observed in US women. The findings of our study indicate that BPA and its analogues, BPS and BPF, are associated with lipid metabolism disorders in addition to obesity in adults. Given the increase in exposure to BPA alternatives, continuous biomonitoring, and further investigation of their health effects through prospective cohort studies are warranted.

Effects of Bisphenol A and Its Alternatives, Bisphenol F and Tetramethyl Bisphenol F on Osteoclast Differentiation.

Bisphenol A (BPA) is a typical environmental endocrine disruptor that exhibits estrogen-mimicking, hormone-like properties and can cause the collapse of bone homeostasis by an imbalance between osteoblasts and osteoclasts. Various BPA substitutes, structurally similar to BPA, have been used to manufacture ‘BPA-free’ products; however, the regulatory role of BPA alternatives in osteoclast differentiation still remains unelucidated. This study aimed to investigate the effects of these chemicals on osteoclast differentiation using the mouse osteoclast precursor cell line RAW 264.7. Results confirmed that both BPA and its alternatives, bisphenol F and tetramethyl bisphenol F (TMBPF), were nontoxic to RAW 264.7 cells. In particular, tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cell staining and activity calculation assays revealed that TMBPF enhanced osteoclast differentiation upon stimulation of the receptor activator of nuclear factor-kappa B ligand (RANKL). Additionally, TMBPF activated the mRNA expression of osteoclast-related target genes, such as the nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1), tartrate-resistant acid phosphatase (TRAP), and cathepsin K (CtsK). Western blotting analysis indicated activation of the mitogen-activated protein kinase signaling pathway, including phosphorylation of c-Jun N-terminal kinase and p38. Together, the results suggest that TMBPF enhances osteoclast differentiation, and it is critical for bone homeostasis and skeletal health.

Comparative toxicities of BPA, BPS, BPF, and TMBPF in the nematode Caenorhabditis elegans and mammalian fibroblast cells

Bisphenol A (BPA) is a chemical compound commonly used in the production of plastics for daily lives and industry. As BPA is well known for its adverse health effects, several alternative materials have been developed. This study comprehensively analyzed the toxicity of BPA and its three substitutes including bisphenol S (BPS), bisphenol F (BPF), and tetramethyl bisphenol F (TMBPF) on aging, healthspan, and mitochondria using an in vivo Caenorhabditis elegans (C. elegans) model animal and cultured mammalian fibroblast cells. C. elegans treated with 1 mM BPA exhibited abnormalities in the four tested parameters related to development and growth, including delayed development, decreased body growth, reduced reproduction, and abnormal tissue morphology. Exposure to the same concentration of each alternative including TMBPF, which has been proposed as a relatively safe BPA alternative, detrimentally affected at least three of these events. Moreover, all bisphenols (except BPS) remarkably shortened the organismal lifespan and increased age-related changes in neurons. Exposure to BPA and BPF resulted in mitochondrial abnormalities, such as reduced oxygen consumption and mitochondrial membrane potential. In contrast, the ATP levels were noticeably higher after treatment with all bisphenols. In mammalian fibroblast cells, exposure to increasing concentrations of all bisphenols (ranging from 50 μM to 500 μM) caused a severe decrease in cell viability in a dose-dependent manner. BPA increased ATP levels and decreased ROS but did not affect mitochondrial permeability transition pores (mPTP). Notably, TMBPF was the only bisphenol that caused a significant increase in mitochondrial ROS and mPTP opening. These results suggest that the potentially harmful physiological effects of BPA alternatives should be considered.

Structural basis for molecular recognition of G protein-coupled estrogen receptor by selected bisphenols

Complicated ligand-dependent signaling pathways of bisphenol A (BPA) and its analogues involve not only intranuclear estrogen receptor but also membrane receptor G protein-coupled estrogen receptor (GPER). However, the structural basis for molecular recognition of GPER by the environmental chemicals remains unknown. To reveal the structural dependence of GPER recognition by bisphenols, a systematic molecular dynamics simulation study was performed for selected bisphenols with different electron hybrid orbitals and substituents on their C atoms connecting two phenol rings. BPA was used as a control, bisphenol C(BPC) as an example for a connecting C with sp2 hybrid orbitals to provide more ligand rigidity, bisphenol E(BPE) and bisphenol F(BPF) for decreased steric hindrance and hydrophobicity around the connecting C, and bisphenol B(BPB) and bisphenol AF(BPAF) for increased hydrophobicity and steric hindrance. All the tested bisphenols can bind with GPER at its classic orthosteric site to obtain GPER-ligand complexes, while van der Waals interactions and direct inter-molecular electrostatic energies provide the driving forces for ligand binding. Bulky substituents and structural rigidity of the connecting C dramatically impair hydrogen bonding between GPER and the bisphenols, which results in decreased contribution of both favorable intermolecular hydrogen bonds and unfavorable polar solvation effect to complex stability of BPB and BPC since decreased number of key residues is expected. Increase in substituent lipophilicity enhances the van der Waals interactions and favorable non-polar solvation effect. The six bisphenols of high structural similarity shared two key recognition residues, Leu137TM3 and Trp272TM6, the latter of which was in the highly conserved CWxP motif of TM6 and has been reported as key residue for G protein-coupled receptor activation. Based on the obtained knowledge, GPER affinity and relevant toxicity of BPA alternatives can be easily predicted, and the calculated binding free energies are consistent with the available experimental observations.

BPA, BPAF and TMBPF Alter Adipogenesis and Fat Accumulation in Human Mesenchymal Stem Cells, with Implications for Obesity.

Bisphenol A (BPA) is an endocrine-disrupting chemical used in the production of plastics, and is linked to developmental, reproductive, and metabolic disorders including obesity. Manufacturers have begun using ‘BPA-free’ alternatives instead of BPA in many consumer products. However, these alternatives have had much less testing and oversight, yet they are already being mass-produced and used across industries from plastics to food-contact coatings. Here, we used human female adipose-derived stem cells (hASCs), a type of adult mesenchymal stem cell, to compare the effects of BPA and BPA alternatives on adipogenesis or fat cell development in vitro. We focused on two commonly used BPA replacements, bisphenol AF (BPAF) and tetramethyl bisphenol F (TMBPF; monomer of the new valPure V70 food-contact coating). Human ASCs were differentiated into adipocytes using chemically defined media in the presence of control differentiation media with and without 17β-estradiol (E2; 10 μM), or with increasing doses of BPA (0, 0.1 and 1 μM), BPAF (0, 0.1, 1 and 10 nM), or TMBPF (0, 0.01 and 0.1 μM). After differentiation, the cells were stained and imaged to visualize and quantify the accumulation of lipid vacuoles and number of developing fat cells. Treated cells were also examined for cell viability and apoptosis (programmed cell death) using the respective cellular assays. Similar to E2, BPA at 0.1 μM and BPAF at 0.1 nM, significantly increased adipogenesis and lipid production by 20% compared to control differentiated cells (based on total lipid vacuole number to cell number ratios), whereas higher levels of BPA and BPAF significantly decreased adipogenesis (p < 0.005). All tested doses of TMBPF significantly reduced adipogenesis and lipid production by 30–40%, likely at least partially through toxic effects on stem cells, as viable cell numbers decreased and apoptosis levels increased throughout differentiation. These findings indicate that low, environmentally-relevant doses of BPA, BPAF, and TMBPF have significant effects on fat cell development and lipid accumulation, with TMBPF having non-estrogenic, anti-adipogenic effects. These and other recent results may provide a potential cellular mechanism between exposure to bisphenols and human obesity, and underscore the likely impact of these chemicals on fat development in vivo.

Evidence of increased estrogenicity upon metabolism of Bisphenol F - Elucidation of the key metabolites

The increasing concern over bisphenol A (BPA) has directed much attention toward bisphenol F (BPF) and bisphenol S (BPS) as BPA alternatives for the development of “BPA-free” products. Consequently, BPS and BPF were frequently detected in surface water, sediment, sewage effluent, indoor dust, and even in food and biological fluids in humans. Thus, environmental researches start to focus on the potential environmental risks of BPA alternatives. While the estrogenically active metabolites and the specific estrogenically active structure are still unknown. In this study, the MTT assay on acute cytotoxicity and the recombinant transactivation assay were carried out to determine whether BPF and BPS are suitable alternatives to BPA. Our results show that the cytotoxic and estrogenic activities of BPS and BPF are lower than those of BPA. However, after the addition of a rat liver homogenate to simulate mammal metabolism, BPF exhibited higher estrogenic activity than BPA. To identify the chemical structures and estrogen receptor binding affinities of active estrogenic metabolites, LC-MS, MetaPrint2D(-React), and VirtualToxLab were integrated. The observed results indicated that the para-hydroxylated BPF and BPF-OCH3 might have strong ER binding affinities. These results demonstrate that metabolization is important to consider upon investigating endocrine disruption of chemicals getting into contact with humans, such as in dental sealing or food packaging. Alternatives to potentially hazardous substances should be thoroughly tested prior to use.

In Vitro Screening of 21 Bisphenol A Replacement Alternatives: Compared with Bisphenol A, the Majority of Alternatives Are More Cytotoxic and Dysregulate More Genes in Avian Hepatocytes.

An avian in vitro screening approach was used to determine the effects of 21 bisphenol A (BPA) alternatives. Cytotoxicity and dysregulation of genes associated with estrogen response and other toxicologically relevant pathways evoked by these alternatives were compared with BPA. Most of the BPA alternatives (15/21) were equally or more cytotoxic than BPA in chicken embryonic hepatocytes; variability in cell viability was associated with chemical structure and the log octanol-water partition coefficient (logP) values. A negative linear relationship (r 2 = 0.745; p = 0.49-07 ; n = 18) was observed between logP and the log median lethal concentration (logLC50) values. The least cytotoxic BPA alternatives elicited the greatest gene dysregulation and, overall, most of the alternatives altered more genes than BPA (measured with a custom polymerase chain reaction array). This overall approach shows promise for use as a screen for hazard-based prioritization of BPA replacement alternatives and to ideally identify those that may be less harmful and/or require additional toxicity testing.Environ Toxicol Chem 2021;40:2026-2033. © 2021 Her Majesty the Queen in Right of Canada Environmental Toxicology and Chemistry © 2021 SETAC. Reproduced with the permission of the Minister of Environment and Climate Change Canada.

Bisphenol A and its effects on the systemic organs of children.

For the past two decades, growing research has been pointing to multiple repercussions of bisphenol A (BPA) exposure to human health. BPA is a synthetic oestrogen which primarily targets the endocrine system; however, the compound also disturbs other systemic organ functions, in which the magnitude of impacts in those other systems is as comparable to those in the endocrine system. To date, the discoveries on the association between BPA and health outcomes mainly came from animal and in vitro studies, with limited human studies which emphasised on children's health. In this comprehensive review, we summarised studies on human, in vivo and in vitro models to understand the consequences of pre-, post- and perinatal BPA exposure on the perinatal, children and adult health, encompassing cardiovascular, neurodevelopmental, endocrine and reproductive effects.Conclusion: Evidence from in vitro and animal studies may provide further support and better understanding on the correlation between environmental BPA exposure and its detrimental effects in humans and child development, despite the difficulties to draw direct causal relations of BPA effects on the pathophysiology of the diseases/syndromes in children, due to differences in body system complexity between children and adults, as well as between animal and in vitro models and humans. What is known: • Very limited reviews are available on how BPA adversely affects children's health. • Previous papers mainly covered two systems in children. What is new: • Comprehensive review on the detrimental effects of BPA on children health outcomes, including expectations on adult health outcomes following perinatal BPA exposure, as well as covering a small part of BPA alternatives. • Essentially, BPA exposure during pregnancy has huge impacts on the foetus in which it may cause changes in foetal epigenetic programming, resulting in disease onsets during childhood as well as adulthood.

Urinary bisphenol A and its alternatives among pregnant women: Predictors and risk assessment

BackgroundExposure to bisphenol A (BPA) has been associated with various adverse health outcomes. Recently, an increasing concern on its alternatives such as bisphenol S (BPS) and bisphenol F (BPF) has been aroused due to the restriction use of BPA. Few studies have identified predictors of exposure to BPA alternatives and assessed their health risks. ObjectiveThe aim of this study was to identify predictors of BPA and its alternatives and to assess their health risks among pregnant women. MethodsWe detected first morning urinary concentrations of BPA and its alternatives (BPS and BPF) among 1097 pregnant women from an established Chinese cohort. A questionnaire was conducted to obtain demographic characteristics, dietary habits, and lifestyles. We examined the predictors of creatinine-adjusted urinary BPA and its alternatives concentrations using multivariable linear regression. Risk assessment of exposure to BPA and its alternatives was calculated based on the estimated of daily intake (EDI). ResultsGeometric means of creatinine-adjusted urinary BPA, BPF, and BPS were 0.92, 0.12, and 0.08 μg/g creatinine, respectively. Pregnant women from Wuhan had lower concentrations of BPA, BPF, and ∑BPs (sum of BPA, BPF, and BPS) than those from Xiaogan. Intake of fried food was related to higher concentrations of BPA, and intake of pickled food was associated with higher concentrations of BPF and ∑BPs. The maximum EDI values for exposure to BPA, BPF, BPS, and ∑BPs ranged from 5.6428 to 13.3356 nmol/kg body weight/day, which were below the tolerable daily intake (TDI) for BPA defined by the European Food Safety Authority (EFSA) (18 nmol/kg body weight/day). The maximum hazard index (HI) value was 0.7409. ConclusionSeveral predictors identified in this study may inform public recommendations to reduce exposure to BPA and its alternatives.

BPA and BPA alternatives BPS, BPAF, and TMBPF, induce cytotoxicity and apoptosis in rat and human stem cells

Bisphenol A (BPA) is a ubiquitous industrial chemical found in everyday plastic products and materials. Due to scientific findings on the reproductive, developmental, and cellular defects caused by BPA and heightened public awareness, manufacturers have begun to use new chemicals in place of BPA in “BPA-free” products. These alternatives are chemical analogs of BPA and include dozens of new compounds that have undergone relatively little testing and oversight, including: bisphenol S (BPS), bisphenol AF (BPAF), and the recently developed tetramethyl bisphenol F (TMBPF; the monomer of valPure V70). Here, we used adult female rat adipose-derived stem cells (rASCs) and human mesenchymal stem cells (hMSCs) to compare the toxicities and potencies of these BPA alternatives in vitro. Rat and human stem cells were exposed to BPA (1–10 μM), 17β-estradiol (E2; 10 μM), BPS (1–100 μM), BPAF (3×10−4–30 μM), TMBPF (0.01–50 μM), or control media alone (with 0.01% ethanol) for varying time intervals from 10 min to 24 h. We found significantly decreased cell viability and massive apoptosis in rat and human stem cells treated with each BPA analog, as early as 10 min of exposure, and at low, physiologically relevant doses. BPAF showed extreme cytotoxicity in a dose-dependent manner (LC50 =0.014 μM (rASCs) and 0.009 μM (hMSCs)), whereas TMBPF showed a bimodal response, with low and high concentrations being the most toxic (LC50 =0.88 μM (rASCs) and 0.06 μM (hMSCs)). Activated caspase-6 levels increased in nearly all cells treated with the BPA analogs indicating the majority of cell death was due to caspase-6-mediated apoptosis. These results in both rat and human stem cells underscore the toxicity and potency of these BPA analogs, and establish a rank order of potency of: BPAF>TMBPF>BPA>BPS. Further, these and other recent findings indicate that these newer BPA analogs may be ‘regrettable substitutions,’ being worse than the original parent compound and lacking proper testing and regulation. This work brings to light the need for further toxicological characterization, better regulation, greater public awareness, and the development of safer, more sustainable chemicals and non-plastic products.

Toxicity Screening of Bisphenol A Replacement Compounds: Cytotoxicity and mRNA Expression in Primary Hepatocytes of Chicken and Double-Crested Cormorant.

A market for bisphenol A (BPA) replacement compounds has emerged as a result of restrictions on the use of BPA. Some of these compounds have been detected in the environment; however, little is known about their toxicological properties. In the present study, an avian in vitro toxicogenomic approach was used to compare the effects of 5 BPA alternatives. Cell viability and mRNA expression were compared in primary embryonic hepatocytes of chicken (CEH) and double-crested cormorant (DCEH) exposed to 4,4'-(propane-2,2-diyl) diphenol (BPA), bis (4-hydroxyphenyl) methane (BPF), bis (3-allyl-4-hydroxyphenyl) sulfone (TGSH), 7-bis (4-hydroxyphenylthio)-3,5-dioxaheptane (DD-70), 2,2-bis (4-hydroxyphenyl) hexafluoropropane (BPAF), and 4-hydroxyphenyl 4-isoprooxyphenylsulfone (BPSIP). Changes in gene expression were determined using 2 polymerase chain reaction (PCR) arrays: 1) species-specific ToxChips that contain genes representing toxicologically relevant pathways, and 2) chicken-specific AestroChip that measures estrogen responsive genes. In CEH and DCEH, BPA alternatives TGSH, DD-70, and BPAF were most cytotoxic. Some of the replacement compounds changed the expression of genes related to xenobiotic metabolism, bile acid, and cholesterol regulation. The rank order based on the number of genes altered on the chicken ToxChip array was TGSH > DD-70 > BPAF = BPF > 17β estradiol (E2) > BPSIP > BPA. On the cormorant ToxChip array, BPSIP altered the greatest number of genes. Based on the chicken AestroChip data, BPSIP and BPF were slightly estrogenic. These results suggest that the replacement compounds have comparable or even greater toxicity than BPA and act via different mechanisms. Environ Toxicol Chem 2021;40:1368-1378. © 2021 Her Majesty the Queen in Right of Canada. Reproduced with the permission of the Minister of Environment and Climate Change Canada.

Prenatal exposure to bisphenol analogues and digit ratio in children at ages 4 and 6 years: A birth cohort study.

Bisphenol analogues (BPs), including bisphenol A (BPA), have been shown to exhibit similar endocrine disrupting activities. However, epidemiological evidence on the reproductive and developmental toxicities of BPs other than BPA is scarce. The second to fourth digit ratio (2D:4D), an endocrine-sensitive endpoint, has been suggested to be a biomarker of prenatal sex steroid exposure and associated with reproductive outcomes in later life. Using the data of 545 mother-child pairs from the Shanghai-Minhang Birth Cohort Study, we prospectively assessed the effects of prenatal exposure to BPs on 2D:4D in children at ages 4 and 6 years. Single-spot urine samples were collected in the third trimester and analyzed for BPs. Digit lengths were measured using a vernier caliper in children at ages 4 and 6 years, and the 2D:4D values for both hands were calculated. A multivariable linear regression model was applied to examine associations between prenatal BPs exposure and 2D:4D digit ratios at each age separately. The generalized estimating equation (GEE) model was used to deal with repeated 2D:4D measures obtained at ages 4 and 6 years. We found that prenatal exposure to BPA alternatives including BPF, BPS, and BPAF was associated with higher digit ratio in boys and/or girls (feminizing), while TCBPA, a halogenated bisphenol, was associated with lower 2D:4D in boys (masculinizing). These associations were more pronounced at 4 years of age, and tended to remain after further considering the potential confounding from prenatal co-exposure to other BPs and childhood BPs exposure. Our study provides epidemiological evidence that BPs exposure during pregnancy may alter the digit development in children, indicative of disrupted reproductive development in later life. Given these new findings, further studies are needed to corroborate our results.

Prenatal exposure to bisphenols and cognitive function in children at 7 years of age in the Swedish SELMA study

BackgroundExperimental evidence demonstrates that exposure to bisphenol A (BPA), and the recently introduced alternatives bisphenol S (BPS) and bisphenol F (BPF) alter normal neurodevelopment. More research is needed to evaluate the associations between exposure to individual BPA alternatives and neurodevelopmental outcomes in humans. ObjectiveThe present study aimed at examining the individual associations between prenatal BPA, BPS and BPF exposure and cognitive outcomes in children at age 7 years. MethodWomen were enrolled in the Swedish Environmental Longitudinal Mother and Child, Asthma and Allergy (SELMA) study, at gestational median week 10.0, and their children were examined for cognitive function at 7 years of age (N = 803). Maternal urinary BPA, BPS, and BPF concentrations were measured at enrollment and childreńs cognitive function at the age of 7 years was measured using the Wechsler Intelligence Scale for Children IV (WISC-IV). ResultsAll three bisphenols were detected in over 90% of the women, where BPA had the highest geometric mean concentrations (1.55 ng/mL), followed by BPF (0.16 ng/mL) and BPS (0.07 ng/mL). Prenatal BPF exposure was associated with decreased full scale IQ (β = −1.96, 95%CI; −3.12; −0.80), as well as with a decrease in all four sub scales covering verbal comprehension, perceptual reasoning, working memory and processing speed. This association corresponded to a 1.6-point lower IQ score for an inter-quartile-range (IQR) change in prenatal BPF exposure (IQR = 0.054–0.350 ng/mL). In sex-stratified analyses, significant associations with full scale IQ were found for boys (β = −2.86, 95%CI; −4.54; −1.18), while the associations for girls did not reach significance (β = −1.38, 95%CI; −2.97; 0.22). No significant associations between BPA nor BPS and cognition were found. DiscussionPrenatal exposure to BPF was significantly associated with childreńs cognitive function at 7 years. Since BPF is replacing BPA in numerous consumer products globally, this finding urgently call for further studies.

Systematic Review of Exposure to Bisphenol A Alternatives and Its Effects on Reproduction and Thyroid Endocrine System in Zebrafish

Bisphenol A (BPA), which is widely used for manufacturing polycarbonate plastics and epoxy resins, has been banned from use in plastic baby bottles because of concerns regarding endocrine disruption. Substances with similar chemical structures have been used as BPA alternatives; however, limited information is available on their toxic effects. In the present study, we reviewed the endocrine disrupting potential in the gonad and thyroid endocrine system in zebrafish after exposure to BPA and its alternatives (i.e., bisphenol AF, bisphenol C, bisphenol F, bisphenol S, bisphenol SIP, and bisphenol Z). Most BPA alternatives disturbed the endocrine system by altering the levels of genes and hormones involved in reproduction, development, and growth in zebrafish. Changes in gene expression related to steroidogenesis and sex hormone production were more prevalent in males than in females. Vitellogenin, an egg yolk precursor produced in females, was also detected in males, confirming that it could induce estrogenicity. Exposure to bisphenols in the parental generation induced a decrease in the hatchability associated with offspring generation. In zebrafish exposed to bisphenols, significant decreases in thyroxine concentrations and increases in thyroid-stimulating hormone concentrations were commonly observed. Alternative compounds used to replace a chemical of concern are believed to be less toxic than the original compound; however, several BPA alternatives appear to have similar or greater effects on the endocrine system in zebrafish. Since endocrine systems interact with each other, further studies are needed to assess the primary target of BPA alternatives among the endocrine axes.