Parabens have been used as antimicrobial preservatives in multiple different types of products for decades, however relatively recent studies have caused concern as to whether their wide-use could be potentially harmful. The following paper reviews the extensive areas of human exposure, from mother to fetus, infants via breast milk, baby and child care products through adult personal care products, and other environmental sources. The potential impacts on human health are also discussed. Parabens predominantly impact biological systems as an endocrine disruptor not only by binding to the human Estrogen Receptor directly, but increasing the availability of naturally occurring 17β-estradiol, further potentiating the effect. Alternative antimicrobial preservatives are also discussed, along with their efficacies and potential health concerns. Common alternatives found in personal care products include phenoxyethanol, methylisothiazolinone, and formaldehyde releasers. Additionally, weak organic acids and plant-derived essential oils are also used in personal care products, but tend to be added more so to food products to prevent the growth of spoilage bacteria, fungi and mold. The potential for these alternatives to replace the use of parabens in personal care products, our greatest area of exposure, is very promising. If parabens in personal care products were replaced with a safe and effective alternative, then the other areas of environmental exposure would likely be negligible to produce any harm on society. Future investigation into the nuances of the various plant-derived essential oils and effective formulations for preservation, is likely the most promising solution, due to their mostly harmless nature. Lastly, the discussion of proposed future research in order to lead to a more definitive connection between paraben exposure and adverse health effects is presented.

The world energy and product consumption keep increasing steadily over the years as the world population keeps growing and more countries become industrialized. As the world reserves deplete it becomes a necessity to find an alternative way to meet the population’s demand. Biomass conversion seems to be the future of a clean and sustainable world. Lignin is the second most abundant polymer in the biomass. Given the unique structure and chemical properties of lignin, a wide variety of bulk and fine chemicals can be obtained and be used for goods and biofuels production. Catalysis, with its selective bond cleavage and lower energy activation, is considered as a potential key solution in the process of lignin conversion into valuable chemicals. To gain insights into that catalytic system, we performed surface science experiments (X-ray Photoelectron Spectroscopy, Temperature Programmed Desorption and Reflection Absorption Infrared Spectroscopy) under Ultra-High Vacuum conditions (UHV). Due to lignin’s physical properties limitation under UHV conditions, lignin models with the same chemical structure such as phenol, anisole, 2-phenoxyethanol and veratrol were used to gain a better understanding of the reactivity of lignin itself. Dosing anisole and 2-phenoxyethanol on Pt(111) surprisingly gave benzene, carbon monoxide and hydrogen as the main desorbing products of decomposition. With the help of Density Functional Theory (DFT), we successfully explain the unexpected selectivity. In the present work, we show in particular that phenoxy PhO stands as a key intermediate. Although the UHV conditions do not allow the hydrogenation of phenoxy into phenol, i.e. the catalytic product, they reveal the key role of both hydrogen and carbonaceous species. Under UHV conditions, anisole and 2-phenoxyethanol are extensively dehydrogenated: it results in the formation of carbonaceous fragments, which can actually perform the deoxygenation of phenoxy into benzene. The reactivity of veratrol on Pt(111) hindered the formation of benzene and only gave carbon monoxide and hydrogen as the main desorbing products of decomposition. Although carbonaceous fragments were formed on the surface, the deoxygenation of the two oxygenated arm moieties does not occur without the total decomposition of the aromatic ring, hence the formation of coke. This detailed work opens the door to a rational design of metal-based catalysts and a route towards lignin valorization.

The aim of this study was to assess the effects of the four most used anaesthetics in European aquaculture MS 222, clove oil, 2-phenoxyethanol and Propiscin on barbel (Barbus barbus). The effects of anaesthetics were assessed based on haematological profile, biomarker of oxidative stress and antioxidant enzymes. This study contributed to the expansion of knowledge on the safety of tested anaesthetics and selected safe anaesthetics for barbel. Barbels were exposed to a 10-minute anaesthesia with MS 222 (in recommended concentration 100 mg×l-1), clove oil (in recommended concentration 33 mg×l-1), 2-phenoxyethanol (in recommended concentration 0.4 ml×l-1) and Propiscin (in recommended concentration 1 ml×l-1). The effects of anaesthetics were evaluated immediately after 10 min. anaesthesia and 24 hours after anaesthesia. Anaesthesia with MS 222, clove oil, 2-phenoxyethanol and Propiscin had no significant effect on haematological indices, level of oxidative stress (TBARS) and activity of glutathione reductase in barbel tissues. The activity of catalase was significantly increased in the muscle 24 h after anaesthesia of all anaesthetics compared to the control. Superoxide dismutase activity was changes in all experimental groups (immediately after 10 min. anaesthesia and 24 hours after anaesthesia). The tested anaesthetics not altered hematopoietic tissue and had not effect on the level of lipid peroxidation in barbel´s tissues. The results of this study suggest that the antioxidant systems of barbel are altered by Propiscin anaesthesia, but they are slightly affected by MS 222, clove oil, and 2-phenoxyethanol anaesthesia. On the basis of the results of this thesis, for anaesthesia of barbel we can recommend clove oil and 2-phenoxyethanol as an alternative MS 222.

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