Download
1 / 59
E N D
What is a Pest? • A pest is any species that competes with US for food (rabbits), invade gardens (aphids, caterpillars) and lawns (grubs, snails, slugs), destroys wood in houses (carpenter ants, termites), spreads disease (fleas, cockroaches, mosquitoes, ticks), or is a nuisance (raccoons, squirrels, Canada Geese).
Biocides “Pesticides” • Insecticide – kills insects • Herbicide – kills weeds • Fungicides – kill fungi • Nematocides – kill roundworm • Rodenticide – kill rodents • Algicide – kills algae • Larvicide – kills larvae
Facts • Over 3 million metric tons of biocides are used annually on Earth (1 lb. per person) • Approximately 25% of the biocides used in the USA are used to rid houses, gardens, lawns, parks, playing fields, swimming pools, and golf courses of unwanted pests. • The average USA homeowner applies 2-6 times more biocides per acre than farmers do!
Biocide Definitions • Broad-spectrum agents: toxic to many species • Narrow-spectrum agents: effective against a narrowly defined group of organisms. • Persistence – the length of time the biocide remains deadly in the environment.
Biocide History • Until the 1950’s, farmers had two weapons to use against crop pests; natural pesticides found in plants and minerals containing arsenic, lead, and mercury (heavy metals!)
Biocide History (1st & 2nd Generation Pesticides) 1400’s As, Pb, Hg Heavy Metals, highly toxic) 1800’s Botanicals Pyrethrum (rotenone) From flower heads of chrysanthemum flower and tropical legumes (pyrethroids) 500 BC Sulfur 1900’s Second Generation Pesticides = synthhetic organic chemicals (SOC’s) 1600’s Nicotine (SiO4) from tobacco leaves
Biocide History • Homeowners used natural defenses that few people use today because of the easy access and affordability of pesticides. • Ants – cayenne pepper, crushed mint leaves, or boric acid, vinegar. • Mosquitoes – basil plants or rubbing basil oil, lime juice, or mugwort (weed) oil on bare skin. • Cockroaches – boric acid, or establishing banana spider populations (not recommended, one of the deadliest spiders from Australia) • Fleas – feed pets brewer’s yeast or use flea repellent soaps. • Garden pests – introduce natural predators. • Ex. Ladybugs LOVE aphids! Also introduce insect-eating birds, toads and frogs, fish, and snakes.
Biocide History – Development of Synthetic Organic Compounds • The use of SOC’s has revolutionized modern agriculture by allowing food production to more than double in developed countries and increase by 120% in developing countries! • SOC’s include pesticides, herbicides, and chemical fertilizers.
Argument for Biocides 1. Pesticides increase food supplies and lower food costs for consumers. • Pesticides increase profits for farmers. • Pesticides work faster and better than natural alternatives as effective killers of pests. • The pesticide industry declares that the health risk of pesticides is insignificant compared with their benefits for food resources and boost to general health. • Many “new” pesticides are used at very low rates per unit area compared to “old” pesticides
Argument Against Pesticides • Pests develop genetic resistance. They will survive and breed and make a second generation more resistant. Must increase concentration or combination of chemicals to be effective. “evolutionary arms race” Becomes a “Pesticide Treadmill”; a situation where farmers pay more and more for pest control that are less and less effective due to insects development of genetic resistance.
Argument Against Pesticides • Broad-spectrum pesticides kill natural predators and parasites that may have been maintaining a pest species population at a reasonable level. The “ideal” pesticide would: • Kill only the target pest and harm no other species. • Disappear quickly and breakdown into something harmless in the environment. • Not cause genetic resistance to target organisms. • Be cheap when true costing occurs (internalities + externalities)
Argument Against Pesticides (SOC’s) • Pesticides bioaccumulate and biomagnify in the environment and in food webs. • A compound is toxic to a wide range of organisms and is persistent in the environment. • Example DDT (dichloro-diphenyl-trichloroethane )
Major Classes of Pesticides 1. Insecticides – DDT; high persistence, biologically magnified, broad-spectrum • Herbicides –low persistence (days to weeks), not biologically magnified, narrow spectrum. • Fungicides –lowest persistence (several days), not biologically magnified, narrow spectrum • Fumigants –high persistence, biologically magnified, broad spectrum.
DDT Case Study • DDT is a chlorinated hydrocarbon and is used as an insecticide. • DDT was first synthesized in 1874 but was forgotten until 1939 when Swiss chemist Paul Mueller found that DDT was highly toxic to insects. • The Swiss government immediately began to use DDT against a major pest, the Colorado potato beetle.
DDT continued • For two decades DDT was used in agriculture against insect pests and by medical workers against disease-carrying organisms. • Malaria is a mosquito-transmitted disease (Anopholese mosquito is the vector species) causing fever, headache, vomitting, etc… and can become life-threatening if not treated.
Endemic in more than 100 countries. Caused by four protozoa species. 270–500 million new cases and 1 million deaths per year. Malaria
Figure 19-14Page 425 Anopheles mosquito (vector) in aquatic breeding area eggs adult larva pupa Life-Cycle of Malaria 1. Female mosquito bites infected human, ingesting blood that contains Plasmodium gametocytes 4. Parasite invades blood cells, causing malaria and making infected person a new reservoir 2. Plasmodium develops in mosquito 3. Mosquito injects Plasmodium sporozoites into human host
Problems with DDT • DDT is toxic ( toxicity = the measure of how harmful a substance can be to organisms) • DDT is persistent in the environment. The half -life of DDT ranges from 3-10 years in soil (half-life = the time it takes for the concentration of that substance to be reduced by half in a biological system) • DDT breaks down to DDE which is persistent in the environment for 200 years and is more toxic than DDT!
Problems with DDT • DDT is soluble in fats; when organisms digest DDT, the pesticide concentrates in fatty parts of the body. • This allows DDT to be passed along in the food web (bioaccumulate) • DDT is biomagnified.
DDT in fish-eating birds (ospreys) 25 ppm DDT in large fish (needle fish) 2 ppm DDT in small fish (minnows) 0.5 ppm DDT in zooplankton 0.04 ppm DDT in water 0.000003 ppm, Or 3 ppt “CIRCLE OF POISON”
Problems with DDT • Some animals no longer reproduce normally when exposed to DDT • Predatory birds at the top of the food chain lay eggs with unusually thin shells • DDE blocks the formation of calcium in egg production in the female. • This caused the near extinction of the American bald eagle, osprey, and peregrine falcon.
Rachel Carson and DDT • Rachel Carson – biologist for Bureau of US Fisheries (later USFWS), became Editor in Chief for bureau’s publications in 1949. • 1951 – wrote “The Sea Around Us” about the natural history of the oceans and anthropogenic effects. • Book was on the best seller list for 86 weeks, sold 2 million copies, was translated in 32 languages, and won a National Book Award.
Rachel Carson • In 1958 DDT was sprayed to control mosquitoes near the home and private bird sanctuary of one of Rachel’s friends (Olga Huckins). • After the sprayings, many of the birds died horrible deaths, so she asked Carson to investigate the effects of pesticides on birds and other wildlife. • Initially, she found there was no independent critical research on environmental effects of pesticides.
Rachel Carson • Carson surveyed the scientific literature and methodically built her case against the widespread use of pesticides. • 1962 she published “Silent Spring”; an allusion to the silencing of robins, catbirds, doves, jays, and wrens and scores of other bird voices because of their exposure to pesticides. • She pointed out that “for the first time in the history of the world, every human being is now subjected to dangerous chemicals, from the moment of conception until death.”
Opposition to Silent Spring • Although the public embraced her book, the chemical industry viewed the book as a serious threat to booming pesticide sales. • The chemical industry mounted a $250,000 campaign to discredit Carson. • Chemical Industry scientists claimed that her book was full of inaccuracies, made selective use of research findings, and failed to give a balanced account of the benefits of pesticides. • Critics claimed that “as a woman, she was incapable of understanding the highly scientific and technical subject of pesticides”.. • Others claimed she was a hysterical woman and a radical nature lover trying to scare the American public in order to sell books. • 18 months after Silent Spring was published, Rachel Carson died from terminal cancer. Silent Spring became one of the driving forces for the Environmental Movement in the United States!
DDT Banned in USA • 1973 The Environmental Protection Agency (EPA) banned the use of DDT in the USA. • 1986 – a study on humans showed that an average level of 1.67 ppm of DDT was retained in fatty tissue, more than 10 years after the compound had been banned. The acceptable limit for DDT in human tissue is 0.2 ppm!
DDT in Breast Milk Around the World • DDT is found to be significantly high in developing nations who still continue spraying DDT for malaria control. • The USA is still the largest manufacturer of DDT in the world! • DDT travels through the wind belts around the world.
Chaos in Borneo • World Health Organization (WHO) sent supplies of DDT to Borneo to combat malaria and kill mosquitoes. • It was very successful and wiped out the mosquito population quickly. • The billions of cockroaches that lived in the village stored the DDT in their tissue. • Small lizards fed on the roaches who became weakened by the DDT and slowed down. • Cats were able to catch the lizards more easily (favorite food). • Since the cats ate a lot of lizards and the DDT biomagnified through the food web, the cats began to die. • Once the cat population decreased, the rats moved in (no natural predators). • The lizard population declined because of the cats predating on them and a caterpillar population that used to be maintained by the lizards was now increasing and feeding on the roof material of the homes of the villagers. • The homes began to collapse. • Emergency workers sent emergency calls for more cats! • Cats were parachuted in to Borneo to kill the rats who were spreading disease (plague)!
Insecticides • Insecticides are chlorinated hydrocarbons and include: • DDT • Aldrin and dieldrin; organochlorine pesticides to treat termites, grasshoppers, woodborers, beetles – impacts to central nervous system. Dieldrin was used to control tse-tse fly to prevent tropical diseases. Causes tremors, disorientation and liver problems. • Chlordane – banned in 1990. Used to treat lawn, turf and ornamentals. Affects lungs, nervous system, and liver. • Organophosphates – (parathion and malathion) Spray for West Nile Virus on Long Island Dieldrin Aldrin
West Nile Virus • West Nile Virus (WNV) is a mosquito-borne virus that can cause encephalitis or meningitis-- an inflammation of the brain -- in humans and other animals. People get West Nile from the bite of a mosquito that is infected with West Nile virus. Mosquitoes become infected with West Nile virus when they feed on infected birds that carry the virus in their blood. West Nile virus is NOT transmitted from person to person. • West Nile virus is closely related to two other mosquito-borne encephalitis viruses in the United States : St. Louis Encephalitis (SLE) and Eastern Equine Encephalitis (EEE). These viruses have been responsible for illnesses requiring hospitalization of over a hundred people in Michigan , with several deaths. Some of these viruses have also caused equine illness with over 200 horse deaths confirmed.
How Did West Nile Virus Get Here? Hypothesis 1: Avian migratory pathways. First outbreaks in USA were in Queens Long Island, 1999. North Atlantic Flyway is the first western flyway for neotropical birds flown off course during storms from Black Sea Mediterranean Flyway (Nile River Region). Hypothesis 2: First terror attack on USA was biological. Evidence that in 1996 Sadaam Hussein made a very large purchase of West Nile Virus from US Biological Supply Companies (traced through chain of custody) and that Queens, New York was the release point. Easy to do by releasing into ponds where mosquitoes breed and larvae develop, become infected and females spread the disease.
Carbamates • Carbamates replaced many of the halogenated hydrocarbons (Aldicarb) and is used primarily as a molluscicide Aldicarb
Fumigants • Carbon tetrachloride, ethelyne dibromide, and methylbromide. • The chemicals used for fumigants are also used in dry cleaning agents and freon refrigerants.
Botanicals • Rotenone and pyrethrum – also used on Long Island to spray for West Nile Virus. • Persistence – low (days to weeks), EPA claims they are not biologically magnified in the environment. • Sprayed at “unnatural” concentrations • CHILDREN AND THE ELDERLY OR PEOLPLE WHO ARE IMMUNOCOMPROMISED ARE AT THE GREATEST RISK TO PESTICIDE POISONING AND TUMOR GROWTH.
Parkinson’s Disease • Researchers have found a link to Parkinson’s Disease (a neurodegenerative disorder) and the botanical pesticide rotenone. • When Michael J. Fox was diagnosed with Parkinson’s Disease, he promoted the need for research and a tremendous amount of money has been targeted toward identifying causes and promoting research to find cures for this disease. • Parkinsons’ Disease was first described by James Parkinson in 1817. The condition kills the nerve cells in the brain that release dopamine, a chemical necessary for controlling body movements. • To reduce the risk of Parkinson’s Disease, Consumers must reduce their exposure to pesticides by washing residue off of foods, not using sanitizers and mildew removers which contain pesticides, and not applying them on their lawns or in their gardens.
How Dangerous Are Biocides? • 50,000 different pesticides are used in the USA! • Hazardous risk to humans depends on: a. Concentration of pesticide in environment or inhaled or ingested. b. How much is absorbed and retained in drinking water or crop. (The higher the solubility, the more dangerous the compound will be.) c. The duration of exposure to the chemical. d. How quickly the compound is metabolized and excreted from the body.
How Dangerous Are Biocides? • EPA defines “acceptable risk” of biocides in our drinking water to be “one that causes no more than one additional case of cancer in a population of a million people who drink the water over the course of a lifetime” • How can we determine if a person’s cancer has been directly caused by ingestion of contaminated drinking water when all of the foods we eat are loaded with carcinogens and when the air we breathe are loaded with hydrocarbons and other toxins from burning fossil fuels, smelting ores, and industrial production of goods?
How Dangerous Are Fumigants? • Fumigants are released through gas cartridges (gases) that infiltrate every crack and space in a room or below ground. • When released, the area must be well ventilated and humans and domestic animals may not re-enter for 6 – 8 hours after treatment. • What do you think?
Fumigants in the Atmosphere • Carbon tetrachloride and chlorides used in refrigeration processes (freon) are the direct cause to the thinning of the ozone layer.
AIR POLLUTANTS FROM COOLANTS Ozone (O3) in the stratosphere forms when HQE UV photons break apart diatomic O2(g) molecules forming reactive free radicals O. The free radicals combine with other diatomic molecules of O2 to from O3. Importance: Each ozone molecule in the stratosphere can absorb a UV photon with a wavelength less than 320 nm. This energy absorption prevents potentially harmful UV rays from reaching the earth’s surface.
OZONE DESTRUCTION • Chlorine from chlorofluorocarbons (CFC’s) emitted from refrigerators, and air conditioners and include freons are highly stable molecules in the troposphere. • Chlorine atoms emitted from fumigants migrate upward in the atmosphere. • HQE UV photons in the stratosphere split chlorine radicals from CFC’s by breaking the C-Cl bond. • The Cl radicals are very reactive and can participate in a series of photochemical reactions that destroy O3 by converting it to O2. When free radicals of O combine to form diatomic molecules of oxygen they prevent additional atoms of O3 from forming. • Every Cl radical can destroy on average 100,000 O3 molecules!
IMPACTS TO HUMAN HEALTH FROM OZONE THINNING • As O3 layer in stratosphere continues to thin, more UV-B radiation will pass through the stratosphere into the troposphere and cause squamous cell cancer and cataracts in humans. • Other human health issues include suppression of the immune system,, lower yields of key crops, serious decline in phytoplankton and forest productivity, and deeper penetration of UV radiation into lakes disrupting ecosystem structure and function.
SOLUTIONS • It will take 50-60 years to return to 1975 levels and 100-200 years to return to 1950 levels. • Use substitutes such as hydrochloroflurocarbons (HCFC’s); less Cl molecules and have shorter lifespan in stratosphere.Can still cause O3 depletion. Other substitutes are hydrofluorocarbons (HJFC’s), propane, and butane. • Developing nations can us HC technology to leap ahead of Industrialized nations. HC’s cannot be patented! • Implement plans and policies to deter CFC useage.
