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Chapter22 Pp Presentation

Chapter22 Pp Presentation






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    Chapter22 Pp Presentation Chapter22 Pp Presentation Presentation Transcript

    • The Pesticide Dilemma Chapter 22
    • What is a Pesticide?
      • Pests are any type of organism that interferes with humans in some way.
      • Pesticides are the toxic chemicals that we use to decrease the numbers of pests.
        • Types: Herbicides, Insecticides, fungicides and rodenticides
        • Some are botanicals (ex: from plants) – nicotine and pyrethrin (ex: from flowers)
        • Some are synthetic – DDT first used in 1939; we didn’t learn of persistence & harm until 1962, Silent Spring.
    • Range of pesticides
      • Narrow-spectrum pesticides :
        • Kills organisms it was intended to.
      • Broad-spectrum pesticides :
        • Kills a variety of organisms.
        • Most pesticides, such as Round-Up
    • Major types of Herbicides
      • Broad Leafed Herbicides
        • Kill plants with broad leaves but leave grasses alone.
          • (Tend to mimic growth hormones & disrupt metabolism.)
      • Grass Herbicides : kill grasses but leave broad leaves alone.
    • Effect of use of Herbicides in Vietnam
        • Agent orange was sprayed over jungles to kill vegetation.
        • It also contained a compound called dioxin , which had severe effects on the Vietnamese and war Veterans.
          • The jungles are about 30% reduced today.
          • Besides birth defects and cancer, the compound is still present within the population; Some Vietnamese have about 1800 ppt.
          • Typically normal people have about 4 ppt.
    • Benefits of Pesticides
      • Disease control
        • Mosquitoes are effective vectors of many diseases, such as malaria in the tropics
        • DDT effectively kills mosquitoes.
          • But the banning of DDT allowed for the return of malaria.
      • Crop production
      • - Farmers save $3-$5 in crops for every $1
      • invested in pesticides
    • Evolution of Genetic Resistance
      • Pesticide treadmill
      • (pest becomes resistant so pesticide needs to be increased &/or it’s chemistry improved)
      • Imbalances in Ecosystems
          • Pesticides also tend to kill the natural predators of the pests by starvation .
        • DDT was sprayed onto lemon trees but allowed a scale insect to proliferate.
      • Bioaccumulation:
        • Most synthetic pesticides are unable to be broken down by bacteria.
          • Slowly this compound will
          • increase in concentration
          • in soil and organisms .
      • Biomagnification:
      • aka Biological amplification
      • - Increase in pesticide concentration as it passes through the food chain.
      • - Many countries subsidize pesticides, hoping for larger crops.
    • Mobility in the Environment (land -> air -> water)
    • Short-term Effects of Pesticides: Handling of food with pesticide residue can result in headache, vomiting, diarrhea etc.
    • Bhopal, India disaster 1984
      • 40 tons of poisonous gas was released from a Union Carbide pesticide plant after water leaked into storage tank, causing a massive explosion
      • covering 30 mi 2 .
      • 600,000 people exposed , many with health problems, especially blindness; 2500 immediately killed.
      • UC paid $500 to each victim but have
      • not cleaned up the land & groundwater.
    • Long-term Effects of Pesticides
      • Higher risk of cancer
      • Sterility
      • Miscarriage / birth defects
      • Higher risk for Parkinson’s disease
      • Acts as an endocrine disrupter , altering reproductive capabilities
      • Suppresses development of intelligence & motor skills of children
    • Alternatives to Pesticides
      • Using Cultivation Methods to Control Pests
      • Intercropping
      • Strip cutting (harvest one segment at a time)
      • Planting, fertilizing & irrigating at proper time
      • Crop rotation
      • Biological Controls
      • Using naturally occurring diseases, parasites, or predators to control a pest.
      • Be careful introducing exotics!
      • Pheromones and Hormones
      • Use pheromones to attract insects to traps
      • Synthetic hormones induce abnormal
      • development
      • Reproductive Controls
      • Sterile-male technique – inundate pest population with large numbers of sterile males
      • Genetic Controls (GMOs) – resistant to pests
      • Quarantine – restriction of the importation of exotic plants & animal materials that might harbor pests.
      • Irradiating foods – especially meat, kills many organisms
      • Integrated Pest Management ( IPM )
      • Identifies the best practices of biological, cultivation & pesticide control for each crop .
      • The pest is managed, not eradicated . Minimal crop damage is expected.
      • Initially requires a lot of money and time for each complete study.
    • IPM & Rice Production in Indonesia IPM introduced 1987 I
      • Rice production good
      • Pests declined
    • Laws Controlling Pesticide Use
      • Food, Drug, and Cosmetics Act (1938) – only recognized the need to regulate pesticides.
      • Pesticide Chemicals Amendment (1954) – established legal limits of pesticidal residue.
      • Federal Insecticide, Fungicide, and Rodenticide Act (1947) (FIFRA) – regulated the effectiveness of pesticides.
      • Food Quality Protection Act – studies all possible negative aspects of pesticides , including
      • smaller legal limits of pesticidal residue
      • injested by children.
    • The Manufacture & Use of Banned Pesticides
      • Some US companies still make banned or seriously restricted pesticides and export the product.
      • This can potentially lead to the importation of food tainted with banned pesticides, known as the Circle of Poison .