L'objectif de cette thèse est d'améliorer la compréhension de la toxicité de diverses nanoparticules de synthèse (ENPs) pour l'homme et l'écosystème. Les travaux réalisés s’appuient sur la combinaison de données toxicologiques et d’un modèle environnemental - le modèle USEtox. En tant qu'élément important de l'évaluation de l'impact du cycle de vie, le facteur de caractérisation (CF) a été utilisé, dans ce travail, comme indicateur de toxicité pour l'homme et l'écosystème. Pour avoir accès aux courbes dose-réponse et à différentes données toxicologiques, des expériences in vitro ont été réalisées en exposant des neutrophiles porcins fraîchement isolés à trois types de nanoparticules de synthèse. Les modifications morphologiques, les taux de mortalité et la chimioluminescence des neutrophiles ont été évaluées. De plus, pour estimer le temps de persistance des nanoparticules de synthèse dans l'écosystème eau douce, un modèle basé sur la science des colloïdes a été développé. Il prend en compte les comportements spécifiques des nanoparticules de synthèse et inclut des recommandations sur le choix des paramètres hydrologiques régionaux. Enfin, une enquête documentaire exhaustive a été réalisée pour recueillir les données écotoxicologiques de diverses nanoparticules de synthèse. Dans le cadre du modèle USEtox, le CF toxicologique non cancérogène pour cuivre NPs et les CF écotoxicologiques pour 14 ENPs sont recommandés. Ces valeurs des CF pourraient être utiles à l'avenir pour évaluer les impacts environnementaux des produits contenant des ENPs. / The objective of this thesis is to improve understandings of toxicity of various engineered nanoparticles (ENPs) to human and ecosystem. It is realized via coordinating toxicological data and a scientific consensus environmental model -- the USEtox model. As an important element in life cycle impact assessment, the characterization factor (CF) is employed as a toxicity indicator for human and ecosystem in this work. To obtain the firsthand dose-response phenomena and human toxicological data, in vitro experiments have been conducted by exposing freshly isolated porcine neutrophils to three kinds of ENPs (i.e. copper, nickel and aluminum oxide nanoparticles). The morphologies, mortality rates, and chemiluminescence, of neutrophils are observed or monitored. Additionally, to estimate the persistence time of ENPs in freshwater ecosystem, a fate model on the basis of colloid science is developed. It takes nano-specific behaviors of ENPs into account and includes recommendations of regionalized hydrological parameters. Finally, a comprehensive literature survey is accomplished to collect the ecotoxicological data of various ENPs. Under the framework of USEtox model, the non-carcinogenic human toxicological CFs for Copper NPs and the ecotoxicological CFs for 14 ENPs are recommended. These CF values could be useful in the future when evaluating the environmental impacts of products containing ENPs.

Natural oils are regularly used in cosmetics and as treatment for numeral skin conditions (Nielsen, 2006:575). The natural products industry is a multibillion dollar industry and has grown tremendously over the past few years. Natural oils used in cosmetics contain a range of fatty acids which contribute to several valuable properties in cosmetic- and personal care products. Fatty acids are divided into saturated acids and unsaturated acids (Vermaak et al., 2011:920,922). Because of the popularity and wide diversity of skin care products, it is necessary to create products that will distinguish themselves from the rest of the commercial products. To include natural oils in skin care products is a new way to prevent skin ageing, as well as other dermatological conditions. In this study, a natural oil, namely crocodile oil was used. Crocodile oil is obtained from the fat of the Nile crocodile (Crocodylus niloticus). Crocodile oil has the same composition as human skin oil. It only differs with regard to the percentages of the ingredients present. Crocodile oil contains saturated and unsaturated fatty acids. Because of the similar composition as human skin oil, crocodile oil will rarely be allergenic when applied to human skin and therefore will be a very accepted and harmless product to use (Croc city, 2012). There are many claims of positive results when crocodile oil containing products have been used. It includes fading of freckles, treatment of acne and pimple marks, dark lines, wrinkles and laugh lines. It also includes vanishing of dark shadows, sun spots and other discolorations. It helps prevent discolorations from forming and makes the skin softer, brighter and more attractive. It also controls rashness and dryness (Croc city, 2012). Because of crocodile oil’s anti-ageing, anti-fungal and anti-bacterial effects claimed by crocodile oil suppliers, and due to the fact that little scientific data is available on crocodile oil, it was decided to investigate the claims. In this study, the aims and objectives were to use natural oil, namely crocodile oil, and investigate the fatty acid profile, anti-microbial and anti-fungal activity, anti-oxidant activity, toxicity studies, stability determination of crocodile oil lotion and clinical efficacy testing of the anti-ageing effects. To determine the fatty acid profile of crocodile oil, fatty acid methyl ester (FAME) analysis with gas chromatography were used. Identification of FAME peaks in the samples was made by comparing the relative retention times of FAME peaks from samples to those of reference standards. The composition of fatty acids in crocodile oil compared well to fatty acids found in human skin oil. Anti-microbial and anti-fungal tests were done by Envirocare Laboratories, North-West University, Potchefstroom. Staphylococcus aureus, Esterichia coli, Pseudomanas aeruginosa, Candida albicans, Brasiliensis, Propionibacterium acnes and Trichophyton rubrum cultures were used to determine the anti-microbial and anti-fungal activity of crocodile oil. Unfortunately no activity was observed. The anti-oxidant properties of crocodile oil and crocodile oil lotion were determined by using the most commonly used method for measuring Malondialdehyde (MDA) in biological samples, namely the thiobarbituric acid (TBA) test. This method is based on spectrophotometric quantification of the pink complex formed after reaction of MDA with two molecules of TBA. No anti-oxidant activity was observed in the oil or the lotion. Toxicity studies were performed by Dr. D. Goosen (BVSc Hons. Pret.) from Tswane University of Technology (Pretoria, South Africa). The studies showed that the lotion had no toxicity in the skin sensitisation, acute dermal toxicity and acute dermal irritation studies. To determine the stability of the crocodile oil lotion, the formulated products were store at 25 °C / 60% RH (relative humidity), 30 °C / 60% RH and 40 °C / 75% RH for 6 months in the original packaging as well as a glass container. The stability tests included pH, viscosity, visual appearance assessment, zeta-potential, droplet size and mass loss. The crocodile cream lotion was stable over the 6 months period in both containers. Clinical efficacy testing was performed at the CEL (Clinical Efficacy Laboratory) of the North-West University, Potchefstroom, South Africa. A short-term study over a period of 3 h was performed to investigate the hydrating effects of crocodile oil lotion. A long-term study over a period of 12 weeks was performed to examine the anti-ageing effects of crocodile oil lotion. An erythema study was also conducted to test the anti-erythema properties of crocodile oil lotion. Although the crocodile oil lotion as well as the placebo lotion showed an increase in skin hydration, there was no significant difference between the two treatments. Crocodile oil lotion also showed no anti-erythema properties. / Thesis (PhD (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

Natural oils are regularly used in cosmetics and as treatment for numeral skin conditions (Nielsen, 2006:575). The natural products industry is a multibillion dollar industry and has grown tremendously over the past few years. Natural oils used in cosmetics contain a range of fatty acids which contribute to several valuable properties in cosmetic- and personal care products. Fatty acids are divided into saturated acids and unsaturated acids (Vermaak et al., 2011:920,922). Because of the popularity and wide diversity of skin care products, it is necessary to create products that will distinguish themselves from the rest of the commercial products. To include natural oils in skin care products is a new way to prevent skin ageing, as well as other dermatological conditions. In this study, a natural oil, namely crocodile oil was used. Crocodile oil is obtained from the fat of the Nile crocodile (Crocodylus niloticus). Crocodile oil has the same composition as human skin oil. It only differs with regard to the percentages of the ingredients present. Crocodile oil contains saturated and unsaturated fatty acids. Because of the similar composition as human skin oil, crocodile oil will rarely be allergenic when applied to human skin and therefore will be a very accepted and harmless product to use (Croc city, 2012). There are many claims of positive results when crocodile oil containing products have been used. It includes fading of freckles, treatment of acne and pimple marks, dark lines, wrinkles and laugh lines. It also includes vanishing of dark shadows, sun spots and other discolorations. It helps prevent discolorations from forming and makes the skin softer, brighter and more attractive. It also controls rashness and dryness (Croc city, 2012). Because of crocodile oil’s anti-ageing, anti-fungal and anti-bacterial effects claimed by crocodile oil suppliers, and due to the fact that little scientific data is available on crocodile oil, it was decided to investigate the claims. In this study, the aims and objectives were to use natural oil, namely crocodile oil, and investigate the fatty acid profile, anti-microbial and anti-fungal activity, anti-oxidant activity, toxicity studies, stability determination of crocodile oil lotion and clinical efficacy testing of the anti-ageing effects. To determine the fatty acid profile of crocodile oil, fatty acid methyl ester (FAME) analysis with gas chromatography were used. Identification of FAME peaks in the samples was made by comparing the relative retention times of FAME peaks from samples to those of reference standards. The composition of fatty acids in crocodile oil compared well to fatty acids found in human skin oil. Anti-microbial and anti-fungal tests were done by Envirocare Laboratories, North-West University, Potchefstroom. Staphylococcus aureus, Esterichia coli, Pseudomanas aeruginosa, Candida albicans, Brasiliensis, Propionibacterium acnes and Trichophyton rubrum cultures were used to determine the anti-microbial and anti-fungal activity of crocodile oil. Unfortunately no activity was observed. The anti-oxidant properties of crocodile oil and crocodile oil lotion were determined by using the most commonly used method for measuring Malondialdehyde (MDA) in biological samples, namely the thiobarbituric acid (TBA) test. This method is based on spectrophotometric quantification of the pink complex formed after reaction of MDA with two molecules of TBA. No anti-oxidant activity was observed in the oil or the lotion. Toxicity studies were performed by Dr. D. Goosen (BVSc Hons. Pret.) from Tswane University of Technology (Pretoria, South Africa). The studies showed that the lotion had no toxicity in the skin sensitisation, acute dermal toxicity and acute dermal irritation studies. To determine the stability of the crocodile oil lotion, the formulated products were store at 25 °C / 60% RH (relative humidity), 30 °C / 60% RH and 40 °C / 75% RH for 6 months in the original packaging as well as a glass container. The stability tests included pH, viscosity, visual appearance assessment, zeta-potential, droplet size and mass loss. The crocodile cream lotion was stable over the 6 months period in both containers. Clinical efficacy testing was performed at the CEL (Clinical Efficacy Laboratory) of the North-West University, Potchefstroom, South Africa. A short-term study over a period of 3 h was performed to investigate the hydrating effects of crocodile oil lotion. A long-term study over a period of 12 weeks was performed to examine the anti-ageing effects of crocodile oil lotion. An erythema study was also conducted to test the anti-erythema properties of crocodile oil lotion. Although the crocodile oil lotion as well as the placebo lotion showed an increase in skin hydration, there was no significant difference between the two treatments. Crocodile oil lotion also showed no anti-erythema properties. / Thesis (PhD (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

CAPES / A utilização de coagulantes naturais no tratamento de água vem sendo uma alternativa cada vez mais empregada a fim de evitar possíveis danos à saúde e ao meio ambiente causados por determinados coagulantes químicos. A Moringa oleifera é uma árvore de múltiplos usos, cujas sementes possuem uma eficiente atividade como coagulante natural. Entretanto, estudos apontam para uma possível toxicidade deste extrato. Baseando-se nisto, o objetivo do presente trabalho foi o de avaliar a toxicidade de três diferentes extratos de M. oleifera (extrato aquoso, extrato salino da semente integral e extrato salino da semente sem óleo) e da água tratada com os mesmos extratos, frente a duas espécies de microcrustáceos utilizadas como bioindicadoras de toxicidade (Daphnia magna e Artemia salina). Nos ensaios de toxicidade aguda dos extratos utilizando D. magna, verificou-se uma CE50 de 314,05 mg.L-1 para o extrato salino da semente integral e 346,76 mg.L-1 para o extrato salino da semente sem óleo. O extrato aquoso não apresentou toxicidade nem mesmo nas maiores concentrações (400 a 600 mg.L-1). Para o organismo A. salina, nenhum dos extratos mostrou-se tóxico. Nos ensaios realizados com a água tratada com os extratos de M. oleifera, foi encontrada toxicidade para D. magna nas frações sobrenadante (CE50=296,02 mg.L-1) e sedimentada (CE50=291,04 mg.L-1) da água tratada com o extrato salino da semente integral. Para a água tratada com o extrato salino da semente sem óleo, da mesma forma encontrou-se toxicidade nas frações sobrenadante (CE50=351,17 mg.L-1) e sedimentada (CE50=342,32 mg.L-1), o que indica que a toxicidade do extrato não é reduzida após a coagulação/floculação/sedimentação. No teste crônico realizado utilizando organismos de D. magna expostos durante 21 dias ao extrato salino da semente integral de M. oleifera, foram observadas alterações nos parâmetros avaliados (mortalidade, fecundidade e crescimento), sendo que quanto maior a concentração testada, maiores os efeitos tóxicos. Ao término dos 21 dias experimentais, havia ocorrido a mortalidade de 100% dos indivíduos expostos às maiores concentrações (10 e 15 mg.L-1). Além disso, houve grande variação na fecundidade entre os grupos. Com base nestes resultados, é possível afirmar que a utilização de elevadas concentrações do extrato de M. oleifera (acima de 300 mg.L-1) pode causar danos agudos ao organismo D. magna. Entretanto, na prática, as concentrações utilizadas deste coagulante são consideravelmente menores, variando principalmente entre 50 e 150 mg.L-1, de acordo com dados da literatura. Da mesma forma, a diluição que ocorreria no meio hídrico dificilmente proporcionaria que a concentração permanecesse elevada, mesmo que grande quantidade do extrato chegasse ao meio ambiente. Com base nisso, é possível afirmar que o uso do extrato da M. oleifera pode ser incentivado, mas desde que utilizado com cautela, evitando-se concentrações elevadas. / The use of natural coagulants for water treatment has been an alternative increasingly employed in order to avoid possible damage to health and the environment caused by certain chemical coagulants. Moringa oleifera is a multipurpose tree whose seeds have an efficient activity as natural coagulant. However, studies point to a possible toxicity of this extract. Based on this, the objective of this study was to evaluate the toxicity of three different extracts of M. oleifera (aqueous extract, saline extract of the whole seed and saline extract of the seed without oil) and water treated with the same extracts, against two species of microcrustaceans used as bioindicators of toxicity (Artemia salina and Daphnia magna). In acute toxicity tests of the extracts using D. magna, there was an EC50 of 314.05 mg.L-1 for the saline extract of the whole seed and 346.76 mg.L-1 for the saline extract of the seed without oil. The aqueous extract showed no toxicity even at the highest concentrations (400 to 600 mg.L-1). For the organism A. saline, none of the extracts proved toxic. In the tests performed with water treated with the extracts of M. oleifera, toxicity was found for D. magna in the supernatant fractions (EC50=296.02 mg.L-1) and sedimented (EC50=291.04 mg.L-1) of treated water with the saline extract of the whole seed. For the treated water with the saline extract of the seed without oil, was found toxicity in the supernatant fraction (EC50=351.17 mg.L-1) and the sedimented fraction (EC50=342.32 mg.L-1), which indicates that the toxicity of the extract is not reduced after coagulation/flocculation. In the chronic test performed using D. magna exposed during 21 days to the saline extract of the whole seed of M. oleifera, changes in the evaluated parameters (mortality, fertility and growth) were observed, and as higher the concentration tested, bigger was the toxicity. At the end of the 21 experimental days, there had been a 100% mortality of individuals exposed to higher concentrations (10 and 15 mg.L-1). Furthermore, there was wide variation in fertility between the groups. Based on these results, we can say that the use of high concentrations of the extract of M. oleifera (above 300 mg.L-1) can cause acute damage for D. magna. However in practice, the concentrations used of this coagulant are considerably smaller, ranging mainly between 50 and 150 mg.L-1, according to literature data. Likewise, the dilution that occur in the aquatic environment, hardly provide high concentration of the extract in the water bodies. Based on this, we can say that the use of the extract of M. oleifera can be encouraged, but if used with caution, avoiding high concentrations.

Os hidrocarbonetos monoaromáticos BTEX (benzeno, tolueno, etilbenzeno e xilenos) têm sido utilizados como solventes e estão presentes no ambiente, incluindo o ar, solo e água. Entre os componentes mais tóxicos estão o benzeno e o tolueno. Para uma correta avaliação do efeito desses contaminantes em águas é imprescindível a realização de estudos ecotoxicológicos. O objetivo deste trabalho foi estudar a toxicidade aguda e crônica dos hidrocarbonetos monoaromáticos por BTEX sobre os organismos testes Daphnia magna, Vibrio fischeri, Desmodesmus subspicatus e comparar os resultados com os limites definidos pelas legislações. Foram preparadas soluções aquosas em presença de metanol empregando-se padrões de BTEX-Mix, benzeno e tolueno (isolados). Essas soluções foram empregadas nos testes de ecotoxicidade conduzidos de acordo com metodologias padronizadas pela ABNT. Os resultados mostraram que para os testes com Daphnia magna os valores de CE50(48h) para BTEX-Mix, benzeno e tolueno foram, respectivamente, 1.187,27 μg.L-1, 73,23 g.L-1, 81,58 μg.L-1. Os testes com Desmodesmus subspicatus não apresentaram sensibilidade para o BTEX-Mix até 1000 μg.L-1 e foram obtidos os valores de CI(96h) para benzeno e tolueno, respectivamente, 197,90 g.L-1, 7.270 g.L-1. Com relação à utilização de metodologias padronizadas foi verificado que os ensaios com Daphnia magna apresentaram maior reprodutibilidade. Os resultados dos ensaios com Vibrio fischeri não apresentaram reprodutibilidade principalmente devido à volatilização das amostras. Comparações realizadas entre os valores das legislações e os resultados obtidos nos testes permitiram afirmar que, na maioria dos casos, os valores máximos permitidos estão abaixo do CE50 encontrado no estudo. Para descarte de efluentes em corpo receptor são preocupantes os valores estipulados quando o corpo receptor não possui grande capacidade de assimilar as altas cargas dos monoaromáticos. Para a Portaria 2914/2011 de consumo de água, o valor de 170 μg.L-1 está acima do CE50 e do CE10 encontrado para Daphnia magna, enquanto para a dessendentação de animais conforme o CONAMA 396/08 está abaixo. Os valores internacionais ambientais coincidem e estão abaixo dos valores encontrados, já as referências no Brasil para avaliação de passivos estão acima. / The hidocarbonetos monoaromatic BTEX (benzene, toluene, ethylbenzene and xylenes) have been used as solvents and are present in the environment, including air, soil and water. Among the most toxic components are benzene and toluene. For a correct evaluation of the effect of these contaminants in water is essential to carry out ecotoxicological studies. The objective of this work was to study the acute and chronic toxicity of monoaromatic hydrocarbons BTEX represented by tests on organisms Daphnia magna, Vibrio fischeri, Desmodesmus subspicatus and compare with the current laws. Aqueous solutions were prepared in the presence of methanol from patterns of BTEX-Mix, benzene, and toluene (isolated). These solutions were used to ecotoxicity tests according to standard procedures by ABNT. The results showed that in tests with Daphnia magna EC50 values (48h) for BTEX (mix), benzene and toluene were respectively 1187.27 μgL-1, 73.23 μgL-1, 81.58 μgL-1. Tests with Desmodesmus subspicatus showed no sensitivity to the BTEX (mix) until 1000 μgL-1 were obtained and the values of CI (96h) for benzene and toluene, respectively, 197.90 μgL-1, 7,270 μgL-1. With respect to the use of standardized methodologies been found that Daphnia magna assays showed higher reproducibility. The results of tests with Vibrio fischeri showed no reproducibility principally due to volatilization of the samples. Comparisons between the values of laws and the results obtained in tests enabled state that in most cases the maximum allowed values are below the EC50 found in the study. For disposal of effluent in the receiving body are disturbing the values stipulated when the receiver does not have great body ability to absorb the high loads of monoaromatic. For Ordinance number 2914/2011 of water amounts to 170 μgL-1. It is above the EC50 and EC10 found for Daphnia magna, while for tooth loss of animals as CONAMA 396/08 is below. The international environmental values coincide and are below the values found in the references already in Brazil for evaluation of liabilities are above.

Os hidrocarbonetos monoaromáticos BTEX (benzeno, tolueno, etilbenzeno e xilenos) têm sido utilizados como solventes e estão presentes no ambiente, incluindo o ar, solo e água. Entre os componentes mais tóxicos estão o benzeno e o tolueno. Para uma correta avaliação do efeito desses contaminantes em águas é imprescindível a realização de estudos ecotoxicológicos. O objetivo deste trabalho foi estudar a toxicidade aguda e crônica dos hidrocarbonetos monoaromáticos por BTEX sobre os organismos testes Daphnia magna, Vibrio fischeri, Desmodesmus subspicatus e comparar os resultados com os limites definidos pelas legislações. Foram preparadas soluções aquosas em presença de metanol empregando-se padrões de BTEX-Mix, benzeno e tolueno (isolados). Essas soluções foram empregadas nos testes de ecotoxicidade conduzidos de acordo com metodologias padronizadas pela ABNT. Os resultados mostraram que para os testes com Daphnia magna os valores de CE50(48h) para BTEX-Mix, benzeno e tolueno foram, respectivamente, 1.187,27 μg.L-1, 73,23 g.L-1, 81,58 μg.L-1. Os testes com Desmodesmus subspicatus não apresentaram sensibilidade para o BTEX-Mix até 1000 μg.L-1 e foram obtidos os valores de CI(96h) para benzeno e tolueno, respectivamente, 197,90 g.L-1, 7.270 g.L-1. Com relação à utilização de metodologias padronizadas foi verificado que os ensaios com Daphnia magna apresentaram maior reprodutibilidade. Os resultados dos ensaios com Vibrio fischeri não apresentaram reprodutibilidade principalmente devido à volatilização das amostras. Comparações realizadas entre os valores das legislações e os resultados obtidos nos testes permitiram afirmar que, na maioria dos casos, os valores máximos permitidos estão abaixo do CE50 encontrado no estudo. Para descarte de efluentes em corpo receptor são preocupantes os valores estipulados quando o corpo receptor não possui grande capacidade de assimilar as altas cargas dos monoaromáticos. Para a Portaria 2914/2011 de consumo de água, o valor de 170 μg.L-1 está acima do CE50 e do CE10 encontrado para Daphnia magna, enquanto para a dessendentação de animais conforme o CONAMA 396/08 está abaixo. Os valores internacionais ambientais coincidem e estão abaixo dos valores encontrados, já as referências no Brasil para avaliação de passivos estão acima. / The hidocarbonetos monoaromatic BTEX (benzene, toluene, ethylbenzene and xylenes) have been used as solvents and are present in the environment, including air, soil and water. Among the most toxic components are benzene and toluene. For a correct evaluation of the effect of these contaminants in water is essential to carry out ecotoxicological studies. The objective of this work was to study the acute and chronic toxicity of monoaromatic hydrocarbons BTEX represented by tests on organisms Daphnia magna, Vibrio fischeri, Desmodesmus subspicatus and compare with the current laws. Aqueous solutions were prepared in the presence of methanol from patterns of BTEX-Mix, benzene, and toluene (isolated). These solutions were used to ecotoxicity tests according to standard procedures by ABNT. The results showed that in tests with Daphnia magna EC50 values (48h) for BTEX (mix), benzene and toluene were respectively 1187.27 μgL-1, 73.23 μgL-1, 81.58 μgL-1. Tests with Desmodesmus subspicatus showed no sensitivity to the BTEX (mix) until 1000 μgL-1 were obtained and the values of CI (96h) for benzene and toluene, respectively, 197.90 μgL-1, 7,270 μgL-1. With respect to the use of standardized methodologies been found that Daphnia magna assays showed higher reproducibility. The results of tests with Vibrio fischeri showed no reproducibility principally due to volatilization of the samples. Comparisons between the values of laws and the results obtained in tests enabled state that in most cases the maximum allowed values are below the EC50 found in the study. For disposal of effluent in the receiving body are disturbing the values stipulated when the receiver does not have great body ability to absorb the high loads of monoaromatic. For Ordinance number 2914/2011 of water amounts to 170 μgL-1. It is above the EC50 and EC10 found for Daphnia magna, while for tooth loss of animals as CONAMA 396/08 is below. The international environmental values coincide and are below the values found in the references already in Brazil for evaluation of liabilities are above.

Waterborne diarrhoeal infections continue to be a major health setback in developing countries, especially in rural areas which lack adequate supply of portable water and sanitation facilities. Globally, waterborne diarrhoeal infections occur with an estimated mortality rate of 10–25 million deaths per year, 95% of which are children under the age of 5 years. The Vibrio species is one of the major groups of enteric pathogens that are responsible for diarrhoeal infections. Many strains of these bacterial species continue to cause epidemics of diarrhoea throughout the world. In this study, the prevalence of Vibrio pathogens in wastewater final effluents was assessed. Wastewater final effluent and discharge point samples were collected monthly between September 2012 and August 2013. All samples were collected aseptically using sterile 1 L Nalgene bottles containing 0.5 ml of sterile sodium thiosulphate solution and transported on ice to the laboratory for analyses within 6 h of collection. The membrane filtration method was used for enumeration of presumptive Vibrio densities on thiosulfate citrate bile salt (TCBS) agar plates. Polymerase chain reaction (PCR) was then used to confirm the identities of the presumptive Vibrio species using the species-specific primers. The confirmed isolates were further subjected to molecular characterization to confirm their respective pathotypes. Presumptive Vibrio densities varied from 0 to 2.11 × 102 cfu/100 ml. Out of 300 confirmed Vibrio isolates; 13.3% (40/300) were Vibrio fluvialis, 22% (66/300) were confirmed to be Vibrio parahaemolyticus, and 24.7% (74/300) proved to be Vibrio vulnificus, and 40% (120/300) were other Vibrio species which were not assessed for in this study. The strains of Vibrio fluvialis were found to exhibit 100% resistance to Polymixin and Tetracycline. However, Gentamicin was active against all the three Vibrio species selected for the purpose of this research. The recovery of Vibrio species in the discharged effluents throughout the sampling period even in adequately disinfected effluents is not acceptable considering the fact that Vibrio is a pathogenic bacterium. The findings of this study underline the need for constant monitoring of the microbiological qualities of discharged effluents and might also be suggestive for a review of the disinfection methods used at the treatment works.

Doctorat en Sciences / info:eu-repo/semantics/nonPublished

M.Sc. (Zoology) / Sediment contamination occurs as a result of various anthropogenic activities; mainly through mining-, agricultural- and industrial practices. Many of the contaminants arising from these activities enter the aquatic system and precipitate from the surrounding water, binding to sediment particles. In the sediment compartment, these contaminants reach concentrations much higher than in solution with the overlying water. Even though the quality of the overlying water may prove acceptable in accordance to water quality uidelines, an aquatic system may still be at risk from the contaminated sediment. If the contaminated sediment were to be disturbed through flooding, bioturbation or changes in the water chemistry, these contaminants will desorb into the water column and as a result be detrimental to life forms in contact and dependent on that water source. Monitoring sediment has been a widespread initiative internationally and has led to the development of various sediment toxicity test methods, including different bioassays. This study focused on sediment bioassays such as the Phytotoxkit-F and Ostracodtoxkit-F, and the Diptera bioassay to assess the sediment quality of the Tweelopiespruit-Rietspruit-Bloubankspruit (TRB) river system in Gauteng, South Africa. This river is known to be impacted by acid mine drainage (AMD) since late August 2002. Exposure of the bioassays to river sediment from preselected sampling sites (Site 1, closest to the mine, to Site 6, furthest from the mine, and Site 7, the reference site) provided an eco-toxicological estimation of the acute toxicity emanating from contaminants in the sediment. Physico-chemical analyses revealed high concentrations of metals and other contaminants in the water and sediment. A general linear decrease in contaminant concentrations was observed from Site 1 to Site 6. The results from the bioassays displayed a similar trend, since there were greater sensitivities (mortalities and growth inhibition) to sediments sampled closer to the mine. Due to high levels of contamination in sediments, compared to the overlying water, and the potential impact on aquatic organisms, sediment toxicity monitoring should be a compulsory requirement for environmental studies in South Africa

The production of final effluents that meet discharged requirements and guidelines remain a major challenge particularly in the developing world with the resultant problem of surface water pollution. This study assessed the physicochemical and microbiological qualities of two wastewater treatment works in the Eastern Cape Province of South Africa in terms of the prevalence of faecal coliforms and Escherichia coli O157:H7 over a five month period. All physicochemical and microbiological analyses were carried out using standard methods. Data were collected in triplicates and analysed statistically using IBM SPSS version 20.0. The ranges of some of the physicochemical parameters that complied with set guidelines include pH (6.7 – 7.6), TDS (107 – 171 mg/L), EC (168 – 266 μS/cm), Temperature (15 – 24oC), NO3- (0 – 8.2 mg/L), NO2- (0.14 – 0.71 mg/L) and PO4 (1.05 – 4.50 mg/L). Others including Turbidity (2.64 – 58.00 NTU), Free Cl (0.13 – 0.65 mg/L), DO (2.20 – 8.48 mg/L), BOD (0.13 – 6.85 mg/L) and COD (40 – 482 mg/L) did not comply with set guidelines. The microbiological parameters ranged 0 – 2.7 × 104 CFU/100 ml for FC and 0 – 9.3 × 103 for EHEC CFU/100 ml, an indication of non-compliance with set guidelines. Preliminary identification of 40 randomly selected presumptive enterohemorrhagic E. coli isolates by Gram’s staining and oxidase test shows 100% (all 40 selected isolates) to be Gram positive while 90% (36 randomly selected isolates) were oxidase negative. Statistical correlation between the physicochemical and the microbiological parameters were generally weak except in the case of free chlorine and DO where they showed inverse correlation with the microbiological parameters. The recovery of EHEC showed the inefficiency of the treatment processes to effectively inactivate the bacteria, and possibly other pathogenic bacteria that may be present in the treated wastewater. The assessment suggested the need for proper monitoring and a review of the treatment procedures used at these treatment works.