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Chapter 17

Chapter 17. Human Health and Environmental Risks. What is Risk?. Risk : possibility of suffering harm from a hazard. Human Health Risks. Physical Biological Chemical . Leading Causes of Death Worldwide. Biological Risks.

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Chapter 17

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  1. Chapter 17 Human Health and Environmental Risks

  2. What is Risk? • Risk: possibility of suffering harm from a hazard

  3. Human Health Risks • Physical • Biological • Chemical

  4. Leading Causes of Death Worldwide

  5. Biological Risks • Disease: any impaired function of the body with a characteristic set of symptoms

  6. Biological Risks • Infectious diseases: those caused by infectious agents, known as pathogens • Ex: pneumonia and venereal diseases

  7. Pathogens • Bacteria: • Cholera • Tuberculosis • Syphilis • Virus: • HIV/AIDS • Hepatitis • Ebola • Protozoa: • Malaria

  8. What causes disease? • Infectious agents (pathogens) that spread by: • Air • Water • Food • Body fluids • Vectors (nonhuman carriers, like mosquitoes)

  9. Biological Risks • Chronic disease: slowly impairs the functioning of a person’s body • Ex: heart disease, cancer, diabetes • 70% of all deaths in the U.S. • Acute disease: rapidly impairs the functioning of a person’s body • Ex: Ebola hemorrhagic fever

  10. Leading Health Risks in the World

  11. Historical Diseases • Plague • Malaria • Tuberculosis

  12. Emergent Diseases • HIV/AIDS • Ebola • Mad Cow Disease • Bird Flu • West Nile Virus

  13. Emergent Diseases

  14. Pathways of Transmitting Pathogens

  15. Chemical Risks • Neurotoxins: chemicals that disrupt the nervous system • Carcinogens: chemicals that cause cancer • Teratogens: chemicals that interfere with the normal development of embryos and fetuses • Allergens: chemicals that cause allergic reactions • Endocrine disruptors: chemicals that interfere with the normal functioning of hormones

  16. Cigarettes Every year, over 400,000 smokers and almost 40,000 non-smokers die from cigarette-related illnesses. In fact, smoking kills more people than HIV, drugs, alcohol, car crashes, and homicide combined. People who work in bars and restaurants, and those who live with smokers are especially at risk for secondhand-smoke related illness. Should cigarettes be made illegal?

  17. Toxicology Studies • Retrospective studies • “Looking back” • Monitoring people who have already been exposed to a chemical to determine the effects • Prospective studies • “Looking forward” • Monitoring people who might become exposed to a chemical to determine the effects

  18. Toxicology Dose– the amount of a substance that a person has in their body Can be: Ingested Inhaled Injected Absorbed “The dose makes the poison”

  19. Dose-Response Studies • LD50: the lethal dose that kills 50% of the individuals within a test population

  20. LD50 LD50 = 5.3

  21. Poisons • Poisons: materials that kill at a very small dose (50 milligrams or less per kilogram of weight)

  22. Threshold

  23. Dose-Response Studies ED50: effective dose that causes 50% of the individuals to display the harmful, but nonlethal, effect

  24. Interactions • Synergistic interactions: when two (or more) risk factors have a greater effect together than each by themselves • Ex: being exposed to asbestos and smoking gives you a 400 times greater chance of developing lung cancer than if you experienced only one of those risks = +

  25. Routes of Exposure

  26. Toxicology Solubility - what can the chemical dissolve in? Water-soluble toxins Oil/Fat-soluble toxins Which do you think is generally “better” for the health of an organism? Water is “better” since it can be diluted Fats aren’t good since chemicals can gather in body fat of animals

  27. Toxicology • Bioaccumulation: an increased concentration of a chemical within an individual organism over time • The chemical is usually stored in body fat • Biomagnification: the increase in a chemical concentration in animal tissues as the chemical moves up the food chain

  28. Persistence • Persistence: how long a chemical remains in the environment

  29. Risk Analysis

  30. Qualitative vs. Quantitative • Qualitative risk assessment: judging the relative risk of various decisions (ex: low, medium, or high) • Quantitative risk assessment: determining the probability of an event occurring using data (ex: 83% chance)

  31. Probabilities of Death in U.S.

  32. Risk Analysis Risk = Probability of being exposed to a hazard x Probability of being harmed if exposed

  33. Chemical Regulation

  34. Chemical Regulation • Trade-off: • Greater safety with slower introduction of beneficial chemicals vs. • Greater potential risk with a greater rate of discovery of beneficial chemicals

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