|
|
Flame retardants and their penetration into the terrestrial ecosystem
Chytil, Václav ; Čáslavský, Josef (referee) ; Vávrová, Milada (advisor)
This diploma thesis was focused on the analysis of four compounds from brominated flame retardants group, namely pentabromoethylbenzene, hexabromocyclododecane, hexabromobenzene and tetrabromobisphenol A. Matrices were represented by four soil samples and four seat of fire samples. In addition, bisphenol A was also determined. First of all, process of extraction of analytes from matrices was optimized. Three different extraction techniques were tested (pressurized solvent extraction, microwave-assisted extraction and ultrasound-assisted extraction). Next step was to verify stability of target compounds in strongly acidic conditions and to optimize clean-up of extract by column chromatography. Gas chromatography with electron capture detection (GC-ECD) was chosen as an appropriate analytical method for the determination of brominated flame retardants. Bisphenol A was determined by gas chromatography with mass spectrometric detection (GC-MS). The derivatization of phenolic analytes before their final analytical determination was also essential.
|
|
|
Bisphenol A in water ecosystem
Nohelová, Gabriela ; Vávrová, Milada (referee) ; Čáslavský, Josef (advisor)
This diploma thesis deals with Bisphenol A, especially with its impact on the aquatic ecosystem. Information about its properties, production and current use are summarized here. Its harmful impact on the environment, especially on the aquatic ecosystem and the human body is characterized. Also the methods of its degradation within the aquatic environment have been described. A summary of the options of a determination of Bisphenol A in water samples is incorporated and the method of gas chromatography with mass spectrometry (GC/TOF MS) and comprehensive two-dimensional gas chromatography with mass spectrometry (GCxGC/TOF-MS) is compared in the experimental part. Analytical determination precedes the isolation of the analyte from the water samples by solid phase extraction (SPE) using SupelcleanTM ENVITM - 18 and derivatization using the silylation reagent, N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). The result of this work is the analysis of a series of real samples from wastewater treatment plants Brno Modřice and Luhačovice by a two-dimensional gas chromatography with mass spectrometry (GCxGC/TOF-MS).
|
|
|
Endocrine-disruptive effects of bisphenol A and other representatives of bisphenols
Kromková, Lucia ; Cajthaml, Tomáš (advisor) ; Vítků, Jana (referee)
Xenoestrogens are substances of anthropogenic origin that disrupt the human endocrine system. This work deals with bisphenol A, a substance found in plastics all around us, and its effect on the human reproductive system. As the toxicity of bisphenol A is gradually being proven, its production is regulated by legislation, and therefore bisphenol A is being replaced by other derivatives. This work focuses only on the 7 most widespread bisphenol derivatives - S, F, E, B, AP and AF. The endocrine-disrupting effect of bisphenols is discussed from carefully selected relevant studies with an emphasis on the last 5 years (2018-2023) and compiled into clear tables. It turns out that bisphenol AP has the least endocrine disruption per organism, while bisphenol AF and bisphenol S have the highest. In in vitro and in vivo studies, bisphenol A has different concentrations that influence disruptiveness, which indicates the interaction of bisphenol A with other factors in the organism. The greatest risk to humanity is the proven cocktail effect of bisphenol A and transgenerational transmission. Key words: endocrine disruptors, xenoestrogens, bisphenol A, in vitro, bisphenol derivatives, in vivo
|
|
|
Release of bisphenol A and its analogues from dental restorative materials
Tichý, Antonín ; Bradna, Pavel (advisor) ; Izakovičová Hollá, Lydie (referee) ; Suchánek, Jakub (referee)
Bisphenol A (BPA) is an endocrine disruptor that may be released from dental polymeric materials. The aim of this study was to examine the kinetics of the long-term release of BPA and its analogues from restorative materials (composites, hybrid glass ionomer cements) and polycarbonates used in dentistry. Extracts in ethanol and artificial saliva were collected after 1-260 days for restorative materials and after 1-84 days for polycarbonates. All extracts were analyzed by ultra high performance liquid chromatography-tandem mass spectrometry. BPA was detected in all tested materials, while its analogues were not found. The release of BPA from all tested materials was highest during the first day, followed by a significant decrease for all materials and a complete stop for the "BPA-free" composites. Among restorative materials, the highest amounts of BPA were released from composites with BPA-based monomers, followed by hybrid glass ionomer cements. The least BPA was released from "BPA-free" composites. Shorter irradiation time did not significantly affect the total amount of BPA released from restorative materials, but it significantly increased the release of BPA during the first day. The release of BPA from polycarbonates was significantly higher than from restorative materials. Given the current...
|
|
|
Dopad různé alimentární expozice bisfenolu na játra potkanů
LABUDOVÁ, Kateřina
Bisphenol S (BPS) is an organic compound widely used in industrial production as a substitute for bisphenol A (BPA) for which negative impacts on the human body have been demonstrated and have therefore been significantly regulated. However, as time progresses, the negative properties of BPS are also shown, especially for the endocrine and reproductive systems. The liver is an organ in which xenobiotics are detoxified and thus BPS and BPA. The aim of the bachelor thesis was to verify whether 10-week oral exposure to BPS (4 g, 50 g, 100 mg/kg bw/day) and BPA (100 mg/kg bw/day) will lead to a negative impact on body weight, weight gain, weight and morphological liver structure and on the concentration of triglycerides, cholesterol, total white-vinas, urea and alkaline phosphatase activity in blood serum. The experiment involved 24 rats. BPA and BPS were administered daily by gastric tube in sunflower oil. The results of our research clearly did not show a negative effect of BPS and BPA in rats on body weight, absolute gain, absolute and relative liver weight in rats. There was also no evidence of histopathological changes in rat liver. In contrast, bio-chemical parameters were altered compared to the control group. Decreases in trigly-cerides, total protein content, urea, alkaline phosphatase activity and increases in serum cholesterol were noted. In the 50 g/kg body weight/day group of rats, the highest and lowest decreases in biochemical parameters were observed, respectively. The exposure dose of 100 mg BPS and BPA in our experiment did not cause liver histopathological changes or changes in biochemical parameters according to the hy-pothesis. A possible explanation could be given by the carrier for which sunflower oil with natural antioxidant content was used.
|
|
|
Optimization of endocrine disruptors determination in wastewater treatment plant sludge and application of the method in environmental samples.
Medková, Jaroslava ; Cajthaml, Tomáš (advisor) ; Tesařová, Eva (referee)
Hormonaly active compounds in wastewaters represent nowdays a serious problem. Proceses currently used in watewater treatment plants (WWTP) are unefficient in removing these compounds from contaminated wastewaters. The compounds are supposed to sorb onto solid sludge elements and sediments. In this work seven endocrine disruptors were detected in the sludge samples from WWTPs. A new sensitive method for detection of seven selected endocrine disruptors (4-nonylphenol, bisphenol A, estriol, 17β-estradiol, estrone, 17α- ethynylestradiol, irgasan) was developed. The method is based on accelerated solvent extraction (ASE), gel permeation chromatography (GPC) and solid phased extraction. For final extract analysis, gas chromatography coupled with mass spectrometry (GC/MS) was used. The efficiency of this method was tested using artificially contaminated sludge and the method was used to analyse real samples from several WWTPs in Czech Republic. The effect of sludge age on detection of individual analytes was assessed as well. The concentrations of endocrine disruptors measured in the samples reached up to 1 µg/g. The results are comparable or higher then those reported in other works and they show the necessity of further research on endocrine disruptors in the environment.
|
|
|
Mechanisms of action of bisphenol A with emphasis on metabolism and fertility
Houška, Jakub ; Daňková, Pavlína (advisor) ; Novák, Jan (referee)
Bisphenol A is an endocrine disruptor, a chemical which is found in environment and also in water and food consumed by people and which disrupts endocrine system of humans and other organisms. Being endocrine disruptor it has a wide scale of negative effects on human health. I have attempted reviewing the molecular mechanism of its action with special respect to obesity and reproduction in this paper including interactions of bisphenol with specific receptors, its impact on enzyme synthesis and also on epigenetic mechanisms as DNA methylation or changes in miRNA expression. Possible ways of elimination of bisphenol A effects are examined in the end of this work. Keywords bisphenol A, molecular mechanisms, obesity, fertility, receptor, epigenetic mechanisms, elimination of effects
|
|
|
The Impact of Selected Endocrine Disruptors on Human Spermatogenesis
Vítků, Jana ; Hill, Martin (advisor) ; Pohanka, Michal (referee) ; Lapčík, Oldřich (referee)
Steroid hormones in testis play an important role in spermatogenesis, maintenance of the male reproductive tract, production of semen and the maintenance of secondary sex characteristics and libido. They are also discussed as a target for substances called endocrine disruptors (EDs). No complex study was conducted on evaluation of relationships between EDs and steroid spectrum in 2 biological fluids; seminal plasma and plasma. The aim of the PhD. thesis was to develop and validate a method for determination of bisphenol A (BPA) and steroid spectrum in plasma and seminal plasma and to shed more light into mechanisms of ED action and effects of BPA and polychlorinated biphenyls (PCBs) on human spermatogenesis and steroidogenesis. Two new liquid-chromatography mass spectrometry methods for determination of BPA and 11 steroids in plasma and seminal plasma were developed and validated. The methods were used for estimation of analyte concentrations in 191 men with a different degree of fertility. Concurrently, the levels of six congeners of PCBs, gonadotropins, selenium and zinc in plasma were estimated. Partial correlations adjusted for age and BMI were calculated to evaluate relationships between these analytes. Seminal BPA, but not plasma BPA, was negatively associated with sperm concentration...
|
|
|
The Impact of Selected Endocrine Disruptors on Human Spermatogenesis
Vítků, Jana
Steroid hormones in testis play an important role in spermatogenesis, maintenance of the male reproductive tract, production of semen and the maintenance of secondary sex characteristics and libido. They are also discussed as a target for substances called endocrine disruptors (EDs). No complex study was conducted on evaluation of relationships between EDs and steroid spectrum in 2 biological fluids; seminal plasma and plasma. The aim of the PhD. thesis was to develop and validate a method for determination of bisphenol A (BPA) and steroid spectrum in plasma and seminal plasma and to shed more light into mechanisms of ED action and effects of BPA and polychlorinated biphenyls (PCBs) on human spermatogenesis and steroidogenesis. Two new liquid-chromatography mass spectrometry methods for determination of BPA and 11 steroids in plasma and seminal plasma were developed and validated. The methods were used for estimation of analyte concentrations in 191 men with a different degree of fertility. Concurrently, the levels of six congeners of PCBs, gonadotropins, selenium and zinc in plasma were estimated. Partial correlations adjusted for age and BMI were calculated to evaluate relationships between these analytes. Seminal BPA, but not plasma BPA, was negatively associated with sperm concentration...
|
|
|
Bisphenol S influence on selected markers of meiotic maturation of porcine oocytes
Černíková, Terezie ; Petr, Jaroslav (advisor) ; Krylov, Vladimír (referee)
Bisphenol A is a widely used chemical in the manufacture of plastics. The presence of BPA in the environment adversely affects human health due to contamination of air, drinking water and food. Growing concerns about the effects of BPA have led to its regulation in production and development of alternative chemicals to BPA, such as bisphenol S (BPS). However, the effects of BPS were not properly tested before its introduction to production and the effects on human reproduction are still unknown. For this reason, it is desirable to test the effect of BPS on mammalian oocyte development. This study hypothesizes that BPS exposure causes inhibition of meiotic maturation of porcine oocytes in vitro. This study aims to investigate the potency of BPS at low concentrations corresponding to normal human exposures to selected porcine oocyte proteins. The results of this study demonstrate the negative effect of BPS on the progression of meiotic maturation and reaching the mature oocyte stage. In addition, the results show an increase in the formation of defective meiotic spindles and a disruption of mitochondrial integrity after exposure to BPS concentrations. However, the effect of BPS on double-strand breaks was not demonstrated in this study, in contrast to the case of BPA. Taken together, the results show...
|
guest ::
