2 RISKS AND HAZARDSRisk is a measure of the likelihood that you will suffer harm from a hazard.We 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.
3 RISKS AND HAZARDSRisk is a measure of the likelihood that you will suffer harm from a hazard.Distinguish betweenPossibilityProbabilityRisk assessmentScientific process to estimate harmRisk managementHow to reduce risk levels
4 Hazard identification Comparative risk analysis Risk AssessmentRisk ManagementHazard identificationComparative risk analysisWhat is the hazard?How does it compare with other risks?Risk reductionHow much should it be reduced?Probability of riskHow likely is the event?Risk reduction strategyHow will the risk be reduced?Figure 18.3Science: risk assessment and risk management.Consequences of riskFinancial commitmentWhat is the likely damage?How much money should be spent?Fig. 18-3, p. 419
5 DISEASE Transmissible or infectious diseases Nontransmissible disease Caused by living organisms such as bacteria and virusesCan spread from person to personFlu, strep throat, monoNontransmissible diseaseNot caused by living organismsCan not spread from one person to anotherHeart disease, asthma
6 Transmissible Disease Pathway for infectious disease in humans.Figure 18-4
7 Transmissible Disease WHO estimates that each year the world’s seven deadliest infections kill 13.6 million people – most of them the poor in developing countries.Figure 18-5
9 Vocabulary Endemic – native to area Mortality – rate of death Morbidity – rate of sickness or ill effectDisease Vector – transmits disease through biteEpidemic – large outbreak in one area or countryPandemic – global outbreakAcute – immediate, usually brief & severeChronic – long duration, usually less severeSynergistic – combined effect is greater than sum of individual effects.
10 Genetic Resistance to Antibiotics Bacteria reproduce quickly: up to 16 million offspring in 24 hoursCan quickly become resistance through natural selection & exchanging genetic materialInternational travel and global tradeOver use of pesticides: increases resistance in disease carrying pestsOver use of antibiotics in humans and livestockOver ½ prescribed unnecessarily
11 Case Study: The Growing Global Threat from Tuberculosis Tuberculosis (TB) – highly infectious.Kills 1.7 million people per year and could kill 25 million peopleRecent increases in TB are due to:Lack of TB screening and control programs especially in developing countries due to cost.Genetic resistance to the most antibiotics.In US Health dept investigates new casesRequires compliance: 6 months drug therapy
12 Viral Diseases – Big 3 Flu, HIV / AIDS hepatitis B infect and kill many more people each year then highly publicized West Nile and SARS viruses.
13 Flu 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.
14 Highly Potent Flu Strains Some strain more virulent than others – can kill 80% of infectedSpanish Flu – killed 50 millionAsian Flu (1957) & Hong Kong Flu(1968) – killed 1 million eachBird and Swine Flu more recentlyNew strain could kill 2 – 360 million peopleOnly a matter of time
15 The Global HIV/AIDS Epidemic According to World Health Organization (WHO), in 2005 about 42 million people worldwide (1.1 million in the U.S.) were infected with HIV.By 2005, 25 million deathsEach year: 3 million more deaths
16 HIV/AIDS EpidemicAIDS has reduced the life expectancy of sub-Saharan Africa from 62 to 47 – 40 years in the seven countries most severely affected by AIDS.Lose ½ adult pop in 10 yrs15 million AIDS orphansProjected age structure of Botswana's population in 2020…dramatically altered population pyramidFigure 18-2
17 HIV/AIDSThe virus itself is not deadly, but it cripples the immune system, leaving the body susceptible to infections such as Kaposi’s sarcoma (above).There is no vaccine for HIV – if you get AIDS, you will eventually die from it.Drugs help some infected people live longer, but only a tiny fraction can afford them.
18 HIV / AIDSHIV is the second biggest killer virus worldwide. Five major priorities to slow the spread of the disease are:Quickly reduce the number of new infections to prevent further spread.Concentrate on groups in a society that are likely to spread the disease.Provide free HIV testing and pressure people to get tested.Implement educational programs.Provide free or low-cost drugs to slow disease progress.
20 Emerging Viral Diseases SARSOutbreak in China 2002Severe acute respiratory syndromeSpreads quicklyLife threatening pneumoniaWest NileRecent increase in TXArial spraying for mosquitoesMost people never even know they had it2004: flu killed 36,000west nile killed 100
21 Malaria – Death by Mosquito Malaria kills about 2 million people per yearMajority that die are childrenKilled more than all of the wars ever fought.Figure 18-7
22 Malaria – Death by Mosquito Cycles of Fever, chills, sweatingWeaknessComaCan relapseMany survivors: permanently impaired
23 Malaria – Death by Mosquito Cases had declined during 1950’s and 60’sSince 1970’s: come roaring backDDT bannedMosquitoes: Increased resistance to pesticides currently usedParasites (Plasmodium): Increased resistance to antimalarial drugsClimate change: increasing range
24 Malaria – Death by Mosquito No vaccinePrevention keyWindow screens, bed nets, clear vegetation, standing water, larva eating fishSpraying 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.Take prophylactic medicine if traveling to endemic areas
25 Malaria – Death by Mosquito 40% of world’s pop live in area where malaria is prevalent
26 Infectious DiseasesMajority of children in develop nations are vaccinatedTenanusMeaslesDiphtheriaTyphoid feverMeningitisPolioPertussisCases have been increasing due to more parents not vaccinatingAccess to healthcare / costAutism scareStudies have shown no correlationFewer vaccinated = increased risk for all
27 Ecological Medicine and Infectious Diseases infectious diseases are moving across species at increasing ratesAIDS: tribesmen eating bush meat (chimps)Mad Cow: feeding sheep parts to cowsLyme disease, hantavirus, SARS, swine/bird fluCaused by crowding, resistance, global trade, poverty, malnutrition, habitat destructionEcological (conservation) medicine tracks down these connections between wildlife and humans to determine ways to slow and prevent disease spread.
28 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 18.8Solutions: 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?Careful hand washing by all medical personnelImmunize children against major viral diseasesOral rehydration for diarrhea victimsGlobal campaign to reduce HIV/AIDSFig. 18-8, p. 424
29 CHEMICAL HAZARDSToxic chemical can cause temporary or permanent harm or deathA hazardous chemical can harm humans or other animals because it:Is flammableIs explosiveAn irritantInterferes with oxygen uptakeInduce allergic reactions.
30 CHEMICAL HAZARDSA toxic chemical can cause temporary or permanent harm or death.Mutagens are chemicals or forms of radiation that cause or increase the frequency of mutations in DNA.Teratogens are chemicals that cause harm or birth defects to a fetus or embryo.Carcinogens are chemicals or types of radiation that can cause or promote cancer.
31 Effects of Chemicals on the Immune, Nervous, and Endocrine Systems Long-term exposure to some chemicals at low doses may disrupt the body’s systems:Immune system:Nervous system:Endocrine system:
32 Immune Systemspecialized cells and tissues that protect the body against disease and harmful substances. (arsenic, dioxins)Disrupting would leave body vulnerable to infectionArsenic & dioxins
33 Nervous System brain, spinal cord, neurons, and peripheral nerves. Damage can cause: behavior changes, learning disabilities, retardation, attention deficit disorder, paralysis, deathNeurotoxins: PCBs, Mercury, arsenic, lead, some pesticides
34 Endocrine SystemComplex network of glands that release hormones into the bloodstream.These hormones control metabolism, growth, sexual production, learning ability, behaviorChemicals can mimic our natural hormones and impair correct functionProblems include: gender bender, thyroid, brain, growth, behavior disorders, cancer, birth defectsBisphenol-A (BPA) & Phthalates: leach from plastics – found in 95% of AmericansDDT, PCBs, atrazine, aluminum, mercury
35 Effects onEndocrine Systems Molecules of certain synthetic chemicals have shapes similar to those of natural hormones and can adversely affect the endocrine system.Figure 18-9
36 A Black Day in Bhopal, India The 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 died50,000 – 60,000 permanent serious injury: blindness, lung damage, neurological problemsIndian officials claim that simple upgrades could have prevented the tragedy.
37 TOXICOLOGY: ASSESSING CHEMICAL HAZARDS Toxicity is a measure of how harmful a substance is – depends on:The amount of exposure - doseThe frequency of exposure - how oftenThe person who is exposed - adult or childThe effectiveness of the body’s detoxification systems - do your liver & kidneys work wellOne’s genetic makeup - some people have a higher sensitivity
38 TOXICOLOGY: ASSESSING CHEMICAL HAZARDS Typical variations in sensitivity to a toxic chemical within a population, mostly because of genetic variation.Figure 18-10
39 Other Factors Solubility: Water or fat Persistence: how long does it hang around in the environmentBioaccumulation – concentrated in tissueBiomagnification – concentration increases as you move up food chain (trophic levels)Chemical interactions:Antagonistic – reduces harm (antioxidents)Synergistic – increases harm (2+2=5)
40 TOXICOLOGY: ASSESSING CHEMICAL HAZARDS Children are more susceptible to the effects of toxic substances because:Children breathe more air, drink more water, and eat more food per unit of body weight than adults.They are exposed to toxins when they put their fingers or other objects in their mouths.Children usually have less well-developed immune systems and detoxification processes than adults.
41 Protecting Children from Toxic Chemicals The U.S. Environmental Protection Agency proposed that regulators should assume children have 10 times the exposure risk of adults to cancer-causing chemicals.Some health scientists contend that regulators should assume a risk 100 times that of adults.
42 Dose is the poisonAny substance, natural or synthetic, can be harmful if ingested in large enough doseWater, saltResponse: health damage from exposureAcuteChronicShould we be concerned with increasing number of chemicals all around us?Even at trace amountsWe lack enough data to assess risk
43 Total health burden is difficult to quantify: Very complex model: Water pollutant levelsAir pollutant levelsSoil/dust levelsFood pesticide levelsTotal healthburden isdifficult toquantify:Very complexmodel:Many variablesNutritional health?Mathematical measurements & modelingOverall healthLifestyleFigure 18.11Science: estimating human exposure to chemicals and their effects is very difficult because of the many and often poorly understood variables involved. QUESTION: Which three of these factors do you think make you more vulnerable to the harmful effects of chemicals?Predicted level of toxicant in peoplePersonal habitsMetabolismGenetic predispositionAccumulationExcretionLung, intestine & skin absorption ratesFig , p. 431
44 TOXICOLOGY: ASSESSING CHEMICAL HAZARDS Under existing laws, most chemicals are considered innocent until proven guilty, and estimating their toxicity is difficult, uncertain, and expensive.Federal and state governments do not regulate about 99.5% of the commercially used chemicals in the U.S.
45 TOXICOLOGY: ASSESSING CHEMICAL HAZARDS Some scientists and health officials say that preliminary but not conclusive evidence that a chemical causes significant harm should spur preventive action (precautionary principle).Manufacturers contend that wide-spread application of the precautionary principle would make it too expensive to introduce new chemicals and technologies.
46 Risk Analysis Risk assessment - identify Comparative risk analysis - rankRisk management – plan to reduce risksRisk communication – inform public and policy makers
47 RISK ANALYSIS – World Cause of death Annual deaths 11 million (75) Poverty/malnutrition/ disease cycleTobacco5 million (34)Pneumonia and flu3.2 million (22)Air pollution3 million (21)HIV/AIDS3 million (21)Malaria2 million (14)Diarrhea1.9 million (13)Tuberculosis1.7 million (12)Figure 18.13Global outlook: number of deaths per year in the world from various causes. Numbers in parentheses give these deaths in terms of the number of fully loaded 400-passenger jumbo jets crashing every day of the year with no survivors. Because of sensational media coverage, most people have a distorted view of 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)Car accidents1.2 million (8)Work-related injury & disease1.1 million (8)Hepatitis B1 million (7)Measles800,000 (5)Parentheses ( ) show deaths in terms of the number of fully loaded 400-passenger jumbo jets crashing every day of the year with no survivors.
48 RISK ANALYSIS - USAnnual deaths in the U.S. from tobacco use and other causes in 2003.
49 Perceiving RiskMost individuals evaluate the relative risk they face based on:Degree of control.Fear of unknown.Whether we voluntarily take the risk.Whether risk is catastrophic.Unfair distribution of risk.Sometimes misleading information, denial, and irrational fears can cloud judgment.
50 Assessing Risk People will do high risk things they enjoy: Motorcycle: 1 death per 50Driving: 1 death per 3,300But will be terrified of low risk:Nuclear accident: 1 death in 200,000Air plane crash: 1 death in 9 million
51 HazardShortens average life span in the U.S. byPoverty7–10 yearsBorn male7.5 yearsSmoking6–10 yearsOverweight (35%)6 yearsUnmarried5 yearsOverweight (15%)2 yearsSpouse smoking1 yearDriving7 monthsAir pollution5 monthsRisk Analysis: Comparison of risks people face expressed in terms of shorter average life span.Alcohol5 monthsDrug abuse4 monthsFlu4 monthsAIDS3 monthsDrowning1 monthPesticides1 monthFigure 18.14Global outlook: comparison of risks people face, expressed in terms of shorter average life span. After poverty and gender, the greatest risks people face come mostly from the lifestyle choices they make. These are merely generalized relative estimates. Individual responses to these risks can differ because of factors such as genetic variation, family medical history, emotional makeup, stress, and social ties and support. QUESTION: Which three of these items are most likely to shorten your life span? (Data from Bernard L. Cohen)Fire1 monthNatural radiation8 daysMedical X rays5 daysOral contraceptives5 daysToxic waste4 daysFlying1 dayHurricanes, tornadoes1 dayLifetime near nuclear plant10 hoursFig , p. 436
52 Risk Analysis & Management 1. Recognize everything is risky2. Recognize media exaggerates risk3. Compare risks rationally: nitrites can cause cancer, but an occasional hotdog will not be what kills you4. Concentrate on most serious risks you can controlEat right, exercise, don’t smoke, drive safely, wear your seat belt, use sunscreen,
53 RISK ANALYSISComparisons of risks people face expressed in terms of shorter average life span.Figure 18-14