Determination of free and conjugated forms of bisphenol A in human urine and serum by liquid chromatography-tandem mass spectrometry

Could endocrine disruptors be a new player for acne pathogenesis? The effect of bisphenol A on the formation and severity of acne vulgaris: A prospective, case-controlled study

BACKGROUND

Acne is one of the most common skin diseases in the adolescent period. Bisphenol A (BPA) is the most frequently observed endocrine-disrupting chemicals that we are exposed to in daily life. BPA can affect acne pathogenesis with similar biological activity on androgenic receptors.

AIMS

To investigate whether BPA levels play a role in the development and severity of acne in adults.

METHODS

Fifty-one adults with acne and 50 healthy controls, whose ages varied between 18 and 25 years and applied to our dermatology outpatient clinic, were evaluated. A questionnaire containing dietary and lifestyle habits for BPA exposure was filled. BPA and BPA glucuronides were analyzed in the LC-MS/MS system in the first-morning urine samples of the patients. Statistical significance was set at p < 0.05.

RESULTS

The median levels of total BPA were significantly higher in the acne group compared with the control group (7.94 (4.69-20.32) vs. 5.62 (1.52-21.05) µg/g creatinine, respectively; p = 0.04)). The acne severity was positively associated with the BPA values (p = 0.00 rs = 0.534). Higher BPA level was noticed in younger acne onset age (p = 0.012 r = -0.349) When the inquiry questions were evaluated, no difference was found between the study groups regarding BPA exposure risk (p > 0.05).

CONCLUSION

BPA could be a factor in acne development and its severity. Therefore, it may be beneficial to prevent BPA exposure and raise awareness in the adolescence and post-adolescence period, in which industrial products such as junk food and plastic bottled water are used more frequently.

An overview of the literature on emerging pollutants: Chlorinated derivatives of Bisphenol A (ClxBPA)

CONTEXT

Bisphenol A (BPA) is a ubiquitous contaminant with endocrine-disrupting effects in mammals. During chlorination treatment of drinking water, aqueous BPA can react with chlorine to form chlorinated derivatives of BPA (mono, di, tri and tetra-chlorinated derivatives) or Cl_xBPA.

OBJECTIVE

The aim of this study is to summarize and present the state of knowledge on human toxicological risk assessment of Cl_xBPA.

MATERIALS AND METHODS

A search on Cl_xBPA in the PubMed database was performed based on studies published between 2002 and 2021. Forty-nine studies on chlorinated derivatives of BPA were found. Available information on their sources and levels of exposure, their effects, their possible mechanisms of action and their toxicokinetics data was extracted and presented.

RESULTS

Cl_xBPA have been essentially detected in environmental aqueous media. There is evidence in toxicological and epidemiological studies that Cl_xBPA also have endocrine-disrupting capabilities. These emerging pollutants have been found in human urine, serum, breast milk, adipose and placental tissue and can constitute a risk to human health. However, in vitro and in vivo toxicokinetic data on Cl_xBPA are scarce and do not allow characterization of the disposition kinetics of these compounds.

CONCLUSION

More research to assess their health risks, specifically in vulnerable populations, is needed. Some water chlorination processes are particularly hazardous, and it is important to evaluate their chlorination by-products from a public health perspective.

Rapid exposure monitoring of six bisphenols and diethylstilbestrol in human urine using fabric phase sorptive extraction followed by high performance liquid chromatography - photodiode array analysis

A novel fabric phase sorptive extraction protocol is developed for rapid exposure monitoring of six bisphenol analogues, including bisphenol A, bisphenol S, bisphenol F, bisphenol E, bisphenol B, bisphenol C, and diethylstilbestrol (DES) from human urine prior to high-performance liquid chromatography-photodiode array analysis. FPSE sample pretreatment protocol ensures the harmonization of the proposed method with the principles of Green Analytical Chemistry (GAC). Among eighteen evaluated FPSE membranes, sol-gel poly (ethylene glycol) (PEG) coated cellulose FPSE membrane resulted in the most efficient extraction. This polar FPSE membrane effectively exploits a number of advantageous features inherent to FPSE including sponge-like porous architecture of the sol-gel sorbent coating, favorable surface chemistry, flexibility and built-in permeability of cellulose fabric substrate, high primary contact surface area for rapid sorbent-analyte interaction, expanded pH, solvent and thermal stability as well as reusability of the FPSE membrane. Optimization was centered on the evaluation of critical parameters, namely the size of the FPSE membrane, the elution solvent mixture, the volume of the sample, the extraction time, the elution time, the kind of the external agitation mechanical stimulus, the ionic strength and the pH of the sample. The chromatographic separation was achieved on a Spherisorb C18 column and a gradient elution program with mobile phase consisted of 0.05 ammonium acetate solution and acetonitrile. The total analysis time was 17.4 min. The developed method was validated in terms of linearity, sensitivity, selectivity, precision, accuracy, stability, and ruggedness. The limits of detection and quantification varied from 0.26-0.62 ng/mL and 0.8-1.9 ng/mL, respectively. The relative recoveries were calculated between 90.6 and 108.8%, while the RSD values were <10% in all cases. The effectiveness of the proposed method was confirmed by its successful implementation in the bioanalysis of real urine samples.

The dose effect of dansyl chloride on the derivative products of bisphenols and its application for the determination of bisphenols in human serum by high-performance liquid chromatography-tandem mass spectrometry

Human exposure to bisphenols has rarely been reported. The most important challenges in this regard are the sensitivity and accuracy of the analytical methods employed. Dansyl chloride derivatization prior to high-performance liquid chromatography-tandem mass spectrometry has been prevalently employed to improve sensitivity. However, the dose effect of the derivatization reagent on the reaction products is not well understood, especially for reactants with two or more active groups. This study investigated the mass ratio of dansyl chloride to bisphenols and found the mass ratio played a vital role in changing the composition of derivatives; further, the optimal ratio for obtaining di-substituted derivatives was confirmed. Under optimal conditions, solid-phase extraction followed by dansyl chloride derivatization coupled with high-performance liquid chromatography-tandem mass spectrometry was used to detect eight bisphenols in human serum samples. The method detection limits of the eight bisphenols were 0.025-0.28 ng/mL, and the recoveries were 72.9-121.7% by spiking bisphenols (2, 5, and 20 ng/mL) into bovine serum. The detection frequencies of bisphenol A and bisphenol F in 73 serum samples obtained from children from Guangzhou were 41.1% and 71.2%, respectively, while the detection frequencies of other bisphenols were below 20%. The concentrations of bisphenol A and bisphenol F were < 0.28-8.0 ng/mL and < 0.028-7.6 ng/mL, respectively.

Investigating the glucuronidation and sulfation pathways contribution and disposition kinetics of Bisphenol S and its metabolites using LC-MS/MS-based nonenzymatic hydrolysis method

Despite showing serious health consequences and widespread exposure, the toxicokinetic information required to evaluate the health risks of BPS is insufficient. Thus, we aim to describe the comprehensive toxicokinetics of BPS and its glucuronide (BPS-G) and sulfate (BPS-S) metabolites in rats. Simultaneous quantification of BPS and its metabolites (authentic standards) was accomplished using UPLC-MS/MS method. BPS displayed rapid absorption, extensive metabolism and fast elimination after oral administration. Following intravenous administration, BPS exhibited CL (8.8 L/h/kg) higher than the rat hepatic blood flow rate suggesting the likelihood of extrahepatic clearance. The CL value differed from those reported previously (sheep and piglets) and the probable reason could be attributed to dose- and/or interspecies differences. BPS was extensively metabolized and excreted primarily through urine as BPS-G (∼56%). BPS and BPS-S exhibited a high protein binding capacity in comparison to BPS-G. In in vitro metabolic stability study, BPS was predominantly metabolized through glucuronidation. The predicted in vivo hepatic clearance of BPS suggested it to be a high and intermediate clearance chemical in rats and humans, respectively. The significant interspecies difference observed in the clearance of BPS between rats and humans indicated that toxicokinetics of BPS should be considered for health risk assessment in humans.

Mechanisms underlying disruption of oocyte spindle stability by bisphenol compounds

Accurate chromosome segregation relies on correct chromosome-microtubule interactions within a stable bipolar spindle apparatus. Thus, exposure to spindle disrupting compounds can impair meiotic division and genomic stability in oocytes. The endocrine disrupting activity of bisphenols such as bisphenol A (BPA) is well recognized, yet their damaging effects on spindle microtubules (MTs) is poorly understood. Here, we tested the effect(s) of acute exposure to BPA and bisphenol F (BPF) on assembled spindle stability in ovulated oocytes. Brief (4 h) exposure to increasing concentrations (5, 25, and 50 µg/mL) of BPA or BPF disrupted spindle organization in a dose-dependent manner, resulting in significantly shorter spindles with highly unfocused poles and fragmented pericentrin. The chromosomes remained congressed in an abnormally elongated metaphase-like configuration, yet normal end-on chromosome-MT attachments were reduced in BPF-treated oocytes. Live-cell imaging revealed a rapid onset of bisphenol-mediated spindle MT disruption that was reversed upon compound removal. Moreover, MT stability and regrowth were impaired in BPA-exposed oocytes, with few cold-stable MTs and formation of multipolar spindles upon MT regrowth. MT-associated kinesin-14 motor protein (HSET/KIFC1) labeling along the spindle was also lower in BPA-treated oocytes. Conversely, cold stable MTs and HSET labeling persisted after BPF exposure. Notably, inhibition of Aurora Kinase A limited bisphenol-mediated spindle pole widening, revealing a potential interaction. These results demonstrate rapid MT disrupting activity by bisphenols, which is highly detrimental to meiotic spindle stability and organization. Moreover, we identify an important link between these defects and altered distribution of key spindle associated factors as well as Aurora Kinase A activity.

Occurrence of Free-Form and Conjugated Bisphenol Analogues in Marine Organisms

Upon exposure, most bisphenol analogues (BPs) are rapidly metabolized to BP conjugates in organisms. Monitoring studies on BPs in aquatic organisms have been mainly focused on free-form BPs. However, the relative amount of conjugated BPs in organisms is still not well known, especially in marine organisms. In this study, we collected marine organisms (13 species; n = 74), as well as seawater (n = 15), from East China Sea, and analyzed them for bisphenol A (BPA) and its eight analogues. In seawater, BPA was the predominant BP (mean ± standard deviation (SD), 18 ± 9.7 ng/L), followed by bisphenol S (BPS; 3.7 ± 2.8 ng/L), bisphenol F (BPF; 0.31 ± 0.17 ng/L), and bisphenol AF (BPAF; 0.24 ± 0.15 ng/L). The whole body of each marine organism was used for BP analysis in this study. BPA (mean 3.8 ng/g, range 1.2-7.7 ng/g) and BPS (1.5 ng/g, 0.19-6.1 ng/g) were still the predominant BPs in marine organisms without hydrolysis. After enzymatic hydrolysis treatment, mean concentrations of BPs increased 1.8 (BPS)-3.7 (BPA) times in marine organisms. Correspondingly, on average, 74, 52, 49, 48, and 45% of BPA, bisphenol Z, BPF, BPS, and BPAF were present in conjugated forms, respectively, in marine organisms. Moreover, bioaccumulation and biomagnification of BPs were evaluated using pooled marine organism samples. We first found that the mean log BAF values of BPs increased 0.091 (BPAF) to 0.31 (BPA) times in marine organisms after hydrolysis. Overall, this study first determines the amount of BPs present in conjugated forms in marine organisms, which are helpful for better understanding the occurrence of BPs in organisms.

Bisphenol A and Metabolites in Meat and Meat Products: Occurrence, Toxicity, and Recent Development in Analytical Methods

Bisphenol A (BPA) is a commonly used compound in many industries and has versatile applications in polycarbonate plastics and epoxy resins production. BPA is classified as endocrine-disrupting chemical which can hamper fetal development during pregnancy and may have long term negative health outcomes in humans. Dietary sources, main route of BPA exposure, can be contaminated by the migration of BPA into food during processing. The global regulatory framework for using this compound in food contact materials is currently not harmonized. This review aims to outline, survey, and critically evaluate BPA contamination in meat products, including level of BPA and/or metabolites present, exposure route, and recent advancements in the analytical procedures of these compounds from meat and meat products. The contribution of meat and meat products to the total dietary exposure of BPA ranges between 10 and 50% depending on the country and exposure scenario considered. From can lining materials of meat products, BPA migrates towards the solid phase resulting higher BPA concentration in solid phase than the liquid phase of the same can. The analytical procedure is comprised of meat sample pre-treatment, followed by cleaning with solid phase extraction (SPE), and chromatographic analysis. Considering several potential sources of BPA in industrial and home culinary practices, BPA can also accumulate in non-canned or raw meat products. Very few scientific studies have been conducted to identify the amount in raw meat products. Similarly, analysis of metabolites and identification of the origin of BPA contamination in meat products is still a challenge to overcome.

Oxidative Stress, Endocrine Disturbance, and Immune Interference in Humans Showed Relationships to Serum Bisphenol Concentrations in a Dense Industrial Area

Bisphenol A (BPA) analogues, used in a range of products due to health concerns regarding BPA, have emerged as ubiquitous environmental contaminants worldwide. This study aims to evaluate the levels of nine bisphenols (BPs) and eight biomarkers (malondialdehyde, MDA; 8-hydroxy-2'-deoxyguanosine, 8-OHdG; estradiol, E2; follicle-stimulating hormone, FSH; luteinizing hormone, LH; complement compound 3, C3; immunoglobulin M, IgM and c-reaction protein, CRP) in human serum (n = 353) to explore their potential relationships. The detection rates (DRs) of eight BPs in serum samples taken from people working in a dense industrial area of Shenzhen (Guangdong Province, China) were over 72% except for bisphenol B (BPB) (DR = 27.5%). The mean concentrations of BPA, bisphenol P (BPP), BPB, bisphenol F (BPF), bisphenol FL (BPFL), 4,4'-dihydroxy-benzophenone (DHBP), bisphenol AF (BPAF), 4,4'-thiodiphenol (TDP) and bisphenol S (BPS) were 42.062, 2.083, 0.765, 0.578, 0.423, 0.402, 0.191, 0.120, and 0.071 ng/mL, respectively. BPA and BPFL were significantly correlated with the level of oxidative stress indices MDA and 8-OHdG; BPAF, BPB, and DHBP were strongly correlated with the level of endocrine disturbance indices E2, FSH, and LH; and BPF, DHBP, and BPAF were apparently related to the level of immune interference indices C3 and IgM. This study also suggests multiple impacts (oxidative stress, endocrine disturbance, and immune interference) mediated by BPs contaminants in vivo. To our knowledge, this is the first study to report the correlations among these nine serum BPs and oxidative stress and endocrine and immune system indices in human serum samples collected from dense industrial areas.

Deposition, depletion, and potential bioaccumulation of bisphenol F in eggs of laying hens after consumption of contaminated feed

Increasing concerns over bisphenol A (BPA) as an endocrine disrupting chemical (EDC) and its adverse effects on both humans and animals have led to the substitution by structural analogs, such as bisphenol F (BPF), in many application areas. Information regarding to the carry-over of this emerging chemical in farm animals is essential for legislation and risk assessment purposes. In this study, a large-scale number of animal experiments were designed to investigate the transfer of BPF from feed to eggs. One control and three experimental groups of laying hens (72 hens per group) were fed with basal diets and BPF-contaminated feed at concentration levels of 0.1, 0.5 and 2.5 mg kg^-1, respectively, for two weeks. The hens were then fed with BPF-free diets for a further four weeks. Eggs were collected daily, and separated into egg yolk and white for BPF analysis. The effects of different levels of BPF exposure on laying performance followed a non-monotonic dose-response curve, since low level BPF (0.1 mg kg^-1) exposure did increase the laying rate, mean egg weight and daily feed intake, while high level BPF (2.5 mg kg^-1) exposure showed a decreasing trend. BPF residues were detected in both egg yolks and whole eggs after two days of administration, and plateau phase was achieved within 9-18 days. There are clear linear dose-response relationships between the plateau BPF concentrations in feed and eggs. The residue of BPF was found mainly in egg yolks with conjugated form and depleted slowly (still detected 21 days after feeding the BPF-free diet of the high level group). Mean carry-over rate of 0.59% BPF from feed to eggs was obtained. Compared with the carry-over rates of PCBs and dioxins, BPF showed a relatively minor trend of bioaccumulation in eggs. To the best of our knowledge, this is the first report on the deposition, depletion, and bioaccumulation study of bisphenols in farm animals. The quantity of data can therefore be helpful in the frame of risk assessment, especially for a comprehensive estimation of consumer exposure to the residues of bisphenols.

Serum levels of non-persistent environmental pollutants and risk of incident hypertension in a sub-cohort from the EPIC study

BACKGROUND

The prevalence of arterial hypertension (AHT), a well-known risk factor for cardiovascular disease, has considerably increased over last decades. Non-persistent environmental pollutants (npEPs) are a group of ubiquitous chemicals, widely used in consumer products such as food packaging and cosmetics, which have been identified as endocrine disrupting chemicals and obesogens. The aim of this study was to assess the potential associations of serum levels of three groups of npEPs with the risk of incident AHT.

METHODS

Cohort study within a sub-cohort of Granada EPIC-Spain center (n = 670). We quantified serum concentrations of three groups of npEPs, i.e., bisphenol A (BPA), four parabens: methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP), and two benzophenones: benzophenone 1 (BP1), benzophenone 3 (BP3), in samples collected at recruitment. Statistical analyses were performed by means of Cox Proportional Hazard Models.

RESULTS

Median follow-up time was 23 years. BPA and MP were found in >80% of the study population. Individuals within the 4th PP quartile (0.53-9.24 ng/ml) showed a statistically significant increased risk of AHT (HR = 1.40, p = 0.015). No associations were found for the rest of pollutants.

CONCLUSIONS

Overall, we evidenced no associations of most npEPs with AHT risk, with the exception of an increased risk in the highest PP percentiles. Considering the limitations of using one spot serum sample for exposure characterization, further research on the potential contribution of npEPs on the development of AHT risk is warranted.

Possible overestimation of bisphenol analogues in municipal wastewater analyzed with GC-MS

This work for the first time showed that sulfated BPA could be directly analyzed as BPA with GC-MS after the derivatization with N,O-bis-(trimethylsilyl) trifluoroacetamide (BSTFA)+1% trimethylchlorosilane (TMCS), i.e. the deconjugation step was not necessary. This was because sulfated BPA indeed could be simultaneously deconjugated and derivatized to BPA derivative during derivatization, suggesting that any co-elution of BPA and sulfated BPA during sample extraction led to BPA overestimation in the GC-MS method with BSTFA +1% TMCS as the derivative reagent. Using BPA 4,4'-disulfates (BPA diS) as the pure standard, the co-elution phenomena of sulfated BPA was confirmed with two widely used elution solvents (i.e. methanol and ethyl acetate) or their mixed solutions with different ratios, which further suggested if only sulfated BPA existed in any wastewater sample, BPA was likely over-determined. To further confirm this finding, both influent and effluent samples collected from a local municipal wastewater treatment plant were analyzed, which clearly showed the overestimation of BPA in the two wastewaters due to co-existence of sulfated BPA in the wastewater samples. In addition to BPA, the results also showed the overestimation of other nine bisphenol analogues. As sulfated micropollutants including estrogens, androgens, phytoestrogens, etc., have been widely found in municipal wastewater, the overestimating phenomenon observed in this study may also be extended to determination of other micropollutants, which should be addressed in future.

Development and Validation of an Analytical Method for Quantitation of Bisphenol S in Rodent Plasma, Amniotic Fluid and Fetuses by UPLC-MS-MS

Bisphenol S (BPS) has been detected in personal care products, water, food and indoor house dust, demonstrating the potential for human exposure. Due to limited data to characterize the hazard of BPS, the National Toxicology Program (NTP) is investigating the toxicity of BPS in rodent models. Generating systemic exposure data is integral to putting toxicological findings into context. The objective of this work was to develop and validate a method to quantitate free (unconjugated parent) and total (free and all conjugated forms of) BPS in rodent plasma, amniotic fluid and fetal homogenate in support of NTP studies. The method used incubation with (total BPS) and without (free BPS) deconjugating enzyme and then protein precipitation followed by ultra-performance liquid chromatography-tandem mass spectrometry. In Sprague Dawley rat plasma, the method was linear (r ≥ 0.99) over the range 5-1,000 ng/mL, accurate (mean relative error (RE) ≤ ±10.5%) and precise (relative standard deviation (RSD) ≤ 7.7%). Mean recoveries were ≥93.1% for both free and total analyses. The limits of detection were 1.15 ng/mL (free) and 0.862 ng/mL (total) in plasma. The method was evaluated in the following study matrices: (i) male Hsd:Sprague Dawley®SD® (HSD) rat plasma, (ii) female HSD rat plasma, (iii) male B6C3F1 mouse plasma, (iv) female B6C3F1 mouse plasma, (v) HSD rat gestational day (GD) 18 dam plasma, (vi) HSD rat GD 18 amniotic fluid, (vii) HSD rat GD 18 fetal homogenate and (viii) HSD rat postnatal day 4 pup plasma (mean %RE ≤ ±8.2 and %RSD ≤ 8.7). Stability of BPS in extracted samples was demonstrated for up to 7 days at various temperatures, and freeze-thaw stability was demonstrated after three cycles over 7 days. BPS in various matrices stored at -80°C for at least 60 days was within 92.1-115% of Day 0 concentrations, demonstrating its stability in these matrices. These data demonstrate that this simple method is suitable for determination of free and total BPS in plasma, amniotic fluid and fetuses following exposure of rodents to BPS.

Exposure to bisphenol A and breast cancer risk in northern Mexican women

OBJECTIVE

To evaluate the association between BC and urinary concentrations of free-bisphenol A (BPA-F), the biological form of BPA, among women residing in Northern Mexico.

METHODS

The population under study comprised 394 histologically confirmed BC cases and 404 age-matched controls. Women were interviewed face to face about their sociodemographic and reproductive characteristics. BPA-F was determined by high-pressure liquid chromatography equipped with a fluorescence detector (HPLC/FLD). Logistic regression models were used to estimate the adjusted BC risk in relation to BPA-F.

RESULTS

BPA-F geometric mean was significantly higher among cases compared to controls (3.16 μg/L in cases and 2.47 μg/L in controls). A significant adjusted BC odds ratio of 2.31 (95% CI: 1.43-3.74) was estimated for the highest category of BPA-F compared to the lowest category.

CONCLUSION

BPA-F may be an environmental cofactor of BC. Since this is the first report on BPA-F association with BC, our results need to be replicated.

Biomarkers, matrices and analytical methods targeting human exposure to chemicals selected for a European human biomonitoring initiative

The major purpose of human biomonitoring is the mapping and assessment of human exposure to chemicals. The European initiative HBM4EU has prioritized seven substance groups and two metals relevant for human exposure: Phthalates and substitutes (1,2-cyclohexane dicarboxylic acid diisononyl ester, DINCH), bisphenols, per- and polyfluoroalkyl substances (PFASs), halogenated and organophosphorous flame retardants (HFRs and OPFRs), polycyclic aromatic hydrocarbons (PAHs), arylamines, cadmium and chromium. As a first step towards comparable European-wide data, the most suitable biomarkers, human matrices and analytical methods for each substance group or metal were selected from the scientific literature, based on a set of selection criteria. The biomarkers included parent compounds of PFASs and HFRs in serum, of bisphenols and arylamines in urine, metabolites of phthalates, DINCH, OPFRs and PAHs in urine as well as metals in blood and urine, with a preference to measure Cr in erythrocytes representing Cr (VI) exposure. High performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) was the method of choice for bisphenols, PFASs, the HFR hexabromocyclododecane (HBCDD), phenolic HFRs as well as the metabolites of phthalates, DINCH, OPFRs and PAHs in urine. Gas chromatographic (GC) methods were selected for the remaining compounds, e.g. GC-low resolution MS with electron capture negative ionization (ECNI) for HFRs. Both GC-MS and LC-MS/MS were suitable for arylamines. New developments towards increased applications of GC-MS/MS may offer alternatives to GC-MS or LC-MS/MS approaches, e.g. for bisphenols. The metals were best determined by inductively coupled plasma (ICP)-MS, with the particular challenge of avoiding interferences in the Cd determination in urine. The evaluation process revealed research needs towards higher sensitivity and non-invasive sampling as well as a need for more stringent quality assurance/quality control applications and assessments.

Different bisphenols induce non-monotonous changes in miRNA expression and LINE-1 methylation in two cell lines

4,4'-Isopropylidenediphenol (bisphenol A, BPA), a chemical substance that is widely used mainly as a monomer in the production of polycarbonates, in epoxy resins, and in thermal papers, is suspected to cause epigenetic modifications with potentially toxic consequences. Due to its negative health effects, BPA is banned in several products and is replaced by other bisphenols such as bisphenol S and bisphenol F. The present study examined the effects of BPA, bisphenol S, bisphenol F, p,p'-oxybisphenol, and the BPA metabolite BPA β-d-glucuronide on the expression of a set of microRNAs (miRNAs) as well as long interspersed nuclear element-1 methylation in human lung fibroblast and Caco-2 cells. The results demonstrated a significant modulation of the expression of different miRNAs in both cell lines including miR-24, miR-155, miR-21, and miR-146a, known for their regulatory functions of cell cycle, metabolism, and inflammation. At concentrations between 0.001 and 10 µg/ml, especially the data of miR-155 and miR-24 displayed non-monotonous and often significant dose-response curves that were U- or bell-shaped for different substances. Additionally, BPA β-d-glucuronide also exerted significant changes in the miRNA expression. miRNA prediction analysis indicated effects on multiple molecular pathways with relevance for toxicity. Besides, long interspersed nuclear element-1 methylation, a marker for the global DNA methylation status, was significantly modulated by two concentrations of BPA and p,p'-oxybisphenol. This pilot study suggests that various bisphenols, including BPA β-d-glucuronide, affect epigenetic mechanisms, especially miRNAs. These results should stimulate extended toxicological studies of multiple bisphenols and a potential use of miRNAs as markers.

Wastewater-based epidemiology to assess human exposure to personal care and household products - A review of biomarkers, analytical methods, and applications

Humans are nowadays exposed to numerous chemicals in our day-to-day life, including parabens, UV filters, phosphorous flame retardants/plasticizers, bisphenols, phthalates and alternative plasticizers, which can have different adverse effects to human health. Estimating human's exposure to these potentially harmful substances is, therefore, of paramount importance. Human biomonitoring (HBM) is the existing approach to assess exposure to environmental contaminants, which relies on the analysis of specific human biomarkers (parent compounds and/or their metabolic products) in biological matrices from individuals. The main drawback is its implementation, which involves complex cohort studies. A novel approach, wastewater-based epidemiology (WBE), involves estimating exposure from the analysis of biomarkers in sewage (a pooled urine and feces sample of an entire population). One of the key challenges of WBE is the selection of biomarkers which are specific to human metabolism, excreted in sufficient amounts, and stable in sewage. So far, literature data on potential biomarkers for estimating exposure to these chemicals are scattered over numerous pharmacokinetic and HBM studies. Hence, this review provides a list of potential biomarkers of exposure to more than 30 widely used chemicals and report on their urinary excretion rates. Furthermore, the potential and challenges of WBE in this particular field is discussed through the review of pioneer WBE studies, which for the first time explored applicability of this novel approach to assess human exposure to environmental contaminants. In the future, WBE could be potentially applied as an "early warning system", which could promptly identify communities with the highest exposure to environmental contaminants.

Bisphenol A exposure and risk of ischemic heart disease in the Spanish European Prospective Investigation into cancer and nutrition study

BACKGROUND

Cardiovascular disease, particularly ischemic heart disease (IHD), is the leading cause of mortality worldwide. Bisphenol A (BPA) is considered an endocrine disruptor and obesogen, present in numerous products of daily use. The aim of this study was to assess the potential association of serum BPA concentrations and the risk of incident IHD in a sub-cohort of the Spanish European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS

We designed a case-cohort study within the EPIC-Spain cohort. The population consisted of 4636 participants from 4 EPIC-Spain centers (946 IHD cases and 3690 sub-cohort participants). BPA exposure was assessed by means of chemical analyses of serum samples collected at recruitment. Follow-up was performed by linking with national and regional databases and reviewing patients' clinical records. Cox Proportional Hazards Models were used for the statistical analyses.

RESULTS

Median follow-up time was 16 years and 70% of the participants showed detectable BPA values (>0.2 ng/ml). Geometric mean (GM) values of cases and sub-cohort were 1.22 ng/ml vs 1.19 ng/ml respectively (p = 0.90). Cox regression models showed no significant association of BPA serum levels and IHD, acute myocardial infarction or angina pectoris risk.

CONCLUSIONS

We evidenced a similar percentage of detection of BPA among cases and sub-cohort participants from our population, and no clear association with IHD risk was observed. However, further investigation is needed to understand the influence of BPA on IHD risk.

Pharmacokinetics of bisphenol A in humans following dermal administration

BACKGROUND

Human exposures to bisphenol A (BPA) are widespread. The current study addresses uncertainties regarding human pharmacokinetics of BPA following dermal exposure.

OBJECTIVE

To examine the absorption, distribution, metabolism and excretion of BPA in humans following dermal administration.

METHODS

We dermally administered deuterated BPA (d6-BPA) to 10 subjects (6 men and 4 women) at a dose of 100 µg/kg over a 12-hour period and conducted blood and urine analysis from the beginning of dosing through a three- or six-day period. We present time-course serum and urine concentrations of total and unconjugated ("free") d6-BPA and used this information to calculate terminal half-life and area under the curve.

RESULTS AND CONCLUSIONS

Detectable serum levels of total d6-BPA were observed at 1.4 h after the start of dosing, and a maximum serum concentration (C_max) of 3.26 nM was observed. Free d6-BPA was detectable in serum 2.8 h after start of dermal administration, with C_max of 0.272 nM. Beginning at approximately seven hours and continuing to 12 h (which corresponds to cessation of exposure), the concentration of free and total serum d6-BPA plateaued. The terminal half-lives of total d6-BPA and free d6-BPA in the body were 21.4 ± 9.81 h and 17.6 ± 7.69 h, respectively. Elimination from the body was rate-limited by kinetics in the dermal compartment. Free d6-BPA was a greater percentage of the area under the curve of total serum BPA (8.81%) compared to the 0.56% observed in our previously published oral study. Recovery of total d6-BPA in urine was <2% of the applied dose after six days. Analysis of the area under the curve for dermal and oral administration revealed that 2.2% of the dermal dose became systemically available. These data are in line with prior studies indicating how pharmacokinetics of BPA differ following oral and dermal exposures. Dermal exposure resulted in a longer apparent half-life and higher free:total d6-BPA ratio compared to oral.

Comparative toxicokinetics of bisphenol S in rats and mice following gavage administration

Bisphenol S (BPS) is a component of polyether sulfone used in a variety of industrial applications and consumer products. We investigated the plasma toxicokinetic (TK) behavior of free (unconjugated parent) and total (parent and conjugated) BPS in rats and mice following a single gavage administration (34, 110, or 340 mg/kg). In male rats, BPS was rapidly absorbed with free BPS maximum concentration (C_max) reached at ≤2.27 h. Elimination of free BPS in male rats was dose-dependent with estimated half-lives of 5.77-11.9 h. C_max and area under the concentration versus time curve (AUC) increased with dose although the increase in AUC was more than dose proportional. In male rats, total BPS C_max was reached ≤2.77 h with both C_max (≥ 10-fold) and AUC (≥ 15-fold) higher than free BPS demonstrating rapid and extensive conjugation of BPS. In male mice, the increase in C_max and AUC of free BPS was dose-proportional; C_max was higher and AUC was lower than in male rats. BPS was cleared more rapidly in male mice (half-life 2.86-4.21 h) compared to male rats (half-life 5.77-11.9 h). Similar to rats, total BPS C_max (≥ 6-fold) and AUC (≥ 12-fold) were higher than corresponding free BPS. Oral bioavailability of free BPS was low to moderate (rats, ≤ 21%; mice, ≤ 19%). There were some species differences in TK parameters of free and total BPS and limited sex difference in rats and mice. In addition, there were dose-related effects of plasma TK parameters in rats.

Prenatal bisphenol A exposure, fetal thyroid hormones and neurobehavioral development in children at 2 and 4 years: A prospective cohort study

Findings about the association between prenatal Bisphenol A (BPA) exposure and neurobehavioral development in children are still inconsistent. In addition, whether fetal thyroid hormones (THs) mediate the reported association remains unclear. The present study aimed to examine the association between prenatal BPA exposure and risks of child behavioral problems at 2 and 4 years of age and whether the association could be explained by alteration of fetal THs as measured in cord plasma. Using the Shanghai-Minhang Birth Cohort Study (S-MBCS), BPA concentration was measured in maternal urine samples collected at 12-16 weeks of gestation. Children's neurobehavioral development was assessed using the Child Behavior Checklist/1.5-5 (CBCL), at 2 and 4 years of age. Using generalized estimating equation (GEE) models, 745 mother-pairs were included to examine associations of BPA with CBCL scores, Using multiple linear regression models, 348 mother-pairs were included to evaluate the association between maternal BPA and THs in cord plasma. A mediation analysis was conducted to explore the potential mediating role of THs. After adjusting for potential confounders, prenatal BPA level was associated with increased risks of Emotionally Reactive problem, Anxious/Depressed problem, having Somatic Complaints, exhibiting Aggressive Behavior, and Internalizing and Externalizing Problems: compared to the lowest tertile, the risks in the highest tertile and middle tertile, ranged between 1.55-fold (95% CI: 1.09, 2.21) and 2.59-fold (95% CI: 1.52, 4.42). The association was more pronounced among boys. None of the associations reached statistical significance among girls. An inverse association between prenatal BPA and fetal TH level was also observed. However, the observed neurotoxic effects of prenatal BPA exposure did not appear to be mediated by THs levels. The current findings suggest that prenatal exposure to BPA may disrupt fetal THs levels and may induce long-lasting behavioral alterations, especially in boys.

Historical exposure to non-persistent environmental pollutants and risk of type 2 diabetes in a Spanish sub-cohort from the European Prospective Investigation into Cancer and Nutrition study

BACKGROUND

Environmental factors are believed to account for a substantial burden of type 2 diabetes mellitus (T2DM). Non-persistent environmental pollutants (npEPs) are a group of widely-used chemicals identified as endocrine/metabolic disrupting chemicals and obesogens. The aim of this study was to analyse the potential associations of serum levels of three groups of npEPs with the risk of incident T2DM.

METHODS

This is a longitudinal study within a sub-sample of Granada EPIC-Spain cohort (n = 670). We quantified serum concentrations of 7 npEPs: four parabens (Methylparaben (MP) ethylparaben (EP), propylparaben (PP) and butilparaben (BP); two benzophenones: Benzophenone 1 (BP1), Benzophenone 3 (BP3); and Bisphenol A (BPA). Exposure was assessed by means of chemical analyses of serum samples collected at recruitment, and information on potential confounders was gathered by using validated questionnaires at baseline. Follow-up was performed by review of patients' clinical records. Cox Proportional Hazards Models were used for the statistical analyses.

RESULTS

Median follow-up time was 23 years. There were 182 (27%) incident T2DM diagnoses in our sub-cohort. MP was the most frequently detected npEP, 88.42% samples above the limit of detection, and BP showed the lowest percentage of detection (19.21%). Those individuals within the fourth PP quartile (0.53-9.24 ng/ml) showed a statistically significant increased risk of T2DM (HR = 1.668 p = 0.012), while BP1 concentrations showed an inverse non-significant trend with the risk.

CONCLUSIONS

We evidenced a potential contribution of npEP exposure on T2DM, but no clear trend was observed. However, limitations in relation to exposure estimation might influence our findings and further research is warranted to confirm our results.

Gene X environment: the cellular environment governs the transcriptional response to environmental chemicals

Background

An individual’s response to environmental exposures varies depending on their genotype, which has been termed the gene-environment interaction. The phenotype of cell exposed can also be a key determinant in the response to physiological cues, indicating that a cell-gene-environment interaction may exist. We investigated whether the cellular environment could alter the transcriptional response to environmental chemicals. Publicly available gene expression array data permitted a targeted comparison of the transcriptional response to a unique subclass of environmental chemicals that alter the activity of the estrogen receptor, xenoestrogens.

Results

Thirty xenoestrogens were included in the analysis, for which 426 human gene expression studies were identified. Comparisons were made for studies that met the predefined criteria for exposure length, concentration, and experimental replicates. The cellular response to the phytoestrogen genistein resulted in remarkably unique transcriptional profiles in breast, liver, and uterine cell-types. Analysis of gene regulatory networks and molecular pathways revealed that the cellular context mediated the activation or repression of functions important to cellular organization and survival, including opposing effects by genistein in breast vs. liver and uterine cell-types. When controlling for cell-type, xenoestrogens regulate unique gene networks and biological functions, despite belonging to the same class of environmental chemicals. Interestingly, the genetic sex of the cell-type also strongly influenced the transcriptional response to xenoestrogens in the liver, with only 22% of the genes significantly regulated by genistein common between male and female cells.

Conclusions

Our results demonstrate that the transcriptional response to environmental chemicals depends on a variety of factors, including the cellular context, the genetic sex of a cell, and the individual chemical. These findings highlight the importance of evaluating the impact of exposure across cell-types, as the effect is responsive to the cellular environment. These comparative genetic results support the concept of a cell-gene-environment interaction.

Toxicokinetics of bisphenol-S and its glucuronide in plasma and urine following oral and dermal exposure in volunteers for the interpretation of biomonitoring data

The measurement of bisphenol-S (BPS) and its glucurono-conjugate (BPSG) in urine may be used for the biomonitoring of exposure in populations. However, this requires a thorough knowledge of their toxicokinetics. The time courses of BPS and BPSG were assessed in accessible biological matrices of orally and dermally exposed volunteers. Under the approval of the Research Ethics Committee of the University of Montreal, six volunteers were orally exposed to a BPS-d8 deuterated dose of 0.1 mg/kg body weight (bw). One month later, 1 mg/kg bw of BPS-d8 were applied on 40 cm² of the forearm and then washed 6 h after application. Blood samples were taken prior to dosing and at fixed time periods over 48 h after treatment; complete urine voids were collected pre-exposure and at pre-established intervals over 72 h postdosing. Following oral exposure, the plasma concentration-time courses of BPS-d8 and BPSG-d8 over 48 h evolved in parallel, and showed a rapid appearance and elimination. Average peak values (±SD) were reached at 0.7 ± 0.1 and 1.1 ± 0.4 h postdosing and mean (±SD) apparent elimination half-lives (t_½) of 7.9 ± 1.1 and 9.3 ± 7.0 h were calculated from the terminal phase of BPS-d8 and BPSG-d8 in plasma, respectively. The fraction of BPS-d8 reaching the systemic circulation unchanged (i.e. bioavailability) was further estimated at 62 ± 5% on average (±SD) and the systemic plasma clearance at 0.57 ± 0.07 L/kg bw/h. Plasma concentration-time courses and urinary excretion rate profiles roughly evolved in parallel for both substances, as expected. The average percent (±SD) of the administered dose recovered in urine as BPS-d8 and BPSG-d8 over the 0-72 h period postdosing was 1.72 ± 1.3 and 54 ± 10%. Following dermal application, plasma levels were under the lower limit of quantification (LLOQ) at most time points. However, peak values were reached between 5 and 8 h depending on individuals, suggesting a slower absorption rate compared to oral exposure. Similarly, limited amounts of BPS-d8 and its conjugate were recovered in urine and peak excretion rates were reached between 5 and 11 h postdosing. The average percent (±SD) of the administered dose recovered in urine as BPS-d8 and BPSG-d8 was about 0.004 ± 0.003 and 0.09 ± 0.07%, respectively. This study provided greater precision on the kinetics of this contaminant in humans and, in particular, evidenced major differences between BPA and BPS kinetics with much higher systemic levels of active BPS than BPA, an observation explained by a higher oral bioavailability of BPS than BPA. These data should also be useful in developing a toxicokinetic model for a better interpretation of biomonitoring data.

Endocrine Disrupting Chemicals and Type 1 Diabetes

Type 1 diabetes (T1D) is the most common chronic metabolic disease in children and adolescents. The etiology of T1D is not fully understood but it seems multifactorial. The genetic background determines the predisposition to develop T1D, while the autoimmune process against β-cells seems to be also determined by environmental triggers, such as endocrine disrupting chemicals (EDCs). Environmental EDCs may act throughout different temporal windows as single chemical agent or as chemical mixtures. They could affect the development and the function of the immune system or of the β-cells function, promoting autoimmunity and increasing the susceptibility to autoimmune attack. Human studies evaluating the potential role of exposure to EDCs on the pathogenesis of T1D are few and demonstrated contradictory results. The aim of this narrative review is to summarize experimental and epidemiological studies on the potential role of exposure to EDCs in the development of T1D. We highlight what we know by animals about EDCs’ effects on mechanisms leading to T1D development and progression. Studies evaluating the EDC levels in patients with T1D were also reported. Moreover, we discussed why further studies are needed and how they should be designed to better understand the causal mechanisms and the next prevention interventions.

Toxicokinetics and bioaccumulation characteristics of bisphenol analogues in common carp (Cyprinus carpio)

Toxicokinetics and bioconcentration of eight common bisphenol analogues, including bisphenol A (BPA), -B, -C, -E, -S, -Z, -AF, and -AP in common carp (Cyprinus carpio) were investigated. Both free (BP_free) and total forms (BP_total) of the bisphenols were measured in various fish tissues. The conjugated forms of bisphenols were calculated based on BP_free and BP_total. The calculated bioconcentration factors (BCFs) based on the total bisphenols (BP_total) in the carp whole body were in the range of 0.3-320, agreeing with previous field results from Taihu Lake, China. The elimination rate constant (k_e) positively correlated with the fraction of conjugated form (f_conjugated), which displayed negative correlation with their log K_ow (r = -0.861, p < 0.05), indicating that conjugation facilitated their elimination and those with higher hydrophobicity were more difficult to be eliminated. Except BPA, the concentrations of all bisphenols in the carp tissues were in the order of kidney > liver ≫ muscle. The uptake rate constants (k_u) in kidney (r = 0.836, p < 0.05) and in liver (r = 0.863, p < 0.05) displayed significantly positive correlations with BCFs, and k_u in kidney was greater than in liver except BPA. These results indicated that kidney and liver played important roles in accumulating bisphenols in carp, and kidney made more contribution than liver for most bisphenols. Biliary excretion predominated for elimination of most bisphenols while BPA and BPS were mainly through urinary excretion.

Bisphenol-A in the European Prospective Investigation into Cancer and Nutrition cohort in Spain: Levels at recruitment and associated dietary factors

Bisphenol A (BPA) is considered an endocrine disruptor and it is present in numerous products of daily use. The aim of this study was to analyze serum BPA concentrations in a subcohort of the Spanish European Prospective Investigation into Cancer and Nutrition (EPIC), as well as to identify potential predictors of the exposure. The population consisted on 3553 subjects from 4 EPIC-Spain centres and BPA levels were measured in serum samples by UHPLC-MS/MS. Almost 70% of the participants showed detectable BPA values (>0.2 ng/ml), with a geometric mean of 1.19 ng/ml (95% CI: 1.12-1.25). By sex, detectable percentages were similar (p = 0.56) but with higher serum levels in men (1.27 vs 1.11 ng/ml, p = 0.01). Based on the adjusted regression models, a 50 g/day increase in the consumption of added fats and oils were associated with 43% lower BPA serum levels, while sugar and confectionary was associated with 25% higher levels of serum BPA. We evidenced differential exposure levels by province, sex and age, but not by anthropometric or lifestyle characteristics. Further investigation is needed to understand the influence of diet in BPA exposure.

Simultaneous determination of bisphenol A and its chlorinated derivatives in human plasma: Development, validation and application of a UHPLC-MS/MS method

Bisphenol A (BPA) is a well-known ubiquitous chemical found in polycarbonate, polysulfone and epoxy resins, used in mass production for many consumer products. BPA exhibits endocrine disruptor properties that can potentially induce adverse health effects. In aquatic environments, it can react with chlorine to produce chlorinated derivatives (ClxBPAs). ClxBPAs exhibit oestrogenic activity 10 to 105 times higher than BPA itself. Assessing human exposure to endocrine disrupting chemicals is mandatory to assess health risk. Blood, as well as urine matrix, are commonly used to perform human biomonitoring. We therefore developed, fully validated and applied a method based on Ultra High Performance Liquid Chromatography couples to a Triple Quad Mass Spectrometer to determine BPA, monochlorobisphenol A (MCBPA), dichlorobisphenol A (DCBPA), trichlorobisphenol A (TCBPA) and tetrachlorobisphenol A (TTCBPA) in human blood plasma. The European Medicines Agency guidelines for bioanalytical method validation have been applied. Precision and trueness of the method were <15% at medium and high levels of quality control and <20% at the limits of quantification (LOQs). The LOQs were settled at 0.1 ng/mL for BPA, 0.02 ng/mL for TTCBPA and 0.005 ng/mL for MCBPA, DCBPA, and TCBPA. The analytical method was applied to ten patients suffering from end stage renal disease. BPA was quantified in all ten patients while MCBPA, DCBPA and TTCBPA were determined in three and TCBPA in four. In conclusion, we have successfully developed a highly sensitive method to determine BPA and ClxBPAs in human plasma. Thanks to this method, for the first time, we could demonstrate ClxBPAs occurrence in human blood.

Rapid, sensitive and simultaneous determination of 16 endocrine-disrupting chemicals (parabens, benzophenones, bisphenols, and triclocarban) in human urine based on microextraction by packed sorbent combined with liquid chromatography tandem mass spectrometry (MEPS-LC-MS/MS)

A high demand exists in human biomonitoring studies for reliable and straightforward methods that generate data faster and simultaneously. Thus, the present study combines microextraction by packed sorbent (MEPS) and liquid chromatography coupled to mass spectrometry (LC-MS/MS) for simultaneous extraction and determination of various classes of endocrine-disrupting chemicals (EDCs), including parabens, benzophenones, bisphenols, and the antimicrobial, triclocarban in human urine samples. Optimized MEPS conditions were: i) MEPS sorbent (C18), ii) pH of sample (3), iii) volume of sample (250 μL), iv) number of draws-eject cycles (5) and (vi) desorption solvent conditions (100 μL of CH₃OH:H₂O 80:20 v/v). The calibration curves were linear over the selected ranges for all studied compound, with correlation coefficients higher than 0.99. The variation coefficient for precision was lower than 20% at lower concentrations and lower than 15% at the higher concentrations studied. The accuracy ranged from 90% to 118%. The proposed strategy affords several advantages over currently published approaches, including simplicity of operation and reduction of sample and solvent volumes and time for matrix clean-up. Moreover, the analytical performance of each MEPS cartridge remained stable over the analysis of at least 70 samples (RSD < 10%). Thus, the current procedure may be an interesting high-throughput alternative for large routine human biomonitoring studies. Urinary geometric mean concentrations of EDCs obtained in this study were close than those previously reported for Brazilian children.

Association of bisphenol A and its alternatives bisphenol S and F exposure with hypertension and blood pressure: A cross-sectional study in China

Epidemiological studies have investigated the associations of bisphenol A (BPA) exposure with hypertension risk or blood pressure levels, but findings are inconsistent. Furthermore, the association between its alternatives bisphenol S and F (BPS and BPF) and hypertension risk are not yet known. We conducted a cross-sectional study in 1437 eligible participants without hypertension-related diseases, with complete data about blood pressure levels, hypertension diagnosis, and urinary bisphenols concentrations. Multivariable logistic and linear models were respectively applied to examine the associations of urinary bisphenols concentrations with hypertension risk and blood pressure levels. The dose-response relationship was explored by the restricted cubic spline model. Compared with the reference group of BPA, individuals in the middle and high exposure group had an adjusted odds ratio (OR) of 1.30 and 1.40 for hypertension, had a 3.08 and 2.82 mm Hg higher systolic blood pressure (SBP) levels, respectively, with an inverted "U" shaped dose-response relationship. Compared with the reference group of BPS, individuals in the second and third tertile had an adjusted OR of 1.49 and 1.48 for hypertension, had a 2.61 and 3.89 mm Hg increased levels of SBP, respectively, with a monotonic curve. No significant associations of BPF exposure with hypertension risk or blood pressure levels were found. BPA and BPS exposure were suggested to be associated with increased hypertension risk and blood pressure levels, with different dose-response relationships. Our findings have important implications for public health but require confirmation in prospective studies.

Determination of bisphenol analogues in food-contact plastics using diode array detector, charged aerosol detector and evaporative light-scattering detector

Freshness protection packages and preservative films are widely used food-contact plastic made of polyethylene. Diode array detector (DAD), charged aerosol detector (CAD) and evaporative light-scattering detector (ELSD) were evaluated for determination of 6 bisphenols (bisphenol A, bisphenol S, bisphenol F, bisphenol B, bisphenol AF and tetrabromobisphenol A.) in polyethylene. DAD presented better parameters including limit of quantification (LOQs) ranging from 0.05 to 0.5 μg/g with relative standard deviations (RSDs, n = 5) lower than 1% at two concentration levels. CAD and ELSD are universal detectors with relative consistent response parameters for different analogues which have potential application by using single calibrant for quantification of multiple analytes. Matrix effects were barely observed on three detectors. Samples of freshness protection packages and preservative films were further analyzed and preliminary profiles of bisphenols in products from Beijing market was obtained. Bisphenol S have become most abundant analogue instead of bisphenol A in investigated products.

Highly Sensitive Determination of Bisphenol A in Bottled Water Samples by HPLC after Its Extraction by a Novel Th-MOF Pipette-Tip Micro-SPE

In this study, a novel thorium metal organic framework was synthesized, characterized and used as a sorbent for very efficient pipette tip micro solid-phase extraction of bisphenol A in bottled drinking water samples using high-performance liquid chromatography as detecting instrument. Parameters which influence extraction efficiency such as pH, sample volume, amount of sorbent, type and volume of eluent, number of aspirating and dispensing cycles for extraction and elution, and volume of the sample solution were studied and optimized. A linear calibration curve was obtained in the range of 0.002–0.456 ng mL−1 (r2 = 0.996) with a detection limit of 0.0010 ng mL−1. Repeatability of batch-to-batch extraction was better than 5.0% and a reproducibility of 3.2% for real samples obtained.

Organophosphate flame retardants and bisphenol A in children's urine in Hong Kong: has the burden been underestimated?

The urine levels of organophosphate flame retardants (PFRs) and bisphenol A (BPA) in kindergarten children (n = 31, 4-6 years old, sampling performed in 2016) in Hong Kong were measured. The detection frequency of the target PFRs, tri(2-chloroethyl)phosphate (TCEP), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), tris(chloroisopropyl)phosphate (TCIPP), triphenyl phosphate (TPHP) and 2-ethylhexyl diphenyl phosphate (EHDPP) ranged from 52% to 84%. The 95th percentile urinary concentrations of TPHP, TDCIPP, TCIPP, EHDPP and TCEP were 1.70, 0.24, 0.03, 0.05, 0.68 and 0.03 ng/mL, respectively. The median urine level of BPA was 1.69 ng/mL, with a detection frequency of 77%. Due to the lack of metabolism information, two scenarios were used to calculate the estimated daily intake (EDI) of these compounds. Back-calculated EDIs of PFRs using the urinary excretion rates from in vivo animal data (scenario 2) were up to 2.97 μg/kg/d (TDCIPP), which was only a little less than that observed in a sample of American infants, and the reference dose (RfD), meaning that the potential health risk of TDCIPP cannot be ignored. Dust ingestion was suggested to be the major pathway of exposure to PFRs, but when the levels in dust and air particles in kindergartens in Hong Kong were used to predict EDIs, these values were nearly half as much as those predicted from urinary TDCIPP in this study. This suggested that children's PFRs burden may be underestimated when considering only PFR levels in dust or air. There is thus a need for further studies with large-scale surveys and investigation of exposure routes.

Competitive Biotransformation Among Phenolic Xenobiotic Mixtures: Underestimated Risks for Toxicity Assessment

Humans are inevitably exposed to a complex mixture of organic contaminants (i.e., xenobiotics) through diet, environment, and behavior. Biotransformation makes key contributions to the elimination of xenobiotics and greatly mediates the toxicity. However, most biotransformation studies were conducted using individual chemical, and whether coexposure of multiple environmental chemicals will affect each other's fate in the human body is still in its infancy. In this study, bisphenol A (BPA) was selected as a model compound. Its biotransformation was investigated under single exposure/coexposure to other phenolic xenobiotics (triclosan, tetrabromobisphenol A, and bisphenol S) in liver microsome and cell models. The result shows that binary exposures exhibit significant inhibitory effects on the BPA metabolism, especially the sulfate conjugation. In combination of analysis on inhibition models and enzyme activity, the inhibition effect was suggested to be primarily driven by competition for metabolizing enzymes. A mixture with 22 phenolic chemicals was further examined to disrupt BPA at various human-relevant levels. Again, the result demonstrates significant inhibition on the BPA metabolism, indicating the possible natural existence of our finding. Overall, our results show that biotransformation of phenolic xenobiotics can be significantly altered by coexposure, which provides referential evidence on underestimated risks of simultaneous exposure to environmental toxicants.

Exposure to bisphenol A and diabetes risk in Mexican women

Bisphenol A (BPA) is an endocrine-disrupting chemical widely used in the production of polycarbonate plastics and epoxy resins, which has been previously linked to diabetes among non-Hispanic populations. As part of a case control study for breast cancer, only controls with BPA information were included in this report. The final sample size comprises 70 self-reported diabetics and 334 non-diabetics. Urinary free bisphenol A (BPA-F) (μg/L) was determined by solid-phase extraction and HPLC/FLD analysis. Logistic regression models were used to evaluate the association between BPA-F and self-reported diabetes. After adjusting by age, urinary BPA-F (4.06-224.53 μg/g creatinine) was associated with diabetes exposure (OR = 1.85; 95% CI 1.04, 3.28) compared with women in the reference category (0.67-4.05 μg/g creatinine). BPA may be an environmental cofactor of diabetes. More studies are needed to confirm this result, especially in Hispanic populations.

Unexpectedly high concentrations of 2,4-di-tert-butylphenol in human urine

Synthetic phenolic antioxidants (SPAs) have received increasing attention due to the reports of toxicity and environmental contamination. Nevertheless, limited information was available on human burdens of these SPAs, with the exception of 2,6-di-tert-butyl-4-methylphenol (BHT). In our study, BHT as well as six other SPAs were analyzed in human urine samples from United States donors. Three SPA congeners were detected in human urine: BHT, 2,4-di-tert-butylphenol (DBP), and 3-tert-butyl-4-hydroxyanisole (BHA). BHT, which is the congener received most concerns, was detected at low concentrations [geometric mean (GM): 0.06 ng/mL], whereas four of its metabolites were detected at relatively high concentrations (GM: 1.68 ng/mL). Surprisingly, DBP was detected at extremely high concentrations (GM: 18.3 ng/mL). The concentrations of DBP (GM: 25.8 ng/mL), BHT (0.853 ng/mL), and metabolites (GM: 10.5 ng/mL) increased significantly after the urine samples were hydrolyzed by β-glucuronidase (p < 0.01), indicating the prevalence of the conjugated forms of SPAs and their metabolites in human urine. DBP, which has previously received little attention, was the predominant congener, contributing 88.2% and 63.6% to total target concentrations in the urine samples before and after β-glucuronidase hydrolysis, respectively. Thus, previous studies have vastly underestimated the burdens of SPAs to humans. To our knowledge, this is the first study revealing the presence of DBP in human urine.

Bisphenol A, Chlorinated Derivatives of Bisphenol A and Occurrence of Myocardial Infarction in Patients with Type 2 Diabetes: Nested Case-Control Studies in Two European Cohorts

A positive association between Bisphenol A (BPA) exposure and coronary heart disease has been shown, but not in patients with type 2 diabetes (T2D). During the treatment of drinking water, chlorination leads to the formation of chlorinated derivatives of Bisphenol A (ClxBPA), that have higher estrogenic activity than BPA. No evidence exists for a relationship between exposure to ClxBPA and myocardial infarction in patients with T2D. The objective of this study was to evaluate the relationship between exposure to BPA, ClxBPA and the occurrence of myocardial infarction (MI) in patients with T2D. Two nested case-control studies in two independent European cohorts were performed. Each case with incident MI during follow-up was matched to one control on age, sex, and personal cardiovascular history in the same cohort. Association between baseline urine concentrations of BPA and of ClxBPA and incident MI was determined. Exposure to BPA was 31% in the ESTHER cohort and 18% in the SURDIAGENE cohort. In a meta-analysis of the two studies, occurrence of MI was significantly associated with urine BPA detection: adjusted OR = 1.97 (1.05-3.70), p = 0.04. Exposure to ClxBPA significantly differed in the SURDIAGENE and ESTHER studies: 24% and 8%, respectively (p = 0.0003). It was very strongly associated with MI in the SURDIAGENE cohort with an adjusted odds ratio (OR) of 14.15 (2.77-72.40) but this association was not replicated in the ESTHER study: adjusted OR: 0.17 (0.02-1.23). Whether these results may be explained by different water chlorination processes in France and Germany, resulting in different ClxBPA exposure levels, requires further investigation.

An ionic liquid functionalized polymer for simultaneous removal of four phenolic pollutants in real environmental samples

An ionic liquid functionalized polymer (IL-P) was prepared feasibly and simply by grafting1-butyl-3-vinylimidazolium bromide onto the silica surface. The IL-P was fully characterized, and the results showed that IL-P has a rough surface with a lower specific surface area (205.49 m² g^-1), and the involvement of ionic liquid significantly improved the adsorption performance of IL-P. The pH, initial concentration, adsorption time and temperature were investigated to discuss the adsorption behaviors of IL-P in aqueous solution. The adsorption process of 2,4-dichlorophenol (2,4-DCP), bisphenol A (BPA) and 2,4-dinitrophenol (2,4-DNP) onto IL-P better fitted the pseudo-second-order model, while that of 2-isonaphthol (2-NP) followed the pseudo-first-order model. The adsorption behaviors of IL-P towards 2,4-DCP and 2,4-DNP fitted well with Liu isotherm model, and that of BPA and 2-NP can be described by Langmuir model. The maximum adsorption capacities of 2,4-DCP, BPA, 2,4-DNP and 2-NP bound on IL-P was 239.7, 68.39, 56.86 and 64.28 mg g^-1, respectively, and the adsorption of IL-P is a spontaneous physical process. Comparing with other adsorbent, the as-prepared IL-P showed excellent recognition ability towards the phenolic compounds and can be applied to adsorb and remove trace 2,4-DCP, 2-NP, 2,4-DNP and BPA simultaneously in complicated wastewater and soil samples.

Determination of 3-Hydroxybenzo[a]pyrene Glucuronide/Sulfate Conjugates in Human Urine and Their Association with 8-Hydroxydeoxyguanosine

While 3-hydroxybenzo[a]pyrene (3-OHBaP) is a preferable biomarker to assess human exposure to benzo[a]pyrene (BaP), a sensitive and simple method is lacking. In this study, a specific and sensitive method based on liquid chromatography coupled with electrospray tandem mass spectrometry (LC-ESI-MS/MS) was developed for direct analysis of 3-OHBaP glucuronide and sulfate conjugates in human urine samples without enzymatic hydrolysis. The limits of detection (LODs) were 0.06 ng L^-1 for BaP-3-sulfate (BaP-3-S) and 0.16 ng L^-1 for BaP-3-glucuronide (BaP-3-G), which showed high sensitivity. Both compounds showed excellent linearity (r² > 0.99) in the range of 0.01-10 μg L^-1 in the instrumental calibration. The absolute recoveries of the target analytes spiked in human urine for the entire analytical procedure were 68.3 ± 4.96% (mean ± SD) and 63.7 ± 5.47% for BaP-3-S and BaP-3-G, respectively. This method was applied to quantify BaP-3-G and BaP-3-S in 150 urine samples collected from healthy volunteers. The mean concentration of BaP-3-S was 0.67 ng g^-1 creatinine (<LOD to 10.20 ng g^-1 creatinine), about 10-fold lower than that of BaP-3-G (6.73 ng g^-1 creatinine, < LOD to 52.64 ng g^-1 creatinine). For comparison, we also detected the concentration of free 3-OHBaP in 15 randomly selected samples without enzymatic hydrolysis and found at least >98% of 3-OHBaP is excreted mainly in these two conjugated forms in human urine. A statistically significant positive association was observed between urinary 3-OHBaP conjugates and urinary 8-OHdG levels (p < 0.001) in the general population. This study developed a sensitive and simple method to determine urinary glucuronide/sulfate conjugated BaP metabolites and for the first time found that BaP exposure associated with 8-OHdG levels in the general population.

Toxicity and multigenerational effects of bisphenol S exposure to Caenorhabditis elegans on developmental, biochemical, reproductive and oxidative stress

Bisphenol A (BPA) is a typical endocrine disruptor. Bisphenol S (BPS) has been widely used as a substitute for various plastic materials due to the limited application of BPA. However, it does not mean that BPS is a safe substitute due to the lack of effective evaluation of BPS. In this study, the clinical model of Caenorhabditis elegans (C. elegans) was used to study the effects of BPS on the locomotion behavior, growth, reproduction, lifespan and antioxidant system. Our study found that C. elegans exposed to 0.01 μM BPS could have significantly inhibited locomotion behavior and growth, as well as damaged reproductive and antioxidant systems and lifespan. It is interesting to note that in multi-generational exposure studies, we found that BPS exhibits complex genotoxicity. With the transmission to the offspring, BPS showed more significant inhibition of the head thrashes of the nematode, while the effect on the body bends and body length was gradually weakened. The effect of BPS on the brood size shows different rules according to different concentrations and offsprings. Therefore, the safety of BPS still needs further evaluation, especially the multi-generational genotoxicity.

Development and validation of an LC-MS/MS method for the simultaneous determination of bisphenol A and its chlorinated derivatives in adipose tissue

Bisphenol A (BPA) and its chlorinated derivatives (Clx-BPA) are environmental pollutants exhibiting endocrine-disrupting (ED) properties suspected to be involved in the pathogenesis of hormone-dependent cancers, such as breast and prostate cancers. Due to their lipophilic properties, they may accumulate in adipose tissue which could therefore be a suitable matrix to assess long-term exposure to these compounds and relationships with the tumorigenesis of these cancers. An LC-MS/MS assay for the determination of BPA and Clx-BPA in adipose tissue samples was developed and fully validated according to current bioanalytical validation guidelines. Ionization was achieved using an electrospray source operating in the negative mode and quantification of target analytes was obtained in the multiple reaction monitoring mode. Both standard and quality control (QC) samples were prepared in blank adipose tissue samples. Linearity was demonstrated over the ranges 0.125 to 8.000 and 0.0125-0.8000 ng/mL for BPA and Clx-BPA, respectively. Accuracy and precision were demonstrated over the whole concentration range: intra and inter-day bias values were in the 85-114% range and imprecision of the method did not exceed 14%. Lower limits of quantification were validated using QCs at 0.1250 and 0.0125 ng/mL for BPA and Clx-BPA, respectively. Internal standard-corrected matrix effects were comparable in breast and prostate adipose tissues, demonstrating that this method could be used to reliably assay BPA and Clx-BPA in both tissues. The method was sensitive enough to determine BPA and Clx-BPA in breast adipose tissue obtained from women undergoing breast surgery, enabling identification of different patterns of exposure to these ED chemicals. The method enables the reliable quantification of BPA and Clx-BPA in adipose tissue and could be used to assess long-term exposure to these compounds and potential associations with hormone-dependent cancers.

Quantitative method for conjugated metabolites of bisphenol A and bisphenol S determination in food of animal origin by Ultra High Performance Liquid Chromatography-Tandem Mass Spectrometry

With the objectives of both generating bisphenols (BPs) conjugates occurrence data in food from animal origin but also investigating the origin of associated contamination, the present study deals with the development of an efficient analytical method aiming at monitoring both BPA and BPS conjugated metabolites in food from animal origin. The objective of such monitoring is to determine the origin of BPs contamination (FCM or animal contamination). The targeted compounds were BPA-monoglucuronide (BPA-1G), BPA-diglucuronide (BPA-2G), BPA-monosulfate (BPA-1S), BPA-disulfate (BPA-2S) and BPS-monoglucuronide (BPS-1G). The developed standard operating procedure includes a preliminary solid-liquid extraction step followed by two successive solid phase extraction (SPE) stages, using successively a non-polar phase and a strong cation exchange polymer. Quantification was achieved according to both the isotopic dilution and surrogated quantification methods, using ¹³C-BPA-1G and BPA-d₆-1S as internal standards. Linearity was validated (R² > 0.99) for each molecule within the concentration range [0-10] μg kg^-1. Detection limits ranged from 0.02 μg kg^-1 (BPA-1G in muscle, BPA-1S and BPA-2G in liver) to 0.50 μg kg^-1 (BPA-2S in muscle). The strategy was then proven on liver samples collected from pregnant ewes subcutaneously exposed to BPA during 105 days, at 50 μg kg^-1 per day. BPA-1G, BPA-2G and BPA-1S were detected and quantified at a concentration of 3.81 μg kg^-1, 0.80 μg kg^-1 and 0.09 μg kg^-1, respectively. The analytical method was finally implemented on fifty unpacked food samples from animal origin in which significant free BPA concentrations were previously measured. Since no metabolites of BPA could be measured (<LOD), it means that such free BPA present in the samples originates from direct contact of the food item with a material containing BPA.

Association of exposure to Bisphenol A with obesity and cardiometabolic risk factors in children and adolescents

In this study, the association of exposure to Bisphenol A (BPA) with obesity and cardiometabolic risk factors was investigated on 132 children and adolescents aged 6-18 years living in Isfahan, Iran. Potential contributors to BPA exposure were assessed by a questionnaire. Total BPA was detected in urine samples of all participants without significant difference in boys and girls. The mean body mass index (BMI) and waist circumference (WC) increased significantly across the BPA tertiles (p for trend = < 0.001). Similar trend was documented for systolic blood pressure (SBP) and diastolic blood pressure (DBP) as well as fasting blood sugar. The risk of obesity was 12.48 times higher in participants in the third tertile of BPA than in others (95% CI: 3.36-46.39, p < 0.001). The current study showed significant association between BPA exposure with obesity and some cardiometabolic risk factors in children and adolescents, however, further longitudinal studies are necessary to evaluate the clinical effects of this finding. Abbreviations: BMI: Body Mass Index; BPA: Bisphenol A; BSTFA: N, O-Bistrifluoroacetamide; CDC: Centers for Disease Control and Prevention; CI: Circumference Interval; DBP: Diastolic Blood Pressure; DLLME: Dispersive liquid-liquid microextraction method; FBS: Fasting Blood Glucose; HDL: high-density lipoprotein cholesterol were; LDL: low-density lipoprotein cholesterol; OR: Odd Ratio; PA: Physical Activity; SBP: Systolic Blood Pressure; TC: total cholesterol; TG: triglycerides; WC: Waist Circumference.

Bisphenol A Exposure and Sperm ACHE Hydroxymethylation in Men

Exposure to bisphenol A (BPA) has been shown to impact human sperm quality. The epigenetic mechanisms underlying the effect remain unknown. The acetylcholinesterase (ACHE) gene is a sperm-expressed gene encoding the acetylcholine hydrolyzing enzyme acetylcholinesterase and participates in the apoptosis of cells, including sperm. This study aimed to examine whether BPA exposure is associated with the hydroxymethylation level of the sperm ACHE gene. A total of 157 male factory workers were studied, among whom 74 had BPA exposure in the workplace (BPA exposure group) and 83 had no BPA exposure in the workplace (control group). Urine samples were collected for BPA measurement and semen samples were collected to assay for ACHE hydroxymethylation. Sperm ACHE hydroxymethylation level was higher in the BPA exposure group (p = 0.041) compared to the control group. When subjects were categorized according to tertiles of detected BPA level, higher ACHE hydroxymethylation levels were observed for the lowest, middle, and top tertiles compared to those with BPA below the limit of detection (LOD). In a linear regression analysis adjusted for confounders, a positive linear association between urine BPA concentration and 5-hydroxymethylcytosine (5hmC) rate of the sperm ACHE gene was observed, although the association did not reach statistical significance in all categories after being stratified by the BPA tertile. In conclusion, 5hmC of the sperm ACHE gene was positively associated with BPA exposure, which may provide supportive evidence for BPA’s effects on male fertility or other health endpoints.

A Phenolphthalein-Dummy Template Molecularly Imprinted Polymer for Highly Selective Extraction and Clean-Up of Bisphenol A in Complex Biological, Environmental and Food Samples

A molecularly imprinted polymer (MIP) for highly selective solid-phase extraction (SPE) of bisphenol A (BPA) was prepared using phenolphthalein (PP) as the novel dummy template by bulk polymerization. A particle diameter distribution of 40⁻60 μm, a specific surface area of 359.8 m²·g-1, and a total pore volume of 0.730 cm³·g-1 for the prepared PP-imprinted polymer (PPMIP) were obtained. Good selectivity and specific adsorption capacity for BPA of the prepared PPMIP were also demonstrated by the chromatographic evaluation and sorption experiments. The PPMIP as a SPE sorbent was evaluated for the selective extraction and clean-up of BPA from complex biological, environmental, and food samples. Meanwhile, an accurate and sensitive analytical method based on the PPMIP-SPE purification procedure coupled with high performance liquid chromatography-diode array detector (HPLC-DAD) detection has been successfully developed for the rapid determination of BPA from these samples, with detection limits of 1.3 ng·mL-1 for bovine serum and milk, 2.6 ng·mL-1 for human urine and edible oil, 5.2 ng·mL-1 for soybean sauce, and 1.3 ng·g-1 for sediment. The BPA recoveries at two different spiking levels were in the range of 82.1⁻106.9%, with relative standard deviation (RSD) values below 7.7%.