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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Développement d’une stratégie analytique dédiée aux dechloranes : Contribution à l’évaluation de l’exposition alimentaire et de l’imprégnation de l’homme à ces contaminants émergents / Development of an analytical strategy dedicated to Dechloranes : Contribution to the assessment of dietary exposure to these persistent and emerging contaminants

Abdel Malak, Inas 29 November 2018 (has links)
Les retardateurs de flamme (RF) sont des substances utilisées dans de nombreux produits synthétiques pour limiter la propagation du feu et ainsi améliorer la sécurité des habitations et des lieux publics. En raison de leur stabilité, de leur bioaccumulation et de leur toxicité, l’utilisation massive de certains RF, en particulier halogénés parmi lesquels la famille de Dechloranes, génère cependant un problème de contamination de l’environnement qui pose aujourd’hui la question d’éventuelles répercussions sur la santé humaine. Les Dechloranes ont été détectés pour la première fois dans l’environnement en 2006 et préoccupent, depuis, la communauté scientifique et les autorités sanitaires. Le présent travail avait pour objectif de contribuer à combler le manque manifeste de données sur les niveaux de prévalence en Dechloranes.Pour ce faire, une stratégie analytique ciblée, dédiée à l’identification et à la quantification des Dechloranes à l’état de traces (pg/g) dans des denrées alimentaires d’origine animale (DAOA) et des huiles végétales et basée sur un couplage GC-HRMS a été développé. Une attention particulière a été portée à la maîtrise des contaminations procédurales, eu égard au caractère ubiquitaire de certains composés. L’application de la méthode développée à 378 échantillons de poissons d’eaux douces de surface en France et de DAOA et huiles végétale collectées en France, au Liban et dans quatre pays d’Afrique subsaharienne a permis de brosser le premier état des lieux des niveaux de contamination environnementale et alimentaire dans ces pays, jusqu’à estimer l'exposition alimentaire de leurs populations à ces composés persistants et émergents. / Flame retardants (FR) are substances used in many synthetic products to limit the spread of fire and thus improve the safety of homes and public places. Due to their stability, bioaccumulation and toxicity, certain FRs, in particular halogenated ones among which the family of Dechloranes, are widely used, generating an issue of environmental contamination with potential repercussions on human health. Dechloranes were detected for the first time in the environment in 2006 and have since raised concerns to the scientific community and health authorities. The purpose of this paper is to help fill the obvious gap in data on prevalence levels of Dechloranes. To this end, a targeted analytical strategy dedicated to the identification and quantification of trace amounts of Dechloranes (pg/g) in animal foods (DAOA)and vegetable oils based on a GC-HRMS method has been developed. Particular attention has been paid to the control of procedural contaminations, given the ubiquitous nature of certain compounds. This method was applied to 378 samples of surface freshwater fish in France and DAOA and vegetable oils collected in France, Lebanon and four sub-Saharan African countries, and draw for the first time an inventory of levels of environmental and food contamination in these countries to estimate the dietary exposure of their populations to these persistent and emerging compounds
32

Avaliação da concentração de elementos químicos essenciais na merenda escolar de crianças da cidade de Ribeirão Preto e estimativa de suas ingestões / Determination of essential chemical elements in children´s school meals in the city of Ribeirão Preto and their estimated intakes

Rodolfo de Freitas 30 April 2013 (has links)
Para uma alimentação saudável, os alimentos consumidos devem conter quantidades adequadas de vários nutrientes. Atualmente, devido às interferências humanas na produção e comercialização de alimentos, os consumidores são incapazes de precisar a composição química e podem não estar ingerindo a quantidade correta de nutrientes. Neste sentido, se faz necessário o monitoramento da composição química dos alimentos e a estimativa de ingestão diária (WHO, 2005b). Deste modo, o objetivo deste trabalho foi, determinar a concentração dos elementos químicos essenciais fósforo (P), zinco (Zn), cálcio (Ca), ferro (Fe), sódio (Na), potássio (K), manganês (Mn), cobalto (Co) e selênio (Se) e a estimativa de ingestão diária no almoço de crianças em idade escolar através dos alimentos fornecidos pela Prefeitura de Ribeirão Preto. A metodologia utilizada no trabalho foi de dupla dieta, no qual os alimentos analisados estão prontos para o consumo. As merendas foram fornecidas por duas escolas municipais (infantil e ensino fundamental) e a cozinha piloto e, foram coletadas durante todos os dias letivos dos meses de março, junho, agosto e novembro de 2011. Os alimentos coletados foram congelados e liofilizados para posterior análise. As análises foram feitas utilizando a espectrometria de massas com plasma acoplado (ICP-MS) com prévia digestão ácida das amostras em ácido nítrico (HNO3)/peróxido de hidrogênio (H2O2). Os alimentos foram avaliados nas categorias arroz, feijão, carnes e verduras/ legumes. A ingestão média de P, Zn, Ca, Fe, Na, K, Mn, Co e Se foi, respectivamente, de 219 mg, 2,3 mg, 67,9 mg, 2,1 mg, 0,39 g, 0,62 g, 0,5 mg, 2,7 ?g e 7,1 ?g na escola de ensino infantil e foi respectivamente de 310 mg, 3,3 mg, 89,7 mg, 2,9 mg, 0,52 g, 0,80 g, 0,68 mg, 3,7 ?g e 10,1 ?g na escola de ensino fundamental. Foi avaliada, ainda, a variação da concentração destes elementos entre os locais de coletas de amostras e entre os períodos de coleta. As carnes foram as amostras em que ocorreram maiores variações estatísticas (p<0.05) entre os elementos estudados, provavelmente devido a associação de verduras e legumes nessas preparações em uma das escolas. Na avaliação sazonal os legumes e verduras apresentaram maior variação estatística nas concentrações dos elementos no decorrer do ano de coleta. / For a healthy eating, foods eaten should contain adequate amounts of various nutrients. Currently, due to human interference in the production and marketing of foods, consumers are unable to specify the chemical composition and cannot be ingesting the correct amount of nutrients. In this sense, it is necessary to monitor the chemical composition of foods and estimated daily intake (WHO, 2005b). Thus, the objective of this study was to determine the concentration of the essential elements phosphorus (P), zinc (Zn), calcium (Ca), iron (Fe), sodium (Na), potassium (K), manganese (Mn), cobalt (Co) and selenium (Se) and the estimated daily intake at lunch to school children through food provided by the city hall of Ribeirão Preto. The methodology used in this study was double-diet, where the foods analyzed are ready for consumption. The meals provided by two local schools and the kitchen pilot were collected during all school days in March, June, August and November of 2011. The food collected was frozen and lyophilized for further analysis. The analyzes were performed using inductively coupled plasma mass spectrometry (ICP-MS) after the acid digestion with nitric acid (HNO3) and hydrogen peroxide (H2O2) of the samples. The foods were evaluated in the categories: rice, beans, meat and vegetables. The average intake of P, Zn, Ca, Fe, Na, K, Mn, Co e Se was respectively 219 mg, 2.3 mg, 67.9 mg, 2.1 mg, 0.39 g, 0.62 g, 0.5 mg, 2.7 ?g e 7.1 ?g in elementary school children and was respectively 310 mg, 3.3 mg, 89.7 mg, 2.9 mg, 0.52 g, 0.80 g, 0.68 mg, 3.7 ?g e 10.1 ?g in meddle school. Was also evaluated the variation of the concentration of these elements between the sample collection sites and between sampling periods. The meats were a category in which there were more cases of statistically significant differences (p <0.05) between the elements studied, due to association of vegetables in these preparations at one of the schools. In assessing the seasonal, the vegetables had higher statistical variation in the concentrations of the elements throughout the year collecting.

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