Pesticide Toxicology-2009 - Pesticide Toxicology NST110,...

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Pesticide Toxicology NST110, Toxicology Department of Nutritional Sciences and Toxicology Univeristy of California, Berkeley
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Pesticides: any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest. Insecticide (insect) Herbicide (weed) Fungicide (fungi) Acaricide or miticide or tickicide (mites or ticks) Bacteriacide (bacteria) Algicide (algae or slugs) Piscicide (fish) Rodenticide (rodents) Avicide (birds)
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History of Pesticides 1000 B.C.: sulfur used by Chinese 1000 B.C.: Homer mentions “pest-averting” sulfur ~1690: extracts of tobacco leaves sprayed on plants as insecticides Mid-1800s, root of Derris eliptica, containing rotenone, was used as an insecticide Mid-1800s, pyrethrum extracted from the flowers of the chrysanthemum flowers and used as an insecticide 1892: Potassium dinitro- o -cresylate-first synthetic organic pesticide marketed 1930-1950 many organic pesticides—DDT, 2,4-D—the “Golden Age” 1950-now: continuing advances and increasing controversy and laws 1990-now: Introduction of Genetically Modified Organisms (GMOs) alters pattern of pesticide use
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Why we need pesticides 1. Population and food: -With population growth, we need to continuously increase food and fiber production -Undernourishment—56% on world basis—79% in underdeveloped countries -Population increase with little change in available arable land and water 2. Pest losses must be reduced for maximum production -1/3 of world’s food crops are lost from pests during growth, harvesting, or storage General problem with pesticides 1. All pesticides possess an inherent degree of toxicity to some living organism- otherwise they would be of no practical use 2. The selectivity of pesticides is not as good as it should be, and non-target species are affected because of similar physiological systems 3. There is no such thing as a completely safe pesticide 4. There are pesticides that can be used safely that present a low level of risk to human health when applied with proper attention **On a worldwide basis, intoxications attributed to pesticides have been estimated to be as high as 3 million cases of acute, severe poisoning annually, with as many or more unreported cases and 220,000 deaths (WHO, 1990). **In California, there are ~25,000 cases of pesticide-related illness annually among agricultural workers with the national estimate ~80,000 cases/year.
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Insecticides: The Nervous System/Neurophysiology : most of chemical insecticides used today are neurotoxicants that poison the nervous system Types of Major Insecticides: 1. Organochlorine Compounds 1. Dichlorodiphenylethanes —target Na+ channel (DDT) 2. Polychlorocycloalkanes and Fipronil : target GABA receptor (lindane, aldrin, dieldrin, endosulfan) 2. Pyrethroids target Na+ channel (deltamethrin, cypermethrin) 3. Organophosphate Compounds —target Acetylcholinesterase (eg.Chlorpyrifos,malathion, diazinon, parathion) 4. Methylcarbamates —target acetylcholinesterase
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Pesticide Toxicology-2009 - Pesticide Toxicology NST110,...

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