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Non-hydrolytic pathway in metabolism of the insecticide sevin, 1-naphthyl n-methylcarbamateDorough, H. Wyman, January 1964 (has links)
Thesis (Ph. D.)--University of Wisconsin, 1964. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 97-103.
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The behavioural effects of formamidine pesticides in LepidopteraBlackwell, Alison January 1987 (has links)
No description available.
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The cause of fruit flavour differences associated with the fungicide prochlorazSnowdon, Philip J. January 1993 (has links)
Commercial development of the fungicide prochloraz for the control of pre- and post-harvest diseases in fruit crops has been restricted by the occasional occurrence of 'musty' taints. The primary aims of this research were to identify the cause of taint and and its means of formation. Sensitive and selective residue methodology based upon determination by gas chromatography with mass selective detection was devised, validated and used to establish 2,4,6-trichloroanisole (2,4,6-TCA) as the direct cause of taint by analysis of field-treated samples and studies involving 14C-radiolabelled prochloraz. Evaluation of analytical results in conjunction with corresponding sensory data led to proposals of flavour threshold levels ranging between 0.04 and 1.0mug/kg for 2,4,6-TCA in different fruit types. Formation of the anisole in pre-harvest treatment situations was shown to proceed via the minor plant metabolite 2,4,6-trichlorophenol (2,4,6-TCP) as the direct precursor; under post-harvest conditions, however, metabolism of prochloraz was minimal, and 2,4,6-TCA taints arose primarily from 2,4,6-TCP as an impurity (measured at 0.9% w/w) in the commercial emulsifiable concentrate formulation. Detailed investigation of the relationship between 2,4,6-TCP and 2,4,6-TCA under controlled conditions demonstrated that certain fruit types possess a capacity for direct O-methylation of the phenol to the anisole, whereas others do not. These findings were generally consistent with occurrences of taints associated with prochloraz. Kinetic studies of the active O-methyltransferase system in apple homogenates indicated the same Vmax value for 2-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol and 2,4,6-TCP. Reactivity in this series was found to be closely related to the ability of the molecules to to form effective nucleophiles for reaction with s-adenosylmethionine as the assumed methyl donor, and a linear relationship was established between chlorophenol pKa and log(apparent Km). The O-methylation of 2,4,6-TCP, whilst inhibited competitively by other o-chlorophenolic substrates, remained unaffected by the addition of representative plant o-diphenolics previously reported as substrates for O-methylation in plants.
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GENETIC SUSCEPTIBILITY OF ORGANOPHOSPHATE INDUCED TOXICITYANGIAH SRIKANTHAN, PRASHANT 08 October 2007 (has links)
No description available.
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Pesticide Exposure During Pregnancy and Low Birth WeightWang, Liang, Wu, Tiejian, Liu, Xuefeng, Anderson, James Li, Alamian, Arsham, Fu, Maosun, Li, Jun 01 January 2012 (has links)
Background: Limited epidemiologic studies have investigated the effects of pesticide exposure during pregnancy on low birth weight in offspring in rural China.Methods: A survey of a total of 503 women was conducted in Ling county of Shandong Province of China following delivery from 1 November 2009 to 8 February 2010.Results: After adjustment for confounding and compared with no pesticide exposure, multiple logistic regression showed a non-significant increased likelihood of low birth weight for both children of mothers exposed to pesticides when not pregnant (OR = 1.80, 95% CI: 0.62, 5.22) and mothers exposed to pesticides during pregnancy (OR = 2.42, 95% CI: 0.73, 8.08); multiple linear regression showed a non-significant reduced birth weight for both children of mothers exposed to pesticides when not pregnant (β=–0.59, p=0.28) and mothers exposed to pesticides during pregnancy (β=–0.89, p=0.15).Conclusions: Exposure to pesticides during pregnancy was associated with a non-significant increase in low birth weight in this rural Chinese population. Future studies using larger sample sizes and longer follow-up periods are warranted.
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Minimising Environmental and Public Health Risk of Pesticide Application Through Understanding the Droplet-Canopy InterfaceMr Gary Dorr Unknown Date (has links)
Accurate placement of pesticide droplets on to crop and weed surfaces is a key step in controlling pests and weeds in agricultural production systems. Droplets impact on plant surfaces, depositing pesticides that give protective coverage on crops and destructive coverage for insect or fungi pests and weeds. Coverage is complex and is determined by a multitude of interactions between factors such as size and density of spray droplets, relative humidity and turbulence of the air through which the droplets travel, and the physical characteristics of the target plant leaves, branches and stems that go to make up the architecture of their canopy. There are, however, concerns over the effect of pesticides on the environment and public health. This thesis combines three dimensional (3-D) computer modelling techniques, physical measurements of droplet movement and impact on a canopy in a wind tunnel and risk management techniques to maximise the effectiveness of pesticides and enable risks to public health and the environment from agricultural spraying activities to be minimised. L-studio, a Windows based software environment for creating simulation models of plant architecture was used in this study. A particle trajectory model, based on the combined ballistic and random-walk approach proposed by Mokeba et al. (1997) and Cox et al. (2000) was used to model spray droplet movement. Algorithms were included in the spray model to account for evaporation of droplets, entrained air and movement of air around the spray, collection efficiency, and droplet splash. Existing functional-structural plant models of cotton (Gossypium hirsutum L.) and sow thistle (Sonchus oleraceus L.) and a static empirical model of immature grass weeds have been combined with the spray model. An environmental program has been used to take the location of the leaves in 3-D space from the plant model and determine if spray droplets will impact on them. Wind tunnel measurements were made to determine initial droplet properties (droplet size, velocity, trajectory, density and fluid properties) and droplet impact characteristics (retention and splash). The results from these measurements were then used to define parameters within the spray model. Additional experiments to measure spray drift and spray deposition on various plant surfaces within the wind tunnel were used to evaluate the combined spray and plant architecture model. The combined spray and plant architectural model developed and evaluated in this thesis has provided a new method to study the influence of plant architecture on spray distribution. This work has shown that 3-D plant architecture can influence the amount of spray depositing on leaf surfaces. Deposition on plant surfaces was also found to increase with decreased wind speed and reduced release height. Droplet size did not have a significant influence on spray deposition onto broadleaf plants such as cotton or sow thistle. There was however, a tendency for fine sprays to give a higher deposit on small, narrow grass leaves. Spray drift was found to increase with decreasing droplet size, increasing the range of droplet sizes generated by a nozzle, decreasing sheet velocity (initial velocity of droplets), increasing wind speed, increasing (difference between dry and wet bulb temperature), decreasing liquid density and increasing release height. The combined spray and architectural model has also enabled the study of how effects such as droplet splash and retention can influence the distribution of the spray. In this study it was found that there was little difference in modelled spray drift, amount of spray on the ground or amount of spray on the cotton plant between situations where most droplets splash on impact and where no droplet splash on impact. Although the total amount of spray retained on the plant surface was similar for both situations, it was found that there were more droplets on the plant under the splash scenario leading to better coverage of the spray over the plant. These results indicate that the majority of the smaller splash droplets were re-distributed onto other parts of the plant rather than becoming lost as spray drift or ground deposit. Decision trees have been used in this thesis to characterise the benefits and risks from pesticide applications. Results from model simulations and/or physical measurements are used to estimate the relative proportion of the spray depositing on plant surfaces, depositing on the ground and drifting away from the treatment area. These deposition results give a measure of pesticide exposure that can be incorporated into the risk management framework to investigate the influence of various application scenarios. The applicability of this approach is shown by the example of endosulfan sprayed on cotton to control Helicoverpa spp. The decision tree model can be used to quickly compare different scenarios, such as deciding which application method should be used. It can be used to effectively aid spray decisions to maximise the effectiveness of pesticides and minimise risks to public health and the environment from agricultural spraying activities.
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Effets d’un mélange de polluants organiques persistants sur le métabolisme hépatique / Effects of a mixture of persistent organic pollutants on hepatic metabolismLeblanc, Alix 21 November 2014 (has links)
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.
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Modélisation de la dispersion aérienne de pesticides des échelles locales aux échelles régionales, influence des aménagements et quantification des niveaux d’exposition / Modelling pesticide dispersal in the atmosphere from local scale to regional scale, effect of topography, configuration and exposure level assessment.Chahine, Ali 13 December 2011 (has links)
L'objectif de cette thèse est l'étude de la dispersion de pesticides à partir de parcelles de vigneet l'influence de l'aménagement de parcelles sur la dispersion. Pour atteindre cet objectif, nous avons utilisé la méthode de simulation des grandes échelles (LES) et l'approche lagrangienne combinées avec des expérimentations. Pour l'étude de la dynamique du vent dans les couverts en rangs, une expérimentation a été conduite sur une parcelle de vigne. Le modèle Atmosphérique ARPS a été utilisé pour la modélisation de l'écoulement atmosphérique dans les couverts en rangs. Pour la validation du modèle, les différentes statistiques mesurées ont été comparées à celles simulées. L'accord entre les mesures et les prédictions du modèle était encourageant. L'expérimentation et la modélisation ont montré que l'écoulement dans les couverts en rangs se comporte différemment selon la direction du vent en termes d'organisation et de paramètres aérodynamiques. De plus, les structures cohérentes turbulentes dans les couverts en rangs sont quasi-indépendantes de la direction du vent et partagent les mêmes propriétés que dans les couverts homogènes horizontalement. Pour l'étude de la dispersion de pesticide à partir de la vigne, une expérimentation sur vigne artificielle a été menée. En parallèle, un modèle numérique de dispersion, qui repose sur le modèle de vigne validé, a été développé. Il est ressortit de la modélisation et de l'expérimentation que, à temps court, la dispersion de pesticides à l'échelle de quelques rangs de vigne est dominée par les jets d'air du sprayer. Les comparaisons qualitative et quantitative de la progression du nuage émis par le sprayer, des pertes verticales et des dépôts obtenus par simulation et expérimentation étaient assez satisfaisantes. Les résultats de l'expérimentation sur la dispersion sur vigne artificielle ont été combinés avec la modélisation numérique pour l'étude de la dispersion à l'échelle de la parcelle et l'analyse de l'influence des aménagements de parcelles sur la dispersion. L'analyse comparative des scénarios a montré que le maximum d'exposition des individus vivant à proximité de parcelle viticoles est observé quand les rangs de vigne sont parallèles à la direction moyenne du vent et que les haies d'arbre constituent une alternative pour réduire les niveaux d'exposition. / The aim of this work is to study pesticide dispersal from vineyards and the effect of the layingout of the vineyards on pesticide dispersal. For this purpose, we have used the Large Eddy Simulation (LES) method and the lagrangian approach combined with the experiments. To examine the wind dynamic in row vegetable canopy, an experiment was achieved on a natural vineyard. The atmospheric model ARPS was used to model the atmospheric wind flow above and within row vegetable canopy. For validating the model, the measured wind flow statistics were compared to the simulated ones. The agreement between the measurement and the prediction of the model was encouraging. In addition, experiment and modeling have shown that the wind flow in the row vegetable canopy behave following the wind direction in term of the flow organization and aerodynamic parameters. Moreover, the turbulent coherent structures in row vegetable canopy are independent on the wind direction and share the same properties as in the horizontally homogeneous canopy. To study the pesticide dispersal from vineyard, an experiment on artificial vineyard was accomplished. In parallel, a numerical model lying on the validated row vegetable canopy model was developed. From both experiment and modeling, it appears that the short term pesticide dispersal at the scale of the few vine rows is dominated by the air jet sprayer. The qualitative and quantitative comparisons of the measured and simulated cloud spreading, upward loss and deposit were promising. The experimental results on pesticide dispersal from the artificial vineyard were combined with numerical modeling in order to analyze the pesticide dispersal at the scale of the vineyard and the effect of the vineyard laying out on the exposure level of the bystanders. Comparative analysis of the scenarios has shown that the maximum level of exposure is reached when the vine rows are parallel to the dominant wind direction and it can be reduced by using tree-wall.
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Metal-organic frameworks as potential agents for extraction and delivery of pesticides and agrochemicalsMahmoud, L.A.M., dos Reis, R.A., Chen, X., Ting, V.P., Nayak, Sanjit 30 January 2023 (has links)
Yes / Pesticide contamination is a global issue, affecting nearly 44% of the global farming population, and disproportionately affecting farmers and agricultural workers in developing countries. Despite this, global pesticide usage is on the rise, with the growing demand of global food production with increasing population. Different types of porous materials, such as carbon and zeolites, have been explored for the remediation of pesticides from the environment. However, there are some limitations with these materials, especially due to lack of functional groups and relatively modest surface areas. In this regard, metal-organic frameworks (MOFs) provide us with a better alternative to conventionally used porous materials due to their versatile and highly porous structure. Recently, a number of MOFs have been studied for the extraction of pesticides from the environment as well as for targeted and controlled release of agrochemicals. Different types of pesticides and conditions have been investigated, and MOFs have proved their potential in agricultural applications. In this review, the latest studies on delivery and extraction of pesticides using MOFs are systematically reviewed, along with some recent studies on greener ways of pest control through the slow release of chemical compounds from MOF composites. Finally, we present our insights into the key issues concerning the development and translational applications of using MOFs for targeted delivery and pesticide control.
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Microalgal biodegradation of pentachlorophenolTikoo, Vidya January 1996 (has links)
Pentachlorophenol (PCP) is a chlorophenol with a pronounced biocidal activity that has led to its use in a number of applications. It was introduced in the 1930s as a preservative for timber and lumber and since then has found wide use as a biocide in agricultural and industrial applications. Many different physical, chemical and biological methods have been tried for the removal of PCP from wastewater. However, using microalgae for the removal of PCP and other organochlorine compounds from water may prove to be a cheaper alternative and give complete degradation of the compounds. The aim of this project was to study the efficiency of microalgae to degrade PCP. An algal strain named VT -1 and a bacterial strain named AT -14 were isolated from PCP containing conditions in the laboratory. The growth of VT -1 in the presence of PCP was compared with Chlorella emersonii and Chlorella vulgaris in two different autotrophic media. It was observed that VT-1 had the highest IC50 value of 25-26mg }-l PCP and EC50 value of 11.3mg }-1 PCP in S&K medium. With glucose as an additional carbon source the IC50 value for VT-1 in S&K medium was 29-30mg t 1 PCP. Bacterium AT-14 could grow in the presence of PCP, only with glucose as a carbon source. Mineralization of PCP by VT -1 and the two Chlorella strains was compared by using 14C_PCp. With all the three algae exposed to 14C_PCp, only VT-1 showed release of 14C02, which was evidence of mineralization of PCP by VT-1 which occurred only in the presence of light. Bacterium AT-14 did not produce 14C02. However, the consortium of VT-1 and AT-14 showed enhanced 14C02 evolution in the presence of glucose. The release of chloride ions from PCP can also indicate PCP dehalogenation and degradation. The evolution of 14C02 lagged behind chloride release (90 %) indicating that dechlorination of PCP could be the first step in its biodegradation. Breakdown of PCP was also followed by its extraction from the cells and medium. Normally dichloromethane (DCM) was used to extract PCP. The changes in the label extracted in DCM and iso-butanol were studied under different light condjtions, which showed that the 14C counts in DCM reduced and those in iso-butanol extract increased with time. The 14C counts in the iso-butanol extract could be a metabolite of PCP which is more hydrophilic. VT-1 appeared not to degrade PCP completely, since only 15% of 14C was recovered as 14C02. It appears that intermediates are formed which are distributed in the growth medium and in the biomass. It can thus be concluded that VT -1 is tolerant of PCP, appears to dechlorinate PCP and then releases some part of it as CO2.
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