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Allergic contact dermatitis from bisphenol A in PVC gloves.

Bisphenol A is used as an antioxidant in polyvinyl chloride (PVC) plastics and as an inhibitor of end polymerization in PVC. Since 1998, we have investigated 4 cases of contact allergy from bisphenol A in PVC gloves. Only the case of the first patient, a packer in the food industry, has been reported in detail. A dentist and an oral hygienist apprentice had used disposable PVC gloves made by the same manufacturer, both in 1999. The dentist's PVC gloves contained 0.044% bisphenol A. In 2002, a cabin servant had used 2 brands of household-type PVC gloves. Her gloves contained 0.12% and 0.07% bisphenol A. Moreover, 2 of the patients reacted to p-tertiary butyl catechol, a polymerization inhibitor in PVC, but the connection between the allergic reaction and the PVC gloves could not be proven. In 2002, we analysed 16 brands of disposable PVC gloves for medical use, covering at least 80% of the Finnish market. We found a very small amount of bisphenol A in 1 brand, and no p-tertiary butyl catechol in any of the gloves. Nowadays, it seems that manufacturers avoid using bisphenol A in the production of disposable gloves for medical use, but bisphenol A should be remembered as a possible contact allergen in PVC products.

Adult↗

Determination of bisphenols in sewage based on supramolecular solid-phase extraction/liquid chromatography/fluorimetry.

Supramolecular sorbents (hemimicelles/admicelles) are proposed for the extraction/preconcentration of bisphenols from aqueous environmental samples prior to their liquid chromatography/fluorimetric determination. A comparative study on the use of cetyltrimethylammonium bromide (CTABr)-coated silica and sodium dodecyl sulphate (SDS)-coated gamma-alumina as sorbent materials, is presented. Bisphenol A (BPA) and bisphenol F (BPF) were quantitatively retained on CTABr admicelles. Addition of tetrabutylammonium chloride (TBAC) to water samples was required to completely retain bisphenols on SDS-gamma-alumina. Retention on both sorbents occurred through hydrophobic and pi-cation interactions between the quaternary ammonium head group of the cationic amphiphile (CTABr or TBAC) and the aromatic rings of the target analytes. TBAC-SDS-gamma-alumina was the sorbent selected for the SPE of bisphenols on the basis of the lower elution volume required (1 ml of methanol) and the greater breakthrough volume allowed (400 ml), which permitted to reach practical detection limits of 10 and 15 ng/l for BPF and BPA, respectively. The proposed method was used to quantify bisphenol A and bisphenol B in wastewater samples from four sewage treatment plants. Recoveries obtained ranged between about 99 and 105% for raw wastewater and between 96 and 106% for treated wastewater.

Chromatography, Liquid↗

Crystal engineering using bisphenols: interwoven ladders, sheet and framework structures in the binary adducts of 4,4'-sulfonyldiphenol with pyrazine (2/1), 4,4'-bipyridyl (1/1), trans-1,2-bis(4-pyridyl)ethene (1/1), 1,2-bis(4-pyridyl)ethane (1/1) and 4,4'-trimethylenedipyridine (1/1), and in 4,4'-sulfonyldiphenol-4,4'-trimethylenedipiperidine-water (2/2/1).

The structures of six hydrogen-bonded adducts of 4,4'-sulfonyldiphenol with heteroaromatic amines have been determined. In 4,4'-sulfonyldiphenol-pyrazine (2/1) the pyrazine molecules lie across centres of inversion. The bisphenol molecules are linked into C(8) chains parallel to [100] by means of O-H.O=S hydrogen bonds, and antiparallel pairs of these chains are cross-linked by the pyrazine molecules, via O-H.N hydrogen bonds, to form molecular ladders containing R(6)(6)(50) rings between the rungs of the ladders. Each ladder is interwoven with two neighbouring ladders, thus producing a continuous two-dimensional sheet. The structure of 4,4'-sulfonyldiphenol-4,4'-bipyridyl (1/1) consists of spiral C(2)(2)(21) chains parallel to [010] containing alternating bisphenol and bipyridyl molecules linked by O-H.N hydrogen bonds: these chains are linked by two types of C-H.O hydrogen bonds which form C(5) chains along [001] and C(2)(2)(10) chains along [101], thus generating two interconnected nets characterized in the one case by a chequerboard pattern of R(6)(6)(44) and R(6)(6)(52) rings, and in the other by a single type of R(6)(6)(46) ring. 4,4'-Sulfonyldiphenol-trans-1,2-bis(4-pyridyl)ethene (1/1) [systematic name: 4,4'-sulfonyldiphenol-trans-4,4'-vinylenedipyridine (1/1)] and 4,4'-sulfonyldiphenol-1,2-bis(4-pyridyl)ethane (1/1) [systematic name: 4,4'-sulfonyldiphenol-trans-4,4'-ethylenedipyridine (1/1)] are isomorphous: the 1,2-bis(4-pyridyl)ethene component exhibits orientational disorder, corresponding approximately to a 180 degrees rotation of ca 23% of the molecules about the N.N vector; in each compound the structure is built from C(2)(2)(23) chains of alternating bisphenol and bis(pyridyl) molecules connected by O-H.N hydrogen bonds, running parallel to [112] and generated by translation. The [112] chains are linked by C-H.O hydrogen bonds which generate C(2)(2)(12) chains parallel to [101], so forming a two-dimensional net built from R(6)(6)(50) rings. The structure of 4,4'-sulfonyldiphenol-4,4'-trimethylenedipyridine (1/1) consists of C(2)(2)(24) chains parallel to [100] generated by translation and consisting of alternating bisphenol and bis(pyridyl) molecules linked by O-H.N hydrogen bonds. Pairs of such chains are coiled together to form double helices, and pairs of such double helices, of opposite hand, are linked together by paired C-H.O hydrogen bonds in R(2)(2)(10) rings to form pairs of interwoven ladders in which the C(2)(2)(24) chains form the uprights and the R(2)(2)(10) rings form the rungs, between which are R(6)(6)(50) rings: an R(2)(2)(10) ring belonging to one ladder lies at the centre of an R(6)(6)(50) ring belonging to the other. 4,4'-Sulfonyldiphenol-4,4'-trimethylenedipiperidine-water (2/2/1) is a salt, 2C(13)H(27)N(2)(+).2C(12)H(9)O(4)S(-).H(2)O, containing two independent singly protonated diamine cations, two independent bisphenolate anions, and neutral water molecules. The two independent diamine cations are linked by N-H.N hydrogen bonds into C(2)(2)(24) chains running parallel to [001] and generated by translation, and each type of bisphenolate anion forms an independent spiral C(12) chain, also parallel to [001]. The three types of chain are linked by the water molecules: the two types of bisphenolate chain are linked by water molecules acting as double donors in O-H.O(-) hydrogen bonds in a C(6)(4)(32) chain parallel to [100], thus generating a two-dimensional net built from R(8)(6)(56) rings; the diamine chains are linked to these nets by means of N-H.O hydrogen bonds in which the water molecules act as acceptors and further hydrogen bonds, of N-H.O(-) and N-H.O=S types, link these two-dimensional nets into a continuous three-dimensional framework.

Journal Article↗

Acid and base-catalyzed hydrolysis of bisphenol A-related compounds.

In order to ascertain whether an estrogenic bisphenol A is produced from bisphenol A-related monomers by chemical-induced hydrolysis and to clarify their hydrolytic mechanisms, bisphenol A dimethacrylate (Bis-DMA) and bisphenol A bis(glycidyl methacrylate) (Bis-GMA) were reacted with phosphoric acid, hydrochloric acid, and sodium hydroxide in methanol or methanol/water mixed media at 37 degrees C. Amounts of monomethacrylate intermediates as well as bisphenol A (BPA) were determined by the use of high-performance liquid chromatography (HPLC), and time-conversion curves of hydrolytic products were prepared. BPA and bisphenol A monomethacrylate were produced by acid-catalyzed hydrolysis of Bis-DMA. Bis-GMA was partly converted into monomethacrylate by phosphoric acid and into monomethacrylate and 2,2-bis[4-(2,3-dihydroxypropoxy) phenyl]propane (BHP) by hydrochloric acid. Hydrolytic reactions by sodium hydroxide were completed almost within 1 day, resulting in the production of BPA from Bis-DMA, and BHP from Bis-GMA. No BPA was formed from Bis-GMA by chemical-induced hydrolysis. The hydrolytic behaviors of these monomers were discussed.

Benzhydryl Compounds↗

Estrogenic activity of dental materials and bisphenol-A related chemicals in vitro.

Twenty-eight chemicals used as dental materials and bisphenol-A related chemicals were diluted with DMSO to concentrations ranging from 10(-7) to 10(-3) M and tested for estrogenicity. Bisphenol-A (BPA), bisphenol-F (BPF) and bisphenol-A-bischloroformate (BPACF) showed estrogenic activity using the yeast two-hybrid system, and BPA, BPF, BPACF and bisphenol-S (BPS) showed estrogenic activity using the fluorescence polarization system. However, none of the remaining chemicals and none of the dental materials showed any activity at concentrations between 10(-7) and 10(-3) M. Although BPA, BPF, BPACF, bisphenol-A-dimethacrylate and BPS showed estrogenic activity in the E-screen test, the remaining chemicals did not. Thus, most of the chemicals showed consistent results, either positive or negative, by the three testing methods, while two chemicals showed conflicting results. Further studies, together with in vivo and epidemiological examinations, are required. Elucidation of the structure-activity relationships of these chemicals is also needed to estimate the estrogenicity of a chemical from its structure.

Analysis of Variance↗

In vivo DNA adduct formation by bisphenol A.

We have previously shown that bisphenol A (BPA) is oxidized to bisphenol-o-quinone in the presence of activation system and that the chemical reaction of DNA or deoxyguanosine 3'-monophosphate (dGMP) with bisphenol-o-quinone produces adducts. In the present study, using the 32P-postlabeling technique, we have investigated the in vivo DNA adduct formation by BPA by examining covalent modification in DNA. Administration of a single or multiple dose of 200 mg/kg of BPA to CD1 male rats produced two major and several minor adducts in liver DNA. The two major in vivo adducts matched the adduct profile of DNA or dGMP-bisphenol-o-quinone. To determine how BPA may be converted to DNA-binding metabolites, adducts were examined after incubation of DNA with BPA in the presence of a microsomal activation system. The in vitro incubation of BPA with DNA in the presence of a microsomal activation system revealed one major adduct and several minor adducts. The formation of adducts in DNA by BPA in the presence of a microsomal activation system was drastically decreased by known inhibitors of cytochrome P450. Adduct formation in DNA when cumene hydroperoxide or NADPH was used as a cofactor showed adducts with similar chromatographic mobilities as those from the reaction of dGMP-bisphenol-o-quinone. These data demonstrate that BPA is capable of binding covalently to DNA. DNA binding can be inhibited by the inhibitors of cytochrome P450. One of the DNA-binding metabolite(s) both in vitro and in vivo may be bisphenol-o-quinone. Covalent modifications in DNA by in vivo exposure of BPA may be a factor in the induction of hepatotoxicity.

Animals↗

Bisphenol A causes hyperactivity in the rat concomitantly with impairment of tyrosine hydroxylase immunoreactivity.

We examined the effects of bisphenol A, an endocrine disruptor, on rat behavioral and cellular responses. Single intracisternal administration of bisphenol A (0.2-20 microg) into 5-day-old male Wistar rats caused significant hyperactivity at 4-5 weeks of age. Rats were about 1.6-fold more active in the nocturnal phase after administration of both 2 and 20 microg of bisphenol A than were control rats. The response was dose-dependent. Based on DNA macroarray analyses of the midbrain, bisphenol A decreased by more than twofold gene expression levels of the dopamine D4 receptor at 4 weeks of age and the dopamine transporter at 8 weeks of age. Furthermore, bisphenol A decreased by more than twofold gene expression levels of the dopamine D4 receptor at 4 weeks of age and the dopamine transporter at 8 weeks of age. We conclude that bisphenol A affected central dopaminergic system activity, resulting in hyperactivity due most likely to a large reduction of tyrosine hydroxylase activity in the midbrain.

Age Factors↗

Chronic exposure to low doses bisphenol A interferes with pair-bonding and exploration in female Mongolian gerbils.

Estrogenic endocrine disruptors, synthetic or naturally occurring substances found in the environment, can interfere with the vertebrate endocrine system and, mimicking estrogens, interact with the neuroendocrine substrates of behavior. Since species vary in their sensitivity to steroids, it is of great interest to widen the range of species included in the researches on neurobehavioral effects of estrogenic endocrine disruptors. We examined socio-sexual and exploratory behavior of Mongolian gerbil females (Meriones unguiculatus), a monogamous rodent, in response to chronic exposure to the estrogenic endocrine disruptor bisphenol A. Paired females were daily administered with one of the following treatments: bisphenol A (2 or 20 microg/kg body weight/day); 17alpha-ethynil estradiol (0.04 microg/kg body weight/day 17alphaE); oil (vehicle). Females were treated for 3 weeks after pairing. Starting on day of pairing, social interactions within pairs were daily recorded. Three weeks after pairing, females were individually tested in a free exploratory paradigm. Bisphenol A and 17alphaE affected male-female social interactions by increasing social investigation. Bisphenol A reduced several exploratory parameters, indicating a decreased exploratory propensity of females. These results highlight the sensitivity of adult female gerbils to bisphenol A during the hormonally sensitive period of pair formation, also considering that the bisphenol A doses tested are well below the suggested human tolerable daily intake.

Analysis of Variance↗

Effects of activated carbon types and service life on removal of endocrine disrupting chemicals: amitrol, nonylphenol, and bisphenol-A.

Removal performances of endocrine disrupting chemicals (EDC) such as amitrol, nonylphenol, and bisphenol-A were evaluated in this study using granular activated carbon (GAC) adsorption. This study found that GAC adsorption was effective in removal of EDCs with high K(ow) value. Nonylphenol and bisphenol-A were effectively adsorbed onto all carbons (including the used carbons) tested in this study. As indicated by K(ow) value, nonylphenol was more effectively adsorbed than bisphenol-A. The coal-based carbon was found more effective than other carbons in the adsorption of nonylphenol and bisphenol-A due to its larger pore volume. The adsorption capacity reduced with the operation year, and the extent of the reduction was different depending upon the carbon type and the operation year. Amitrol was effectively removed by biological degradation, but was poorly adsorbed. Since the microbes residing at the used carbons already accustomed to amitrol, the used carbons removed amitrol better than the virgin carbons. Although the coal-based carbon showed the best removal performance of amitrol, GAC adsorption could not be recommended for amitrol removal because considerable portion of incoming amitrol (9-87%) passed through GAC adsorption column. According to this study, pore volume mainly influenced the adsorption capacity, but the surface charge was also important due to electrical interaction. The adsorption parameters for nonylphenol and bisphenol-A provided by this study could be valuable when GAC adsorption was considered to handle an accidental spill of nonylphenol and bisphenol-A.

Adsorption↗

Prenatal and neonatal exposure to low-dose of bisphenol-A enhance the morphine-induced hyperlocomotion and rewarding effect.

Bisphenol-A has been extensively evaluated for toxicity in a variety of tests as the most common environmental endocrine disruptors. In the previous study, we reported that prenatal and neonatal exposure to high-dose of bisphenol-A affects the development of central dopaminergic system in the mouse limbic area. The present study was then undertaken to investigate whether prenatal and neonatal exposure to lower dose of bisphenol-A could change the morphine-induced several pharmacological actions such as rewarding effect and hyperlocomotion in mice. Prenatal and neonatal exposure to low-dose of bisphenol-A enhanced the morphine-induced hyperlocomotion and rewarding effect. Additionally, the treatment with bisphenol-A produced an up-regulation of dopamine receptor function to activate G-protein in the mouse limbic forebrain, which is thought to play a critical role for hyperlocomotion and rewarding effects by drugs of abuse. These findings suggest that prenatal and neonatal exposure to low-dose of bisphenol-A can potentiate the central dopamine receptor-dependent neurotransmission, resulting in the supersensitivity of the morphine-induced hyperlocomotion and rewarding effects in the mouse.

Animals↗

Effects of bisphenol A-related diphenylalkanes on vitellogenin production in male carp (Cyprinus carpio) hepatocytes and aromatase (CYP19) activity in human H295R adrenocortical carcinoma cells.

The present study investigated the effects of the known xenoestrogen bisphenol A (BPA) relative to eight BPA-related diphenylalkanes on estrogen receptor (ER)-mediated vitellogenin (vtg) production in hepatocytes from male carp (Cyprinus carpio), and on aromatase (CYP19) activity in the human adrenocortical H295R carcinoma cell line. Of the eight diphenylalkanes, only 4,4'-(hexafluoropropylidene)diphenol (BHF) and 2,2'-bis(4-hydroxy-3-methylphenyl)propane (BPRO) induced vtg, i.e., to a maximum of 3% to 4% (at 100 microM) compared with 8% for BPA relative to the maximum induction by 17beta-estradiol (E2, 1 microM). Bisphenol A diglycidyl ether (BADGE) was a potent antagonist of vtg production with an IC50 of 5.5 microM, virtually 100% inhibition of vtg at 20 microM, and an inhibitive (IC50) potency about one-tenth that of the known ER antagonist tamoxifen (IC50, 0.6 microM). 2,2'-Diallyl bisphenol A, 4,4'-(1,4-phenylene-diisopropylidene)bisphenol, BPRO, and BHF were much less inhibitory with IC50 concentrations of 20-70 microM, and relative potencies of 0.03 and 0.009 with tamoxifen. Bisphenol ethoxylate showed no anti-estrogenicity (up to 100 microM), and 4,4'-isopropylidene-diphenol diacetate was only antagonistic at 100 microM. When comparing the (anti)estrogenic potencies of these bisphenol A analogues/diphenylalkanes, anti-estrogenicity occurred at lower concentrations than estrogenicity. 4,4'-Isopropylidenebis(2,6-dimethylphenol) (IC50, 2.0 microM) reduced E2-induced (EC50, 100 nM) vtg production due to concentration-dependent cytotoxicity as indicated by a parallel decrease in MTT activity and vtg, whereas the remaining diphenylalkanes did not cause any cytotoxicity relative to controls. None of the diphenylalkanes (up to 100 microM) induced EROD activity indicating that concentration-dependent, CYP1A enzyme-mediated metabolism of E2, or any Ah-receptor-mediated interaction with the ER, was not a likely explanation for the observed anti-estrogenic effects. At concentrations as great as 100 microM, none of the diphenylalkanes directly inhibited aromatase (CYP19) activity in H295R cells. Environmental exposure of fish to BPA and related diphenylalkanes, depending on the structure, may pose anti-estrogenic, and to a lesser extent estrogenic, risks to development and reproduction.

Adrenocortical Carcinoma↗

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

A new technique is proposed for the determination of bisphenol A in environmental water. The sample preparation consists of a single-step extraction of bisphenol A from a water sample with methylene chloride and the cyanomethyl derivatization of bisphenol A. 2,2'-Biphenol is used as an internal standard. Bisphenol A and biphenol can be quantitatively converted to their corresponding cyanomethyl ethers, which are then measured by gas chromatography with nitrogen-phosphorus detection. Peak shape and quantification of bisphenol A are excellent, with linear calibration curves over a range of 0.1-100 ng/ml. The detection limit is 0.1 ng/ml in water samples. The average recovery and RSD at a concentration of 5 ng/ml are 89.3 and 4.5%, respectively. The procedure is applicable to the quantification of bisphenol A in tap water, raw water and stream water.

Benzhydryl Compounds↗

Exposure with the environmental estrogen bisphenol A disrupts the male reproductive tract in young mice.

Environmental estrogens (endocrine disruptive chemicals) have been shown to affect reproduction in wild life and it has been reported that maternal exposure with those chemicals have adverse effects on the male reproductive tract. However, little is known about the potential effects of prepubertal or pubertal exposure with environmental estrogens on the male reproductive tract. Here we examine plasma hormone levels and histology in the testis of mice following either 4- or 8-week oral administration of bisphenol A. Plasma free testosterone levels were dramatically decreased following 8 weeks of bisphenol A treatment compared with control group and morphologically multinucleated giant cells having greater than three nuclei were found in seminiferous tubules in the testis following the 8-week bisphenol A treatment. No differences in plasma corticosterone and luteinizing hormone levels were seen between bisphenol A and control groups. Thus, exposure with bisphenol A around pubertal period may directly disrupt the male reproductive tract. These facts suggest that more detailed studies will warrant the assessment of the risk to the developing human testis from exposure to bisphenol A and other environmental estrogens in prepubertal and pubertal period.

Administration, Oral↗

Protective effect of diltiazem, a L-type calcium channel antagonist, on bisphenol A-enhanced hydroxyl radical generation by 1-methyl-4-phenylpyridinium ion in rat striatum.

The present study examined whether bisphenol A enhanced 1-methyl-4-phenylpyridinium ion (MPP+)-induced hydroxyl radical (*OH) generation in rat striatum using microdialysis technique. These elevations were detected by increases in non-enzymatic formation of 2,3-dihydroxybenzoic acid levels. Bisphenol A significantly enhanced MPP+-induced.OH generation. Further, the effect of diltiazem, a L-type Ca2+ channel antagonist, on bisphenol A (10 microM) and MPP+ (5 mM)-induced.OH generation were studied. Ddiltiazem (100 microM) significantly suppressed bisphenol A and MPP+-induced.OH generation. The results indicate bisphenol A augmented *OH generation, and diltiazem may have preventive effect on bisphenol A and MPP+-induced.OH generation.

1-Methyl-4-phenylpyridinium↗

Assessment of pubertal development in juvenile male rats after sub-acute exposure to bisphenol A and nonylphenol.

The effects of bisphenol A and nonylphenol on pubertal development in the intact juvenile/peripubertal male Sprague-Dawley rats was observed in this study from PND23-52/53. Two groups of rats were administered orally with either 100 mg/kg body weight of nonylphenol or bisphenol A. Another group of rats were administered orally with a mixture of 100 mg/kg body weight of nonylphenol and bisphenol A. Control group was administered with the vehicle of Tween-80 with corn oil (1:9 v/v). Observations made in this study included growth, age at preputial separation, thyroid, liver, testis and kidney weight and histology, epididymal and seminal vesicle plus coagulation gland weight. Nonylphenol and bisphenol A have been observed to cause delay in puberty onset as well as testicular damage in the treatment groups when compared to the control; spermatogenesis was affected in most treated rats. Bisphenol A also caused the enlargement of the kidney and hydronephrosis. Administration of nonylphenol and bisphenol A as a mixture has caused less than additive effects.

Animals↗

Bisphenol A and its biomaterial monomer derivatives alteration of in vitro cytochrome P450 metabolism in rat, minipig, and human.

Bisphenol A (BPA) is a common structural component in a wide variety of biomaterial monomers. The effects of BPA and the following derivatives: bisphenol A glycidyl methacrylate (BisGMA), bisphenol A glycidyl diacrylate (BAGDA), bisphenol A ethoxylate dimethacrylate (BAEDM), bisphenol A dimethacrylate (BADM), and bisphenol A diglycidyl ether (BADGE) on mixed function oxidases (MFOs) are reported in this study. The rate of formation of metabolites from isoform-specific substrates for the MFOs (or cytochromes) CYP 1A, 2A, 2C, 2E, 3A, and 4A in the absence (control) and presence of BPA and derivatives was used to assess inhibition or stimulation of human, rat (male and female) liver, and minipig liver microsomal MFO activity. For human preparations the strongest inhibition by BPA was observed for CYP 2C. The inhibition was most prominent when a lower dose of BPA was used on the complete post-mitochondrial fraction. BPA inhibited rat microsomal CYP 1A isoform-specific metabolite production to 29 +/- 3% of control levels (100%). Biomaterial monomers exhibited mixed effects. For example, BPA stimulated CYP 4A in pooled human S9 to 129 +/- 1% of control. Also, BADM and BAGDA stimulated CYP 4A to 141% and 142% of control values, respectively.

Animals↗

Bisphenol A removal from water by activated carbon. Effects of carbon characteristics and solution chemistry.

The present study aimed to analyze the behavior of different activated carbons in the adsorption and removal of bisphenol A (2-2-bis-4-hydroxypheniyl propane) from aqueous solutions in order to identify the parameters that determine this process. Two commercial activated carbons and one prepared in our laboratory from almond shells were used; they were texturally and chemically characterized, obtaining the surface area, pore size distribution, mineral matter content, elemental analysis, oxygen surface groups, and pH of the point of zero charge (pH(PZC)), among other parameters. Adsorption isotherms of bisphenol A and adsorption capacities were obtained. The capacity of the carbons to remove bisphenol A was related to their characteristics. Thus, the adsorption of bisphenol A on activated carbon fundamentally depends on the chemical nature of the carbon surface and the pH of the solution. The most favorable experimental conditions for this process are those in which the net charge density of the carbon is zero and the bisphenol A is in molecular form. Under these conditions, the adsorbent-adsorbate interactions that govern the adsorption mechanism are enhanced. Influences of the mineral matter present in the carbon samples and the solution chemistry (pH and ionic strength) were also analyzed. The presence of mineral matter in carbons reduces their adsorption capacity because of the hydrophilic nature of the matter. The presence of electrolytes in the solution favor the adsorption process because of the screening effect produced between the positively charged carbon surface and the bisphenol A molecules, with a resulting increase in adsorbent-adsorbate interactions.

Adsorption↗

Effects of the environmental oestrogens bisphenol A, tetrachlorobisphenol A, tetrabromobisphenol A, 4-hydroxybiphenyl and 4,4'-dihydroxybiphenyl on oestrogen receptor binding, cell proliferation and regulation of oestrogen sensitive proteins in the human breast cancer cell line MCF-7.

Bisphenol A is extensively used in the manufacturing of epoxy resins and polycarbonate plastics, whereas several brominated and chlorinated analogues are used as flame retardants and intermediates in the plastic industry. Due to the structural relationship between these chemicals and the high production volumes, we wanted to characterize and compare their potential oestrogen-like potency using several end-points in MCF-7 cells: induction of pS2 protein and progesterone receptor, reduction of oestrogen receptor level, and stimulation of cell growth. Bisphenol A, tetrachloro- and tetrabromo-bisphenol A, 4-hydroxybiphenyl and 4,4'-dihydroxybiphenyl all showed oestrogen-like properties in MCF-7 cells. The chemicals tested had affinity to the oestrogen receptor isolated from MCF-7 cells, although their EC50s were 1,000 to 80,000 times higher than the EC50 of 17beta-oestradiol. Bisphenol A and 4-hydroxybiphenyl induced cell growth in MCF-7 cells, and the highest test concentrations induced responses, apparently exceeding the cell growth induced by 17beta-oestradiol. The other chemicals tested induced less than 50% of the maximum 17beta-oestradiol-stimulated cell growth. Bisphenol A, 4-hydroxybiphenyl, tetrabromobisphenol A and tetrachlorobisphenol A all increased the level of the oestrogen-regulated proteins, progesterone receptor and pS2, whereas 4,4'-dihydroxybiphenyl showed no such effect. Bisphenol A was the only chemical tested that clearly mimicked 17beta-oestradiol in its ability to reduce the level of cytosolic oestrogen receptors in MCF-7 cells. By measuring several oestrogen-dependent endpoints it seems that some xeno-oestrogens cause an imbalanced oestrogen-response. Their ability and potency in mimicking 17beta-oestrogen in one parameter is not necessarily accompanied by a similar effect in another oestrogen-linked parameter.

Benzhydryl Compounds↗