• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 38
  • 17
  • 7
  • 5
  • 2
  • 1
  • Tagged with
  • 83
  • 13
  • 11
  • 8
  • 8
  • 8
  • 6
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 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.
71

Resistencia do carrapato Boophilus microplus (Acari: Ixodidae) aos piretroides e organofosforados e o tratamento carrapaticida em pequenas fazendas / Resistance to pyrethroids and organophosphorus acaricides in cattle tick Boophilus microplus (Acari Ixodidae)

Mendes, Marcia Cristina 15 December 2005 (has links)
Orientador: Angelo Pires do Prado / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-05T17:23:06Z (GMT). No. of bitstreams: 1 Mendes_MarciaCristina_D.pdf: 1282171 bytes, checksum: b6fcf8f3ba4709b8f115eb5ced83bcf8 (MD5) Previous issue date: 2005 / Resumo: Entre os ectoparasitos dos animais bovinos, o carrapato ¿ Boophilus microplus (Acari: Ixodidae) - continua sendo uma das principais causas das perdas econômicas na pecuária do Estado de São Paulo. A situação atual do controle do carrapato caracteriza-se por uma crise na produção de novas moléculas de parasiticidas e o desenvolvimento acelerado da resistência dos parasitas aos produtos usados. O presente trabalho teve por objetivo verificar o perfil de sensibilidade do carrapato B. microplus nas fazendas localizadas em alguns municípios do Vale do Ribeira e no município de Pindamonhangaba e propor um sistema de tratamento carrapaticida com base na infestação de paternóginas. Foram realizados testes de larvas - LPT (larval packet test) adotado pela FAO - teste de imersão com a fêmea adulta e o levantamento sobre as práticas de controle adotadas nas duas regiões. Os resultados de resistência para as fazendas de Pindamonhangaba mostraram que, para cipermetrina 15,4% das fazendas foram classificadas como sensível; 7,7% com resistência nível I; 69,2% com resistência nível II e 7,7% com resistência nível III. Para a deltametrina 23% sensível; 38,5% com resistência nível II e 38,5% com resistência nível III. Para o organofosforado clorpirifós 54% mostraram-se sensível; 38,4% com resistência nível I e 7,6% com resistência nível II. A região do Vale do Ribeira apresenta uma média de eficácia inferior a 20% para os piretróides; eficácia entre 49% e 72% para as associações piretróides e organofosforados; 66,83% para o amitraz e acima de 90% para as associações entre os organosfosforados. Para o teste de larvas a cipermetrina apresentou uma porcentagem de 42,85% de amostras sensível; 14,3% com resistência nível I e 42,85% com resistência nível II. Deltametrina, 50% sensível; 25% com resistência nível II e 25% com resistência nível III. O organofosforado clorpirifós mostrou uma porcentagem de 50% de amostras sensível; 25% com resistência nível I e 25% com resistência nível II. Constatouse, para as duas regiões estudadas, a falta de conhecimento dos principais grupos químicos usados no controle dos carrapatos. O produto amitraz é o mais usado e a maioria das fazendas usam o método de pulverização na aplicação dos carrapaticidas. Experimento realizado no ano de 2001 a 2003 num sítio localizado no município de Ibiúna mostrou que a avaliação de infestação de paternóginas do carrapato B. microplus na área do úbere ou escroto e baixo períneo é um critério que pode ser empregado para se determinar a aplicação de carrapaticidas. Quando se realiza a aplicação de carrapaticidas nos animais infestados com bastante paternóginas diminui a infestação de larvas no campo. Testes de bioensaios, usando fêmeas adultas, realizados num intervalo de três meses, e teste de larvas no período de seis meses servem como orientação para o proprietário na avaliação da sensibilidade dos carrapatos aos produtos químicos / Abstract: The cattle tick - Boophilus microplus (Acari: Ixodidae) ¿ is one of the principal causes of economic losses in the cattle farms in São Paulo state. The current situation of the tick control is characterized by a crisis in the production of new molecules with acaricidal properties and by an increasing in the parasites resistance to the products used to control them. The current study aimed to verifying the sensibility profile of tick B. microplus in farms located in the municipalities of Vale do Ribeira and in the region of Pindamonhangaba, and propose a tick control treatment system based on nymph infestation. The resistance diagnosis tests have been carried by the larval bioassay (Larval packet test), adult immersion test and the survey of the tick control practices applied in both regions. The results for the farms at Pindamonhangaba show that to Cypermethrin 15,4% of the farms were classified as sensible, 7,7% resistance level I, 69,2% resistance level II and 7,7% resistance level III. To deltamethrin 23% were considered sensible, 38,5% Resistance level II, and 38,5% resistance level III. To organophosphate chlorpyriphos 54% presented a sensible frame, 38,4% resistance level I and 7,6% resistance level II. The Vale do Ribeira region presents an average efficacy lower than 20% for all pyrethroids; efficacy between 49% and 72% to associations with pyrethroids and organophosphates; 66,83% to amitraz, and over 90% to organophosphates associations. For the larval test, the cypermethrin presented a percentage of 42,85% from samples sensible; 14,3% resistance level I and 42,85% resistance level II. Deltamethrin, 50% sensible; 25% resistance level II and 25% resistance level III. The organophosphate chlorpyriphos presented a percentage of 50% from samples sensible; 25% resistance level I and 25% resistance level II. It has been proved, that for both regions under this study, there is a lack of knowledge concerning the main chemical groups used in the tick control. The amitraz is the most used and most farms apply the pulverization method when performing the tick control. An experiment taken from 2001 to 2003 in a little farm located in the municipality of Ibiúna has shown the evaluation in the infestation of tick B. microplus in the udder area or escrotum and low perineum is a good criteria to be applied in order to determine the application of anti-ticks. When the application of anti-ticks is undertaken on infested animals full of pathenogens, the field larvae infestation is diminished. Bioassay, using engorged female ticks, undertaken at three months intervals and larval packet test undertaken at six months intervals serve as orientation for the owners for the evaluation of ticks¿ sensibility to the chemical products / Doutorado / Entomologia / Doutor em Parasitologia
72

Étude de la cinétique de biomarqueurs d’exposition à la perméthrine dans des conditions d’exposition réelles chez les travailleurs agricoles au Québec

Ferland, Stéphanie 11 1900 (has links)
La perméthrine fait partie de la famille des pyréthrinoïdes qui sont abondamment utilisés en agriculture. Le but de cette étude était d'obtenir des données sur la cinétique des biomarqueurs d'exposition à la perméthrine en condition réelle d'exposition chez les travailleurs agricoles. Douze travailleurs (un applicateur, un superviseur et dix cueilleurs) exposés à la perméthrine dans le cadre de leur emploi ont été recrutés dans une ferme maraichère de la Montérégie (Québec). Ils ont fourni toutes leurs urines sur une période de trois jours suivant le début des travaux dans un champ traité. Les trois principaux métabolites de la perméthrine, l'acide cis-/trans-3-(2,2-dichlorovinyle)-2,2-diméthylecyclopropane carboxylique (cis-/trans-DCCA) et l'acide 3-phénoxybenzoïque (3-PBA) ont été analysés par chromatographie liquide à ultra-haute performance couplée à la spectrométrie de masse à temps de vol. Pour l'applicateur, une augmentation progressive des valeurs d'excrétion a été observée avec un pic unique atteint environ 30 h après le début de l'exposition d'une durée de 3,5 h suivi d'une élimination avec une demi-vie de 8 h. Pour le superviseur et l'un des cueilleurs, les profils d'excrétion de trans-DCCA et de 3-PBA étaient compatibles avec de multiples entrées dans la zone traitée pendant la période d'échantillonnage accompagné d'une élimination rapide entre les épisodes d'exposition.L'applicateur aurait été exposé indirectement par contact main-bouche, alors que les autres travailleurs auraient été exposés par la voie cutanée. Pour une surveillance biologique adéquate, nous recommandons de mesurer deux biomarqueurs de la perméthrine, soit le trans-DCCA et le 3-PBA et de prendre un minimum de trois échantillons urinaires, un avant et deux pendant ou suivant la période d'exposition. / Permethrin is a synthetic pyrethroid insecticide widely used in agriculture worldwide. This study aimed at obtaining data on the time courses of biomarkers of exposure to permethrin in agricultural workers following typical exposure conditions. Twelve workers (an applicator, a supervisor and ten harvesters) exposed to permethrin were recruited from a corn production farm in the Montérégie (Quebec). They provided all their urine voided over a period of three days following the onset of a spraying episode of permethrin or work in a treated area. Three major metabolites of permethrin, cis-/trans-3-(2,2-dichlorovinyl)-2,2-dimethylycyclopropane carboxylic acid (cis-/trans-DCCA) and 3-phenoxybenzoic acid (3-PBA) were analyzed by ultra-high performance liquid chromatography coupled to quadripole time-of-flight mass spectrometry (UHPLC/Q-TOF MS). For the applicator, a progressive rise in excretion values was observed with a single peak being reached about 30 h following the onset of the 3.5 h exposure and ensuing elimination with a half-life of 8 h. For the supervisor and one harvester excretion profiles of trans-DCCA and 3-PBA were more compatible with multiple entries in the treated area during the 3-day sampling period and rapid elimination between exposure episodes. The applicator would have been indirectly exposed by hand-to-mouth contact, while other workers would have been exposed by the dermal route. Time-dependent variability in excretion values of workers confirms the need for serial urine sampling of at least two biomarkers of exposure for routine biomonitoring, with minimally pre-exposure, end-of-shift sample the day of the onset of exposure and following morning void.
73

Suivi temportel des niveaux de concentration en atmosphère intérieure lors de l'application d'insecticides ménagers

Vesin, Aude 18 April 2013 (has links)
L'étude du comportement dynamique des substances actives pendant l'épandage de produits insecticides ménagers commerciaux dans les atmosphères intérieures nécessite le développement et l'adaptation de procédures analytiques de mesure en ligne ayant une résolution temporelle élevée. Un HS-PTR-MS et un HR-ToF-AMS ont par conséquent été utilisés pour mesurer les contaminants à la fois en phase gazeuse et particulaire. Les substances actives ciblées par cette étude appartiennent à la famille des pyréthrinoïdes, présentes dans différentes formulations commerciales du type diffuseurs électriques et sprays aérosols, qui ont été appliqués dans une pièce d'étude simulant une atmosphère réelle dans la maison expérimentale MARIA du Centre Scientifique et Technique du Bâtiment. Les résultats de ces mesures montrent des pics de concentration compris entre 1,5 et 8,5 µg.m-3, après 8 heures de branchement des diffuseurs électriques. Les pics de concentration des substances actives après l'application des sprays peuvent atteindre plusieurs dizaines de µg.m-3. La ventilation et la sédimentation des aérosols apparaissent comme des mécanismes majeurs d'élimination des polluants du compartiment air. Par ailleurs, une distribution importante des substances actives avec les surfaces de la pièce (murs, sol, plafond, particules en suspension et poussières) est observée. L'évaluation de l'exposition par inhalation aux produits insecticides étudiés montre qu'il n'existe a priori pas de risque pour la santé. Néanmoins, une évaluation intégrée, prenant en compte toutes les voies d'exposition est nécessaire avant de conclure à une absence de risque sanitaire. / The study of the dynamic behaviour of the active substances during the application of commercial household insecticide products in indoor atmospheres requires the development of the adaptation of on-line analytical procedures with high time resolution. A HS-PTR-MS and a HR-ToF-AMS have therefore been used to measure contaminants both in the gaseous and particulate phase. The active substances targeted by this study belong to the pyrethroids, which are present in different commercial formulations like electric vaporizers and sprays that were applied in a full-scale test room simulating a real atmosphere in the experimental house MARIA of the French scientific and technical centre for building. The results of these measurements show that peak concentrations during a 8h-emission of electric vaporizers range from 1,5 et 8,5 µg.m-3. The peak concentrations of active substances during spraying can reach several dozens of µg.m-3. Ventilation and deposition of aerosols are major elimination mechanisms of pollutants from the air compartment. Moreover, an important distribution of active substances with the surfaces of the room (walls, floor, ceiling, suspended particles and dust) is observed. The evaluation of inhalation exposure to the studied insecticide products show that adverse effects are not likely to occur. Nevertheless, to conclude that these products are safe, it is necessary to perform an integrated evaluation, taking into account all exposure routes.
74

Exposure to organochlorine compounds at the aerly stages of DDT use for indoor residual spraying in domestic environments in Manhiça, Mozambique.

Manaca, Maria Nélia Joquim 27 September 2011 (has links)
Past and present uses of DDT and pyrethroids have led to their incorporation into humans, mainly through the food chain and sometimes by direct exposure. The present work focuses on establishing the levels of DDT, its analogous compounds (DDE and DDD), and pyrethroids in humans and the human environment in Manhiça, a rural area where they have been used as insecticides for indoor residual spraying (IRS) and insecticide treated nets (ITN) in malaria control programs. Thatch samples from human dwellings, breast milk from pregnant women and cord blood from newborns were analyzed for assessment of the concentration levels of these compounds. The results showed that DDT and its analogues were already present in humans and dwellings before reintroduction of this insecticide for IRS. As consequence of these applications DDT concentrations increased significantly. The higher proportion of 4,4’-DDT than 4,4’-DDE evidenced that the observed amounts were due to recent applications of this insecticide. Concerning pyrethroids, their presence has been identified in both breast milk and human dwellings showing that both agricultural applications and use for ITN may be responsible for their occurrence in humans and human environments of Manhiça. / L’ús en el passat i en temps actuals del DDT i piretroides ha donat lloc a la seva incorporació en els humans, principalment mitjançant la cadena tròfica i a vegades per exposició directa. Aquest treball té com objectiu establir els nivells de DDT i els seus compostos anàlegs (DDE i DDD), i piretroides en humans i l’ambient humà a Manhiça, una àrea rural on aquests s’han utilitzat com insecticides per aplicació interna (indoor residual spraying, IRS) i tractament de xarxes de protección (insecticide treated nets, ITN) en programes de control de la malària. Per a esbrinar els nivells de concentració d’aquests compostos s’analitzaren mostres de palla de cabanes, de llet materna i de sang de cordó de nou nats. Els resultats mostraren que el DDT i els seus compostos anàlegs ja eren presents en humans i cabanes abans de la reintroducció d’aquest insecticida per IRS. L’ús del DDT en aquest programa féu augmentar considerablement les concentracions d’aquest insecticida. La major proporció de 4,4’-DDT que 4,4’-DDE posà de manifest que les quantitats observades corresponien a aplicacions recents d’aquest insecticida. Respecte als piretroides, s’han trobat en mostres de llet materna i cabanes tot mostrant que tant les aplicacions agrícoles com el seu ús en ITN poder esser la causa de la seva presència en els humans i els ambients humans de Manhiça.
75

Resistência fisiológica e comportamental de populações de Sitophilus zeamais à permetrina, esfenvalerato e esfenvalerato + fenitrotiona / Physiological and behavioral resistance of populations of Sitophilus zeamais to permethrin, esfenvalerate and esfenvalerate + fenitrothion

Corrêa, Alberto Soares 13 February 2009 (has links)
Made available in DSpace on 2015-03-26T13:30:23Z (GMT). No. of bitstreams: 1 texto completo.pdf: 819713 bytes, checksum: bc07208206271366ce40b847926f6f9c (MD5) Previous issue date: 2009-02-13 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The maize weevil, Sitophilus zeamais Motschulsky, 1855 (Coleoptera: Curculionidae) is considered the main pest of stored maize in Brazil and its control is achieved mainly by insecticides. The massive and intensive use of these compounds may lead to selection of resistant populations and consequently compromise the control efficacy of this insect pest in Brazilian storage facilities. This work was a survey of physiological and behavioral resistance to the insecticides esfenvalerate, permethrin and the insecticide mixture esfenvalerate + fenitrothion in 27 populations of S. zeamais collected in several Brazilian counties and Paraguay, and also investigated possible costs associated with this phenomenon. The insects were subjected to concentration-mortality bioassays to determine the lethal concentrations LC50 and CL95. The populations were also subjected to two walking trials on surfaces treated and untreated with dried insecticide residues for detection of behavioral resistance. We also determined the instantaneous rate of population increase (ri), maize consumption and body mass of individuals of each population. We also determined the respiration rate, as well as amylase and lipase activity of the insects from each population as an indication of their metabolic rate. The concentrationmortality bioassays indicated resistance ratios ranging from 0.63 to 66.65x for esfenvalerate, 1.00 to 5.02x for the insecticide mixture esfenvalerate + fenitrothion from 0.79 to 69.59x for permethrin compared with the susceptible standard population (Sete Lagoas). These results indicate a decrease in pyrethroid resistance in Brazilian populations of maize weevil compared with previous studies. The behavioral characteristics of walking in treated area varied among populations and sex. There was avoidance to permethrin- and esfenvalerate- treated surfaces by females from different populations. There was no correlation between physiological and behavioral resistance, indicating that physiological resistance is independent of behavioral resistance in the populations tested. There was no significant difference in the instantaneous rate of increase (ri), body mass and respiration rate among the insects. In contrast, there were significant differences in food consumption and amylase and lipase activity among populations. Therefore, we conclude that there was no fitness cost associated with levels of resistance observed in the populations studied. / O caruncho do milho, Sitophilus zeamais Motschulsky, 1855 (Coleoptera: Curculionidae) é considerado a principal praga do milho armazenado no Brasil, sendo o seu controle realizado principalmente por inseticidas. A utilização maciça e intensa destes compostos pode levar à seleção de populações resistentes e, conseqüentemente, à diminuição da eficiência do controle deste inseto-praga em armazéns brasileiros. Neste trabalho foi realizado um levantamento da resistência fisiológica e comportamental aos inseticidas esfenvalerato, permetrina e a mistura esfenvalerato + fenitrotiona em 27 populações de S. zeamais coletadas em várias cidades brasileiras e no Paraguai, investigando também, possíveis custos adaptativos relacionados ao fenômeno. Os insetos foram submetidos a bioensaios de concentração-mortalidade com determinação das concentrações letais CL50 e CL95. As populações foram também submetidas a dois ensaios de caminhamento em superfície tratada e não-tratada com resíduo seco de inseticida para detecção de resistência comportamental. Foram também determinados a taxa instantânea de crescimento populacional (ri), o consumo de grão de milho e massa corporal dos indivíduos de cada população estudada. Determinou-se ainda a taxa respiratória, a atividade de amilase e de lipase como indicativo da taxa metabólica dos insetos. Os resultados dos bioensaios de mortalidade indicaram variação da razão de resistência de 0,63 a 66,65 vezes para esfenvalerato, de 1,00 a 5,02 vezes para a mistura esfenvalerato + fenitrotiona e de 0,79 a 69,59 vezes para permetrina em relação à população padrão de suscetibilidade (Sete Lagoas). Estes resultados indicam uma diminuição da resistência a piretróides em populações brasileiras de caruncho do milho em relação a estudos anteriores. As características comportamentais de caminhamento na área tratada variaram entre as populações e sexo. Houve repelência de fêmeas para permetrina e esfenvalerato quando comparado entre as populações. Não foi detectada correlação entre a resistência fisiológica e a resistência comportamental, evidenciando que a resistência fisiológica é independente da resistência comportamental nas populações testadas. Não se detectou diferença significativa na taxa instantânea de crescimento (ri), na massa corpórea e na taxa respiratória dos insetos. Detectou-se diferenças no consumo alimentar e na atividade de amilase e atividade de lipase entre as populações testadas. Assim, podemos concluir que não houve custo adaptativo associado aos níveis de resistência verificados nas populações estudadas.
76

Ocorrência de princípios ativos de agrotóxicos em águas superficiais da região hidrográfica do médio curso do rio Paraíba - grupos Carbamato e Piretróide.

NASCIMENTO, Dayvison José Nunes do. 27 July 2018 (has links)
Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-07-27T15:07:10Z No. of bitstreams: 1 DAYVISON JOSÉ NUNES DO NASCIMENTO - DISSERTAÇÃO (PPGECA) 2016.pdf: 2467199 bytes, checksum: 6112558d9b477651302684cf6df39802 (MD5) / Made available in DSpace on 2018-07-27T15:07:10Z (GMT). No. of bitstreams: 1 DAYVISON JOSÉ NUNES DO NASCIMENTO - DISSERTAÇÃO (PPGECA) 2016.pdf: 2467199 bytes, checksum: 6112558d9b477651302684cf6df39802 (MD5) Previous issue date: 2016-08-26 / Capes / Corpos hídricos superficiais são mais susceptíveis à contaminação por agrotóxicos devido às atividades agrícolas desenvolvidas em suas áreas de recarga. Este trabalho avaliou a presença de agrotóxicos do grupo carbamato e piretróide em águas brutas e tratadas dos reservatórios Epitácio Pessoa (Boqueirão), a montante, e Argemiro de Figueiredo (Acauã), a jusante da região hidrográfica do médio curso do rio Paraíba, por meio de metodologia analítica por cromatografia líquida de alta eficiência. Os resultados indicaram que as metodologias apresentaram seletividade, linearidade (R² ≥ 0,9982), precisão e exatidão (DPR ≤ 4,27 %) e robustez, dentro das especificações estabelecidas pela ANVISA e Inmetro. Do grupo químico carbamato, foram detectados os agrotóxicos aldicarbe sulfona, carbaril e metiocarbe no reservatório de montante e aldicarbe sulfona no reservatório de jusante. Todas as concentrações mantiveram-se dentro dos limites exigidos pelos padrões de potabilidade de água de consumo humano, nacional e/ou internacionais. Apenas o agrotóxico carbaril não apresentou conformidade com a Resolução CONAMA 357/2005, que define as concentrações máximas permitidas para enquadramento de águas superficiais. Do grupo químico piretróide foram detectados os agrotóxicos ciflutrina e flumetrina em ambos os reservatórios estudados. A concentração do agrotóxico cilfutrina manteve-se dentro do padrão de potabilidade internacional, no entanto o princípio ativo flumetrina não apresenta valores limites indicados nos padrões de potabilidade nacional e internacionais. O tratamento convencional para potabilização de água empregado na área de estudo não se mostrou eficiente para a remoção de agrotóxicos. / Superficial water bodies are more susceptible to pesticide contamination due to agricultural activities in their recharging areas. This study evaluated the presence of carbamate and pyrethroid pesticides group in raw and treated waters from the upstream reservoir Epitácio Pessoa (Boqueirão) and the downstream reservoir Argemiro de Figueiredo (Acauã), in the hydrographic region of the middle course of Paraiba River, northern Brazil, through an analytical methodology by high-performance liquid chromatography. Results indicated that the methodology presented selectivity, linearity (R² ≥ 0.9982), accuracy and precision (RSD ≤ 4.27%) and robustness within the specifications set by ANVISA and Inmetro. Of Chemical group carbamate, the pesticides aldicarb sulfone, carbaryl and methiocarb were detectes in the upstream reservoir and aldicarb sulfone was detectes in the downstream reservoir. All concentrations have remained within the limits required by the national and/or international drinking water standards. Only the pesticide carbaryl did not show compliance with Resolution 357/2005, of Brazilian Environment Ministry, which defines the maximum allowable concentrations for classification of surface waters. The pyrethroid chemical group the cyfluthrin and flumethrin pesticides were detected in both studied reservoirs. The concentration of the pesticide cilfutrina remained within the international potability standard, however the active flumethrin principle has no limits indicated in the standards of national and international potability. Conventional water treatment applied in the study area did not show ability for the removal of carbamate pesticides.
77

Estudo de indicadores de estresse em Brycon amazonicus (matrinxã) exposto a deltametrina (Keshet®)

Soares, Camila Aparecida Pigão 25 February 2016 (has links)
Submitted by Alison Vanceto (alison-vanceto@hotmail.com) on 2017-02-06T10:50:13Z No. of bitstreams: 1 DissCAPS.pdf: 2325968 bytes, checksum: 1ef9c551b609d3ee485174289e0d2d65 (MD5) / Approved for entry into archive by Camila Passos (camilapassos@ufscar.br) on 2017-02-06T18:58:03Z (GMT) No. of bitstreams: 1 DissCAPS.pdf: 2325968 bytes, checksum: 1ef9c551b609d3ee485174289e0d2d65 (MD5) / Approved for entry into archive by Camila Passos (camilapassos@ufscar.br) on 2017-02-06T18:58:17Z (GMT) No. of bitstreams: 1 DissCAPS.pdf: 2325968 bytes, checksum: 1ef9c551b609d3ee485174289e0d2d65 (MD5) / Made available in DSpace on 2017-02-06T18:59:14Z (GMT). No. of bitstreams: 1 DissCAPS.pdf: 2325968 bytes, checksum: 1ef9c551b609d3ee485174289e0d2d65 (MD5) Previous issue date: 2016-02-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / In the last 40 years, the use of pesticides increased 700% in Brazil, setting this country into the very consumers of this kind of chemicals in the world. There among the most used pesticides in Brazil are the pyrethroids, a class of insecticides largely used for the stability to light rays and being not accumulated in the trophic chain. Deltamethrin is a pyrethroid classified as moderately toxic and it may work as endocrine disruptor. It is widely used in the farms and preserving stocked foods. Pyrethroids are low toxic to mammals and birds. Although, new studies pointed out their noxiousness to aquatic organisms such as fishes. The high toxicity of pyrethroids to fishes may be related to damages caused to nervous system and to their mechanisms of biochemical degradation. Biomarkers are a way of monitoring the pesticides effects on the environments. Among them, cholinesterases and metabolites such as glucose, cortisol and lactate can be used. In the present monography is reported a work carried out in vivo with matrinxa exposed to deltamethrin (Keshet®) at 20, 40 and 60% of CL50:96h for 96 hours, and other in vitro with matrinxa exposed to the analytical formulation of deltamethrin (Pestanal®). After the pesticide exposure, fish were anesthetized, blood was withdrawn and then the fish were killed for brain, liver, gut, gills and white muscle excision. From the observations we can say that glucose, protein and ammonia were increased in liver, and amino acids and ammonia were increased in plasma. The glycogen bulks of liver and plasma lactate were decreased. In white muscle, protein and amino acids levels were decreased, and ammonia, glucose and lactate increased. Concerning the studied enzymes, it was observed inhibition of brain AChE in vivo and in vitro activities while CbE was inhibited in the gills and gut but increased in white muscle and plasma. The enzyme activities of ALAT and ASAT increased in liver and LDH activity was reduced. Therefore, we may conclude that matrinxa presented metabolic changes in order to supply the energetic demand caused by deltamethrin poisoning. The inhibition of AChE was observed, as expected, in addition to CbE increase, showing the activation of mechanisms to degrade deltamethrin. It is possible to assert that Brycon amazonicus exposed to deltamethrin is biochemically responsive to the poisoning using adaptive strategies which enable it to escape from toxic effects of a contaminated environment by such xenobiotic. / Nos últimos 40 anos, o consumo nacional de agrotóxicos aumentou 700%, fazendo do Brasil um dos maiores consumidores desse tipo de compostos no mundo. Dentre os agrotóxicos mais utilizados no Brasil estão os piretroides, um grupo de inseticidas muito utilizados por ter alta estabilidade à luz e não sofrer bioacumulação na cadeia trófica. A deltametrina é um piretróide, classificado como medianamente tóxico e pode funcionar como um interruptor endócrino sendo amplamente utilizado nas lavouras e na conservação de produtos estocados. Os piretroides possuem baixa toxicidade aos mamíferos e aves. Contudo, estudos recentes apontam sua nocividade a organismos aquáticos, tais como os peixes. A alta toxicidade dos piretroides aos peixes pode estar relacionada aos danos causados ao sistema nervoso e aos mecanismos de metabolização desse xenobiótico. Uma forma de monitorar os efeitos dos agrotóxicos no meio ambiente é através de biomarcadores, como as colinesterases e os intermediários metabólicos, como glicose, cortisol e lactato. Assim, foi feito nesse trabalho um experimento in vivo com B. amazonicus exposto por 96h a 20%, 40% e 60% da CL/50 96h de deltametrina (Keshet®), e um experimento in vitro com o B. amazonicus exposto por uma hora a deltametrina na formulação analítica (Pestanal®). Após a exposição os peixes foram anestesiados para retirada de sangue e posteriormente abatidos para retirada de: cérebro, fígado, intestino, brânquias e músculo branco. De acordo com os resultados observados, no fígado houve aumento dos níveis de glicose, proteína e amônia, enquanto no plasma houve aumento das concentrações de aminoácidos e amônia. Em contrapartida, os níveis de glicogênio caíram no fígado, assim como os níveis de lactato do plasma. No músculo observou-se redução nos níveis de proteína e aminoácidos e aumento de amônia, glicose e lactato. Com relação aos parâmetros enzimáticos observou-se inibição da colinesterase cerebral “in vivo” e “in vitro”, enquanto a CbE apresentou inibição nas brânquias e intestino e aumento da atividade no músculo e plasma. As atividades enzimáticas de ALAT E ASAT aumentaram no fígado enquanto a LDH apresentou inibição. Sendo assim, podemos concluir que o B. amazonicus apresentou alterações do metabolismo intermediário no sentido de suprir a demanda energética causada pelos processos de intoxicação causada pela deltametrina. E apresentou inibição da colinesterase, tal como esperado, além de apresentar atividade da CbE evidenciando a tentativa de degradar a deltametrina. Podemos assim afirmar que Brycon amazonicus exposto à deltametrina responde bioquimicamente à intoxicação através de respostas adaptativas que o permitem inicialmente escapar aos efeitos tóxicos do meio contaminado por esse xenobiótico.
78

Étude de la cinétique des pesticides pyréthrinoïdes en conditions contrôlées et en milieu de travail dans un objectif de biosurveillance

Ratelle, Mylène 10 1900 (has links)
Les pyréthrinoïdes sont des insecticides largement utilisés. La population générale y est exposée par l’alimentation tandis que les travailleurs agricoles y sont exposés lors de tâches diverses en champs. Leurs effets neurotoxiques, immunitaires et endocriniens potentiels en font des composés à surveiller pour assurer la santé de la population. La mesure de biomarqueurs d’exposition, qui consiste à quantifier la concentration dans l’organisme d’une substance ou de ses métabolites, permet d’estimer les doses absorbées. Les biomarqueurs peuvent également être des molécules répondant à un stress physiologique, identifiées comme des biomarqueurs d’effets. Pour raffiner les stratégies de biosurveillance de l’exposition, on se doit de bien connaître la toxicocinétique d’un xénobiotique; actuellement, les études de biosurveillance considèrent rarement la variabilité temporelle, intra-invidivuelle et inter-individuelle, qui pourrait influencer l’estimation de l’exposition. L’objectif de la thèse est donc d’appliquer une approche cinétique pour l’évaluation de l’exposition aux pyréthrinoïdes en conditions contrôlées et en milieu de travail. Dans un volet exploratoire, l’effet de cette exposition sur des changements métaboliques précoces a également évalué. Trois métabolites finaux (cis-DCCA, trans-DCCA et 3-PBA) de deux pyréthrinoïdes les plus utilisés, soient la perméthrine et la cyperméthrine, ont été mesurés dans le plasma et l’urine de six volontaires oralement exposés à une dose équivalente à la dose de référence. Une demi-vie moyenne (t½) d’élimination apparente du trans-DCCA, cis-DCCA et 3-PBA dans le plasma de 5,1, 6,9 et 9,2 h, respectivement, a été obtenue après exposition orale à la cyperméthrine, comparativement à 7,1, 6,2 et 6,5 h après exposition à la perméthrine. Dans l’urine, la demi-vie d'élimination apparente (t½) était de 6,3, 6,4 et 6,4 h pour le trans-DCCA, cis-DCCA et 3-PBA, respectivement, après administration de la cyperméthrine comparé à 5,4, 4,5 et 5,7 h après administration de la perméthrine. Les profils temporels étaient semblables suite à l’exposition à la cyperméthrine et perméthrine. Ensuite, une étude en milieu agricole a été réalisée avec la participation de travailleurs pour évaluer leur exposition et raffiner les stratégies de biosurveillance. La variabilité intra-individuelle dans les niveaux de biomarqueurs d’exposition chez plusieurs travailleurs était plus importante que la variabilité inter-individuelle. Les échantillons urinaires ont également été utilisés pour identifier des modifications du métabolome pouvant fournir de nouveaux biomarqueurs d’effets précoces. Chez les travailleurs, une augmentation de l'hippurate urinaire (p <0,0001) a été observée après exposition aux pyréthrinoïdes, un biomarqueur de la conjugaison de l’acide benzoïque. En conclusion, cette étude a permis de mieux documenter la cinétique de biomarqueurs d’exposition aux pyréthrinoïdes dans des conditions contrôlées et réelles afin de raffiner les stratégies de biosurveillance. Elle a aussi contribué à renseigner sur les niveaux d’exposition agricole québécois et sur les paramètres professionnels associés à une plus forte exposition. Ce projet s’insère dans une démarche d’analyse de risque en santé au travail. / Pyrethroids are widely used insecticides. The general population is exposed to these compounds through the diet while agricultural workers are exposed during various tasks in the fields. Pyrethroids are compounds of interest given their neurotoxic, immune and endocrine disruptor effects; they should thus be monitored to ensure the health of the population. Measurement of biomarkers of exposure, which consists of quantifying concentrations of a substance or its metabolites in accessible biological matrices, allows estimating absorbed doses. Biomarkers can also be endogenous molecules that respond to a physiological stress and identified as biomarkers of effects. To refine biomonitoring of exposure strategies , one must be familiar with the toxicokinetics of xenobiotics; to date, biomonitoring studies rarely consider temporal variability, hence intra- and inter-individual variability, which may influence estimation of exposure The aim of the thesis was to apply a kinetic approach for the assessment of exposure to pyrethroids in controlled conditions and in the workplace. In an ancillary study, the effect of pyrethroid exposure on early metabolic changes was also evaluated. Three final metabolites (cis-DCCA, trans-DCCA and 3-PBA) of two of the most used pyrethroids, permethrin and cypermethrin, were measured in plasma and urine of six volunteers orally exposed to a dose similar to the reference dose, as analyzed by mass spectrometry. After oral exposure to cypermethrin, the mean apparent elimination half-life (t½) of trans-DCCA, cis-DCCA and 3-PBA in plasma was 5.1, 6.9 and 9.2 h, respectively, as compared to 7.1, 6.2 and 6.5 hours after permethrin exposure. In urine, the mean apparent elimination half-life (t½) of trans-DCCA, cis-DCCA and 3-PBA was 6.3, 6.4 and 6.4 h, respectively, after the administration of cypermethrin compared to 5.4, 4.5 and 5.7 h after permethrin exposure. The time profiles were similar following exposure to cypermethrin and permethrin. The data help to interpret the significance of biological measurements and optimal sampling strategies. Later, a biomonitoring study in agricultural workers was conducted for the assessment of their exposure and refinement of biomonitoring strategies. Within-subject variability in biomonitoring data of several workers was more important than inter-subject variability. Urine samples were also used to identify changes in the metabolome and hence potentially identify new biomarkers of early effects. In particular, an increased urinary excretion of hippurate (p <0.0001) was observed in workers exposed following an exposure episode to pyrethroid, a biomarker of the conjugation of benzoic acid. In conclusion, this study allowed to better document the toxicokinetics of key biomarkers of exposure to pyrethroids, in order to refine biomonitoring of exposure strategies. It has also provided more information on agricultural exposure in Quebec workers and professional parameters associated with high exposure. This project is part of a risk assessment in occupational health.
79

Action des pyréthrinoïdes sur le canal sodique activé par le potentiel des neurones du système olfactif de l'abeille domestique Apis mellifera / Action of pyrethroids on the voltage-gated sodium channels from the honeybee Apis mellifera's olfactory system

Kadala, Pyabalo Aklesso 13 December 2011 (has links)
Chez les abeilles domestiques, les neurones à récepteurs olfactifs hébergés dans les antennes sont des neurones sensoriels primaires responsables de la détection des odeurs et des phéromones. L'information olfactive est ensuite acheminée par les nerfs antennaires jusqu'aux lobes antennaires qui constituent le premier étage d'intégration de l'information olfactive. Les abeilles butineuses sont exposées aux insecticides, notamment ceux de la classe des pyréthrinoïdes, qui sont utilisés pour la protection des plantes et la lutte contre les insectes considérés comme étant nuisibles.Nous avons caractérisé l'effet des pyréthrinoïdes sur les canaux sodiques activés par le potentiel (responsables des potentiels d'action) dans les deux premiers étages du système olfactif de l'abeille. Nos enregistrements électrophysiologiques en mode potentiel imposé dans les neurones à récepteurs olfactifs mis en culture révèlent que l'effet des pyréthrinoïdes de type I et II (notamment la tétraméthrine et la deltaméthrine) est amplifié par une intensification de l'activité électrique neuronale. Cette amplification survient notamment via le démasquage de canaux sodiques silencieux que nous avons également mis en évidence avec la toxine d'anémone de mer ATX-II. Le niveau maximal de canaux sodiques modifiés est atteint en quelques centaines de millisecondes. Dans les neurones centraux des lobes antennaires, cette amplification apparait très limitée voire absente avec les pyréthrinoïdes mais elle peut toutefois survenir en présence de l'alcaloïde végétal vératridine. Par ailleurs, dans ces neurones centraux, les pyréthrinoïdes semblent être à l’origine d’une accélération de l'inactivation lente des canaux sodiques auparavant décrite en présence de certains anesthésiques locaux. Les modifications différentielles observées dans les neurones périphériques et centraux pourraient être responsables des effets délétères des pyréthrinoïdes sur les capacités de perception, d'orientation et d'apprentissage de l'abeille domestique. / In domestic honeybees, the olfactory receptor neurons localized in the antennae are primary sensory neurons responsible for the detection of odor and pheromone compounds. The olfactory information is further conveyed to the antennal lobes by the antennal nerves. The antennal lobes are the first stage of integration of the olfactory information. Forager bees are exposed to insecticides, especially pyrethroids that are used for plant protection and eradication of pests.In the honeybee olfactory pathway, we investigated the effects of pyrethroids on the voltage-gated sodium channels (which underlie action potentials). Our patch-clamp recordings in the antennal olfactory receptor neurons maintained in cell culture reveal that the effects of type I and type II pyrethroids (e.g. tetramethrin and deltamethrin) are increased by an augmentation of neuronal electrical activity. The amplification of the effects of pyrethroids occurs as a result of the unmasking of silent sodium channels that we have also shown evidence for, with sea anemone toxin ATX-II. The maximal sodium channels modification takes place within few hundreds of milliseconds. In the central antennal lobe neurons, that amplification is rather limited or absent with pyrethroids but the plant alkaloid veratridine is able to induce such an amplification. Furthermore, in the latter cell type, pyrethroids cause an acceleration of the sodium channels slow inactivation. Such an effect has been previously reported for some local anesthetics. The differential actions of pyrethroids that we have observed in the peripheral and central neurons may be responsible for the impairment of learning performance, perception and disorientation exhibited by pyrethroid-exposed honeybees.
80

Desenvolvimento e validação de metodologia para determinação de resíduos de pesticidas piretróides por HPLC em feijão / Development and validation of methodology for determination of pyrethroid pesticide residues by HPLC beans

Monteiro, Sérgio Henrique 13 September 2006 (has links)
Um método rápido utilizando cromatografia liquida (LC) foi desenvolvido para determinação simultânea de 7 pesticidas piretróides (bifentrina, cipermetrina, fenpropatrina, fenvalerato, permetrina, lambda-cialotrina, e deltametrina). Os resíduos são extraídos com acetona e a partição realizada de acordo com o método multi-resíduos DFG-S19, substituindo diclorometano por acetato de etila/ciclohexano (1+1) e purificação usando cromatografia de permeação a gel com uma coluna Biobeads SX3 e acetato de etila/ciclohexano (1+1) como eluente. A separação por LC é realizada com uma coluna LiChrospher 100 RP-18 e acetonitrila/água (8+2) como fase móvel. Os pesticidas são detectados em 212nm. As recuperações dos 7 pesticidas piretróides em amostras de feijão fortificadas em 0,010; 0,100; e 1,000 mg/kg ficaram entre 71-105%. A diferença particular deste método é o limite de quantificação, os quais ficaram entre 0,004-0,011 mg/kg, abaixo de muitos outros métodos de LC descritos na literatura. A cromatografia a gás (GC) com detector de captura de elétrons é mais sensível que a LC, mas o método com LC facilita a identificação dos picos. A GC apresenta muitos picos enquanto a LC apresenta apenas um para a maioria dos piretróides. A análise com LC é uma boa alternativa para a determinação de resíduos de piretróides em feijão. Durante o ano de 2005, um total de 48 amostras de feijão comercializadas na cidade de São Paulo, foram analisadas. Nenhum resíduo de pesticida piretróide foi detectado nas amostras. / A rapid liquid chromatographic (LC) method has been developed for simultaneous determination of 7 pyrethroid insecticides (bifenthrin, cypermethrin, fenpropathrin, fenvalerate, permethrin, lambda-cyhalothrin and deltamethrin) in beans. Residues are extracted from beans with acetone and the partition realized according to the multi-residue method DFG-S19, replacing dichloromethane by ethyl acetate/cyclohexane (1+1) and cleaned up using gel-permeation with a Biobeads SX3 column and ethyl acetate/cyclohexane (1+1) as eluant. LC separation is performed on a LiChrospher 100 RP-18 column with acetonitrile/water (8+2) as mobile phase. The pesticides are detected at 212 nm. Recoveries of 7 pyrethroid insecticides from beans fortified at 0.010; 0.100; 1.000 mg/kg levels were 71-105 %. The particular differential of this method is the quantification limits, which were between 0.004-0.011 mg/kg, lower than most of the limits reported for LC methods described in the literature. The gas chromatographic (GC) with electron capture detection is more sensitive than LC, but the LC method facilitates the identification of the peaks. Analysis of pyrethroids by GC shows several peaks, but LC shows only one for most pyrethroids. The analysis by LC was a good alternative for determination pyrethroid residues in beans. During 2005 year, a total of 48 bean samples commercialized in Sao Paulo City were analyzed. No residues of pyrethroids pesticides were detected in the samples.

Page generated in 0.0302 seconds