Pesticides systemic

Betarbet, R. et al. Chronic systemic pesticide exposure reproduces features of Parkinson s disease. Nature Neurosci. 3 1301-1306,2000. 

Pal, D., Weber, J.B., Overcash, M.R. (1980) Fate of polychlorinated biphenyls (PCBs) in soil plant systems. Pesticide Reviews 74, 45-98. 

The two main pathways for the uptake of toxic substances by plants are through their root systems and across their leaf cuticles. Stomata, the specialized openings in plant leaves that allow carbon dioxide required for photosynthesis to enter the leaves and oxygen and water vapor to exit, are also routes by which toxic substances may enter plants. The mechanisms by which plants take up systemic pesticides and herbicides, which become distributed within the plant, have been studied very intensvively. 

The possibility of evaluating agricultural systems is limited - except for the certified organic farming - because the systems - even the certified - do not follow a strict scheme. It can happen for example that in a traditional system, pesticides and herbicides are applied once in ten years or always, but only for one out of 20 crops which are cultivated. 

Tn applying pesticide sprays, the first problem is that of distributing a small quantity of active material over a large target area. The uniformity and extent of the distribution required depend on the type of pest to be controlled and the mode of action of the toxicant a patchy distribution may be satisfactory to control mobile insects or to apply systemic pesticides to foliage, whereas for static pests and contact pesticides, a more uniform spray deposit may be required. The degree of distribution attained depends on ... 

Significant degradation of compounds can also be obtained in the presence of electron-acceptor sensitizers. In a very recent example, triadimenol, a systemic pesticide widely applied in horticulture and viticulture that is very difficult to degrade by direct UV photolysis, could be significantly decomposed in the presence of electron acceptors such as 9,10-dicyanoanthracene or 2,4,6-triphenylpyrylium tetrafluoroborate. Decomposition was accelerated by the presence of oxygen [17]. 

The pesticide residues remaining in mans food and in animal feed may exist as a surface deposit, penetrate the cuticle to a limited extent, or be transported to various sections of the plant or animal by systemic action. The pesticide, once deposited, is usually metabolized or broken down to its end products by various means. Systemic pesticides often exhibit complex breakdown patterns which can differ somewhat, depending on whether a plant or mammalian metabolic mechanism is involved ... 

Phorate (0,0-diethyl S-ethylthiomethyl phosphorodithioate), although a systemic pesticide, is per se a relatively weak cholinesterase inhibitor. However, when the compound is chemically oxidized in nature, the final oxidized product (oxygen analog sulfone) is considerably more potent as a cholinesterase inhibitor. Fortunately, however, this oxidized metabolite is relatively unstable and does not seem to accumulate to any significant degree. Investigations have proved that oxidation attacks the coordinate sulfur and thioether linkages. 

Fleming, J. P. Hazen, J. L. in "Development of Water Dispersible Granule Systems" Pesticide Formulation and Application Systems 3rd Conference STP 828, American Society of Testing and Materials Philadelphia PA December, 1983. 

GUn L, KuiseuJ, Thiam A, Vodouhe DS, Ferrigno S, Dinham B (2006), Living -with Poison Problems of endosulfanin West African cotton growing systems. Pesticide Action Network UJ Chemicals Program of the United Nations Environment Programme (2004) op dt... 

The soil is a dynamic biotic and abiotic system. Pesticides deposited in or on the soil have varying capacities to be adsorbed to clay minerals and organic matter. Such adsorption reduces both the movement and the biological activity of the pesticide. In addition to soil adsorption, several other factors are known to influence the behavior and fate of pesticides after the chemicals are in contact with soil. 

Toxaphene (CAS toxaphene mixture [8001-35-2]) or Camphechlor was introduced in 1945 by Hercules Inc. as a non-systemic pesticide under the product name Hercules 3956 [5,20]. The crude product (see below) is a yellow to amber waxy solid that smells like turpentine [21]. The major producer remained Hercules Inc. although other producers also introduced similar products on the market (see Table 2). 

Pesticides may also be divided into two main types contact or nons-ystemic pesticides and systemic pesticides. Contact or surface coating pesticides do not appreciably penetrate plant tissue and are consequently not transported, or translocated, within the plant vascular system. The earlier pesticides were of this type their disadvantages were that they are susceptible to the effects of the weather and new plant growth was not protected. 

Penetrants are wetting agents, oils, or oil concentrates that enhance the absoip-tion of a systemic pesticide by the plant Examjies are AgriTtex , Induce , and Penetrator . 

Your mouth, throat, and stomach can be burned severely by some pesticides. Other pesticides that you swallow will not bum your digestive system, but will be absorbed and carried in your blood throughout your body and may cause you harm in various ways. These chemicals that are transported throughout the body are termed systemic pesticides. For some pesticides, swallowing even a few drops from a splash or wiping your mouth with a contaminated glove can make you very ill or make it difficult to eat and drink and get nourishment. 

Betarbet R., Sherer T. B., MacKenzie G., Garcia-Osuna M., Panov A. V., and Greenamyre J. T. (2000) Chronic systemic pesticide exposure reproduces features of Parkinson s Nature Neurosci. 3(12), 1301-1306. 

Note that many of these pest-control practices are important components of a system known as integrated pest management. However, in that system pesticides are often used as a last resort, when other methods do not work effectively enough. In organic agriculture, pesticides are not used (other than the natural ones just referred to). 

Use A systemic pesticide primarily for ornamental and non-food plants. 

With an excessive, single exposure, the result will be either a systemic pesticide poisoning or a topical lesion frequently observed on the skin or in the eyes. Since most acute intoxications are from the carbamate and organoposphate insecticides, the systemic manifestations are cholinergic and are due to the inhibition of acetyl cholinesterase and the resultant accumulation of the neurotransmitter acetylcholine, at the synapse. Topical effects, in contrast, either are the result of the irritant properties of the chemicals in the formulation or have an allergenic basis for their occurrence (3). However, topical effects are not necessarily exclusively the result of exposure to the active ingredient in the formulation but may result from a reaction to one or more inerts as well. 

Controlled release of agrochemicals (e.g., by hydrolysis of a polymeric ester) can offer the advantages of constant level, smaller dose, reduced evaporation loss, lower toxicity, longer life, decreased environmental pollution, and reduced effect on nontarget species by wind or runoff.20 Systemic pesticides are preferred. This ensures protection of the growing tip of the plant. For weed killers, this means that it is not necessary to hit every leaf of the plant with the herbicide. Pesticides are often applied on a spray schedule according to the calendar as a prophylactic measure. Chemical pesticides are used 98% of the time. 

Introduction. A problem involving the movement of aldicarb in groundwater in the central sand plain area of Wisconsin (Figure 1) will be presented to illustrate the difficulties involved in model calibration. Aldicarb is a systemic pesticide manufactured by Union Carbide under the trade name Temik. In Wisconsin, Temik is applied in potato furrows during planting to control a variety of insects, mites and nematodes. The field study which supplied the field data... 

Second stage - optimization. In case of having incomplete information about the system "pesticide-environment" determinated mathematical methods of analysis are of little use. That is why, in the block of optimization of the model system, a dynamic stochastic model based on Bellman s method of dynamic programming, has been used. Markov process was taken as a mathematical model of the system (Hovard, 1964). The main goal of the optimization model is to find out the optimal value of X taking into account the ecological negative influence of pesticide. In... 

A compound s solubility depends upon the work required to separate the molecules from one another in the crystalline lattice or liquid form and the afiinity of the molecules of the compound for water molecules. To dissolve in water, bonds must be disrupted between pesticide molecules and the hydrogen bonded network of the water system. Pesticide molecules must simultaneously become hydrogen bonded to or form dipole-dipole bonds with water molecules to become hydrated. Compounds of extremely low solubility, which do not readily dissolve and thus do not form hydrogen bonds with water molecules, exist as holes in the water structure. Such compounds usually tend to escape the solution phase and adhere to lipophilic substances which may occur in the system, or if their vapor pressures are high enough, they gradually volatilize into the atmosphere. 

P.M. Kramer, R.D. Schmid, Automated Quasi-conti-nuous Immunoanalysis of Pesticides with a Flow Injection System , Pesticide Sci., 32,451-462 (1991). 

Pesticide Action Network (1996), Pesticide and the Immune System, Pesticide News N032, http //www.pan-uk.org/pestnews/Issue/Pn32/pn32pi5a.hcm... 

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