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Environmental Hazards and Human Health Chapter 17.

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Presentation on theme: "Environmental Hazards and Human Health Chapter 17."— 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 infections In 2007, ~60,000 people in the US infected No vaccine to prevent or cure AIDS Expensive drugslive longer, only 90% can afford 25 Million deaths, so far; alter countrys age structure

3 Lesions That Are a Sign of Kaposis Sarcoma

4 Global Outlook: Worldwide, AIDS Is the Leading Cause of Death for Ages 15–49

5 17-1 Risks Are Usually Expressed as Probabilities Risk is the probability of suffering harm from a hazard that cause injury, disease, death, economic loss, or damage Probability (estimate of the likelihood ) and possibility (could happen) Risk Assessment Scientific process of using statistical methods to estimate how much harm a particular hazard can cause to human health Risk Management Involves deciding whether or how to reduce a particular risk

6 6 © 2004 Brooks/Cole – Thomson Learning 7-10 years Poverty Born male Smoking Overweight (35%) Unmarried Overweight (15%) Spouse smoking Driving Air pollution Alcohol Drug abuse AIDS Drowning Pesticides Fire Natural radiation Medical X rays Oral contraceptives Toxic waste Flying Hurricanes, tornadoes Living lifetime near nuclear plant 6-10 years 5 years 2 years 1 year 7 months 5 months 4 months 3 months 2 months 1 month 8 days 5 days 4 days 1 day 10 hours Flu Air Pollution 6 years 5 months 1 month 7.5 years Hazard Shortens average life span in the United States by

7 We Face Many Types of Hazards Five major types of hazards Biological: pathogens Chemical: harmful chemicals in air, water, soil Physical: fire, earthquakes, floods, storms Cultural: criminal assault, poverty, working conditions Lifestyle choices: smoking, drinking, eating too much, unsafe sex

8 17-2 Some Diseases Can Spread from One Person to Another Nontransmissible disease Cardiovascular disease, cancer, asthma, diabetes Transmissible disease (contagious or communicable disease) Caused by a pathogen (bacteria, virus or parasite) that invades the body transmitted from one person to the next Flu, HIV, malaria, measles

9 Some Diseases Can Spread from One Person to Another Since 1950, death from infectious diseases have declined due to Better health care Antibiotics Vaccines

10 Infectious Diseases Are Still Major Health Threats Infectious diseases spread through Air Water Food Body fluids Epidemics (area or country) and pandemics (global) Resistance of bacteria and insects

11 Science Focus: Genetic Resistance to Antibiotics Is Increasing Bacteria: rapid reproduction, easily spread Over use of antibiotics

12 Science Focus: Genetic Resistance to Antibiotics Is Increasing Methicillin-resistant Staphylococcus aureus (MRSA)

13 Case Study: The Growing Global Threat from Tuberculosis Effects ~9.2 million people per year Kills 1.7 million a year (84% in developing countries Why is tuberculosis on the rise? Not enough screening and control programs Genetic resistance to a majority of effective antibiotics Person-to-person contact has increased AIDS individuals are very susceptible to TB

14 1/1/ Deaths per 100,000 people < Current tuberculosis epidemic

15 Some Viral Diseases Kill Large Numbers of People Influenza or flu virus #1 Killer Transmission HIV #2 Killer Antiviral drugs

16 Some Viral Diseases Kill Large Numbers of People Global strategy to slow down the spread of HIV Reduce the number of new infections Concentrate on those most likely to spread HIV Free testing Education for prevention Provide free or low-cost drugs Research

17 Some Viral Diseases Kill Large Numbers of People Hepatitis B virus (HBV) #3 Killer Mode of transmission Viruses that move form animals to humans West Nile virus Severe acute respiratory syndrome (SARS) Reduce chances of infection: Wash your hands

18 Case Study: MalariaDeath by Parasite- Carrying Mosquitoes Malaria on the rise since 1970 Drug resistant Plasmodium Insecticide resistant mosquitoes Effect of global warming AIDS patients particularly vulnerable

19 1/1/ Anopheles mosquito (vector) in aquatic breeding area 1. Female mosquito bites infected human, ingesting blood that contains Plasmodium gametocytes 4. Parasite invades blood cells, causing malaria and making infected person a new reservoir 3. Mosquito injects Plasmodium sporozoites into human host 2. Plasmodium develops in mosquito eggs larva pupa adult The Life Cycle of malaria

20 1/1/ Malaria Endemic in more than 100 countries. Caused by four protozoa species. 270–500 million new cases and 1 million deaths per year. Malaria

21 We Can Reduce the Incidence of Infectious Diseases Good news Vaccinations on the rise Oral rehydration therapy- only a few cents per person Used to prevent dehydration million deaths from dehydration million deaths from dehydration Bad news More money needed for medical research in developing countries

22 1/1/ Disease (type of agent) 3.2 million Pneumonia and flu (bacteria and viruses) HIV/AIDS (virus) Diarrheal diseases (bacteria and viruses) Tuberculosis (bacteria) Malaria (protozoa) Hepatitis B (virus) Measles (virus) Deaths per year 3.0 million 1.9 million 1.7 million 1 million 800,000

23 17-3 Some Chemicals Can Cause Cancers, Mutations, and Birth Defects Toxic chemicals Carcinogens- cause cancer Mutagens- change in DNA Teratogens- causes harm or birth defects to a fetus

24 Case Study: PCBs Are EverywhereA Legacy from the Past Class of chlorine-containing compounds polychlorinated biphenyls Very stable Nonflammable Break down slowly in the environment Travel long distances in the air Fat soluble Biomagnification Food chains and webs Banned in 1976, but found everywhere

25 Some Chemicals May Affect Our Immune, Nervous, and Endocrine Systems Some natural and synthetic chemicals in the environment can weaken and harm Immune system Are weakened arsenic, methyl mercury, dioxins Nervous system PCBs, methyl mercury, arsenic, lead, and certain pesticides Endocrine system Aluminum, atrazine, DDT, mercury, PCBs, bisphenol A

26 Science Focus: Mercurys Toxic Effects Hg: teratogen and potent neurotoxin Once airborne, persistent and not degradable 1/3 from natural sources 2/3 from human activities Coal-burning power plants, waste incinerators, chemical manufacturing plants, Enters the food chain: biomagnification

27 Science: Cycling of Mercury in Aquatic Environments

28 Science Focus: Mercurys Toxic Effects 2007: Hg hotspots identified New England, New York, Nova Scotia How are humans exposed? Inhalation: vaporized Hg or particulates of inorganic salts Eating fish with high levels of methylmercury Effects of Hg on humans Brain damage in fetuses and young children Lower IQ, poor school performance Harm the heart, kidneys and immune system in adults

29 Science Focus: Bisphenol A Estrogen mimic Found in many common products Water and baby bottles, food- containers and dental fillings Laboratory findings 94 studies by independent labs found numerous adverse health effects from low level exposure 12 studies funded by chemical industry found no adverse effects Effects on human health Brain damage, prostate disease, early puberty, reduced sperm count, hyperactivity, decrease sex drive in males, obesity

30 17-4 Many Factors Determine the Harmful Health Effects of a Chemical Toxicology Study of harmful effects of chemicals on humans Toxicity measures how harmful a substance is in causing injury, illness, or death to a living organism dependent on Dose Age Genetic makeup Multiple chemical sensitivity (MCS) Solubility and persistence of the chemical Water soluble (move throughout environment) Oil or fat soluble (accumulate in tissue) Biomagnification

31 1/1/ DDT in fish-eating birds (ospreys) 25 ppm DDT in large fish (needle fish) 2 ppm DDT in small fish (minnows) 0.5 ppm DDT in zooplankton 0.04 ppm DDT in water ppm, Or 3 ppt Bioaccumulation and Biomagnifications

32 © 2004 Brooks/Cole – Thomson Learning 1/1/ Very sensitive Majority of population Very insensitive Dose (hypothetical units) Number of individuals affected Typical variations in sensitivity to a toxic chemical

33 Many Factors Determine the Harmful Health Effects of a Chemical Response The damage to health resulting from exposure to a chemical Acute effect Immediate or rapid reaction Dizziness or nausea to death Chronic effect Permanent or long- lasting consequences Kidney or liver damage

34 Scientists Use Live Lab Animals and Nonanimal Tests to Estimate Toxicity Dose-response curve: median lethal dose (LD50) The dose that can kill 50% of the animals in a test population within an 18- day period. Nonthreshold dose-response model Any dosage causes harm that increase with dosage Threshold dose-response model A threshold dose must be reached before any detectable harmful effects occur Can the data be extrapolated to humans?

35 1/1/ LD Dose (hypothetical units) Percentage of population killed by a given dose LD

36 1/1/ © 2004 Brooks/Cole – Thomson Learning Effect Dose Nonlinear dose-response Linear dose-response No threshold Effect Threshold level Dose

37 37 Table 9-1 Toxicity Ratings and Average Lethal Doses for Humans Toxicity Rating Supertoxic Extremely toxic Very toxic Toxic Moderately toxic Slightly toxic Essentially nontoxic LD50 (milligrams per kg of body weight)* Less than 0.01 Less than 5 5–50 50– –5,000 5,000–15,000 15,000 or greater Examples Nerve gases, botulism toxin, mushroom toxins, dioxin (TCDD) Potassium cyanide, heroin, atropine, parathion, nicotine Mercury salts, morphine, codeine Lead salts, DDT, sodium hydroxide, sodium fluoride, sulfuric acid, caffeine, carbon tetrachloride Methyl (wood) alcohol, ether, Phenobarbital, amphetamines (speed), kerosene, aspirin Ethyl alcohol, Lysol, soaps Water, glycerin, table sugar Average Lethal Dose Less than 1 drop Less than 7 drops 7 drops to 1 teaspoon 1 teaspoon to 1 ounce 1 ounce to 1 pint 1 pint to 1 quart More than 1 quart *Dosage that kills 50% of individuals exposed Amounts of substances in liquid form at room temperature that are lethal when given to a 70.4-kg (155-pound) human

38 Scientists Use Live Lab Animals and Nonanimal Tests to Estimate Toxicity More humane methods using animals Replace animals with other models Computer simulations Tissue culture and individual animal cells Chicken egg membranes What are the effects of mixtures of potentially toxic chemicals?

39 1/1/ Reality 2% of chemicals in use have been tested 99.5% of used chemicals not regulated

40 Some Potentially Harmful Chemicals Found in Most Homes

41 Are Trace Levels of Toxic Chemicals Harmful? We do not know

42 Pollution Prevention and the Precautionary Principle Those introducing a new chemical or new technology would have to follow new strategies A new product is considered harmful until it can be proved to be safe Existing chemicals and technologies that appear to cause significant harm must be removed 2000: global treaty to ban or phase out the dirty dozen (POPs)

43 POPs – The Dirty Dozen

44 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 chemicals Ray Turner: citrus-based solvents to clean circuit boards

45 17-5 The Greatest Health Risks Come from Poverty, Gender, and Lifestyle Choices Risk analysis Greatest health risks Poverty Gender Lifestyle choices

46 Fig , p. 461 Cause of death Annual deaths Poverty/malnutrition/ disease cycle 11 million (150) Tobacco 5.4 million (74) Pneumonia and flu 3.2 million (44) Air pollution3 million (41) HIV/AIDS 2.1 million (29) Diarrhea 1.9 million (26) Tuberculosis 1.7 million (23) Automobile accidents 1.2 million (16) Work-related injury and disease 1.1 million (15) Malaria 1 million (14) Hepatitis B 1 million (14) Measles 800,000 (11)

47 Comparison of Risks People Face in Terms of Shorter Average Life Span

48 Case Study: Death from Smoking (1) Most preventable major cause of suffering and premature death Nicotine: additive Effects of passive smoking (secondhand smoke)

49 Case Study: Death from Smoking (2) How to reduce smoking Taxes Ban Classify and regulate nicotine Education

50 Fig , p. 463 Cause of Death in USDeaths Tobacco use442,000 Accidents101,500 (43,450 auto) Alcohol use85,000 Infectious diseases 75,000 (17,000 from AIDS) Pollutants/toxins 55,000 Suicides30,600 Homicides20,622 Illegal drug use17,000

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