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

18. 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?

19. 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

20. 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”

21. Dose-Response Studies LD 50 : the lethal dose that kills 50% of the individuals within a test population

22. LD 50 LD 50 = 5.3

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

25. Threshold

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

27. 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 + =

28. Routes of Exposure

29. 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

30. 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

31. Persistence Persistence: how long a chemical remains in the environment

32. Risk Analysis

33. 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)

34. Probabilities of Death in U.S.

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

36. Chemical Regulation

37. Trade-off: – Greater safety with slower introduction of beneficial chemicals vs. – Greater potential risk with a greater rate of discovery of beneficial chemicals