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Chapter 11

Chapter 11. Risk Toxicology, and Human Health. APES 1/24/11. Stamp on NB for 12 Notes on Chapter 11 Work on Population ? And FRQ Tomorrow Test Prep! Final on Wed.. Scantron bring a number 2 pencil!. Think of an activity you do : What are the risks?

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Chapter 11

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  1. Chapter 11 Risk Toxicology, and Human Health

  2. APES 1/24/11 • Stamp on NB for 12 • Notes on Chapter 11 • Work on Population ? And FRQ • Tomorrow Test Prep! • Final on Wed.. • Scantron bring a number 2 pencil! • Think of an activity you do: • What are the risks? • Are there other activities you do that are less risky?

  3. Chance of DYING 1 in a 1,000,000 chance • 1 in a 100,000 chance • 1 in a 10,000 chance • 1 in a 1,000 chance • 1 in a 100 chance • 1 in a 10 chance

  4. RISKS AND HAZARDS • Risk 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.

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  11. Becoming Better at Risk Analysis • We can carefully evaluate or tune out of the barrage of bad news covered in the media, compare risks, and concentrate on reducing personal risks over which we have some control. Figure 18-3

  12. TOXICOLOGY: ASSESSING CHEMICAL HAZARDS • Factors determining the harm caused by exposure to a chemical include: • The amount of exposure (dose). • The frequency of exposure. • The person who is exposed. • The effectiveness of the body’s detoxification systems. • One’s genetic makeup.

  13. TOXICOLOGY: ASSESSING CHEMICAL HAZARDS • Typical variations in sensitivity to a toxic chemical within a population, mostly because of genetic variation. Figure 18-10

  14. BIOACCUMULATION • Bioaccumulation is the lifetime accumulation of a toxic substance in an individual organism’s body. Some toxic substances such as mercury or DTT (pesticide) do not easily leave the body once they have been absorbed and therefore accumulate over time.

  15. Biomagnification • Biomagnification, also known as bioamplification, or biological magnification is the increase in concentration of a toxic substance, such as the pesticide DDT or the heavy metal Mercury, as it moves upward through a food chain.

  16. Effects of Chemicals on the Immune, Nervous, and Endocrine Systems • Long-term exposure to some chemicals at low doses may disrupt the body’s: • Immune system: specialized cells and tissues that protect the body against disease and harmful substances. • Nervous system: brain, spinal cord, and peripheral nerves. • Endocrine system: complex network of glands that release minute amounts of hormones into the bloodstream.

  17. CHEMICAL HAZARDS • A hazardous chemical can harm humans or other animals because it: • Is flammable • Is explosive • An irritant • Interferes with oxygen uptake • Induce allergic reactions.

  18. CHEMICAL HAZARDS • A 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.

  19. Effects of Chemicals on the Immune, Nervous, and Endocrine Systems • Molecules of certain synthetic chemicals have shapes similar to those of natural hormones and can adversely affect the endocrine system. Figure 18-9

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  21. TOXICOLOGY: ASSESSING CHEMICAL HAZARDS • Estimating human exposure to chemicals and their effects is very difficult because of the many and often poorly understood variables involved. Figure 18-11

  22. 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.

  23. 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.

  24. 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.

  25. 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.

  26. Pathogens-

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  29. BIOLOGICAL HAZARDS: DISEASE IN DEVELOPED AND DEVELOPING COUNTRIES • Diseases not caused by living organisms cannot spread from one person to another (nontransmissible disease), while those caused by living organisms such as bacteria and viruses can spread from person to person (transmissible or infectious)

  30. Transmissible Disease • Pathway for infectious disease in humans. Figure 18-4

  31. 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

  32. Case Study: Growing Germ Resistance to Antibiotics • Rabidly producing infectious bacteria are becoming genetically resistant to widely used antibiotics due to: • Genetic resistance: Spread of bacteria around the globe by humans, overuse of pesticides which produce pesticide resistant insects that carry bacteria. • Overuse of antibiotics: A 2000 study found that half of the antibiotics used to treat humans were prescribed unnecessarily.

  33. Case Study: The Growing Global Threat from Tuberculosis • The highly infectious tuberculosis (TB) kills 1.7 million people per year and could kill 25 million people 2020. • Recent increases in TB are due to: • Lack of TB screening and control programs especially in developing countries due to expenses. • Genetic resistance to the most effective antibiotics.

  34. Viral Disease· • The viral life cycle • · must have a host cell • Treating Viral Disease • · vaccines • · why are vaccines not always effective ?

  35. Examples of Viral Disease • Influenza (flu) • World Influenza Pandemic (1918-19) • ·1. global epidemic (pandemic) killed 20 • million people, 500 000 in the U.S. alone • ·2. airborne and direct contact • ·3. no vaccine • ·4.particularly virulent strain

  36. Human Immunodeficiency Virus (HIV) • 1. virus responsible for AIDS (acquired immunodeficiency syndrome) • 2. sexually transmitted disease, also blood borne… infected needles in IV drug users • 3. attacks the immune system and allows for secondary infections • most people do not die from AIDS, but from the resulting secondary infections (pneumonia or TB) • 4. no vaccine available • 5. some antiviral drugs show effectiveness and prolong the lives of those who are HIV positive • · Internet article on HIV.. what’sworking to halt the spread ?

  37. Viral Diseases • Flu, HIV, and hepatitis B viruses infect and kill many more people each year then highly publicized West Nile and SARS viruses. • 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.

  38. Viral Diseases • HIV 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.

  39. The Global HIV/AIDS Epidemic • The virus itself is not deadly, but it cripples the immune system, leaving the body susceptible to infections such as Kaposi’s sarcoma (above). Figure 18-1

  40. The Global HIV/AIDS Epidemic • AIDS has reduced the life expectancy of sub-Saharan Africa from 62 to 47 years – 40 years in the seven countries most severely affected by AIDS. Projected age structure of Botswana's population in 2020. Figure 18-2

  41. How Would You Vote? • Should developed and developing nations mount an urgent global campaign to reduce the spread of HIV and to help countries afflicted by the disease? • a. No. A global AIDS campaign could divert attention and resources from efforts to combat other serious threats. • b. Yes. The disease is decimating the populations and destroying the economies of many developing countries.

  42. Avian Bird Flu • Spread among birds • · Most cases of avian influenza infection in humans have resulted from contact with infected poultry (e.g., domesticated chicken, ducks, and turkeys) or surfaces contaminated with secretion/excretions from infected birds. • · You cannot contract bird flu by eating poultry • · The strain that has spread to humans (H5N1) has a mortality rate of 50% • · There have been a few cases of human to human transmission, but these are rare and unsustained • · Some antiviral drugs have shown some effectiveness • · Vaccines could be produced but stockpiles and ability to ramp up production in a pandemic are inadequate • http://www.cdc.gov/flu/avian/gen-info/facts.htm

  43. Bacterial Disease • Treating Bacterial Infections • · Antibiotics • · Why do antibiotics lose their effectiveness ?

  44. Tuberculosis (the silent global epidemic) • Kills 1.6 million and infects 8 million • · Respiratory infection spreads airborne droplets containing the • bacterium • · 1 in 3 people globally infected with TB • · About 10% will develop active TB infections and then spread the • disease to about 10-15 others • · Treatment • o There are drugs that are effective but they must be taken for about 6-8 weeks • o Strains resistant to commonly used antibiotics have arisen • o Screening a population is very effective in identifying infected individuals • · AIDS make infected individuals less able to fight the disease • · Population growth and urbanization makes spreading the disease • more likely

  45. Cholera • · A water borne infection that is spread by unclean water supplies • · Clean water video • · http://www.globalwater.org/video-dyingofthirst.html • · NPR cleaning water • ·http://www.npr.org/templates/story/story.php?storyId=5043050 • · Information on cholera • · http://www.cdc.gov/ncidod/dbmd/diseaseinfo/cholera_g.htm#What%20is%20cholera

  46. Diseases Caused by Protozoans • Malaria • · Caused by the protozoan Plasmodium • · Vector for the disease is the female Anopheles mosquito • ·

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