2 This lecture will help you understand: Environmental health hazardsToxicants in the environmentHazards and their effectsPhilosophical approaches to riskPolicy and regulation in the U.S. and worldAlligator hatchling from Lake Apopka Florida(Start, 11/04/2008)
3 This lecture will help you understand: Environmental health hazardsToxicants in the environmentHazards and their effectsRisk assessment and risk managementPhilosophical approaches to riskPolicy and regulation in the U.S. and worldAlligator hatchling from Lake Apopka Florida(Start, 11/04/2008)
4 Central Case: Lake Apopka alligators, 1985 Alligators in Lake Apopka, Florida, had reproductive problems:unhealthy eggs, abnormal sex hormone levelThe lake had high levels of agricultural runoffChemical contaminants were disrupting the endocrine systems of alligators during egg development- Pesticides, fertilizer(Nitrate) runoff to the lake (Guillette, 2003).
5 There are many types of environmental hazards (Four Types) Environmental health : assesses environmental factors that influence human health and quality of lifeNatural and human-caused factors are both considered1. Physical hazards : occur naturally in our environmentEarthquakes, volcanoes, fires, floods, droughtswe can prepare for some of themWe increase our vulnerability by deforesting slopes (landslides), channelizing rivers (flooding), etc.We can reduce risk by better environmental choices
6 Chemical & biological environmental hazards 2. Chemical: synthetic chemicals such as pesticides, disinfectants, pharmaceuticalsHarmful natural chemicals also existUrushiol (an oil in poison ivy, etc.)3. Biological : result from ecological interactionsViruses, bacteria, and other pathogensInfectious (communicable, or transmissible) disease other species parasitize humans, fulfilling their ecological rolesWe can’t avoid risk, but we can reduce the likelihood of infectionUrushiol:
7 Cultural environmental hazards 4. Cultural: result from the place we live, our socioeconomic status, our occupation, our behavioral choicesSmoking, drug use, diet and nutrition, crime, mode of transportation
9 Disease is a major focus of environmental health Despite our technology, disease kills most of usDisease has a genetic and environmental basisCancer, heart disease, respiratory disordersPoverty and poor hygiene can foster illnesses
10 Infectious diseases kill millions Infectious diseases kill 15 million people per yearHalf of all deaths in developing countriesDeveloped countries have better hygiene, access to medicine, and moneyVector : an organism that transfers pathogens to a host Mosquito, MalariaPlasmodium apicomplexanLice, Typhus,Rickettsia prowazekiiTicks, Lime Disease, BorreliaMalaria is a mosquito-borne infectious disease caused by a eukaryotic protist of the genus Plasmodium.
11 Many diseases are increasing Tuberculosis (TB) - mycobacteriaAcquired immunodeficiency syndrome (AIDS), & the West Nile virus - virus (ss-RNA)Our mobility spreads diseases - GlobalizationDiseases are evolving resistance to antibioticsTo predict and prevent diseases, experts deal with complicated interrelationships
12 Bacteria: Mycobacteria(Tuberculosis) Single Stranded-RNA: Many old diseases are gone (w/ antibiotics), but new ones emerging Pathogens: bacteria, viruses, viroids, prionsBacteria: Mycobacteria(Tuberculosis)Single Stranded-RNA:Tobacco Mosaic VirusHuman ImmunoDeficiency Virus (HIV):Acquired ImmunoDeficiency Syndrome (AIDS)West Nile Virus : Meningitis, EncephalitisViroids (circilar RNA):Cadang cadang (coconut palm disease)Prions (Proteins): mad cow disease, kuru - long incubation periodDiseases are evolving resistance to antibiotics
13 Bacteria: Mycobacteria(Tuberculosis) Virus: Single Stranded-RNA: Many old diseases are gone (w/ antibiotics), but new ones emerging Pathogens: bacteria, viruses, viroids, prionsBacteria: Mycobacteria(Tuberculosis)Virus: Single Stranded-RNA:Tobacco Mosaic VirusHuman ImmunoDeficiency Virus (HIV):Acquired ImmunoDeficiency Syndrome (AIDS)West Nile Virus : Meningitis, EncephalitisViroids (circilar RNA):Cadang cadang (coconut palm disease)Prion (Protein + Infection): Mis-folded Protein, neuro-degerativeMad Cow Disease (bovine spongiform encephalopathy, BSE),1986, UK, ~ 4.5 M cows slaughtered/burnedKuru (Fore Tribe in Papua)Diseases are evolving resistance to antibiotics
14 Bacteria: Mycobacteria(Tuberculosis) Many old diseases are gone (w/ antibiotics), but new ones emerging Pathogens: Bacteria, Viruses, Viroids, PrionsBacteria: Mycobacteria(Tuberculosis)Virus: RNS/DNA + Protein Coat (+ Lipid Envelope)Tobacco Mosaic Virus: Single Stranded-RNA:Human ImmunoDeficiency Virus (HIV):Acquired ImmunoDeficiency Syndrome (AIDS)West Nile Virus : Meningitis, EncephalitisViroids (circilar RNA): Plant pathogenCadang cadang (coconut palm disease)Prion (Protein + Infection): Mis-folded Protein, neuro-degerativeBovine Spongiform Encephalopathy(BSE, Mad Cow Disease),1986, UK, ~ 4.5 M cows slaughtered/burnedCreutzfeldt–Jakob Disease (CJD), Kuru (Fore Tribe in Papua)claimed ~200 people in late 2000s in UKDiseases are evolving resistance to antibiotics
15 AIDSAcquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS or Aids) is a set of symptoms and infections resulting from the damage to the human immune system caused by the human immunodeficiency virus (HIV). This condition progressively reduces the effectiveness of the immune system and leaves individuals susceptible to opportunistic infections and tumors. HIV is transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV, such as blood, semen, vaginal fluid, preseminal fluid, and breast milk. This transmission can involve anal, vaginal or oral sex, blood transfusion, contaminated hypodermic needles, exchange between mother and baby during pregnancy, childbirth, or breastfeeding, or other exposure to one of the above bodily fluids.AIDS is now a pandemic. In 2007, an estimated 33.2 million people lived with the disease worldwide, and it killed an estimated 2.1 million people, including 330,000 children. Over three-quarters of these deaths occurred in sub-Saharan Africa, retarding economic growth and destroying human capital. Most researchers believe that HIV originated in sub-Saharan Africa during the twentieth century. AIDS was first recognized by the U.S. Centers for Disease Control and Prevention in 1981 and its cause, HIV, identified by American and French scientists in the early 1980s.Although treatments for AIDS and HIV can slow the course of the disease, there is currently no vaccine or cure. Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but these drugs are expensive and routine access to antiretroviral medication is not available in all countries. Due to the difficulty in treating HIV infection, preventing infection is a key aim in controlling the AIDS epidemic, with health organizations promoting safe sex and needle-exchange programmes in attempts to slow the spread of the virus.
16 Immune SystemAn immune system is a collection of mechanisms within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own healthy cells and tissues in order to function properly. Detection is complicated as pathogens can evolve rapidly, producing adaptations that avoid the immune system and allow the pathogens to successfully infect their hosts.To survive this challenge, multiple mechanisms evolved that recognize and neutralize pathogens. Even simple unicellular organisms such as bacteria possess enzyme systems that protect against viral infections. Other basic immune mechanisms evolved in ancient eukaryotes and remain in their modern descendants, such as plants, fish, reptiles, and insects. These mechanisms include antimicrobial peptides called defensins, phagocytosis, and the complement system. Vertebrates such as humans have even more sophisticated defense mechanisms. The immune systems of vertebrates consist of many types of proteins, cells, organs, and tissues, which interact in an elaborate and dynamic network. As part of this more complex immune response, the human immune system adapts over time to recognise specific pathogens more efficiently. This adaptation process is referred to as "adaptive immunity" or "acquired immunity" and creates immunological memory. Immunological memory created from a primary response to a specific pathogen, provides an enhanced response to secondary encounters with that same, specific pathogen. This process of acquired immunity is the basis of vaccination.Disorders in the immune system can result in disease. Immunodeficiency diseases occur when the immune system is less active than normal, resulting in recurring and life-threatening infections. Immunodeficiency can either be the result of a genetic disease, such as severe combined immunodeficiency, or be produced by pharmaceuticals or an infection, such as the acquired immune deficiency syndrome (AIDS) that is caused by the retrovirus HIV. In contrast, autoimmune diseases result from a hyperactive immune system attacking normal tissues as if they were foreign organisms. Common autoimmune diseases include rheumatoid arthritis, diabetes mellitus type 1 and lupus erythematosus. Immunology covers the study of all aspects of the immune system which has significant relevance to human health and diseases. Further investigation in this field is expected to play a serious role in promotion of health and treatment of diseases.
17 Environmental health hazards exist indoors Radon: Can build up in basements86Rn-222 → 84Pb α-ray (24He)a highly toxic, radioactive gas colorless & undetectable.Carbon Monoxide (CO):Lead (Pb2+) poisoning: from lead pipesby mimicking Ca2+, Fe2+, & Zn2+ ionsDamages organs (Brain, Liver, Kidney, etc); causes learning problems, behavior abnormalities, & deathAsbestos: Mg3[Si2O5](OH)4 (white)insulates heats, muffles sounds, & resists fire (retardant): - does not degradeAsbestosis: scarred lungs may cease to function , & Lung CancerRemoving Asbestos
18 40K → 40Ar(g) (1.28 Gy) Source of atmospheric Ar Natural Disintegrations of Radiosotpopes The major source of geothermal energy (γ-ray) Occurs in Earth Crust, Mantle, &Core40K → 40Ar(g) (1.28 Gy) Source of atmospheric Ar238U → → → 226Ra → 222Rn(g) → → → 206Pb (4.47G y)235U → → → 223Ra → 219Rn(g) → → → 207Pb (0.704 Gy)232Th → → → 224Ra → 220Rn(g) → → → 208Pb (14 Gy)Artificial Disintegrations (“forced”)Atomic Bomb & Nuclear Power Plant :235U + n → 91Kr Kr +3n Add(9/12/2013)7th Mtg starts (9/9/08)
19 A recently recognized hazard Polybrominated diphenyl ethers (PBDEs):has fire-retardant propertiesUsed in computers, televisions, plastics, and furniturePersist and accumulate in living tissueEndocrine disruptors: compounds that mimic hormones and interfere with the functioning of animals’ endocrine (hormone) systemsAffect brain and nervous system development, and may cause cancer
20 Toxicology is the study of poisonous substances Toxicology: the study of the effects of poisonous substances on humans and other organismsToxicity : the degree of harm a toxicant can cause“The dose makes the poison” :Paracelsus( )toxicity depends on the combined effect of the chemical and its quantityAnalogous to pathogenicity or virulence : the degree of harm of biological hazards that spread diseaseToxicant : any toxic agent
21 Toxicology is the study of poisonous substances Toxicology: the study of the effects of poisonous substances on humans and other organismsToxicity : the degree of harm a toxicant can cause“The dose makes the poison” : toxicity depends on the combined effect of the chemical and its quantityToxicant : any toxic agent
22 Environmental toxicology Deals with toxic substances that come from or are discharged into the environmentStudies the health effects on humans, other animals, and ecosystemsFocus mainly on humans, using other animals as test subjectsCan serve as indicators of health threatsDon’t forget, chemicals have given us our high standard of living
23 Toxic agents in the environment The environment contains countless natural chemicals that may pose health risksBut, synthetic chemicals are also in our environmentEvery human carries traces of industrial chemicals80% of U.S. streams contain at least trace amounts of 83 wastewater contaminants
24 Very few chemicals have been thoroughly tested 10 M chemical substances (Natural & Artificial) KnownTable 14.2100,000 chemicals (1% of the 10 M) are on the market today72,000 Industrial8,700 Food additives2,000 New chemicals introduced per year600 Pesticides7,500 Cosmetic ingredients3,300 PharmaceuticalsWe don’t know the effects, if any, they have
25 Silent Spring began public debate over chemicals Dichloro-Diphenyl-Trichloroethane (DDT): a neurotoxininhibit normal function of neuron → spasm, deathRachel Carson published Silent Spring in 1962Brought together studies to show DDT risks to people, wildlife, and ecosystems (banned in US in 1972)In the 1960s, pesticides were mostly untested and were sprayed over public areas, assuming they would do no harmThe book generated significant social change: (cf. p 68)triggering enactment of Many Environmental Protection Laws since 1963(→ saved bald eagles)Mechanism of insecticide actionIn insects it opens sodium ion channels in neurons, causing them to fire spontaneously, which leads to spasms and eventual death. Insects with certain mutations in their sodium channel gene are resistant to DDT and other similar insecticides. DDT resistance is also conferred by up-regulation of genes expressing cytochrome P450 in some insect species.In humans, however, it may affect health through genotoxicity or endocrine disruption. See Effects on human health.
26 Carcinogens: cause cancer Mutagens: cause DNA mutations Types of toxicants:Carcinogens: cause cancerMutagens: cause DNA mutationsCan lead to severe problems, including cancerTeratogens: cause birth defectsAllergens: induce unnecessary immune responsesNeurotoxins: assault the nervous systemEndocrine disruptors: interfere with the normal hormonal functionThalidomide,sedative,late 50s, 60sA hormone (from Greek ὁρμή "impetus") is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one cell to another. All multicellular organisms produce hormones; plant hormones are also called phytohormones. Hormones in animals are often transported in the blood. Cells respond to a hormone when they express a specific receptor for that hormone. The hormone binds to the receptor protein, resulting in the activation of a signal transduction mechanism that ultimately leads to cell type-specific responses.Endocrine hormone molecules are secreted (released) directly into the bloodstream, whereas exocrine hormones (or ectohormones) are secreted directly into a duct, and, from the duct, they flow either into the bloodstream or from cell to cell by diffusion in a process known as paracrine signalling.Recently it has been found that a variety of exogenous modern chemical compounds have hormone-like effects on both humans and wildlife. Their interference with the synthesis, secretion, transport, binding, action, or elimination of natural hormones in the body are responsible of homeostasis, reproduction, development, and/or behavioural changes sameway as the endogenous produced hormones."
27 Endocrine disruption may be widespread Theo Colburn, et al. (World Wildlife Fund) wrote Our Stolen Future in 1996Synthetic industrial chemicals may be altering the hormones of animalsThis book integrated scientific work from various fieldsShocked many readers and brought criticism from the chemical industry1996: Our Stolen Future (Theo Colborn, Dianne Dumanoski, John Peterson Myers of World Wildlife Fund) – some synthetic chemicals disrupt hormonal systems to cause of abnormalities in animals.Epinephrine (also known as adrenaline) is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. Chemically, epinephrine is a catecholamine, a monoamine produced only by the adrenal glands from the amino acids phenylalanine and tyrosine.The term adrenaline is derived from the Latin roots ad- and renes and literally means "on the kidney", in reference to the adrenal gland's anatomic location on the kidney. The Greek roots epi and nephros have similar meanings, and give rise to "epinephrine". The term epinephrine is often shortened to epi in medical jargon.Adrenal extracts containing adrenaline were first obtained by Polish physiologist Napoleon Cybulski in These extracts, which he called nadnerczyna, contained epinephrine and other catecholamines. Japanese chemist Jokichi Takamine and his assistant Keizo Uenaka independently discovered adrenaline in 1900. In 1901, Takamine successfully isolated and purified the hormone from the adrenal glands of sheep and oxen. Adrenaline was first synthesized in the laboratory by Friedrich Stolz and Henry Drysdale Dakin, independently, in 1904.Insulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle.
28 Evidence for hormone disruption Frogs also have gonadal abnormalitiesMale frogs became feminized from atrazine (herbicide) concentrations well below EPA→ inhibit photosynthesisPCB (PolyChlorinated Biphenyls):Coolants, Insulating fluids in transformer, additives in plasticscontaminated human babies were born weighing less, with smaller heads.→ Banned in 1970Atrazine, 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine, an organic compound consisting of an s-triazine-ring is a widely used herbicide. Its use is controversial due to widespread contamination in drinking water and its associations with birth defects, menstrual problems, and cancer when consumed by humans at concentrations below government standards. Although it has been excluded from a re-registration process in the European Union, it is still one of the most widely used herbicides in the world.Atrazine is prepared from cyanuric chloride, which is treated sequentially with ethylamine and isopropyl amine. Like other triazine herbicides, atrazine functions by binding to the plastoquinone-binding protein in photosystem II, which animals lack. Plant death results from starvation and oxidative damage caused by breakdown in the electron transport process. Oxidative damage is accelerated at high light intensity.Photosystem II (or water-plastoquinone oxidoreductase) is the first protein complex in the Light-dependent reactions. It is located in the thylakoid membrane of plants, algae, and cyanobacteria. The enzyme uses photons of light to energize electrons that are then transferred through a variety of coenzymes and cofactors to reduce plastoquinone to plastoquinol. The energized electrons are replaced by oxidizing water to form hydrogen ions and molecular oxygen. By obtaining these electrons from water, photosystem II provides the electrons for all of photosynthesis to occur. The hydrogen ions (protons) generated by the oxidation of water help to create a proton gradient that is used by ATP synthase to generate ATP. The energized electrons transferred to plastoquinone are ultimately used to reduce NADP+ to NADPH or are used in Cyclic Photophosphorylation.Research Scientist (Academia) vs. Industry-backed Scientist
29 Male sperm counts are dropping Drop in men’s sperm counts may be caused by endocrine disruptorsThe number and motility of sperm has dropped 50% since 1938, in more industrialized country in particularTesticular cancer, undescended testicles, and genital birth defects are also increasing
30 Endocrine disruption research is controversial Research results are uncertain, which is inherent in any young fieldNegative findings pose economic threats to chemical manufacturersBanning a top-selling chemical could cost a company millions of dollarsBisphenol-A, found in plastics, can cause birth defects, but the plastics industry protests that the chemical is safeepoxy resins & other plastics(bottles, CD/DVD, etc.)Studies reporting harm are publicly funded, but those reporting no harm are industry fundedis used to make a variety of common products including baby and water bottles, sports equipment, medical and dental devices, dental fillings and sealants, eyeglass lenses, CDs and DVDs, and household electronics. BPA is also used in the synthesis of polysulfones and polyether ketones, as an antioxidant in some plasticizers, and as a polymerization inhibitor in PVC. Epoxy resins containing bisphenol A are used as coatings on the inside of almost all food and beverage cans, however, due to BPA health concerns, in Japan epoxy coating was mostly replaced by PET film.
31 Toxins may concentrate in water Runoff carries toxins from large land areas to small volumes of surface waterChemicals can leach into the soilChemicals enter organisms through drinking or absorptionAquatic organisms are effective pollution indicators→ Oyster
33 Airborne toxicants travel widely, globally Chemicals can travel by air, their effects can occur far from the site of chemical usePesticide drift = airborne transport of pesticidesSynthetic chemical contaminants are found globallyThey appear in arctic polar bears, Antarctic penguins, and people living in Greenland
34 Some toxicants persist for a long time Toxins can degrade quickly and become harmlessOr, they may remain unaltered and persist for decadesRates of degradation depends on temperature, moisture, and sun exposurePersistent chemicals have the greatest potential for harmBreakdown products = toxicants degrade into simpler productsMay be more or less harmful than the original substanceDDT degrades into DDE, which is also highly persistent
35 Some toxicants can be excreted or metabolized Toxicants can accumulate and biomagnify DDT (from Zooplankton to Fish to Falcon)Some toxicants can be excreted or metabolizedHowever, many Fat-soluble toxicants are stored in fatty tissuesBioaccumulation = toxicants build up in animal tissuesBiomagnification = toxicants concentrate in top predatorsNear extinction of peregrine falcons and brown pelicansNote: ppm = 10,000 x %
36 Not all toxicants are synthetic Chemical toxicants also exist naturally and in our foodDon’t assume natural chemicals are all healthy and synthetic ones are all harmfulSnake venom (mixture of various proteins)urushiol(poison ivy), tetrodotoxin (puff fish)Some scientists feel that natural toxicants dwarf our intake of synthetic chemicalsNatural defenses against toxins are effective against synthetic ones, tooCritics say natural toxins are more readily metabolized and excreted, and synthetic chemicals persist and accumulateSnake venom consists of proteins, enzymes, substances with a cytotoxic effect, neurotoxins and coagulants.Phosphodiesterases are used to interfere with the prey's cardiac system, mainly to lower the blood pressure.Phospholipase A2 causes hemolysis through esterolysis of red cell membranes and promotes muscle necrosis.Snake venom inhibits cholinesterase to make the prey lose muscle control.Hyaluronidase increases tissue permeability to increase the rate that other enzymes are absorbed into the prey's tissues.Amino acid oxidases and proteases are used for digestion. Amino acid oxidase also triggers some other enzymes and is responsible for the yellow color of the venom of some species.Snake venom often contains ATPases which are used for breaking down ATP to disrupt the prey's energy fuel use.
37 Wildlife studiesMuseum collections provide data from times before synthetic chemicals were usedMeasurements from animals in the wild can be compared to controlled experiments in the labScientists can first measure effects in the lab, then look for correlations in the wildConspicuous mortality events can trigger researchMany sea otters died and washed ashoreResearch showed they died from parasites carried in sewage runoff containing cat litter
38 Human studies Case histories = studying sickened individuals directly AutopsiesDon’t tell about future risksEpidemiology = large-scale comparisons between groups of peopleStudies between exposed and unexposed people last for yearsYield accurate predictions about riskAnimals are used as test subjectsSome people object to animal researchNew techniques (human cell cultures, bacteria, etc.) may replace some live-animal testing
39 Dose-response analysis Dose-response analysis: measuring how much effect a toxicant produces at different dosesAnimal testingDose: the amount of toxicant the test animal receivesResponse: the type or magnitude of negative effects of the animalDose-response curve: the plot of dose given against response
40 Dose response curvesLD50: the amount of toxicant required to kill 50% of the subjectsThe smaller this value, the more toxicThreshold: the dose level where certain responses occurScientists extrapolate downward from animal studies to estimate the effect on humansRegulatory agencies set allowable limits well below toxicity levels in lab studies
41 LD50 for some chemicals (mostly, for rats, oral route) mg/kgTable Sugar 29,700Vitamin C 11,900EtOH ,060NaCl ,000FeSO ,500CaffeineNaNOHeroinmg/kgPbCocaineNaCNNicotineTetrodotoxinSnake Venom ~0.025DioxinPolonium
42 Individuals vary in their responses to hazards Different people respond differently to hazardsAffected by genetics, surroundings, etc.People in poor health are more sensitiveSensitivity also varies with sex, age, and weightFetuses, infants, and young children are more sensitiveStandards for responses are set by the Environmental Protection Agency (EPA)Often, standards are not low enough to protect babies
43 The type of exposure affects the response Acute exposure: high exposure for short periods of time to a hazardEasy to recognizeStem from discrete events: ingestion, oil spills, nuclear accidentChronic exposure: low exposure for long periods of time to a hazardHard to detect and diagnoseAffects organs gradually: lung cancer, liver damageCause and effect may not be easily apparent
44 Mixes may be more than the sum of their parts We can’t determine the impact of mixed hazardsThey may act in ways that cannot be predicted from the effects of each in isolationSynergistic effects = interactive impacts that are more than or different from the simple sum of their constituent effectsMixed toxicants can sum, cancel out, or multiply each other’s effectsNew impacts may arise from mixing toxicants
45 Risk assessmentRisk: the probability that some harmful outcome will result from a given actionExposure to environmental health threats doesn’t automatically produce an effectRather, it causes some probability (likelihood) of harmProbability entailsIdentity and strength of threatChance & frequency that an organism will encounter itAmount of exposure to the threatAn organism’s sensitivity to the threat
46 Risk assessmentRisk: the probability that some harmful outcome will result from a given actionExposure to environmental health threats doesn’t automatically produce an effectRather, it causes some probability (likelihood) of harmProbability involvesIdentity and strength of threatChance/frequency that an organism will encounter itAmount of exposure to the threatAn organism’s sensitivity to the threat
47 Perception of Risk vs. Reality of Risk Everything we do involves some riskWe try to minimize risk, but we often misperceive it- Flying poses 50 x less riskthan DrivingWe feel more at risk when we cannot control a situationWe fear nuclear power and toxic waste, but not smoking or overeating
48 Analyzing risk quantitatively Risk assessment: the quantitative measurement of risk and the comparison of risks involved in different activities or substancesIt is a way of identifying and outlining problemsSeveral steps:Scientific study of toxicityAssessing an individual or population’s likely extent of exposure to the substance, including frequency, concentrations, and length of exposureStudies are often performed by industry-associated scientists, which may undermine the study’s objectivity
49 Risk management Combines decisions and strategies to minimize risk Scientific assessments are considered with economic, social, and political needs and valuesDeveloped nations have federal agencies to manage riskThe U.S. has the Centers for Disease Control (CDC), the EPA, and the Food and Drug Administration (FDA)Comparing costs and benefits is hardBenefits are economic and easy to calculateHealth risks (costs) are hard-to-measure probabilities of a few people being affected
51 One approach to determining safety Innocent until proven guilty approach: product manufacturers must prove a product is safeBenefits: now slowing down technological innovation and economic advancementDisadvantage: putting into wide use some substances that may later on turn out to be dangerous
52 Another approach to determining safety Precautionary principle approach:(~ Guilty until proven innocent approach)the government, scientists, and the public are required to prove a product is dangerousAssume substances are harmful until they are proven harmlessIdentifies troublesome toxicants before they are releasedBut, this may impede the pace of technology and economic advance
53 Two approaches to determining safety Innocent until proven guilty approach:Guilty until proven innocent approach:(Precautionary principle approach)the government, scientists, and the public are required to prove a product is dangerousAssume substances are harmful until they are proven harmlessIdentifies troublesome toxicants before they are releasedBut, this may impede the pace of technology and economic advance
55 Philosophy affects policy Different nations use different policies; most use a mix between the “innocent until proven guilty” principle and the precautionary principleEurope is shifting more towards the precautionary principleIndustries like the “innocent until proven guilty” approach because it allows them to produce more and make more money
56 The EPA regulates many substances Federal agencies apportion responsibility for tracking and regulating synthetic chemicalsFDA: food, food additives, cosmetics, drugs, and medical devicesEPA: pesticidesOccupational Safety and Health Administration (OSHA): workplace hazardsMany public health and environmental advocates fear it isn’t enoughMany synthetic chemicals are not actually testedOnly 10% have been tested for toxicityFewer than 1% are government regulated
57 International regulation Nations address chemical pollution with international treatiesStockholm Convention on Persistent Organic Pollutants (POPs) was ratified by 140 nations in 2004Ends the release of the 12 most dangerous POPs“ The Dirty Dozen” (Table 14.3, p407)8 pesticides and othersEU’s Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) ProgramAims to evaluate and restrict dangerous chemicals while giving industries a streamlined regulatory systemIt will cost the chemical industry 2.8 – 5.2 billion euros (U.S. $3.8 – 7.0 billion), but will save more than 10 times that in health benefits(End, 11/04/2008)
58 ConclusionInternational agreements represent a hopeful sign that governments are working to protect society, wildlife, and ecosystems from toxic chemicals and environmental hazardsOnce all the scientific results are in, society’s philosophical approach to risk management will determine what policies are enactedA safe and happy future depends on knowing the risks that some hazards pose and on replacing those substances with safer ones
59 QUESTION: Review Which of the following is a biological hazard? EarthquakeSmokingVirusA pesticideAll are biological hazardsAnswer: c
60 QUESTION: Review A “vector” is defined as … A highly toxic, radioactive compoundAn organism that transfers pathogens to a hostA compound with fire-retardant propertiesA compound that mimics natural substancesAnswer: b
61 QUESTION: Review Toxicity is … The study of the effects of poisonous substancesAny toxic agentAny substance that causes environmental degradationThe degree of harm a substance can causeAnswer: d
62 QUESTION: Review A “teratogen” causes…? Cancer Mutations Birth defects Problems in the hormonal systemAnswer: c
63 QUESTION: ReviewWhy is research into endocrine disrupters controversial?Negative findings threaten the industry’s economicsResearch is still only beginningMuch research is funded by industryAll of these are reasons why research is controversialAnswer: d
64 QUESTION: ReviewA human-based study that compares a group of smokers to non-smokers to determine the effects of smoking is …An epidemiological studyA case studyNot likely to be fundedNot going to tell about future risksAnswer: a
65 QUESTION: Interpreting Graphs and Data Our perception, and the reality, of risk often do not match. Given this graph (reality), and your knowledge of sources of anxiety (perception), which statement is correct?Smoking is very dangerous and we are very anxious about itSmoking is not dangerous, but we are very anxious about itAirplane accidents are dangerous, and we are very anxious about itAirplane accidents are not dangerous, but we are very anxious about itAnswer: d
66 Smoking is very dangerous and we are very anxious about it Our perception, and the reality, of risk often do not match. Given this graph (reality), and your knowledge of sources of anxiety (perception), which statement is correct?Smoking is very dangerous and we are very anxious about itSmoking is not dangerous, but we are very anxious about itAirplane accidents are dangerous, and we are very anxious about itAirplane accidents are not dangerous, but we are very anxious about itAnswer: d
67 QUESTION: Interpreting Graphs and Data If the “low” dose = 5 units of a chemical, the “medium” dose = 10 units, and the “high” dose = 15 units, how much of the chemical is required to kill 50% of the study population?About 5 unitsAbout 10 unitsAbout 15 unitsYou can’t tell from the graphAnswer: bFrom The Science behind the Stories
68 QUESTION: ViewpointsIs it unethical for a country that has banned a chemical to manufacture and export it to other countries?Yes; if we won’t have it in the U.S., we shouldn’t make itYes, but the money we get from selling it will help our economyNo; let people decide what they want to doNo; in fact, chemicals should not be banned in the U.S. eitherAnswer: any
69 QUESTION: ViewpointsShould the government follow the precautionary principle and force industries to prove their products are safe?Absolutely; it is up to industry to prove its chemicals are safeMaybe, if it is not too expensiveNo; let the government and scientists prove a chemical is dangerous before it is taken off the marketNo, as long as the product makes money and jobs for the industry, it should be allowedAnswer: any
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