Sensitive determination of bisphenol A in environmental water by gas chromatography with nitrogen-phosphorus detection after cyanomethylation

Development of CuFe2O4 microspheres/carbon sheets composite materials as a sensitive electrochemical sensor for determination of bisphenol A

A composite material based on CuFe-ZIF-derived CuFe2O4 nano-microspheres grown in situ and well-ordered on carbon sheets (CS) was prepared and applied for highly effective determination of bisphenol A (BPA). The composite material possessed inherently high redox activity due to the presence of both Cu and Fe ions with various oxidation states (Cu²⁺/Cu⁺ and Fe³⁺/Fe²⁺), high specific surface area, uniform distribution of Cu and Fe ions, and a robust framework imparted by its precursor CuFe-ZIF. This led to increased active sites for electrochemical reactions, improved electron transfer efficiency, and structural integrity during electrochemical cycling. Furthermore, combining CS with CuFe2O4 not only provided a large surface area to support well-ordered CuFe₂O₄ nano-microspheres without aggregation, but also enhanced the conductivity and mechanical stability of the CuFe₂O₄/CS composite. This results in synergistic effects that enhanced the overall performance of the composite material. In addition, both copper and iron are relatively non-toxic and abundant, making CuFe₂O₄/CS safe and cost-effective for large-scale applications. Consequently, the CuFe2O4/CS-modified electrode shows highly efficient electrochemical sensing properties with a wider detection range of 0.009-168 µM and lower detection limit of 0.0027 µM (S/N = 3) compared with most reported BPA sensors. It also has an optimized current at pH 7 which is convenient for real world applications. This CuFe2O4/CS modified electrode as a highly sensitive electrochemical platform can be applied to monitor BPA concentrations in bottled water with good recovery (97.2-102.2%).

Development of a novel green catalyzed nanostructured Cu(II) macrocyclic complex-based disposable electrochemical sensor for sensitive detection of bisphenol A in environmental samples

BPA is an endocrine disruptor and the leading environmental pollutant due to its use as raw material in industries. Therefore, the present work reports the sensitive, efficient, and disposable electrochemical paper-based SPE for determining the BPA sensor using an amide-based macrocyclic complex (nanostructured complex of copper acetate with macrocyclic ligand, i.e., CuL (CH3COO)2) synthesized using Citrus limon (lemon) extract via sonication for the first time. The structural, morphological, and electrochemical analyses have been characterized by mass spectroscopy, FTIR, UV-Vis, XRD, FESEM-EDX, elemental mapping and electrochemical techniques. The sensor platform for detecting BPA was fabricated by simple drop-casting on the disposable paper-based SPE using macrocyclic complex, i.e., CuL (CH3COO)2/SPE. After optimizing the conditions, CuL (CH3COO)2/SPE electrode was employed for determining BPA via CV with a wide linear range of 31 × 10-9 μM-0.205 μM, low LOD of 0.027 nM, and high sensitivity of 49.71 μA (log nM)-1 cm-2 having correlation coefficient (R2) of 0.976 which is quite better in compared to other reported SPE sensor for detection of BPA. Further, our sensor also showed good selectivity and reproducibility, in addition to detecting BPA in environmental samples (tube well water, river water and drain water) with acceptable recoveries and RSDs values. In this work, the combination of macrocyclic complex and paper-based SPE has turned out to be a cost-effective electrochemical sensor.

A paper-analytical device for detecting bisphenol-A in foods

Bisphenol A (BPA) is a plastic monomer that can leach into food and cause adverse health effects with long-term exposure. In this study, we developed simple paper-analytical devices (PADs) for detecting BPA in food. The PADs were designed with hydrophilic and hydrophobic areas via wax printing. The hydrophilic areas were designed as a detection zone and modified with carboxymethyl cellulose (CMC) for the immobilisation of BPA-bovine serum albumin (BSA). The monoclonal antibodies against BPA were generated and modified with quantum dots (QDs) to synthesise QD-antibody (QD-Ab) probes. Detection conditions of the assay were optimized, with results of 0.1 μg of BPA-BSA and 30-fold diluted QD-Ab probes. The detection limit was 0.098 μg L^-1 using ImageJ analysis. Samples of drinking water, green tea beverage and peanut cooking oil were selected to conduct the matrix effect study. The recovery rates of BPA in different samples ranged from 78.77% to 118.96%, proving that the PADs were a simple and sensitive detection method for easy, low-cost analysis of real food samples.

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.

Co-exposure to ketoconazole alters effects of bisphenol A in Danio rerio and H295R cells

Chemicals are present in combination in ambient water, however toxicities of their mixtures are not well understood. This study investigated the effects of ketoconazole (KCZ) on the responses induced by bisphenol A (BPA) in zebrafish and in human adrenocarcinoma (H295R) cells. After exposure to BPA alone or mixed with KCZ for 21 d, egg production, relative tissue weights, sex hormone levels, cytochrome P450 (CYP)3a activity, and transcriptions of genes related to CYP metabolism, vitellogenesis, and steroidogenesis were determined in zebrafish. Male fish were more sensitive to the adverse effects of BPA than females, and the presence of KCZ potentiated the BPA-induced estrogenic responses in the male and anti-estrogenic responses in the female fish. In male zebrafish exposed to BPA, a significant reduction in egg number and relative gonad weight, an increase in 17β-estradiol (E2) to testosterone (T) ratio, and an upregulation of vtg, erα, and cyp19a genes were observed. Under KCZ, BPA exposure resulted in a significant downregulation of cyp3a65 and pxr genes and an increase in estrogenic responses in males. In female fish, anti-estrogenic effects, such as a decrease in E2 concentration, were observed following the combined exposure. These results indicate that KCZ could increase the toxicity of the chemicals that depend on the given CYP metabolism for their elimination or other crucial functions such as steroidogenesis. Co-exposure to BPA and KCZ in H295R cells also increased E2 and decreased T production. Release and presence of this azole compound warrant caution, because it could modify adverse effects of BPA.

Construction of a nanostructure-based electrochemical sensor for voltammetric determination of bisphenol A

A novel carbon paste electrode modified with graphene oxide nanosheets and an ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate) was fabricated. The electrochemical study of the modified electrode, as well as its efficiency for voltammetric oxidation of bisphenol A, is described. The electrode was also employed to study the electrochemical oxidation of bisphenol A, using cyclic voltammetry, chronoamperometry, square wave voltammetry and electrochemical impedance spectroscopy as diagnostic techniques. Square wave voltammetry exhibits a linear dynamic range from 9.0 × 10(-8) to 2.5 × 10(-4) M and a detection limit of 55.0 nM for bisphenol A. Finally, this new sensor was used for determination of bisphenol A in water samples using the standard addition method.

Detection of bisphenol A in food packaging based on fluorescent conjugated polymer PPESO3 and enzyme system

Bisphenol A (BPA) is a kind of carcinogen, which can interfere with the body's endocrine system. In this paper, a new kind of fluorescent sensor for BPA detection was established based on the fluorescent conjugated polymer PPESO3. The oxidative product of BPA is able to quench PPESO3 in the presence of HRP and H2O2, and the quenched PL intensity of PPESO3 was proportionally to the concentration of BPA in the range of 1-100 μmol/L with a detection limit of 4 × 10(-7) mol/L. The proposed method has been applied to detect BPA in eight food packaging samples with satisfactory results. The proposed method has the potential for the assay of BPA in food or food packaging samples.

A portable optic fiber aptasensor for sensitive, specific and rapid detection of bisphenol-A in water samples

Bisphenol A (BPA) is a known endocrine disruptor and one of the most serious environmental contaminants, often present at low levels in various water sources. Therefore, it is very important and necessary to develop a fast, cost-effective, sensitive, and selective method for on-site detection of BPA. Herein, we developed a portable, evanescent, wave fiber-optic aptasensor for rapid, on-site detection of BPA with high sensitivity and selectivity. In this system, the probe DNA molecule, which is the complementary sequence of a small part of the BPA aptamer, was covalently immobilized onto the optical fiber sensor surface. Using an indirect competitive detection mode, samples containing different concentrations of bisphenol A were premixed with a given concentration of fluorescence-labeled BPA aptamer, which binds to bisphenol A with high specificity. Then, the sample mixture was pumped to the sensor surface, and a higher concentration of BPA led to less fluorescence-labeled BPA aptamer hybridized with surface immobilized probe DNA and thus to a lower fluorescence signal. The developed sensing system exhibits a sensitive response to BPA in the range of 2 nM to 100 nM with a low detection limit of 1.86 nM (0.45 ng ml(-1)) under the optimal conditions. The biosensors showed good reproducibility, stability, and selectivity for BPA detection. Finally, this proposed sensor was successfully employed to determine the presence of BPA in wastewater samples.

Electrochemical determination of bisphenol A in plastic bottled drinking water and canned beverages using a molecularly imprinted chitosan-graphene composite film modified electrode

Herein, a novel electrochemical sensor based on an acetylene black paste electrode modified with molecularly imprinted chitosan-graphene composite film for sensitive and selective detection of bisphenol A (BPA) has been developed. Several important parameters controlling the performance of the sensor were investigated and optimised. The imprinted sensor offers a fast response and sensitive BPA quantification. Under the optimal conditions, a linear range from 8.0 nM to 1.0 μM and 1.0 to 20 μM for the detection of BPA was observed with the detection limit of 6.0 nM (S/N=3). Meanwhile, the fabricated sensor showed excellent specific recognition to template molecule among the structural similarities and coexistence substances. Furthermore, this imprinted electrochemical sensor was successfully employed to detect BPA in plastic bottled drinking water and canned beverages.

Phytodegradation potential of bisphenolA from aqueous solution by Azolla Filiculoides

Many organic hazardous pollutants such as bisphenolA (BPA) which are toxic and not easily biodegradable can concerns for environmental pollution worldwide. The objective of this study was to examine whether Azolla Filiculoides is able to remove BPA from aqueous solutions. In this study, the Azolla with different biomass (0.3, 0.6, 0.9, 1.2 g) has been cultured in solution that was contained 5, 10, 25 and 50 ppm BPA. Samples were collected every 2 days from all of containers. The analytical determination of BPA was performed by using of DR4000 uv-visible at λmax = 276 nm. The results indicated that Azolla has high ability to remove BPA from aqueous solutions. The BPA removal was 60-90%. The removal efficiency is increasing with decreasing of BPA concentration and increasing of biomass amount and vice versa. The removal efficiency was more than 90% when BPA concentration was 5 ppm and amount of biomass was 0.9gr. It is concluded that Azolla able remove BPA by Phytodegradation from the aqueous solutions. Since conventional methods of BPA removal need to high cost and energy, phytoremediation by Azolla as a natural treatment system can decrease those issues and it can be a useful and beneficial method to removal of BPA.

Determination of bisphenol-type endocrine disrupting compounds in food-contact recycled-paper materials by focused ultrasonic solid-liquid extraction and ultra performance liquid chromatography-high resolution mass spectrometry

Focused ultrasonic solid-liquid extraction (FUSLE) and reverse-phase ultra performance liquid chromatography (UPLC) coupled to a quadrupole-time of flight mass spectrometer (Q-TOF-MS) was applied to the determination of bisphenol-type endocrine disrupting compounds (EDCs) in food-contact recycled-paper materials. Recycled paper is a potential source of EDCs. Bisphenol A (BPA), bisphenol F (BPF) and their derivatives bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE) are used for the production of epoxy resins employed in the formulation of printing inks. The FUSLE of bisphenol-type EDCs from packaging is reported for the first time. First, different extraction solvents were studied and methanol was selected. Then, the main FUSLE factors affecting the extraction efficiency (solvent volume, extraction time and ultrasonic irradiation power) were studied by means of a central composite design. The FUSLE conditions selected for further experiments were 20 ml of methanol at ultrasonic amplitude of 100% for 5s. Finally, the number of extraction cycles necessary for complete extraction was established in two. The analysis of the FUSLE extracts was carried out by UPLC-Q-TOF-MS with electrospray ionization and the determination of the four analytes took place in only 4 min. The FUSLE and UPLC-ESI-QTOF-MS method was validated and applied to the analysis of different food-contact recycled-paper-based materials and packaging. The proposed method provided recoveries from 72% to 97%, repeatability and intermediate precision under 9% and 14%, respectively, and detection limits of 0.33, 0.16, 0.65 and 0.40 μg/g for BPA, BPF, BADGE and BFDGE, respectively. The analysis of paper and cardboard samples confirmed the presence of EDCs in these packaging.

Amperometric biosensor based on tyrosinase immobilized onto multiwalled carbon nanotubes-cobalt phthalocyanine-silk fibroin film and its application to determine bisphenol A

An amperometric bisphenol A (BPA) biosensor was fabricated by immobilizing tyrosinase on multiwalled carbon nanotubes (MWNTs)-cobalt phthalocyanine (CoPc)-silk fibroin (SF) composite modified glassy carbon electrode (GCE). In MWNTs-CoPc-SF composite film, SF provided a biocompatible microenvironment for the tyrosinase to retain its bioactivity, MWNTs possessed excellent inherent conductivity to enhance the electron transfer rate and CoPc showed good electrocatalytic activity to electrooxidation of BPA. The cyclic voltammogram of BPA at this biosensor exhibited a well defined anodic peak at 0.625 V. Compared with bare GCE, the oxidation signal of BPA significantly increased; therefore, this oxidation signal was used to determine BPA. The effect factors were optimized and the electrochemical parameters were calculated. The possible oxidation mechanism was also discussed. Under optimum conditions, the oxidation current was proportional to BPA concentration in the range from 5.0 x 10(-8) to 3.0 x 10(-6) M with correlation coefficient of 0.9979 and detection limit of 3.0 x 10(-8) M (S/N=3). The proposed method was successfully applied to determine BPA in plastic products and the recovery was in the range from 95.36% to 104.39%.

Exposure to Bisphenol A prenatally or in adulthood promotes T(H)2 cytokine production associated with reduction of CD4CD25 regulatory T cells

BACKGROUND

Bisphenol A (BPA) is a widespread endocrine-disrupting chemical that can affect humans and animals.

OBJECTIVES

We investigated the effects of adult or prenatal exposure to BPA on T-helper (T(H))1/T(H)2 immune responses and the mechanisms underlying these effects.

METHODS

To evaluate the effects of exposure to BPA in adulthood, male Leishmania major-susceptible BALB/c and -resistant C57BL/6 mice were subcutaneously injected with 0.625, 1.25, 2.5, and 5 micromol BPA 1 week before being infected with L. major. To evaluate prenatal exposure, female mice were given BPA-containing drinking water at concentrations of 1, 10, and 100 nM for 2 weeks, then mated, and given BPA for another week. Male 10-week-old offspring were infected with L. major. Footpad swelling was assessed as a measure of the course of infection.

RESULTS

Mice exposed to BPA prenatally or in adulthood showed a dose-dependent increase in footpad swelling after being infected with L. major. Exposure to BPA in adulthood significantly promoted antigen-stimulated production of interleukin (IL)-4, IL-10, and IL-13 but not interferon-gamma (IFN-gamma). However, mice prenatally exposed to BPA showed increased production of not only IL-4 but also IFN-gamma. The percentages of CD4(+)CD25(+) cells were decreased in mice exposed to BPA either prenatally or in adulthood. Effects of prenatal BPA exposure were far more pronounced than effects of exposure in adulthood.

CONCLUSION

BPA promotes the development of T(H)2 cells in adulthood and both T(H)1 and T(H)2 cells in prenatal stages by reducing the number of regulatory T cells.

Derivation of a bisphenol A oral reference dose (RfD) and drinking-water equivalent concentration

Human exposure to bisphenol A (BPA) is due to that found in the diet, and BPA and its metabolites were detected at parts per billion (or less) concentrations in human urine, milk, saliva, serum, plasma, ovarian follicular fluid, and amniotic fluid. Adverse health effects in mice and rats may be induced after parenteral injection or after massive oral doses. Controlled ingestion trials in healthy adult volunteers with 5 mg d16-BPA were unable to detect parent BPA in plasma despite exquisitely sensitive (limit of detection = 6 nM) methods, but by 96 h 100% of the administered dose was recovered in urine as the glucuronide. The extensive BPA glucuronidation following ingestion is not seen after parenteral injection; only the parent BPA binds plasma proteins and estrogen receptors (ER). The hypothesis that BPA dose-response may be described by a J- or U-shape curve was not supported by toxicogenomic data collected in fetal rat testes and epididymes (after repeated parenteral exposure at 2-400,000 microg/kg-d), where a clear monotonic dose-response both in the numbers of genes and magnitude of individual gene expression was evident. There is no clear indication from available data that the BPA doses normally consumed by humans pose an increased risk for immunologic or neurologic disease. There is no evidence that BPA poses a genotoxic or carcinogenic risk and clinical evaluations of 205 men and women with high-performance liquid chromatography (HPLC)-verified serum or urinary BPA conjugates showed (1) no objective signs, (2) no changes in reproductive hormones or clinical chemistry parameters, and (3) no alterations in the number of children or sons:daughters ratio. Results of benchmark dose (BMD10 and BMDL10) calculations and no-observed-adverse-effect level (NOAEL) inspections of all available and reproducible rodent studies with oral BPA found BMD and NOAEL values all greater than the 5 mg/kg-d NOAELs from mouse and rat multigeneration reproduction toxicity studies. While allometric and physiologically based pharmacokinetic (PBPK) models were constructed for interspecies scaling of BPA and its interaction with ER, multigeneration feeding studies with BPA at doses spanning 5 orders of magnitude failed to identify signs of developmental toxicity or adverse changes in reproductive tract tissues; the 5-mg/kg-d NOAELs identified for systemic toxicity in rats and mice were less than the oral NOAELs for reproductive toxicity. Thus, it is the generalized systemic toxicity of ingested BPA rather than reproductive, immunologic, neurobehavioral, or genotoxic hazard that represents the point of departure. Using U.S. Environmental Protection Agency (EPA) uncertainty factor guidance and application of a threefold database uncertainty factor (to account for the fact that the carcinogenic potential of transplacental BPA exposure has yet to be fully defined and comprehensive neurobehavioral and immunotoxicologic evaluations of BPA by relevant routes and at relevant doses have yet to be completed) to the administered dose NOAEL results in an oral RfD of 0.016 mg/kg-d. Assuming the 70-kg adult consumes 2 L of water each day and adopting the default 20% U.S. EPA drinking water relative source contribution yields a 100 microg/L BPA total allowable concentration (TAC).

Exposure of mouse oocytes to bisphenol A causes meiotic arrest but not aneuploidy

Mouse oocytes isolated from large antral follicles were exposed to a wide range of concentrations of bisphenol A (BPA) during maturation in vitro (50 ng/ml to 10 microg/ml BPA in medium). Exposure to high concentrations of BPA (10 microg/ml) affected spindle formation, distribution of pericentriolar material and chromosome alignment on the spindle (termed congression failure), and caused a significant meiotic arrest. However, BPA did not increase hyperploidy at meiosis II at any tested concentration. Some but not all meiosis I arrested oocytes had MAD2-positive foci at centromeres of chromosomes in bivalents, suggesting that they had failed to pass the spindle checkpoint control. In a second set of experiments prepubertal mice were exposed sub-chronically for 7 days to low BPA by daily oral administration, followed by in vitro maturation of the denuded oocytes to metaphase II in the absence of BPA, as this treatment protocol was previously reported to induce chromosome congression failure and therefore suspected to cause aneuploidy in oocytes. The sub-chronic exposure subtly affected spindle morphology and oocyte maturation. However, as with the exposure in vitro, there was no evidence that low BPA doses increased hyperploidy at meiosis II. In conclusion, the data suggest that mouse oocytes from mice respond to BPA-induced disturbances in spindle formation by induction of meiotic arrest. This response might result from an effective checkpoint mechanism preventing the occurrence of chromosome malsegregation and aneuploidy. Low chronic BPA exposure in vivo as such does not appear to pose a risk for induction of errors in chromosome segregation at first meiosis in mouse oocytes. Additional factors besides BPA may have caused the high rate of congression failure and the temporary increase in hyperploidy in mouse metaphase II oocytes reported previously.

Elevated serum bisphenol A levels under hyperandrogenic conditions may be caused by decreased UDP-glucuronosyltransferase activity

This study was performed to investigate the effect of androgen on the metabolism of bisphenol A (BPA), an endocrine disruptor, in order to clarify the mechanism of the higher levels of serum BPA in men and hyperandrogenemic women compared with normal women. Castrated female rats (OVX) were subcutaneously injected with testosterone propionate (TP) (0.01, 0.1, and 1 mg) every day for 2 weeks. Serum BPA concentrations in OVX rats showed a TP dose-dependent increase and were significantly higher at 0.1 and 1.0 mg of TP. The enzyme reaction of BPA glucuronidation in the rat liver microsomes showed that the ratio of glucuronide in the OVX rats was significantly reduced in a TP dose-dependent manner. Analysis of the mRNA expression of UDP-glucuronosyltransferase 2B1 (UGT2B1) by real-time quantitative RT-PCR revealed that the relative expression level of UGT2B1 mRNA showed a TP dose-dependent decrease. The results of enzyme analyses demonstrated that the ratio of BPA glucuronidation and the expression level of UGT2B1 mRNA were significantly lower under the hyperandrogenemic conditions. The clearance of BPA may be slowed in a TP dose-dependent manner, resulting in an increase of serum BPA concentration under hyperandrogenemic conditions.

Analysis of bisphenol A in natural waters by means of an optical immunosensor

This work describes a very simple, fast and sensitive method based on the use of the optical immunosensor "RIver ANAlyser" (RIANA) to the determination of bisphenol A in a waters. RIANA is based on a rapid solid-phase indirect inhibition immunoassay that takes place at an optical transducer chip chemically modified with an analyte derivative. Fluorescence produced by labelled antibodies bound to the transducer is detected by photodiodes and can be correlated with the analyte concentration. The sensor surface can be regenerated thus allowing the performance of several measurements (around 300) with the same transducer. Each test cycle, including one regeneration step, is accomplished in 15 min. The detection limit achieved in the direct determination of bisphenol A in water with this system was 0.014 microg/L. Satisfactory repeatability, with relative standard deviations (RSD) ranging between 1.48% and 6.93% were obtained. The immunosensor method developed was applied to the monitoring of bisphenol A in various types of water collected in a waterworks (from the river water source to the finished drinking water) and validated against the results obtained in the same approach by a more traditional method, based on solid-phase extraction followed by liquid chromatography-mass spectrometry. Results obtained by both techniques were in general good agreement (considering the typical overestimation bias of immunoassays), and served to prove the satisfactory removal efficiency of the overall purification process applied in the waterworks and, in particular, of the sand filtration step.

Determination of alkylphenols and bisphenol-A

A functional polymer (hydroxylated polymethacrylate) coated on porous polysulfone hollow fiber membrane (PS-HFM) was used as an adsorbent for the extraction of alkylphenols and bisphenol-A from seawater samples. Analyses of the extracts were performed using gas chromatography-mass spectrometry (GC-MS) after injection-port derivatization using bis(trimethylsilyl)trifluoroacetamide (BSTFA). We term the procedure as polymer-coated hollow fiber microextraction (PC-HFME). Owing to high porosity PS-HFM coated with hydroxylated polymer showed high extraction efficiency. Compared with solid-phase microextraction (SPME), PC-HFME showed good selectivity and sensitivity. Detection limits of alkylphenols and bisphenol-A ranged between 0.07 and 2.34 ng l(-1). The linearity range was from 0.01 to 15 microg l(-1) and the correlation coefficient (r) up to 0.997. The sensitivity and selectivity of the coated HFM could be potentially tuned by changing the characteristics of the coated hydroxylated polymer. The PC-HFME procedure was applied to the detection of alkylphenols and bisphenol-A in the coastal waters of Singapore.

Gender difference in serum bisphenol A levels may be caused by liver UDP-glucuronosyltransferase activity in rats

Gender difference in human bisphenol A (BPA) concentrations was revealed by determining serum BPA. We studied the serum concentrations and the metabolism of BPA in rats by an HPLC system. Rat serum BPA concentrations were significantly higher in males (24.9+/-7.38 ng/ml, P=0.026, n=10) than in females (8.27+/-3.11 ng/ml, n=10), as in humans. The resultant enzyme reaction products of BPA glucuronidation in the rat liver microsomes fraction were analyzed by an HPLC system. The ratio of BPA glucuronidation in the microsome reaction was significantly higher (P=0.015) in female than in male rats. The mRNA expression of UDP-glucuronosyltransferase 2B1 (UGT2B1), an isoform of UGT related to BPA glucuronidation, in the rat liver was analyzed by a real-time quantitative RT-PCR. The relative expression level of UGT2B1 mRNA was significantly higher (P<0.001) in female than in male rat livers. The gender difference in serum BPA concentrations may be explained by the difference in clearance based on the UGT activities.

Determination of Bisphenol-A in Water by Semi-Micro Column High-Performance Liquid Chromatography Using 2-Methoxy-4-(2-phthalimidinyl)-phenylsulfonyl Chloride as a Fluorescent Labeling Reagent

A highly sensitive method for the determination of bisphenol-A in water with semi-micro column high-performance liquid chromatography using 2-methoxy-4-(2-phthalimidinyl)phenylsulfonyl chloride as a fluorescent labeling reagent has been developed. The labeling reaction was carried out at 70 degrees C for 20 min in borate buffer (pH 9.5). The derivative eluted at 11.6 min on a reversed-phase column with methanol-water (78:22, v/v) at a flow-rate of 0.2 ml/min. The fluorescence was monitored at 308 nm for excitation and 410 nm for emission. The detection limit (S/N = 3) was 10 fmol per injection. The labeling yield was about 95%.

Sex reversal effects on Caiman latirostris exposed to environmentally relevant doses of the xenoestrogen bisphenol A

Exposure to environmental contaminants known as endocrine disruptors (EDs) alters the development and function of reproductive organs in several species. Bisphenol A (BPA) is an estrogenic chemical that leaches from dental materials and plastic food and beverage containers. BPA has been found in sewage, surface and drinking water, and therefore poses a potentially significant risk for human and wildlife. Prenatal exposure of rodents to environmentally relevant doses of BPA alters the development of the reproductive organs of male and female offspring. Species with temperature dependent sex determination (TSD) could act as sentinels of ecosystem health by providing sensitive biomarkers of endocrine disruptor's effects. We selected Caiman latirostris as an animal model to study endocrine disruption caused by BPA. The aim of this study was to determine whether exposure in ovum to BPA could cause estrogen-like effects on the reproductive system of C. latirostris. Sex determination and gonadal histoarchitecture were the endpoints evaluated after in ovum exposure to different doses of BPA and 17beta-estradiol (E(2)). We confirmed that C. latirostris is a species with TSD and additionally demonstrated that BPA causes estrogen-like developmental effects by reversing gonadal sex and altering gonadal histoarchitecture. Differences in responses to BPA and E(2) in our in vivo system were on the order of 100-fold. In contrast published in vitro studies have reported differences on the order of 10,000x or more. These results support the utility of C. latirostris, a species in which sex determination is temperature dependent, as a tool in assessing estrogenic activity in vivo and as a sentinel to monitor EDs in aquatic environment.

Parent bisphenol A accumulation in the human maternal-fetal-placental unit

Bisphenol A (BPA), an endocrine disruptor, is employed in the manufacture of a wide range of consumer products. The suggestion that BPA, at amounts to which we are exposed, alters the reproductive organs of developing rodents has caused concern. At present, no information exists concerning the exposure of human pregnant women and their fetuses to BPA. We therefore investigated blood samples from mothers (n = 37) between weeks 32 and 41 of gestation. Afer the births, we also analyzed placental tissue and umbilical cord blood from the same subjects. We developed a novel chemical derivatization-gas chromatography/mass spectrometry method to analyze parent BPA at concentrations < 1 micro g/mL in plasma and tissues. Concentrations of BPA ranged from 0.3 to 18.9 ng/mL (median = 3.1 ng/mL) in maternal plasma, from 0.2 to 9.2 ng/mL (median = 2.3 ng/mL) in fetal plasma, and from 1.0 to 104.9 ng/g (median = 12.7 ng/g) in placental tissue. BPA blood concentrations were higher in male than in female fetuses. Here we demonstrate parent BPA in pregnant women and their fetuses. Exposure levels of parent BPA were found within a range typical of those used in recent animal studies and were shown to be toxic to reproductive organs of male and female offspring. We suggest that the range of BPA concentrations we measured may be related to sex differences in metabolization of parent BPA or variable maternal use of consumer products leaching BPA.