The organochlorine pesticide endosulfan has been shown to be highly toxic to fish and there is some evidence to support that it may act as an endocrine disrupting chemical. Juvenile rainbow trout (Oncorhynchus mykiss) were caged at 4 sites in Oshawa Creek during the fall and spring of 2008 and 2009 while another group was intra-peritoneal injected in the laboratory with varying concentrations (ppm) of endosulfan. Plasma vitellogenin (VTG) levels, liver ethoxyresorufin-O-deethylase (EROD), citrate synthase (CS), lactate dehydrogenase (LDH), and brain acetylcholine esterase (AChE) (caged fish only) enzymatic activities were measured. Trout injected with endosulfan experienced an increase of the anaerobic (LDH activity) and a decrease of the aerobic (CS activity) metabolic pathways, while male VTG levels increased. Since it was a singular injection, VTG results have to be confirmed. Fall caged trout showed increased EROD activity and inhibited AChE activity while those caged in the spring experienced an unexpected exposure to the lampricide 3-Trifluoro-Methyl-4-Nitro-Phenol (TFM) which disrupted metabolic parameters (inhibited CS and increased LDH activity). Both fall and spring caged trout experienced no induction of VTG activity. Further research is needed since the spring exposure was altered due to the unplanned TFM treatment and thus did not represent a valid temporal replicate.

Des études épidémiologiques ont montré que l’exposition à certains xénobiotiques est associée à une augmentation de la prévalence des maladies métaboliques. L’Homme est exposé à des mélanges de xénobiotiques de manière chronique et inévitable. Nous avons étudié les effets de l’interaction de deux xénobiotiques sur le métabolisme du foie, organe majeur de détoxification de l’organisme. Nous avons choisi deux perturbateurs endocriniens et polluants organiques persistants, qui activent des voies de signalisation différentes: la 2, 3, 7, 8 tétrachlorodibenzo-p-dioxine (TCDD), agissant via le récepteur aux hydrocarbures aromatiques (AhR), et l’α-endosulfan, un pesticide organochloré, qui peut agir via la voie du récepteur aux oestrogènes (ER) ou du récepteur X aux pregnanes (PXR). Notre objectif est de déterminer l’effet du mélange de ces polluants par rapport à chaque polluant isolé sur la régulation de certaines voies du métabolisme hépatique in vitro dans la lignée hépatocytaire humaine, HepaRG. Dans une première publication, une étude du transcriptome de cellules HepaRG différenciées a été effectuée. Ces cellules ont été exposées pendant 30 heures à 25nM de TCDD, 10μM d’α-endosulfan, ou au mélange. Nous avons observé que le mélange inhibe fortement l’expression de certains gènes impliqués dans le métabolisme glucidique et dans celui des alcools. Dans une seconde étude, nous avons donc étudié le mécanisme d’action du mélange sur le métabolisme glucidique. L’expression de deux gènes de la néoglucogenèse hépatique, le transporteur de glucose 2 (Glut2) et la glucose 6 phosphatase (G6Pc), est réduite de plus de 80% par le mélange. L’expression d’autres gènes du métabolisme glucidique (pyruvate kinase, glycogène synthase, glycogène phosphorylase, pyruvate déhydrogénase 2) est aussi diminuée, suggérant que le mélange peut affecter ce métabolisme de manière significative. De plus, la production de glucose diminue de 80% avec le mélange dans des conditions néoglucogéniques. En condition glycolytique, l’oxydation du glucose en CO2 diminue de 30% après 72 heures d’exposition au mélange. Un traitement à plus long terme (8 jours) avec des doses plus faibles des polluants (0.2 à 5nM de TCDD, 3μM d’α-endosulfan) diminue aussi l’expression de la G6Pc et de Glut2. Nous avons montré que la TCDD active bien la voie du AhR, et que le ER est impliqué dans l’action de l’α-endosulfan. Dans la troisième partie de cette thèse, nous avons étudié la régulation de plusieurs enzymes impliquées dans le métabolisme de l’alcool (alcool déshydrogénases, ADHs, cytochrome P450 2E1, CYP2E1) après l’activation du AhR. Les agonistes du AhR entrainent la diminution de l’expression des ARNm des ADH1, 4, 6 et du CYP2E1 et des protéines correspondantes. Nous avons montré que cette régulation utilise la voie génomique du AhR. De plus, cet effet est également observé après traitement de 8 jours par de faibles doses de TCDD. L’exposition chronique de l’Homme à de faibles doses de xénobiotiques en mélange pourrait affecter le métabolisme glucidique hépatique et contribuer, en partie, au développement du syndrome métabolique. / Epidemiological studies have shown that exposure to certain xenobiotics is associated with an increased prevalence of metabolic diseases. Humans are exposed to mixtures of xenobiotics in a chronic and inevitable way. We studied the effects of the interaction of two xenobiotics on metabolism in the liver, the major organ for detoxification in the body. We chose two endocrine disruptors and persistent organic pollutants which activate different signaling pathways: 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD), which uses the AhR (Aryl hydrocarbon receptor) pathway, and α-endosulfan, an organochlorine pesticide, which acts via the PXR (pregnane X receptor) and/or the ER (estrogen receptor) pathway. Our aim was to determine the effects of this pollutant mixture, as compared to each pollutant alone, on the regulation in vitro of some hepatic metabolism pathways in the human hepatic cell line, HepaRG. In the first publication, a transcriptomic study of differentiated HepaRG cells was performed. The cells were exposed for 30h to 25nM TCDD, to 10 µM α-endosulfan or to the mixture. We observed that the mixture strongly inhibited the expression of some genes involved in the metabolism of glucose and alcohol. In the second study, we studied the mechanism of action of the mixture of pollutants on the metabolism of glucose. The expression of two genes involved in hepatic gluconeogenesis, glucose transporter 2 (GLUT2) and glucose-6-phosphatase (G6Pc), were reduced 80% by the mixture. The expression of other glucose metabolism genes (pyruvate kinase, glycogen synthase, glycogen phosphorylase, pyruvate dehydrogenase 2) also was decreased suggesting that the mixture might impact markedly carbohydrate metabolism. Furthermore, glucose production decreased 40% with the mixture under gluconeogenic conditions. Under glycolytic conditions, the oxidation of glucose into CO2 decreased 30% after 72h of exposure of the cells to the mixture. Long-term treatment (8 days) with lower doses (0.2 to 5 nM TCDD, 3 µM α-endosulfan) similarly decreased G6Pc and GLUT2 expression. We showed that TCDD activated the AhR pathway, and that ER was partly involved in the α-endosulfan effect. In the third part of this thesis, we studied the regulation of several enzymes involved in the metabolism of alcohol (alcohol dehydrogenase, ADH, cytochrome P450 2E1, CYP2E1) after activation of AhR. AhR agonists led to a decrease in the amounts of mRNAs for ADH1, 4, 6 and CYP2E1 and the corresponding proteins. We showed that this regulation uses the AhR genomic pathway. Furthermore, this effect was also observed after 8 days of treatment with lower doses of TCDD. Chronic exposure of individuals to low doses of xenobiotics in mixtures might significantly affect hepatic carbohydrate metabolism and be a contributing factor for the development of the metabolic syndrome.

Type 2 diabetes mellitus (T2DM) is classified as a metabolic disorder characterized by hyperglycemia that results from defects in insulin action and/or secretion, and currently affects 8.3% of the US population according to the CDC’s 2011 National Diabetes Fact Sheet. Several contributing factors have been identified to development of this disease. Published evidence indicates type 2 diabetes mellitus (T2DM) patients display lower overall paraoxonase activity and that this may be partially due to genetic variations in the paraoxonase-1 (PON-1) gene. Some bioaccumulative organochlorine (OC) pesticides have been shown to contribute to increased T2DM prevalence. In addition, these OC compound levels have been associated with alterations in adipocyte cytokine levels as well as increased inflammatory markers. Three hundred blood samples with clinical and demographic information were obtained from two US Air Force hospitals. A total of 151 non-diabetics and 149 T2DM subjects were evaluated for PON-1 activity, PON-1 Q192R and L55M genetic polymorphisms, OC compound concentrations, inflammatory marker levels and adipokine concentrations. PON-1 activity, using diazoxon as the substrate, was decreased in the T2DM subjects. Some of the PON-1 genetic polymorphisms tested were also associated with decreased PON-1 activity. OC compound levels were increased in the T2DM subjects. The non-diabetic subjects possessing elevated DDE and trans-nonachlor were associated with increased inflammation, a common hallmark of early T2DM development. Additionally, elevated OC levels were seen in association with altered adipokine concentrations. Overall, a decrease in the antioxidant properties of PON-1 as well as factors contributing to chronic low level inflammation such as elevated OC plasma concentration appear to be significant contributors to T2DM prevalence in the population studied.

Introdução: Áreas contaminadas por agentes químicos perigosos em regiões urbanas representam riscos importantes à saúde humana e ao ambiente. Vila Carioca, localizada na cidade de São Paulo, é uma área contaminada por pesticidas organoclorados considerada crítica, pela magnitude da contaminação, pela presença de pessoas residentes e pela complexidade de fontes da contaminação. Vários estudos de riscos já foram realizados por uma das empresas contaminadoras, no entanto, ainda há muita incerteza e controvérsias sobre os riscos à saúde da população. Objetivo: Avaliar o incremento de risco de câncer no tempo de vida para população exposta por meio de uma avaliação probabilística. Método: Foram utilizados dados secundários das contaminações obtidos nos estudos de riscos efetuados pela empresa produtora de pesticidas organoclorados e também em documentos oficiais dos órgãos de saúde e meio ambiente do Estado de São Paulo, resultantes do monitoramento da água e do solo na área residencial no período de 1997 a 2012, para 335 substâncias. Foram selecionadas substâncias carcinogênicas presentes na água subterrânea e solo com melhor conjunto de dados. Para a avaliação probabilística foi empregado o método de simulação de Monte Carlo, por meio do software comercial ModelRisk. Foram utilizados os métodos recomendados pela United States Environmental Protection Agency para a avaliação de risco de exposição dérmica e de incremento de riscos de câncer para substâncias mutagênicas. Foram consideradas a ingestão de água e solo, e contato dérmico com água. Resultados: O incremento de risco de câncer no tempo de vida (IRLT) foi de 4,7x10-3 e 4,1x10-2 para o percentil 50% e 95%, respectivamente. As rotas de exposição mais importantes foram ingestão e contato dérmico com a água subterrânea, seguido da ingestão de solo. O grupo etário que apresentou maior risco foi o das crianças de 0 a 2 anos de idade. Conclusão: Os riscos estimados são superiores aos valores considerados toleráveis. A avaliação realizada foi conservativa, mas ressalta-se que a restrição do uso da água subterrânea deve ser mantida e que a população deve ser devidamente informada dos riscos envolvidos na área, em especial, relacionados ao solo contaminado / Introduction: Contaminated areas by hazardous chemical agents represent risks to human health and the environment. Vila Carioca, a neighborhood of Sao Paulo city, is a contaminated area by organochlorine compounds. This area is considered critical because of the high levels of contamination, the people exposed and the sources of contamination. A organochlorine pesticides company, one of the sources of contamination, have conducted some risks studies, however there is still controversy and uncertainty about the health risks. Objective: Conduct a cancer risk assessment to the exposed people, following a probabilistic approach. Method: It were used the data of contaminant concentration values in soil and water, obtained of the environmental studies conducted from 1997 to 2012, for 335 chemicals. The carcinogenic substances with better set of data were selected. For the probabilistic assessment were used the Monte Carlo simulation, by means of commercial software ModelRisk (Vose Software). The methods recommended by the United States Environmental Agency were used, including its recent recommendations for the risk assessment of dermic exposure and increment of cancer risk for mutagenic substances. Results: The risk of cancer found were 4,7x10-3 and 4,1x10-2 , to the percentile 50% and 95%, respectively. The most important exposure routes were ingestion and dermic contact with water, followed by ingestion of soil. The age group that showed highest risk was child group with age between 0 and 2 years. Conclusion: The estimated risks are not tolerable. This study was conservative, but is important maintain the restriction of the water use, and people resident have to be informed about the health risks, principally in relation to the contaminated soil

Introdução: Áreas contaminadas por agentes químicos perigosos em regiões urbanas representam riscos importantes à saúde humana e ao ambiente. Vila Carioca, localizada na cidade de São Paulo, é uma área contaminada por pesticidas organoclorados considerada crítica, pela magnitude da contaminação, pela presença de pessoas residentes e pela complexidade de fontes da contaminação. Vários estudos de riscos já foram realizados por uma das empresas contaminadoras, no entanto, ainda há muita incerteza e controvérsias sobre os riscos à saúde da população. Objetivo: Avaliar o incremento de risco de câncer no tempo de vida para população exposta por meio de uma avaliação probabilística. Método: Foram utilizados dados secundários das contaminações obtidos nos estudos de riscos efetuados pela empresa produtora de pesticidas organoclorados e também em documentos oficiais dos órgãos de saúde e meio ambiente do Estado de São Paulo, resultantes do monitoramento da água e do solo na área residencial no período de 1997 a 2012, para 335 substâncias. Foram selecionadas substâncias carcinogênicas presentes na água subterrânea e solo com melhor conjunto de dados. Para a avaliação probabilística foi empregado o método de simulação de Monte Carlo, por meio do software comercial ModelRisk. Foram utilizados os métodos recomendados pela United States Environmental Protection Agency para a avaliação de risco de exposição dérmica e de incremento de riscos de câncer para substâncias mutagênicas. Foram consideradas a ingestão de água e solo, e contato dérmico com água. Resultados: O incremento de risco de câncer no tempo de vida (IRLT) foi de 4,7x10-3 e 4,1x10-2 para o percentil 50% e 95%, respectivamente. As rotas de exposição mais importantes foram ingestão e contato dérmico com a água subterrânea, seguido da ingestão de solo. O grupo etário que apresentou maior risco foi o das crianças de 0 a 2 anos de idade. Conclusão: Os riscos estimados são superiores aos valores considerados toleráveis. A avaliação realizada foi conservativa, mas ressalta-se que a restrição do uso da água subterrânea deve ser mantida e que a população deve ser devidamente informada dos riscos envolvidos na área, em especial, relacionados ao solo contaminado / Introduction: Contaminated areas by hazardous chemical agents represent risks to human health and the environment. Vila Carioca, a neighborhood of Sao Paulo city, is a contaminated area by organochlorine compounds. This area is considered critical because of the high levels of contamination, the people exposed and the sources of contamination. A organochlorine pesticides company, one of the sources of contamination, have conducted some risks studies, however there is still controversy and uncertainty about the health risks. Objective: Conduct a cancer risk assessment to the exposed people, following a probabilistic approach. Method: It were used the data of contaminant concentration values in soil and water, obtained of the environmental studies conducted from 1997 to 2012, for 335 chemicals. The carcinogenic substances with better set of data were selected. For the probabilistic assessment were used the Monte Carlo simulation, by means of commercial software ModelRisk (Vose Software). The methods recommended by the United States Environmental Agency were used, including its recent recommendations for the risk assessment of dermic exposure and increment of cancer risk for mutagenic substances. Results: The risk of cancer found were 4,7x10-3 and 4,1x10-2 , to the percentile 50% and 95%, respectively. The most important exposure routes were ingestion and dermic contact with water, followed by ingestion of soil. The age group that showed highest risk was child group with age between 0 and 2 years. Conclusion: The estimated risks are not tolerable. This study was conservative, but is important maintain the restriction of the water use, and people resident have to be informed about the health risks, principally in relation to the contaminated soil

M. Tech. (Biotechnology) Vaal University of Technology / One of the major problems encountered in qualitative and quantitative determination of residual pesticides by gas chromatography is the matrix effects. Matrix components have a considerable effect on the way analysis is conducted and the quality of results obtained, introducing problems such as inaccurate quantification, low analyte delectability and reporting of false positive or even false negative results. It was aimed to develop and validate a suitable method for counteracting the matrix effects so as to improve the detection and quantification of selected organochlorine pesticide residues from real water samples. The real water samples used were sampled from three points along the Jukskei River catchment area in Gauteng, South Africa for a period of 7 months from January to July 201 0 so as to create a representative sample. An automated solid phase extraction (SPE) method coupled to Gas ChromatographyMass Spectrometry (GC-MS) method for the analysis of 20 selected organochlorine pesticides was developed and validated for the purposes of studying the matrix effects. The analytical method showed a significant degree of validity when tested against parameters such as linearity, repeatability and sensitivity. Endosulphan beta, 4,4' Dichlorodiphenyldichloroethane, and Heptachlor-epoxide had the broadest linear calibration ranges of 1 ppm- 0.0156 ppm. Benzene hexachloride (BHC) delta and Lindane had the lowest statistical limits of detection of 0.018 ppm. Statistical hypothesis testing indicated that there was significant linearity in all selected organochlorine calibration curves. Four different reversed sorbent phases, including LC18, SC18- E and Strata-X (styrene divinyl benzene) were tested for organochlorine retention efficiency. The LC-18 200 mg cartridge proved to be the most robust and effective sorbent phase as it produced better recoveries varying from 90-130% for most analytes. A breakthrough volume of 100 ml for the LC-18 200 mg cartridge was determined using an optimum matrix load curve. It was then concluded that the method developed was suitable for further research towards the influence of the matrix on selective determination of the selected organochlorine pesticides. Four different calibration methods, namely matrix-free external standard, matrixmatched external standard, matrix-free internal standard and matrix-matched internal standard were applied to test the efficiency of computing recoveries. All calibration curves for the 20 organochlorine pesticides showed significant linearity > 0.99 when plotted on both Chemstation and Excel. The calibration methods were tested on three different matrices composed of a high sample matrix (synthetic matrix), a low sample matrix (real sample matrix) and a no sample matrix (ultrapure water). Statistical hypothesis testing led to the decision that there are significant differences between the mean recoveries of the three water sample matrices and also that the differences in the mean recoveries of the three sample matrices are independent of the both the two calibration techniques (internal standard and external standard) and calibration types (matrix-matched and matrix-free) applied. This led to the overall conclusion that the matrix effects have an overwhelming influence on the selective determination of the selected organochlorine pesticides.