Binary Mixtures of Selected Bisphenols in the Environment: Their Toxicity in Relationship to Individual Constituents

Mixture Effects of Bisphenol A and Its Structural Analogs on Estrogen Receptor Transcriptional Activation

Bisphenol A (BPA) exposure has been widely linked to endocrine-disrupting effects. Recently, many substitutes for BPA have been developed as safe structural analogs. However, they have still been reported to have similar adverse effects. The current study evaluated the effects of bisphenol A and eight structural analogs on the transcription of estrogen receptor alpha (ERα). The effects of binary and ternary mixtures prepared from different combinations of BPA analogs were also evaluated for transcription activity. The measured data of the mixtures were compared to the predicted data obtained by the full logistic model, and the model deviation ratio (MDR) was calculated to determine whether the effects were synergistic, antagonistic, or additive. Overall, the results suggest that the effect of bisphenol compound are additive in binary and ternary mixtures.

Concentrations of bisphenols and phthalate esters in the muscle of Mediterranean striped dolphins (Stenella coeruleoalba)

Bisphenols (BPs) and phthalate esters (PAEs) are important compounds for the plastics industry, also called "everywhere chemicals" due to their ubiquity in daily use products. Both chemical groups are well-known environmental contaminants, whose presence has been reported in all environmental compartments, and whose effects, mainly associated to endocrine disruption, are detrimental to living organisms. Cetaceans, due to their long life-span, low reproduction rate and high position in the trophic web, are especially vulnerable to the effects of contaminants. However, little is known about BP and PAE concentrations in cetacean tissues, their potential relation to individual biological variables, or their trends over time. Here, the concentration of 10 BPs and 13 PAEs was assessed in the muscle of 30 striped dolphins (Stenella coeruleoalba) stranded along the Spanish Catalan coast (NW Mediterranean) between 1990 and 2018. Six BP and 6 PAE compounds were detected, of which only 4,4'-(cyclohexane-1,1-diyl)diphenol (BPZ) was detected in all the samples, at the highest concentration (mean 16.06 μg g-1 lipid weight). Sex or reproductive condition were largely uninfluential on concentrations: only dimethylphthalate (DMP) concentrations were significantly higher in immature individuals than in adults, and the overall PAE concentrations were significantly higher in males than in females. Temporal variations were only detected in bis(4-hydroxyphenyl)ethane (BPE), diethylphthalate (DEP) and dimethylphthalate (DMP), whose concentrations were lower, and 9,9-Bis(4-hydroxyphenyl)fluorene (BPFL), which were higher, respectively, in samples taken between 2014 and 2018, probably reflecting shifts in the production and use of these chemicals. These results provide the first assessment of concentrations of several BP and PAE compounds in the muscle of an odontocete cetacean.

Bisphenol A and its substitutes in the aquatic environment: Occurrence and toxicity assessment

Bisphenol A is classified as a high production volume chemical commonly used in the manufacture of polycarbonate plastics, epoxy resins and thermal paper. The endocrine disrupting properties of this xenobiotic have led to the restriction and prohibition of its use in many consumer products. To date, many chemical compounds with a chemical structure similar to bisphenol A have been used in consumer products as its replacement. The ubiquitous occurrence of bisphenol A and its substitutes in the environment and their endocrine activity as well as adverse effects on aquatic organisms is a global concern, especially because many available literature reports show that many substitutes (e.g. bisphenol AF, bisphenol AP, bisphenol B, bisphenol C, bisphenol F, bisphenol G, bisphenol FL, tetrabromobisphenol A) exert adverse effects on aquatic organisms, similar to, or even stronger than bisphenol A. Therefore, the objective of this paper is to provide a comprehensive overview of the production, sources, occurrence and associated toxicity, as well as the endocrine activity of bisphenol A and its substitutes on aquatic species. The environmental levels and ecotoxicological data presented in this review allowed for a preliminary assessment and prediction of the risk of bisphenol A and its substitutes for aquatic organisms. Furthermore, the data collected in this paper highlight that several compounds applied in bisphenol A-free products are not safe alternatives and regulations regarding their use should be introduced.

Impact of a bisphenol A, F, and S mixture and maternal care on the brain transcriptome of rat dams and pups

Products containing BPA structural analog replacements have increased in response to growing public concern over adverse effects of BPA. Although humans are regularly exposed to a mixture of bisphenols, few studies have examined effects of prenatal exposure to BPA alternatives or bisphenol mixtures. In the present study, we investigate the effect of exposure to an environmentally-relevant, low-dose (150 ug/kg body weight per day) mixture of BPA, BPS, and BPF during gestation on the brain transcriptome in Long-Evans pups and dams using Tag RNA-sequencing. We also examined the association between dam licking and grooming, which also has enduring effects on pup neural development, and the transcriptomes. Associations between licking and grooming and the transcriptome were region-specific, with the hypothalamus having the greatest number of differentially expressed genes associated with licking and grooming in both dams and pups. Prenatal bisphenol exposure also had region-specific effects on gene expression and pup gene expression was affected more robustly than dam gene expression. In dams, the prelimbic cortex had the greatest number of differentially expressed genes associated with prenatal bisphenol exposure. Prenatal bisphenol exposure changed the expression of over 2000 genes in pups, with the majority being from the pup amygdala. We used Gene Set Enrichment Analysis (GSEA) to asses enrichment of gene ontology biological processes for each region. Top GSEA terms were diverse and varied by brain region and included processes known to have strong associations with steroid hormone regulation, cilium-related terms, metabolic/biosynthetic process terms, and immune terms. Finally, hypothesis-driven analysis of genes related to estrogen response, parental behavior, and epigenetic regulation of gene expression revealed region-specific expression associated with licking and grooming and bisphenol exposure that were distinct in dams and pups. These data highlight the effects of bisphenols on multiple physiological process that are highly dependent on timing of exposure (prenatal vs. adulthood) and brain region, and reiterate the contributions of multiple environmental and experiential factors in shaping the brain.

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 1 mM 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.

Urinary levels of dimethoate, bisphenol A and benzo[a]pyrene in first-year students of Hohai University from different geographical regions

BACKGROUND

The objective of this study was to detect the urinary levels of dimethoate, benzo(a) pyrene (BaP), and bisphenol A (BPA) in first-year Hohai University students with different geographic origins.

METHODS

First-morning urine samples were collected from 540 healthy freshmen aged 17 to 19 years. Chemical levels were measured using β-glucuronidase hydrolysis followed by a high-performance liquid chromatography-tandem mass spectrometry-based method. Geometric means (GMs) of these three chemicals are presented by body mass index (BMI) and location in a volume-based and creatinine-standardized way.

RESULTS

GM concentrations of omethoate, BPA and 3-OHBaP were 9.47 μg/L (10.80 μg/g creatinine), 3.54 μg/L (4.04 μg/g creatinine) and 0.34 ng/L (0.39 ng/g creatinine), respectively. The GM concentration of omethoate in males was significantly higher than that in females. The individuals with a BMI higher than 23.9 had higher GM concentrations of omethoate, BPA, and 3-OHBaP. The inhabitants of Southwest China had significantly lower GM concentrations of omethoate, BPA, and 3-OHBaP than those who lived in other locations in China.

CONCLUSION

The average level of environmental chemical accumulation in freshmen is lower in Southwest China and differs in youth who live in different regions. In addition, obesity is correlated with higher toxin levels in youth.

Identification of synergistic and antagonistic actions of environmental pollutants: Bisphenols A, S and F in the presence of DEP, DBP, BADGE and BADGE·2HCl in three component mixtures

Ecosystems are facing increased pressure due to the emission of many classes of emerging contaminants. However, very little is known about the interactions of these pollutants, such as bisphenols (BPs), plasticizers or pharmaceuticals. By employing bioluminescent bacteria (Microtox assay), we were able to define interactions between selected emerging pollutants (namely BPA, BPS, BPF, BADGE, BADGE·2HCl, DEP, DBP) in ternary mixtures, at environmentally relevant concentration levels (down to as low as 1.89, 1.42, 3.08, and 0.326 μM for, respectively, BPA, BPF, BPS and BADGE·2HCl). We provide the first systematic analysis of bisphenols and phthalates in three component mixtures. Using this system, we performed toxicity modelling with concentration addition (CA) and independent action (IA) approaches, followed by data interpretation using Model Deviation Ratio (MDR) evaluation. Interestingly, we mathematically and experimentally confirmed a novel synergy between BPA, BADGE and BADGE·2HCl. The synergy of BPA, BADGE and BADGE·2HCl is distinct, with both models suggesting these analytes have a similar mode of action (MOA). Moreover, we unexpectedly found a strong antagonistic impact with DEP, in mixtures containing BPA and BADGE analogues, which is confirmed with both mathematical models. Our study also shows that the impact of BPS and BPF in many mixtures is highly concentration dependent, justifying the necessity to perform mixture studies using wide concentration ranges. Overall, this study demonstrates that bioluminescent bacteria are a relevant model for detecting the synergistic and antagonist actions of environmental pollutants in mixtures, and highlights the importance of analyzing combinations of pollutants in higher order mixtures.

A new approach based on inversion of a partial least squares model searching for a preset analytical target profile. Application to the determination of five bisphenols by liquid chromatography with diode array detector

The paper shows a procedure for selecting the control method parameters (factors) to obtain a preset 'analytical target profile' when a liquid chromatographic technique is going to be carried out for the simultaneous determination of five bisphenols (bisphenol-A, bisphenol-S, bisphenol-F, bisphenol-Z and bisphenol-AF), some of them regulated by the European Union. The procedure has three steps. The first consists of building a D-optimal combined design (mixture-process design) for the control method parameters, which are the composition of the ternary mobile phase and its flow rate. The second step is to fit a PLS2 model to predict six analytical responses (namely, the resolution between each pair of consecutive peaks, and the initial and final chromatographic time) as a function of the control method parameters. The third final step is the inversion of the PLS2 model to obtain the conditions needed for attaining a preset analytical target profile. The computational inversion of the PLS2 prediction model looking for the Pareto front of these six responses provides a set of experimental conditions to conduct the chromatographic determination, specifically 22% of water, mixed with 58% methanol and 20% of acetonitrile, keeping the flow rate at 0.66 mL min^-1. These conditions give a chromatogram with retention times of 2.180, 2.452, 2.764, 3.249 and 3.775 min for BPS, BPF, BPA, BPAF and BPZ, respectively, and excellent resolution among all the chromatographic peaks. Finally, the analytical method is validated under the selected experimental conditions, in terms of trueness and precision. In addition, the detection capability for the five bisphenols were: 596, 334, 424, 458 and 1156 μg L^-1, with probabilities of false positive and of false negative equal to 0.05.

Toxic effects of bisphenol A and its analogues on cyanobacteria Anabaena variabilis and Microcystis aeruginosa

In the last decades, the use of bisphenol A has attracted global attention resulting from its actions as an endocrine disrupting compound. In this regard, various bisphenol analogues have been manufactured as a replacement for this compound in consumer products. As a result of the high production volumes, different bisphenol analogues are entered into the terrestrial and aquatic environment, which consequently leads to their increasing contamination and may pose serious risk to organisms. Nevertheless, only few studies have reported on the toxic effect of bisphenol analogues on phytoplankton. Therefore, in this study, the anticyanobacterial activity of six bisphenol analogues and their mixture were investigated for the first time. Bisphenol AF, bisphenol B and bisphenol C (14 d, EC₅₀ 12.88-54.87 mg L^-1) exhibit more toxic effect to both tested species in comparison to bisphenol A (14 d, EC₅₀ 55.27-78.96 mg L^-1). Moreover, data show that mixture of bisphenol analogues (14 d, EC₅₀ 32.32-60.88 mg L^-1) exhibit toxic effect similar to or even stronger than that of bisphenol A. The toxic effect of bisphenol analogues, singly and in combination on the growth of both cyanobacteria species was arranged in the following order: bisphenol AF > bisphenol C> bisphenol B> bisphenol A> bisphenol E> bisphenol BP and bisphenol B> bisphenol AF > bisphenol C> bisphenol A> bisphenol E> bisphenol BP for Anabaena variabilis and Microcystis aeruginosa, respectively. This research aims to assure a basic understanding of the toxic effects of bisphenol analogues on cyanobacteria and provides a more comprehensive view on environmental risk assessment.

Electron ionization induced fragmentation of fluorinated derivatives of bisphenols

RATIONALE

Fluorinated derivatization agents allow for the identification and quantification of emerging pollutants with high sensitivity, yet details of their potential applications using electron ionization are lacking. The fluorine atom itself does not effectively participate in electron ionization. Furthermore, limited information exists regarding the effect of fluorine during electron ionization-induced fragmentation. To fill this gap, this report presents the fragmentation pathways of the fluorinated derivatives of ten bisphenol analogues as exemplary emerging pollutants.

METHODS

The bisphenols were derivatized by the acetylation reagent trifluoroacetic anhydride and a new silylation reagent, namely dimethyl(3,3,3-trifluoropropyl)silyldiethylamine (DIMETRIS; previously applied for the analysis of selected pharmaceuticals in environmental samples), and analyzed using GC/MS (electron ionization, 70 eV). Deuterated bisphenol A was added to the group of analytes to confirm the proposed fragmentation pathways.

RESULTS

The specific chemical structure of bisphenols gives the possibility of several resonance hybrids of C-centered radicals. This, in turn, results in several fragmentation pathways, unique for each resonance hybrid. Sequential losses of radicals and neutral fragments were observed in both types of derivative, with final stable carbenium ions. McLafferty-type rearrangements were observed between the native structure of the analytes and the introduced substituents. The gamma-shift of F onto Si in the Si(CH₂ )₂ CF₃ substituent is proposed to explain the loss of the fragment with a mass of 78 u.

CONCLUSIONS

Both types of derivatization reagent used were found to be applicable, although the use of DIMETRIS was limited for high-mass bisphenols. The introduction of fluorine by derivatization brings benefits for the qualitative and quantitative analysis of bisphenol-type compounds using GC/MS because of the presence of characteristic ions in the mass spectra.

The quantification of bisphenols and their analogues in wastewaters and surface water by an improved solid-phase extraction gas chromatography/mass spectrometry method

The study focused on the application of GC in the quantitative analysis of bisphenols and their analogues (12 analytes), and the improvement of solid-phase extraction for the whole water analysis of complex water samples. The role of silylation in the qualitative and quantitative analysis of bisphenols was investigated. Partial degradation occurred for selected targets during hot injection with the presence of a silylation agent. A PSA (primary and secondary amines) sorbent placed on the top of the solid-phase extraction (SPE) column sorbent was found to be a matrix component trap, mostly for humic acids. The whole water analysis was performed by washing the filters with methanol and recycling the extract to the sample. The validation of SPE-GC/MS(SIM) gave limits of detection of 1-50 ng/L for ten target bisphenols with a method recovery of between 87 and 133%. The application of the method was tested by the analysis of wastewater sampled from three wastewater treatment plants located in Poland, and municipal surface waters. The only analytes found were BPA and BPS, within the range of 16-1465 ng/L and < MDL-1249 ng/L in wastewater, and 170-3113 ng/L and < MDL-1584 ng/L in surface water, respectively.

Bisphenols as a Legacy Pollutant, and Their Effects on Organ Vulnerability

Bisphenols are widely used in the synthesis of polycarbonate plastics, epoxy resins, and thermal paper, which are used in manufacturing items of daily use. Packaged foods and drinks are the main sources of exposure to bisphenols. These chemicals affect humans and animals by disrupting the estrogen, androgen, progesterone, thyroid, and aryl hydrocarbon receptor functions. Bisphenols exert numerous harmful effects because of their interaction with receptors, reactive oxygen species (ROS) formation, lipid peroxidation, mitochondrial dysfunction, and cell signal alterations. Both cohort and case-control studies have determined an association between bisphenol exposure and increased risk of cardiovascular diseases, neurological disorders, reproductive abnormalities, obesity, and diabetes. Prenatal exposure to bisphenols results in developmental disorders in animals. These chemicals also affect the immune cells and play a significant role in initiating the inflammatory response. Exposure to bisphenols exhibit age, gender, and dose-dependent effects. Even at low concentrations, bisphenols exert toxicity, and hence deserve a critical assessment of their uses. Since bisphenols have a global influence on human health, the need to discover the underlying pathways involved in all disease conditions is essential. Furthermore, it is important to promote the use of alternatives for bisphenols, thereby restricting their uses.

Integrative Assessment of Mixture Toxicity of Three Ionic Liquids on Acetylcholinesterase Using a Progressive Approach from 1D Point, 2D Curve, to 3D Surface

The joint toxicities of [BMIM]BF₄, [BMIM]PF₆, and [HMIM]BF₄ on acetylcholinesterase (AChE) were systematically investigated by using a progressive approach from 1D single effect point, 2D concentration-response curve (CRC), to 3D equivalent-surface (ES) level. The equipartition equivalent-surface design (EESD) method was used to design 10 ternary mixtures, and the direct equipartition ray (EquRay) design was used to design 15 binary mixtures. The toxicities of ionic liquids (ILs) and their mixtures were determined using the microplate toxicity analysis (MTA) method. The concentration addition (CA), independent action (IA), and co-toxicity coefficient (CTC) were used as the additive reference model to analyze the toxic interaction of these mixtures. The results showed that the Weibull function fitted well the CRCs of the three ILs and their mixtures with the coefficient of determination (R²) greater than 0.99 and root-mean-square error (RMSE) less than 0.04. According to the CTC integrated with confidence interval (CI) method (CTCICI) developed in this study, the 25 mixtures were almost all additive action at 20% and 80% effect point levels. At 50% effect, at least half of the 25 mixtures were slightly synergistic action, and the remaining mixtures were additive action. Furthermore, the ESs and CRCs predicted by CA and IA were all within the CIs of mixture observed ESs and CRCs, respectively. Therefore, the toxic interactions of these 25 mixtures were actually additive action. The joint toxicity of the three ILs can be effectively evaluated by the ES method. We also studied the relationship between the mixture toxicities and component concentration proportions. This study can provide reference data for IL risk assessment of combined pollution.

Bisphenols (A, S, and F) affect the basic hormonal activity determined for pharmaceuticals - Study of Saccharomyces cerevisiae

Pharmaceuticals and analogs of bisphenol A (BPA) are increasingly threatening environmental pollutants. In this study, mixtures of selected pharmaceuticals (diclofenac sodium salt, chloramphenicol, oxytetracycline hydrochloride, fluoxetine hydrochloride, estrone, ketoprofen, progesterone, gemfibrozil and androstenedione) were prepared with BPA and its two analogs (namely, bisphenols F and S) at such ratios to reflect environmentally detectable levels. Then, the mixture solutions were studied with a XenoScreen YES/YAS assay to determine the variations in the initial hormonal response of each pharmaceutical compound due to the presence of a bisphenol analog. The results obtained were modeled with the concentration addition (CA) and independent action (IA) approaches, the trueness of which was studied with model deviation ratios (MDR). The estrogenic agonistic activity of the drugs studied was most strongly affected by the presence of BPA in solution (twenty-one cases of synergy observed for CA models versus twelve cases of antagonism in the case of IA predictions). BPS shows a strong agonistic estrogenic impact on most of the drugs studied at medium and high concentration levels; androgenic agonistic activity was also impaired with elevated concentrations of BPS. Increasing the concentration of BPF in a reaction mixture also increased the number of YES + synergism incidences (for CA modeling). Estrone, progesterone and androstenedione were mostly affected by the highest BPF concentrations studied in the case of androgenic agonistic research performed.