Chapter 23 The Pesticide Dilemma
What is a Pesticide? • First-Generation Pesticides • Inorganic compounds (e.g., lead, mercury) • Botanicals (e.g., nicotine, pyrethrin) Pyrethrin is used against mosquitos Nicotine has been banned as pesticide since 2001
What is a Pesticide? • Second-Generation Pesticides • Synthetic botanicals (e.g., pyrethroids) • DDT
What is a Pesticide? • The Major Groups of Insecticides • Chlorinated hydrocarbon (e.g., DDT) • Organophosphates (e.g., malathion) The chemicals in this class kill insects by disrupting their brains and nervous systems. Unfortunately, these chemicals also can harm the brains and nervous systems of animals and humans • Carbamates (e.g., carbaryl)
SHORT-TERM HEALTH HAZARDS - The carbamate pesticides listed above are highly poisonous chemicals, with the exception of carbaryl (SEVIN), which is moderately poisonous. - All these chemicals can be absorbed through the skin, especially through cuts and scratches, so direct contact should be avoided. - Carbamates are highly irritating to the eyes. LONG-TERM HEALTH HAZARDS - Carbamates are generally not considered to be cancerous, with two exceptions. Carbaryl (SEVIN) and carbofuran (FURADAN) can mix with other elements in the stomach to form possible cancerous chemicals. - Some carbamates, such as carbofuran (FURADAN), have been shown to cause birth defects or reproduction problems in laboratory animals. Further studies are required for specific compounds. - Carbamates do not accumulate and persist in the body.
What is a Pesticide? • The Major Kinds of Herbicides • Selective herbicides • (e.g., 2,4-D – kills broad-leaved plants) • Nonselective herbicides • (e.g., glyphosate, aka: Round-UpTM) • http://www.scotts.com/smg/brand/roundup/game/roundup_game.html
Did somebody say “roundup”? I love horsies!!!
Benefits and Problems with Pesticides Location of malaria • Benefit: Disease Control
Benefits and Problems with Pesticides • Benefit: Crop production • Farmers save ~$3 - $5 in crops for every $1 invested into pesticides Mo money, mo money, mo money!!!
Benefits and Problems with Pesticides # of species exhibiting genetic resistance to pesticides • Problem: Evolution of Genetic Resistance
Benefits and Problems with Pesticides Kills most pests Resistant survive INCREASE Numbers increase EVEN MORE New population genetically resistant • Problem: Evolution of Genetic Resistance • Creates a pesticide treadmill Pesticide application
Benefits and Problems with Pesticides • Problem: Evolution of Genetic Resistance • Resistance Management • Create a “refuge” (no pesticide applied) • Avoid repeated use of same pesticide
Benefits and Problems with Pesticides • Problem: Imbalances in the Ecosystem
California red scale was introduced into California between 1868 and 1875, apparently on citrus seedlings from Australia. The scale insect is native to Southeast Asia but has been transported on citrus seedlings to all arid and semiarid regions of the world where citrus is grown. It occurs in all of California's citrus growing areas.
Benefits and Problems with Pesticides • Problem: Imbalances in the Ecosystem • Creation of New Pests
Benefits and Problems with Pesticides Biomagnification of DDT • Problem: Persistence, Bioaccumulation, and Biological Magnification
Benefits and Problems with Pesticides • Problem: Mobility in the Environment
Risks of Pesticides to Human Health • Short-term Effects of Pesticides • Handling of food with pesticide residue
There are two types of exposure: chronic and acute, like me!!! Move over Bowles, that’s my line!!!
Risks of Pesticides to Human Health • Short-term Effects of Pesticides • Case-in-Point: The Bhopal Disaster • 40 tons of methyl isocyanate gas released • 600,000 people exposed • 2,500 immediately killed • 2,500 more killed through time • 50,000-60,000 have serious health problems
Risks of Pesticides to Human Health • Long-term Effects of Pesticides • Potentially higher risk of cancer • Sterility • Miscarriage / birth defects • Potentially higher risk for Parkinson’s disease
Alternatives to Pesticides • Using Cultivation Methods to Control Pests • Interplant mixtures of plants • Strip cutting • Planting, fertilizing, and irrigating at proper time • Crop rotation
Alternatives to Pesticides • Biological Controls • Using naturally occurring diseases, parasites, or predators to control a pest • 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
Alternatives to Pesticides • Genetic Controls • Using Genetically Modified plants (GMOs) • Case-in-Point: Bt, Its Potential and Problems • Genetically modified corn to produce Bt toxin • Potential problem: may affect non-target species, such as monarch butterfly • Quarantine
Alternatives to Pesticides • Integrated Pest Management
Alternatives to Pesticides IPM introduced • Integrated Pest Management Rice Production in Indonesia
Alternatives to Pesticides • Irradiating Foods • Predominantly used on meats • Kills many microorganisms This really makes Zombies! No listen to me, they will take over the world, they already live in the oceans!!!
Laws Controlling Pesticide Use Estimates of Risk of Cancer from Pesticide Residue • Food, Drug, and Cosmetics Act (1938) • Pesticide Chemicals Amendment (1954) • Delaney Cause (1958) • Federal Insecticide, Fungicide, and Rodenticide Act (1947)
Laws Controlling Pesticide Use • Food, Drug, and Cosmetics Act (1938) • Pesticide Chemicals Amendment (1954) • Delaney Cause (1958) • Federal Insecticide, Fungicide, and Rodenticide Act (1947) • Food Quality Protection Act (1996)
The Manufacture and 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 Soylent Green is People!
The Manufacture and Use of Banned Pesticides • The Global Ban of Persistent Organic Pollutants