Presentation on theme: "Environmental Hazards and Human Health"— Presentation transcript:
1 Environmental Hazards and Human Health Chapter 17
2 Core Case Study: The Global HIV/AIDS Epidemic Acquired immune deficiency syndrome (AIDS) caused by human immunodeficiency virus (HIV); many secondary infectionsNo vaccine to prevent or cure AIDSExpensive drugs—live longer25 Million deaths, so far; alter country’s age structure
4 Global Outlook: Worldwide, AIDS Is the Leading Cause of Death for Ages 15–49
5 Population (thousands) 100+95–9990–9485–8980–8475–7970–7465–6960–6455–59MalesFemales50–54Age45–4940–4435–3930–3425–2920–24Figure 17.2Global outlook: Worldwide, AIDS is the leading cause of death for people of ages 15–49. This loss of productive working adults affects the age structure of a population. In Botswana, more than 24% of this age group is infected with HIV. This figure shows the projected age structure of Botswana’s population in 2020 with and without AIDS. (Data from the U.S. Census Bureau) Question: How might this affect Botswana’s economic development?15–1910–145–90–4120402020 406080100120Population (thousands)With AIDSWithout AIDSFig. 17-2, p. 438
6 17-1 What Major Health Hazards Do We Face? Concept People face health hazards from biological, chemical, physical, and cultural factors, and from the lifestyle choices they make.
7 Risks Are Usually Expressed as Probabilities Probability and possibilityRisk AssessmentRisk Management
9 Risk Assessment Risk Management Hazard identification What is the hazard?Comparative risk analysisHow does it compare with other risks?Risk reductionHow much should it be reduced?Probability of risk How likely is the event?Risk reduction strategyHow will the risk be reduced?Figure 17.3Science: risk assessment and risk management. Question: What is an example of how you have applied this process in your daily living?Consequences of riskWhat is the likely damage?Financial commitmentHow much money should be spent?Fig. 17-3, p. 440
10 We Face Many Types of Hazards Five major types of hazardsBiological: pathogensChemicalPhysicalCulturalLifestyle choices
11 17-2 What Types of Biological Hazards Do We Face? Concept In terms of death rates, the most serious infectious diseases are flu, AIDS, diarrheal diseases, malaria, and tuberculosis; most of these deaths occur in developing countries.
12 Some Diseases Can Spread from One Person to Another (1) Nontransmissible diseaseInfectious diseaseTransmissible disease (contagious or communicable disease)
13 Some Diseases Can Spread from One Person to Another (2) Since 1950, death from infectious diseases have declined due toBetter health careAntibioticsVaccinesDisability-adjusted life years (DALYs)
14 Major Causes of Death in the World and in the United States in 2005
15 Cardiovascular disease World30%Cardiovascular diseaseUnited States39%World30%Infectious diseasesUnited States7%Figure 17.4Major causes of death in the world and in the United States in Questions: Why do you think that a higher percentage of the people in the United States die of cardiovascular disease than in the world? Why do you think that a much higher percentage of people in the world die from infectious diseases than in the United States? (Data from the World Health Organization and the U.S. Centers for Disease Control and Prevention)World17%CancersUnited States23%Fig. 17-4, p. 441
16 Cardiovascular disease World30%Cardiovascular diseaseUnited States39%World30%Infectious diseasesUnited States7%Figure 17.4Major causes of death in the world and in the United States in Questions: Why do you think that a higher percentage of the people in the United States die of cardiovascular disease than in the world? Why do you think that a much higher percentage of people in the world die from infectious diseases than in the United States? (Data from the World Health Organization and the U.S. Centers for Disease Control and Prevention)World17%CancersUnited States23%Stepped ArtFig. 17-4, p. 441
17 Infectious Diseases Are Still Major Health Threats Infectious diseases spread throughAirWaterFoodBody fluidsEpidemics and pandemicsResistance of bacteria and insects
18 Science: Pathways for Infectious Diseases in Humans
19 Wild animals Pets Livestock Insects Food Water Air Fetus and babies Figure 17.5Science: pathways for infectious disease in humans. Question: Can you think of other pathways not shown here?Fetus and babiesOther humansHumansFig. 17-5, p. 441
20 The World’s Seven Deadliest Infectious Diseases Kill 12 The World’s Seven Deadliest Infectious Diseases Kill 12.5 Million People
21 (bacteria and viruses) 3.2 million Disease(type of agent)Deaths per yearPneumonia and flu(bacteria and viruses)3.2 millionHIV/AIDS (virus)2.1 millionDiarrheal diseases (bacteria and viruses)1.9 millionTuberculosis (bacteria)1.7 millionFigure 17.6Global outlook: The World Health Organization estimates that each year, the world’s seven deadliest infectious diseases kill 12.5 million people—most of them poor people in developing countries (Concept 17-2). This amounts to an average of about 34,200 mostly preventable deaths every day. Question: How many people, on average, die prematurely from these diseases every hour? (Data from the World Health Organization, 2007)Malaria(protozoa)1 millionHepatitis B(virus)1 millionMeasles(virus)800,000Fig. 17-6, p. 442
22 (bacteria and viruses) 3.2 million Disease(type of agent)Deaths per yearPneumonia and flu(bacteria and viruses)3.2 millionHIV/AIDS (virus)2.1 millionDiarrheal diseases (bacteria and viruses)1.9 millionTuberculosis (bacteria)1.7 millionFigure 17.6Global outlook: The World Health Organization estimates that each year, the world’s seven deadliest infectious diseases kill 12.5 million people—most of them poor people in developing countries (Concept 17-2). This amounts to an average of about 34,200 mostly preventable deaths every day. Question: How many people, on average, die prematurely from these diseases every hour? (Data from the World Health Organization, 2007)Malaria(protozoa)1 millionHepatitis B(virus)1 millionMeasles(virus)800,000Stepped ArtFig. 17-6, p. 442
23 Science Focus: Genetic Resistance to Antibiotics Is Increasing (1) Bacteria: rapid reproduction, easily spreadOver use of antibioticsOver use of pesticides
24 Science Focus: Genetic Resistance to Antibiotics Is Increasing (2) Methicillin-resistant Staphylococcus aureus (MRSA)Resistant to most antibioticsSymptoms of MRSAHow will it be controlled?
25 Case Study: The Growing Global Threat from Tuberculosis Why is tuberculosis on the rise?Not enough screening and control programsGenetic resistance to a majority of effective antibioticsPerson-to-person contact has increasedAIDS individuals are very susceptible to TB
26 Some Viral Diseases Kill Large Numbers of People (1) Influenza or flu virus#1 KillerTransmissionHIV#2 KillerAntiviral drugs
27 Some Viral Diseases Kill Large Numbers of People (2) Global strategy to slow down the spread of HIVReduce the number of new infectionsConcentrate on those most likely to spread HIVFree testingEducation for preventionProvide free or low-cost drugsResearch
28 Some Viral Diseases Kill Large Numbers of People (3) Hepatitis B virus (HBV)#3 KillerMode of transmissionViruses that move form animals to humansWest Nile virusSevere acute respiratory syndrome (SARS)Reduce chances of infection: Wash your hands
29 Tracking the Spread of Infectious Diseases to Humans from Other Animals Ecological medicineHuman practices that encourage the spread of diseases from animals to humansEmerging infectionsHIVSARSWest Nile virusLyme virus
30 Case Study: Malaria—Death by Parasite-Carrying Mosquitoes (1) Caused by Plasmodium sp. carried by Anopheles mosquitoesSpreadSymptomsMalarial cycle
31 Case Study: Malaria—Death by Parasite-Carrying Mosquitoes (2) Malaria on the rise since 1970Drug resistant PlasmodiumInsecticide resistant mosquitoesEffect of global warmingAIDS patients particularly vulnerablePrevention of spread and current research
33 A Boy in Brazil’s Amazon Sleeps Under an Insecticide-Treated Mosquito Net
34 We Can Reduce the Incidence of Infectious Diseases Good newsVaccinations on the riseOral rehydration therapyBad newsMore money needed for medical research in developing countries
35 Solutions: Infectious Diseases, Ways to Prevent or Reduce Their Occurrence
36 SOLUTIONS Infectious Diseases Increase research on tropical diseases and vaccinesReduce povertyDecrease malnutritionImprove drinking water qualityReduce unnecessary use of antibioticsEducate people to take all of an antibiotic prescriptionReduce antibiotic use to promote livestock growthFigure 17.10Solutions: ways to prevent or reduce the incidence of infectious diseases, especially in developing countries. Question: Which three of these approaches do you think are the most important?Require careful hand washing by all medical personnelImmunize children against major viral diseasesProvide oral rehydration for diarrhea victimsConduct global campaign to reduce HIV/AIDSFig , p. 447
45 17-3 What Types of Chemical Hazards Do We Face? Concept There is growing concern about chemicals that can cause birth defects and cancers and disrupt the human immune, nervous, and endocrine systems.
46 Some Chemicals Can Cause Cancers, Mutations, and Birth Defects Toxic chemicalsCarcinogensMutagensTeratogens
47 Case Study: PCBs Are Everywhere—A Legacy from the Past Class of chlorine-containing compoundsVery stableNonflammableBreak down slowly in the environmentTravel long distances in the airFat solubleBiomagnificationFood chains and websBanned, but found everywhere
48 Potential Pathways on Which Toxic Chemicals Move Through the Environment
49 Atmosphere Vegetation Crops Surface water Humans Animals Surface water FishGroundwaterWater tableVegetationGroundwaterFigure 17.11Potential pathways on which toxic chemicals move through the living and nonliving environment.SoilRockWater tableRockFig , p. 449
50 Some Chemicals May Affect Our Immune, Nervous, and Endocrine Systems (1) Some natural and synthetic chemicals in the environment can weaken and harmImmune systemNervous systemEndocrine system
51 Some Chemicals May Affect Our Immune, Nervous, and Endocrine Systems (2) Hormonally active agents (HAAs)Gender bendersThyroid disruptersToxic chemicalsPhthlatesEffects on the endocrine systemCancer
52 Science Focus: Mercury’s Toxic Effects (1) Hg: teratogen and potent neurotoxinOnce airborne, persistent and not degradable1/3 from natural sources2/3 from human activitiesEnters the food chain: biomagnification
53 Science Focus: Mercury’s Toxic Effects (2) 2007: Hg hotspots identifiedHow are humans exposed?Inhalation: vaporized Hg or particulates of inorganic saltsEating fish with high levels of methylmercuryEffects of Hg on humansWho is most at risk?
54 Science: Cycling of Mercury in Aquatic Environments
55 Photo-chemical oxidation WINDSPRECIPITATIONWINDSPRECIPITATIONHg and SO2Hg2+ and acidsHg2+ and acidsPhoto-chemical oxidationHuman sourcesElemental mercury vapor(Hg)Inorganic mercury and acids(Hg2+)Inorganic mercury and acids(Hg2+)Coal-burning plantIncineratorDepositionRunoff of Hg2+ and acidsDepositionDepositionLarge fishVaporizationSmall fishBIOMAGNIFICATION IN FOOD CHAINZooplanktonPhytoplanktonFigure 17.AScience: cycling of mercury in aquatic environments, in which mercury is converted from one form to another. The most toxic form to humans is methylmercury (CH3Hg+), which can be biologically magnified in aquatic food chains and webs. Some mercury is also released back into the atmosphere as mercury vapor.Bacteria and acidsElemental mercury liquid (Hg)OxidationInorganic mercury (Hg2+)Organic mercury (CH3Hg+)BacteriaSettles outSettles outSettles outSEDIMENTFig. 17-A, p. 450
57 SOLUTIONS Mercury Pollution Prevention Control Phase out waste incinerationSharply reduce mercury emissions from coal-burning plants and incineratorsRemove mercury from coal before it is burnedSwitch from coal to natural gas and renewable energy resources such as wind, solar cells, and hydrogenTax each unit of mercury emitted by coal-burning plants and incineratorsConvert coal to liquid or gaseous fuelFigure 17.BWays to prevent or control inputs of mercury into the environment from human sources—mostly coal-burning power plants and incinerators. Question: Which four of these solutions do you think are the most important?Require labels on all products containing mercuryPhase out use of mercury in batteries, TVs, compact fluorescent lightbulbs, and all other products unless they are recycledCollect and recycle mercury-containing electric switches, relays, and dry-cell batteriesFig. 17-B, p. 451
59 Normal Hormone Process Hormone Mimic Hormone Blocker Estrogen-like chemicalAntiandrogen chemicalReceptorCellFigure 17.12Hormones are molecules that act as messengers in the endocrine system to regulate various bodily processes, including reproduction, growth, and development. Each type of hormone has a unique molecular shape that allows it to attach to specially shaped receptors on the surfaces of, or inside, cells and to transmit its chemical message (left). Molecules of certain pesticides and other synthetic chemicals have shapes similar to those of natural hormones and can disrupt the endocrine systems in humans and other animals (center and right). These molecules are called hormonally active agents (HAAs). Because of the difficulty of determining the harmful effects of long-term exposure to low levels of HAAs, there is uncertainty about their effects on human health.Normal Hormone ProcessHormone MimicHormone BlockerFig , p. 452
60 Normal Hormone Process Hormone Mimic Hormone Blocker Estrogen-like chemicalAntiandrogen chemicalReceptorCellFigure 17.12Hormones are molecules that act as messengers in the endocrine system to regulate various bodily processes, including reproduction, growth, and development. Each type of hormone has a unique molecular shape that allows it to attach to specially shaped receptors on the surfaces of, or inside, cells and to transmit its chemical message (left). Molecules of certain pesticides and other synthetic chemicals have shapes similar to those of natural hormones and can disrupt the endocrine systems in humans and other animals (center and right). These molecules are called hormonally active agents (HAAs). Because of the difficulty of determining the harmful effects of long-term exposure to low levels of HAAs, there is uncertainty about their effects on human health.Normal Hormone ProcessHormone MimicHormone BlockerStepped ArtFig , p. 452
61 Science Focus: Bisphenol A Estrogen mimicFound in many common productsLaboratory findingsEffects on human healthShould it be banned?
62 17-4 How Can We Evaluate and Deal with Chemical Hazards? Concept 17-4A Scientists use live laboratory animals, non-animal tests, case reports of poisonings, and epidemiological studies to estimate the toxicity of chemicals, but these methods have limitations.Concept 17-4B Many health scientists call for much greater emphasis on pollution prevention to reduce our exposure to potentially harmful candidates.
63 Many Factors Determine the Harmful Health Effects of a Chemical (1) ToxicologyToxicity dependent onDoseAgeGenetic makeupMultiple chemical sensitivity (MCS)Solubility and persistence of the chemicalBiomagnification
64 Many Factors Determine the Harmful Health Effects of a Chemical (2) ResponseAcute effectChronic effect
65 Science: Estimating Human Exposure to Chemicals and Measuring Their Effects
66 Water pollutant levels Scientific measurements and modeling Air pollutant levelsSoil/dust levelsFood pesticide levelsNutritional healthOverall healthScientific measurements and modelingLifestyleFigure 17.13Science: Estimating human exposure to chemicals and measuring their effects are very difficult because of the many and often poorly understood variables involved. Question: What three of these factors might make you more vulnerable to the harmful effects of chemicals?Predicted level of toxicant in peoplePersonal habitsMetabolismGenetic predispositionAccumulationExcretionLung, intestine, and skin absorption ratesFig , p. 454
67 Case Study: Protecting Children from Toxic Chemicals Analysis of umbilical cord blood: significanceInfants and children more susceptible to the toxic effects of chemicals than adultsEat, drink water, and breathe more per unit of body weight than adultsPut their fingers in their mouthsLess well-developed immune systems and body detoxification processes
68 Scientists Use Live Lab Animals and Nonanimal Tests to Estimate Toxicity (1) Dose-response curve: median lethal dose (LD50)Nonthreshold dose-response modelThreshold dose-response modelCan the data be extrapolated to humans?
69 Scientists Use Live Lab Animals and Nonanimal Tests to Estimate Toxicity (2) More humane methods using animalsReplace animals with other modelsComputer simulationsTissue culture and individual animal cellsChicken egg membranesWhat are the effects of mixtures of potentially toxic chemicals?
70 Hypothetical Dose-Response Curve Showing Determination of the LD50
71 Percentage of population killed by a given dose 10075Percentage of population killed by a given dose5025Figure 17.14Science: hypothetical dose-response curve showing determination of the LD50, the dosage of a specific chemical that kills 50% of the animals in a test group. Toxicologists use this method to compare the toxicities of different chemicals.LD50246810121416Dose (hypothetical units)Fig , p. 455
72 Toxicity Ratings and Average Lethal Doses for Humans
74 Nonlinear dose-response EffectEffectFigure 17.15Science: two types of dose-response curves. The linear and nonlinear curves in the left graph apply if even the smallest dosage of a chemical has a harmful effect that increases with the dosage. The curve on the right applies if a harmful effect occurs only when the dosage exceeds a certain threshold level. Which model is better for a specific harmful agent is often uncertain and controversial because of the difficulty in estimating the responses to very low dosages?Threshold levelDoseDoseNo thresholdThresholdFig , p. 456
75 There Are Other Ways to Estimate the Harmful Effects of Chemicals Case reports and epidemiological studiesLimitations of epidemiological studiesToo few people testedLength of timeCan you link the result with the chemical?Can not be used for new hazards
76 Are Trace Levels of Toxic Chemicals Harmful? We do not knowAre the dangers increasing or are the tests just more sensitive?
77 Some Potentially Harmful Chemicals Found in Most Homes
78 Perfluorochemicals to add shine ShampooTeddy bearClothingBaby bottlePerfluorochemicals to add shineSome stuffed animals made overseas contain flame retardants and/or pesticidesCan contain perfluorochemicalsCan contain bisphenol-ANail polishPerfluorochemicals and phthalatesMattressFlame retardants in stuffingPerfumePhthalatesCarpetPadding and carpet fibers contain flame retardants, perfluorochemicals, and pesticidesHairsprayPhthalatesFoodSome food contains bisphenol-ATVWiring and plastic casing contain flame retardantsMilkFat contains dioxins and flame retardantsSofaFigure 17.16Some potentially harmful chemicals found in most homes. Most people have traces of these chemicals in their blood and body tissues. We do not know the long-term effects of exposure to low levels of such chemicals. (Data from U.S. Environmental Protection Agency, Centers for Disease Control and Prevention, and New York State Department of Health) Question: Does the fact that we do not know much about long-term harmful effects of these chemicals make you more likely or less likely to minimize your exposure to them? Why?Frying panFoam padding contains flame retardants and perfluorochemicalsNonstick coating contains perfluorochemicalsFruitWater bottleComputerToysTennis shoesTile floorImported fruit may contain pesticides banned in the U.S.Can contain bisphenol-AFlame retardant coatings of plastic casing and wiringVinyl toys contain phthalatesCan contain phthalatesContains perfluorochemicals, phthalates, and pesticidesFig , p. 458
79 Why Do We Know So Little about the Harmful Effects of Chemicals? Severe limitations estimating toxicity levels and risksAcceptable levels vary between 1/100 and 1/1000 of the estimated harmful levels
80 Pollution Prevention and the Precautionary Principle Those introducing a new chemical or new technology would have to follow new strategiesA new product is considered harmful until it can be proved to be safeExisting chemicals and technologies that appear to cause significant harm must be removed2000: global treaty to ban or phase out the dirty dozen (POPs)
81 Individuals Matter: Ray Turner and His Refrigerator 1974: Ozone layer being depleted by chlorofluorocarbons (CFCs)1992: International agreement to phase out CFCs and other ozone-destroying chemicalsRay Turner: citrus-based solvents to clean circuit boards
82 17-5 How Do We Perceive Risks and How Can We Avoid the Worst of Them? Concept We can reduce the major risks we face if we become informed, think critically about risks, and make careful choices.
83 The Greatest Health Risks Come from Poverty, Gender, and Lifestyle Choices Risk analysisGreatest health risksPovertyGenderLifestyle choices
84 Comparative Risk Analysis: Most Serious Ecological and Health Problems
85 Figure 17.17Science: comparative risk analysis of the most serious ecological and health problems, according to scientists acting as advisers to the EPA. Risks under each category are not listed in rank order. Question: Which two risks in each of the two high-risk problem lists do you think are the most serious? Why? (Concept 17-5) (Data from Science Advisory Board, Reducing Risks, Washington, D.C.: Environmental Protection Agency, 1990)Stepped ArtFig , p. 461
86 Global Outlook: Number of Deaths per Year in the World from Various Causes
87 Cause of death Annual deaths Poverty/malnutrition/ disease cycle 11 million (150)Tobacco5.4 million (74)Pneumonia and flu3.2 million (44)Air pollution3 million (41)HIV/AIDS2.1 million (29)Diarrhea1.9 million (26)Tuberculosis1.7 million (23)Automobile accidents1.2 million (16)Figure 17.18Global outlook: number of deaths per year in the world from various causes (Concept 17-5). Numbers in parentheses give these deaths in terms of the number of fully loaded 200-passenger jet airplanes crashing every day of the year with no survivors. Because of sensational media coverage, most people are misinformed about the largest annual causes of death. Question: Which three of these items are most likely to shorten your life span? (Data from World Health Organization)Work-related injury and disease1.1 million (15)Malaria1 million (14)Hepatitis B1 million (14)Measles800,000 (11)Fig , p. 461
88 Comparison of Risks People Face in Terms of Shorter Average Life Span
89 Case Study: Death from Smoking (1) Most preventable major cause of suffering and premature deathNicotine: additiveEffects of passive smoking (secondhand smoke)
90 Case Study: Death from Smoking (2) How to reduce smokingTaxesBanClassify and regulate nicotineEducation
91 Annual Deaths in the U.S. from Tobacco Use and Other Causes in 2004
92 Cause of Death Deaths Tobacco use 442,000 Accidents 101,500 (43,450 auto)Alcohol use85,000Infectious diseases75,000 (17,000 from AIDS)Pollutants/toxins55,000Figure 17.20Annual deaths in the United States from tobacco use and other causes in Smoking is by far the nation’s leading cause of preventable death, causing more premature deaths each year than all the other categories in this figure combined. (Data from U.S. National Center for Health Statistics, the Centers for Disease Control and Prevention, and the U.S. Surgeon General)Suicides30,600Homicides20,622Illegal drug use17,000Fig , p. 463
93 Estimating Risks from Technologies Is Not Easy System reliability = Technological reliability x Human reliabilityTo err is human
94 Most People Do Not Know How to Evaluate Risks FearDegree of controlWhether a risk is catastrophicOptimism biasUnfair distribution of risks
95 Several Principles Can Help Us to Evaluate and Reduce Risk Compare risksDetermine how much you are willing to acceptDetermine the actual risk involvedConcentrate on evaluating and carefully making important lifestyle choices