Presentation on theme: "should be to show that pollution options"— Presentation transcript:
1should be to show that pollution options The burden of proof imposed on individuals, companies, and institutionsshould be to show that pollution optionshave been thoroughly examined, evaluated and usedbefore lesser options are chosen.JOEL HIRSCHORN
2PROTECTING FOOD RESOURCES: PEST MANAGEMENT Pest: Any organism that interferes in some way with human welfare or activitiesBiological control is a bioeffector-method of controlling pests (including insects, mites, weeds and plant diseases) using other living organisms.[Spiders control populations of most pest species as part of the earth’s free ecological services.Ladybugs, and in particular their larvae which are active between May and July in the northern hemisphere, are voracious predators of aphids, and will also consume mites, scale insects and small caterpillars.Importation (or "classical biological control") involves the introduction of a pest's natural enemies to a new locale where they do not occur naturally.Biological control programs aim to reduce or eliminate populations of ecologically and agriculturally harmful invasive species.Ecologists must be sure that the biological control attacks only its intended target and not harm any other useful species.
3Biological Control in not enough: Chemical Warfare To speed up the process of biological control we use chemicals to repel or kill pest organisms as plants have done for millions of years.The geranium, for example, produces a unique chemical compound in its petals to defend itself from Japanese beetles. Within 30 minutes of ingestion the chemical paralyzes the herbivore. While the chemical usually wears off within a few hours, during this time the beetle is often consumed by its own predatorsAlthough more beneficial for the environment, natural chemicals (Biopesticides ) are not enough to support the food needs of a growing human population.Biopesticides are certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals. For example, canola oil and baking soda have pesticidal applications and are considered biopesticides. At the end of 2001, there were approximately 195 registered biopesticide active ingredients and 780 products.
4Types of pesticidesChemists have developed hundreds of synthetic chemicals (pesticides) that can kill or repel pests.Herbicide: A toxic substance that kills weeds.Used to control weeds and invasive plants.Fungicide: A toxic chemical that kills fungi. Used most commonly on mildew and mold.Rodenticide: A toxic chemical that kills rodents. Used most commonly on mice and rats.Insecticide: A toxic chemical that kills insects. Used to control insects and invasive species.Nematicides: A toxic chemical that kills nematodes (roundworms). Microscopic, worm-like organisms that feed on plant rootsAlgaecides: A toxic chemical that kills algae. Used to control algae in lakes, canals, swimming pools, water tanks, and other sitesBactericides (biocides): A toxic chemical that kills bacteria.Piscicides: A toxic chemical that kills fish (unwanted species)
5Each year more than 250,000 people in the U. S Each year more than 250,000 people in the U.S. become ill from household pesticides.
6Synthetic Pesticides Advantages 1. They save human lives: Since 1945, DDT and others insecticides have saved million people from insect transmitted diseases like malaria (Anopheles mosquito) and bubonic plague (rat fleas).2. They increase food supplies: about 55% of world’s food supply is destroyed by pests. These would increase without pesticides and food prices would skyrocket.3. They increase profits for farmers: Every 1$ spent on pesticides yields crops worth 4$.4. They work fast, are safe to use when used in the approved regulatory manner.
75. Fiber Production: Saves crops like cotton by killing pests like the cotton boll weevil. This keeps clothing cost down.
8Efficiency When Compared to Alternatives 1. Pesticides control most pests quickly and at a reasonable cost.2. They have a long shelf life3. Easily shipped and applied4. Are safe when handled properly.5. When genetic resistance occurs, farmers can use stronger doses or switch to other pesticides.Development of Safer Practices1. Use of (biopesticides) botanicals and micro-botanicals: safer to users and less damaging to the environment.2. Genetic engineering (GMF) holds promise in developing pest-resistant crop strains.3. It is very expensive to develop these, so they are only doing it for large-market crops like wheat, corn, and soybeans.4. Crossing a modern crop with it ancestor can bring back some genetic variety lost from modern agriculture. Genetic diversity increase a crop’s resistance to pest and disease.
9Synthetic Pesticides Disadvantages They accelerate the development of genetic resistance to pesticides: Insect breed rapidly and because of natural selection can come back stronger. Since 1945, about 1000 pest species and 450 plant species have pesticide resistance.These include 520 insect and mite species, 273 weed species, 150 plant diseases, and 10 rodent species (mostly rats) have developed genetic resistance to pesticides.At least 17 insect pest species are resistant to all major classes of insecticidesGenetic resistance puts farmers on a financial treadmillOccurs within specific insect populations in response to the application of a pesticideRandom genetic mutation might allow a few individuals to be resistant to a pesticide>Does not favor (nor harm) these species until that pesticide is widely applied>after pesticide application, this small subgroup of the population is better equipped to survive and reproduce, therefore future generations will likely contain greater percentages of members that are resistant to the pesticide.
10Pesticide Treadmill Cont. Because insect generations are relatively short, the pesticide might be rendered ineffective within a few growing seasons due to heightened genetic resistance.Force farmers to spend more money on increased amounts of the pesticide or on a different pesticide altogetherCommonly referred to as the pesticide treadmillIn the worst-case scenario, increased resistance, increased cost for more or different pesticides, further increased resistance, further cost ?, continues indefinitely (hence the term treadmill).Superbugs (Forming a new pest)Superbugs are resistant to pesticides.Superbugs like the silver whitefly challenge farmers as they cause more than $200 million per year in U.S. crop losses.
11Impact on Non-target Organisms Pesticides don’t stay put.2. The USDA says that only 2% of the insecticides from aerial or ground spraying actually reaches the target pests3. Only 5% of herbicides applied to crops reaches the target weeds.4. They end up in the environmentExample of resistance1. In the US, studies have shown that fruit flies that infest orange groves were becoming resistant to malathion, a pesticide used to kill them.2. In England, rats in certain areas have evolved such a strong resistance to rat poison that they can consume up to five times as much of it as normal rats without dying.3. DDT is no longer effective in preventing malaria in some places, a fact which contributed to a resurgence of the disease.4. In the southern United States, the weed Amaranthus palmeri, which interferes with production of cotton, has evolved widespread resistance to the herbicide glyphosate.5. Colorado potato beetle has evolved resistance to 52 different compounds belonging to all major insecticide classes. Resistance levels vary greatly among different populations and between beetle life stages, but in some cases can be very high (up to 2,000-fold).
12Killing one May Cause New Problems The natural predators, parasites, & competitors of a pest may be killed by a pesticide it allows the pest population to rebound.EX. DDT to control insect pests on lemon trees caused an outbreak of a scale insect (a sucking insect that attacks plants) that had not been a problem.
13Pesticides Vary in Their Persistence Persistence: Refers to how long a pesticide stay in the environment.Hard/Persistent Pesticides:Composed of compounds that retain their toxicity for long periods of time. They work their way up the food chain through animals and may accumulate in their fatty tissues and stay indefinitely. Ex: DDTSoft PesticidesReduced-risk pesticides. They are short-term and don’t harm or are far less harmful to the environment or man.Ex: soaps, oils, plant extracts, baking soda, and dish liquid.Broad SpectrumNarrow SpectrumKills many different speciesSelected to kill only one targetCan kill good species: Bees, spiders and ladybugsRaid: Ant, roach and spider spray. Sometimes called “bug spray”DDT-chlorinated Hydrocarbons and Organophosphates like malathionHow Pesticides Kill
14Bioaccumulation Vs. Biomagnification Bioaccumulation refers to the accumulation of substances, such as pesticides, or other organic chemicals in an organism. Bioaccumulation occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost. Thus, the longer the biological half-life of the substance the greater the risk of chronic poisoning, even if environmental levels of the toxin are not very high.Biomagnification, occurs when the concentration of a substance, such as DDT or mercury, in an organism exceeds the background concentration of the substance in its diet. This increase can occur as a result of:Persistence – where the substance can't be broken down by environmental processesFood chain energetics – where the substance concentration increases progressively as it moves up a food chainLow or non-existent rate of internal degradation or excretion of the substance – often due to water-insolubility
15For example, though mercury is only present in small amounts in seawater (it is deposited into aquatic systems from the atmosphere), it is absorbed by algae. It is efficiently absorbed, but only very slowly excreted by organisms. Bioaccumulation result in buildup in the adipose tissue of successive trophic levels: zooplankton, small nekton, larger fish, etc. Anything which eats these fish also consumes the higher level of mercury the fish have accumulated. This process explains why predatory fish such as swordfish and sharks or birds like osprey and eagles have higher concentrations of mercury in their tissue than could be accounted for by direct exposure alone. For example, herring contains mercury at approximately 0.01 ppm and shark contains mercury at greater than 1 ppm.Biological magnification often refers to the process whereby certain substances such as pesticides or heavy metals move up the food chain, work their way into rivers or lakes, and are eaten by aquatic organisms such as fish, which in turn are eaten by large birds, animals or humans. The substances become concentrated in tissues or internal organs as they move up the chain. Bioaccumulants are substances that increase in concentration in living organisms as they take in contaminated air, water, or food because the substances are very slowly metabolized or excreted.
17Food/Water Contamination Pesticides run off into our water as we spray for bugs and stay on our food.A pesticide poisoning occurs when chemicals intended to control a pest affect non-target organisms such as humans, wildlife, or bees.There are two general types of pesticide poisoning1. Short-term very high level of exposure which can be experienced by individuals who commit suicide, as well as pesticide formulators. Results in harm to organs and even death2. Long-term low-level exposure, which individuals are exposed to from sources such as pesticide residues in food as well as contact with pesticide residues in the air, water, soil, sediment, food materials, plants and animals. Lower levels of pesticides can cause cancer.
18Why Children May be Especially Sensitive to Pesticides Infants and children may be especially sensitive to health risks posed by pesticides for several reasons:1. Their internal organs are still developing and maturing,2. In relation to their body weight, infants and children eat and drink more than adults, possibly increasing their exposure to pesticides in food and water.3. Certain behaviors--such as playing on floors or lawns or putting objects in their mouths--increase a child's exposure to pesticides used in homes and yards.Pesticides may harm a developing child by blocking the absorption of important food nutrients necessary for normal healthy growth. Another way pesticides may cause harm is if a child's excretory system is not fully developed, the body may not fully remove pesticides.For these reasons, and as specifically required under the Food Quality Protection Act (1996) , EPA carefully evaluates children's exposure to pesticide residues in and on foods they most commonly eat, i.e., apples and apple juice, orange juice, potatoes, tomatoes, soybean oil, sugar, eggs, pork, chicken and beef. EPA is also evaluating new and existing pesticides to ensure that they can be used with a reasonable certainty of no harm to adults as well as infants and children.
19Symptoms of Pesticide Poisoning Kinds of PoisoningAcute poisoning is the severe poisoning which occurs after exposure to a single dose of pesticide. The appearance of symptoms may be sudden and dramatic or they may be delayed.Chronic poisoning is the poisoning which occurs as a result of repeated, small, non-lethal doses over a long period of time. Many symptoms may appear, such as nervousness, slowed reflexes, irritability, or a general decline in health. Some test animals are unable to reproduce normally after repeated exposure to pesticides.General SymptomsMild Poisoning or Early Symptoms of Acute Poisoning headache, fatigue, weakness, dizziness, restlessness, nervousness, perspiration, nausea, diarrhea, loss of appetite, loss of weight, thirst, moodiness, soreness in joints, skin irritation, eye irritation, irritation of the nose and throat.Severe or Acute Poisoning fever, intense thirst, increased rate of breathing, vomiting, uncontrollable muscle twitches, pinpoint pupils, convulsions, inability to breathe, unconsciousness.The W.H.O. (World Health Organization) estimates that more than 3 million people are poisoned by pesticides each year, and about 220,000 die.
20Effects of Pesticide Chemicals on the Human Body Chemical FamilyType of PesticideAction on Human SystemSymptoms Internal ExposureSymptoms External ExposureSymptoms Chronic ExposureOrgano- phosphates diazinonC SpectracideTInsecticides, acaricidesInhibits acetylcholi- nesterase (an enzyme) in the tissuesHeadache, dizziness, weak- ness, shaking, nausea, stomach cramps, diarrhea, sweatingMinimal rashes but readily ab- sorbed through the skinLoss of appetite, weakness, weight loss, and general feeling of sicknessCarbamates carbaryl C Sevin TInsecticides acaricidesReversible changes in acetylcholines- terase enzyme of tissuesLoss of appetite weakness, weight loss, and general feeling of sicknessOrgano- chlorines (Chlorinated Hydrocarbons) methoxychlor C Marlate TInsecticides, acaricides (HCB is a fungicide)Disrupt function of nervous system, mainly the brainHeadache, dizziness, weak- ness, shaking, nausea, excita- bility, disor- ientationSome buildup in the fat tissues. May cause nerv- ousness, weak- ness, and shaking
21Chloro- phenoxy Pesticides 2,4-D C Weed-B-Gon T HerbicidesIrritant to lung, stomach and in- testinal linings. Injure liver, kidney, and nervous systemPrompt vomit- ing, burning sensation in stomach, dia- rrhea, muscle twitchingModerately irritating to eyes, skin, and lungsDo not remain in body; passed out within hours or daysParaquat and DiquatInjure skin, nails, cornea, liver, kidney, linings of stomach and intes- tine, and respiratory systemBurning pain, nausea, vomiting, and diarrheaIrritates and injures skin and nailsThiocarbamates and Dithiocarbamates Zineb TFungicidesLow human toxicityNausea, vomiting, diarrhea, weak-ness, and nasal stuffinessIrritating to skin, eyes, nose, and throatArsenical PesticidesRodenticides, insecticides, acaricides, marine anti- fouling com- pounds, desi- ccants, herbi- cides, fungicidesToxic to liver, kidney, brain, bone marrow, and nervous systemHeadache, burning stomach pain, vomiting, diarrhea, dizzi- ness. Garlic odor on breath and fecesSwelling of mouth and throat, irritating to nose, throat, and eyesAccumulates in body. Chronic headaches, dizzi- ness, stomach- aches, salivation, low fever, garlic breath
22National Cancer Institute According to the National Cancer Institute, pesticides have been shown to cause lymphomas, leukemia, brain, lung, and testicular cancers.The issue of whether certain pesticides cause breast cancer remains unresolvedResearchers have noted a correlation between a high level of pesticides in the breast's fatty tissue and cancer.
23How Pesticides Function LD-50 (Median Lethal Dose): A measurement used to calculate the amount of pesticide it will take, in one dose, to kill ½ of all the target organisms. The LD-50 is usually referring to rats and mice in a laboratory experiment.The threshold level of toxicity: The dose below which no toxic or lethal effects are observed and/ or above which the toxic or lethal effects are apparent. Simply the minimum dose of a medication or herbal remedy required to produce toxicity (the moment death rate increases above the norm)Synergistic effect: The toxicity of two chemicals may be within their safe limits and alone don’t kill organisms. Sometimes two chemicals within their safe limits enter the same ecosystem and will kill organisms. The combination of two or more chemicals within their safe limits that when occurring together become lethal is known as synergism.1. Pesticides attack the nervous system: Some interfere with the nervous system, causing uncontrollable muscle twitching or paralysis.Ex. Spectracide, Nicotine, DDT, Dursban, & Diazinon.2. Herbicides stop photosynthesis: Some herbicides inhibit photosynthesis and prevent chlorophyll formation.Ex. Stampede, Pyrazon.3. Some smother the pest: The vapors kill the pest by suffocating the animal. Soap can smother soft bodies of insects.4. Dehydration methods use the fossilized remains of tiny, one-celled organisms called diatoms. It kills insects by scratching their wax outer covering and causing them to dehydrate. This is a soft pesticide.
24The ideal Pesticide and the Nightmare Insect Pest 5. Inhibition of Blood Clotting: Other types of pesticides cause animals (especially rats) to bleed to death by preventing their blood from clotting.The ideal Pesticide and the Nightmare Insect PestThe ideal pest-killing chemical has these qualities:Kill only target pest.Not cause genetic resistance in the target organism.Disappear or break down into harmless chemicals after doing its job. The perfect pesticide would break down into safe materials such as water, carbon dioxide, and oxygen. It would stay exactly where it was put and not move around in the environment.Be more cost-effective than doing nothing.There is no such thing!
25Laws and RegulationsEPA regulates the use of pesticides under the authority of two federal statutes: the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Federal Food, Drug, and Cosmetic Act (FFDCA).Days to Harvest: The EPA sets the last day you can spray crops before you harvest them for human consumption. This varies from chemical to chemical.Pesticide companies must use 3 methods to determine pesticides health threats:Case Reports – (made to physicians) about people suffering from adverse health effectsLaboratory Investigations – (usually on animals) to determine toxicity, residence time, what parts of the body are affected and how the harm takes place.Epidemiology – (in populations of humans exposed) used to find why some people get sick while others do not
26Label Requirements 1. the brand name 2. the ingredient statement 3. the percentage or amount of activeingredient(s) by weight4. Emergency information5. the net contents of the container6. the name and address of the manufacturer7. Registration and establishment numbers8. Signal words and symbols9. Precautionary statement10. Statement of practical treatment11. Environmental hazard statement12. Classification statement13. Directions for use14. Re-entry statement15. Harvesting and/or grazing restrictions16. Storage and disposal statement.
27ActsFederal Insecticide, Fungicide, and Rodenticide Act (FIFRA): It was first established in 1947 & revised as recently as Gives the EPA authority to regulate the sale, use and distribution of pesticides. States what must be on a pesticide label & requires registration of all pesticides.Federal Food, Drug, and Cosmetic Act (FFDCA): Strengthened in Gives the EPA authority to set limits on the amount of pesticide residues allowed on food or animal feed. These limits are called tolerances.Food Quality Protection Act of 1996 (FQPA): This act amended FIFRA and FFDCA by increasing the safety standards for new pesticides used on foods. FQPA also required older pesticides and previously established tolerances (link) to be periodically re-assessed using the new, tougher standards.Pesticide Registration Improvement Act (PRIA): Establishes the fees and time-lines associated with pesticide registration (link to registration page) actions.Endangered Species Act (ESA): Requires the EPA to assess the risk of pesticides to threatened or endangered species and their habitats.PERSISTENT ORGANIC POLLUTANTS (POPSTREATY): International treaty (not ratified by US in 2009) to phase out 12 organic persistent pollutants known as the “dirty dozen” such as DDT and PCBs
28Rachel CarsonRachel Carson lived from 1907 to She published her famous work Silent Spring in 1962.Pesticide sprays, dusts, and aerosols are now applied almost universally to farms, gardens, forests, and homes - non selective chemicals that have the power to kill every insect, the good and the bad, to still the song of birds and the leaping of fish in the streams, to coat the leaves with a deadly film and to linger on soil - all this though the intended target may be only a few weeds or insects. Can anyone believe . . .it is possible to lay down such a barrage of poisons on the surface of the earth without making it unfit for life? They should not be called insecticides, but biocides.”Silent Spring heightened public awareness and concern about the dangers of uncontrolled use of DDT and other pesticides, including poisoning wildlife and contaminating human food supplies.
30Integrated Pest Management(IPM) GOAL: reduce the number of pests to a economically tolerable level. A combination of methods to control a pest. The aim is long term control, not eradication, with minimal environmental impactEXAMPLES IPM STRATEGIESNatural enemies of pestsCrop rotationUse of pheromones or sterile males into population to interfere with reproductionLimited use of narrow-spectrum or natural pesticidesThey production of organic crops must follow the IPM rules above, according to the United States Department of Agriculture.
31Other Ways to Control Pests There are cultivation, biological, and ecological alternatives to conventional chemical pesticides.Methods include:Acceptable pest levels: allow some to live in an area but take action if the threshold is crossed.2. Preventive cultural practices: quarantine, crop sanitation removal of diseased plants, and beneficial fungi and bacteria are added to the potting media.Fool the pest through cultivation practices. This includes rotating between different crops, selecting pest-resistant varieties, planting pest-free rootstock, and vacuuming up harmful bugs.Traditional “EcoFarmer”: Each crop is evaluated as parts of an ecological system.A control program is developed that includes a mix of cultivation, biological, and chemical methods applied in proper sequence with the proper timing.
32Timing of Application: Adjusting planting times so that major insect pests either starve or get eaten by their natural predators.Type of Crops: Switching from vulnerable monocultures to polyculture techniques like agroforestry, and intercropping, which use plant diversity to reduce losses to pests.Polyculture is agriculture using multiple crops in the same space, in imitation of the diversity of natural ecosystems, and avoiding large stands of single crops, or monoculture.Polyculture, though it often requires more labor, has several advantages over monoculture:The diversity of crops avoids the susceptibility of monocultures to disease.The greater variety of crops provides habitat for more species, increasing local biodiversity.3. Mechanical controls: They include simple hand-picking, erecting insect barriers, using traps, vacuuming, and tillage to disrupt breeding. Use pheromones to lure pests into traps.
334. Biological controls: The main focus here is to promote beneficial insects that eat or parasitize target pests. (ex: Ladybugs and aphids)Provide homes for the pest enemies.Bring in natural enemies.Use hormones to disrupt life cycles.Ex: Biological pest control: Wasp parasitizing a gypsy moth caterpillar.Using disease organisms (bacteria and viruses) to control pests.EX. The Bacillus thruingensis (Bt) toxin is a registered pesticide sold commercially as a dry powder.Each of the thousands of strains of this common soil bacteria kills a specific pest.5. Responsible Pesticide Use: Synthetic pesticides are used as required and often only at specific times in a pests life cycle. Many of the newer pesticide groups are derived from plants or naturally occurring substances.
34Example insect control: Habitat managementShorten grass and cut back bushes (takes away their habitat)Expose areas to more direct sunlight which heat up the soil and removes moisture.Controlled burning of brush.Introduce plants the repel the insects.Biological controlIntroduce a predator to the insect (Birds, ants or other insects)Introduce a disease that kill ONLY that insectControl the host population by reducing the number of a specific animal that the insect needs to survive.Introduce a competitor to the insectChemical controlsPesticide use, when to use it, where to use it and how much to use.Herbicide use, when to use it, where to use it and how much to use.
35Insect SterilizationMales of some insect species can be raised in the laboratory, sterilized by radiation or chemicals, and released into an infested area to mate unsuccessfully with fertile wild females.Males are sterilized rather than females because the male insects mate several times, whereas the females only mate once.
36Genetic MethodsGenetic engineering can be used to develop pest and disease resistant crop strains.Both tomato plants were exposed to destructive caterpillars. The genetically altered plant (right) shows little damage.Resistant crops: Plants that are resistant to certain pest insects, fungi, and diseases can be developed.
37What Can You Do? Reducing Exposure to Pesticides • Grow some of your food using organic methods.• Buy organic food.• Wash and scrub all fresh fruits, vegetables, and wild foods you pick.• Eat less or no meat.• Trim the fat from meat.
38Growing Germ Resistance to Antibiotics Rabidly producing infectious bacteria are becoming genetically resistant to widely used antibiotics due to:Genetic resistance: Spread of bacteria around the globe by humans, overuse of pesticides which produce pesticide resistant insects that carry bacteria.Overuse of antibiotics: A 2000 study found that half of the antibiotics used to treat humans were prescribed unnecessarily.RISKS AND HAZARDSRisk is a measure of the likelihood that you will suffer harm from a hazard.Humans can suffer from:Biological hazards: from more than 1,400 pathogens.Chemical hazards: in air, water, soil, and food.Physical hazards: such as fire, earthquake, volcanic eruption…Cultural hazards: such as smoking, poor diet, unsafe sex, drugs, unsafe working conditions, and poverty.
39BIOLOGICAL HAZARDS: DISEASE IN DEVELOPED AND DEVELOPING COUNTRIES Diseases not caused by living organisms cannot spread from one person to another (nontransmissible disease), while those caused by living organisms such as bacteria and viruses can spread from person to person (transmissible or infectious)Transmissible Disease
40Infectious (Transmissible) Disease W.H.O. estimates that each year the world’s seven deadliest infections kill 13.6 million people – most of them the poor in developing countries.
41Rise of Infectious Disease Increased travel has increased the spread of infectious disease.Unprotected sexual practices (about 6000 young people, 15-25, are infected with HIV/AIDS each day.Global economy: Shipping and transporting goods all over the globeLarge population of humans living closely togetherUnclean water supplies in some countriesMalnutritionLimited access to medicine and vaccinesAntibiotic resistance of some bacterium
42Case Study: The Growing Global Threat from Tuberculosis The highly infectious tuberculosis (TB) kills 1.7 million people per year and could kill 25 million people 2020.Recent increases in TB are due to:Lack of TB screening and control programs especially in developing countries due to expenses.Genetic resistance to the most effective antibiotics.Mostly because of human activities, infectious diseases are moving at increasing rates from one animal species to another (including humans).Ecological (or conservation) medicine is devoted to tracking down these connections between wildlife and humans to determine ways to slow and prevent disease spread.
43Viral DiseasesFlu, HIV, and hepatitis B viruses infect and kill many more people each year then highly publicized West Nile and SARS viruses.The influenza virus is the biggest killer virus worldwide.Pigs, chickens, ducks, and geese are the major reservoirs of flu. As they move from one species to another, they can mutate and exchange genetic material with other viruses.HIV is the second biggest killer virus worldwide. Five major priorities to slow the spread of the disease are:1. Quickly reduce the number of new infections to prevent further spread. Through education and condoms.2. Intensify HIV prevention efforts in communities where HIV is most heavily concentrated.3. Provide free HIV testing and pressure people to get tested.4. Provide free or low-cost drugs to slow disease progress.5. Implement educational programs.
44Malaria – Death by Mosquito Malaria kills about 2 million people per year and has probably killed more than all of the wars ever fought.Spraying insides of homes with low concentrations of the pesticide DDT greatly reduces the number of malaria cases.Under international treaty enacted in 2002, DDT is being phased out in developing countries.Environmental factors such as decreased predator populations to the mosquito and increasing human population density have caused a reemergence of the disease both factors have increased transmission opportunities.
45Solution Infectious Disease 1. Increase research on tropical disease and vaccines2. Reduce poverty3. Decrease malnutrition4. Improve drinking water quality5. Reduce unnecessary use of antibiotics6. Educate people to take all of an antibiotic prescription7. Reduce antibiotics in livestock8. Require carful hand washing by all medical personnel9. Immunize children against major viral disease10. Provide oral rehydration for diarrhea victims11. Conduct global campaign to reduce HIV/AIDS
46A Black Day in Bhopal, India CHEMICAL HAZARDSA toxic chemical can cause temporary or permanent harm or death. Although toxic threats are everywhere, most hazardous wastes come from chemical and petroleum industries (70%)Mutagens are chemicals or forms of radiation that cause or increase the frequency of mutations in DNA. As many mutations cause cancer, mutagens are therefore also likely to be carcinogens. Not all mutations are caused by mutagens: so-called "spontaneous mutations" occur due to spontaneous errors in DNA replication.Ex: UV, X-rays, Radioactive decay, benzene, arsenicTeratogens are chemicals that cause harm or birth defects to a fetus or embryo. Ex: AlcoholA Black Day in Bhopal, IndiaThe world’s worst industrial accident occurred in 1984 at a pesticide plant in Bhopal, India.An explosion at Union Carbide pesticide plant in an underground storage tank released a large quantity of highly toxic methyl isocyanate (MIC) gas.15,000-22,000 people diedIndian officials claim that simple upgrades could have prevented the tragedy.
47Risk AnalysisRisk analysis involves identifying hazards and evaluating their associated risks.After poverty and gender, the greatest risks of premature death result from lifestyle choice.Most people do not know how to evaluate risk.Many people deny their high risk behavior if they enjoy the activity.Ex: Motorcycling (1 death in 50), Hang gliding (1 in 1250) or driving (1 in 6070 with seat belt)Many people are terrified of:Ex: Killed by gun (1 in 28,000 in U.S.), Lighting (1 in 3 million), airplane crash (1 in 9 million), snakebite (1 in 36 million) or shark attack (1 in 281 million)Evaluate the risk:1. Compare risk: What is the risk? Is it worth it?2. Determine how much risk you are willing to accept. 1 in 100,000 chance of dying is the normal threshold for humans.3. Determine the actual risk involved4. Concentrate on evaluating and carefully making important lifestyle choices.
48TOXICOLOGY: ASSESSING CHEMICAL HAZARDS Toxicology is the study of harmful effects of chemicals on the human body. Toxicity is the measure of how harmful a substance is-its ability to cause injury, illness or death to an organism. Factors determining the harm caused by exposure to a chemical include:1. The amount of exposure (dose).2. The frequency of exposure.3. The person who is exposed.4. The effectiveness of the body’s detoxification systems.5. One’s genetic makeup.United StatesFor most of human history, pathogenic (disease-causing) organisms were are greatest threat to human health. Today cardiovascular, cancer and other non-infectious diseases have become the major killers.
49HazardShortens average life span in the U.S. byPoverty7–10 yearsBorn male7.5 yearsSmoking6–10 yearsOverweight (35%)6 yearsUnmarried5 yearsOverweight (15%)2 yearsRISK ANALYSISComparisons of risks people face expressed in terms of shorter average life spanSpouse smoking1 yearDriving7 monthsAir pollution5 monthsAlcohol5 monthsDrug abuse4 monthsFlu4 monthsAIDS3 monthsDrowning1 monthPesticides1 monthFire1 monthNatural radiation8 daysMedical X rays5 daysOral contraceptives5 daysToxic waste4 daysFlying1 dayHurricanes, tornadoes1 dayLifetime near nuclear plant10 hours
50Why do Males Die Earlier? 1. Males are burdened with natural genetic deficits. While every cell in a woman's body has two large X chromosomes, men have one X and one smaller Y chromosome; the Y is half the size. The "spare" X chromosomes allow women's bodies to compensate when faced with damage in ways that men's cells cannot.2. The womb is more treacherous for boys. Baby boys are one-and-a-half to two times more likely to die at birth than girls. A weaker immune system, a tendency for immature lung development, inadequate blood flow to male fetuses, and high vulnerability to maternal stresses seem to be the culprits.3. Males are more likely to have developmental disorders. An article published in the British Medical Journal notes that a variety of disorders—including reading delays, deafness, autism, ADHD, blindness, seizure disorders, hyperactivity, clumsiness, stammering, and Tourette's syndrome are three to four times more common in boys than girls. There are 10 males for every female with Asperger's syndrome, a mild form of autism.4. They're biologically more prone to risky behavior. Slower development of the area of the brain that governs judgment makes males—especially adolescents—more likely than girls to die in accidents.5. A "suck-it-up" culture means men often languish (suffer from being forced to remain in an unpleasant place or situation) with depression. Although women are more likely to make suicide attempts, the ratio of men to women who actually kill themselves is nearly 4 to 1.
516. Men choose more dangerous occupations 6. Men choose more dangerous occupations. The bulk of sailors, firefighters, police officers, construction workers, and farmers are men.7. Coronary artery disease strikes men early. Estrogen seems to protect women from heart disease until they are well into midlife, but it is common for symptoms to begin in men by the age of 35. Making matters worse, men have naturally low levels of protective HDL cholesterol.
52Case Study: DDTFirst synthesized in 1874, DDT's insecticidal properties were not discovered until 1939, and it was used with great success in the second half of World War II to control malaria and typhus among civilians and troops. After the war, DDT was made available for use as an agricultural insecticide, and its production and use increased.Effects on human healthDDT was used to control the spread of typhus-carrying lice. Potential mechanisms of action on humans are genotoxicity and endocrine disruption. Endocrine disruptors are chemicals that at certain doses, can interfere with the endocrine (or hormone system) in mammals. These disruptions can cause cancerous tumors, birth defects, and other developmental disorders. Any system in the body controlled by hormones, can be derailed by hormone disruptors. Specifically, endocrine disruptors may be associated with the development of learning disabilities, severe attention deficit disorder, cognitive and brain development problems; deformations of the body (including limbs); breast cancer, prostate cancer, thyroid and other cancers; sexual development problems such as feminizing of males or masculine effects on femalesEndocrine disrupting compounds encompass a variety of chemical classes, including drugs, pesticides, compounds used in the plastics (BPA) industry and in consumer products, industrial by-products and pollutants, and even some naturally produced botanical chemicals. Some are pervasive and widely dispersed in the environment and may bio-accumulate. Some are persistent organic pollutants (POP's), and can be transported long distances across national boundaries and have been found in virtually all regions of the world, and may even concentrate near the North Pole, due to weather patterns and cold conditions.
53In 1962, Silent Spring by American biologist Rachel Carson was published. The book catalogued the environmental impacts of the indiscriminate spraying of DDT in the US and questioned the logic of releasing large amounts of chemicals into the environment without fully understanding their effects on ecology or human health. The book suggested that DDT and other pesticides may cause cancer and that their agricultural use was a threat to wildlife, particularly birds. Its publication was one of the signature events in the birth of the environmental movement, and resulted in a large public outcry that eventually led to DDT being banned for agricultural use in the US in 1972.] DDT was subsequently banned for agricultural use worldwide under the Stockholm Convention, but its limited use in disease vector control continues to this day and remains controversial.DDT is thought to biomagnify and biomagnification is one of the most significant reasons it was deemed harmful to the environment by the EPA and other organizations. DDT is stored in the fat of animals and takes many years to break down, and as the fat is consumed by predators, the amounts of DDT biomagnify.DDT is still found in human due to the fact that other countries still use DDT for pest control and the United States imports food from some of these countries.DDT has traveled the globe through ocean currents and migrating organisms. DDT has been found in the Antarctic regions and near the North Pole.
54Effects on wildlife and eggshell thinning DDT is toxic to a wide range of living organisms, including marine animals such as crayfish, sea shrimp and many species of fish. It is less toxic to mammals, but may be moderately toxic to some amphibian species, especially in the larval stage. DDT, through its metabolite DDE (dichlorodiphenyldichloroethylene), caused eggshell thinning and resulted in severe population declines in multiple North American and European bird of prey species. Eggshell thinning lowers the reproductive rate of certain bird species by causing egg breakage and embryo deaths. DDE related eggshell thinning is considered a major reason for the decline of the bald eagle, brown pelican, peregrine falcon, and osprey. However, different groups of birds vary greatly in their sensitivity to these chemicals. Birds of prey, waterfowl, and song birds are more susceptible to eggshell thinning than chickens and related species, and DDE appears to be more potent than DDT. Even in 2010, more than forty years after the U.S. ban, California condors which feed on sea lions at Big Sur seemed to be having continued thin-shell problems. The biological thinning mechanism is not entirely known, but there is strong evidence that DDT inhibits calcium ATPase in the membrane of the shell gland and reduces the transport of calcium carbonate from blood into the eggshell gland. This results in a dose-dependent thickness reduction. There is also evidence that o-DDT disrupts female reproductive tract development, impairing eggshell quality later. Multiple mechanisms may be at work, or different mechanisms may operate in different species. Some studies show that although DDT levels have fallen dramatically, eggshell thickness remains 10–12 percent thinner than before DDT was first used. ]Along with the passage of the Endangered Species Act, the US ban on DDT is cited by scientists as a major factor in the comeback of the bald eagle, the national bird of the United States, and the peregrine falcon from near-extinction in the contiguous US