1. Core Case Study: The Global HIV/AIDS Epidemic

• According to the World Health Organization (WHO), in 2005 about 42 million people worldwide (1.1 million in the U.S.) were infected with HIV.

2. There is no vaccine for HIV if you get AIDS, you will eventually die from it.

3. Drugs help some infected people live longer, but only a tiny fraction can afford them. 4. Core Case Study: 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 5. RISKS AND HAZARDS

Risk is a measure of the likelihood that you will suffer harm from a hazard.

6. We can suffer from:

• Biological hazards : from more than 1,400 pathogens.

7. Chemical hazards : in air, water, soil, and food.

8. Physical hazards : such as fire, earthquake, volcanic eruption 9. Cultural hazards : such as smoking, poor diet, unsafe sex, drugs, unsafe working conditions, and poverty. 10. 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 ( transmissibleorinfectious )

11. Transmissible Disease

Pathway for infectious disease in humans.

Figure 18-4 12. Transmissible Disease

WHO estimates that each year the worlds seven deadliest infections kill 13.6 million people most of them the poor in developing countries.

Figure 18-5 13. 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.

14. Overuse of antibiotics : A 2000 study found that half of the antibiotics used to treat humans were prescribed unnecessarily.

15. 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.

16. 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.

17. Concentrate on groups in a society that are likely to spread the disease.

18. Provide free HIV testing and pressure people to get tested. 19. Implement educational programs. 20. Provide free or low-cost drugs to slow disease progress. 21. Case Study:Malaria Death by Mosquito

Economists estimate that spending $2-3 billion on malaria treatment may save more than 1 million lives per year.

Figure 18-6 22.

Spraying 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.

Case Study:Malaria Death by Mosquito 23. Ecological Medicine andInfectious Diseases

Mostly because of human activities, infectious diseases are moving at increasing rates from one animal species to another (including humans).

24. Ecological (or conservation) medicine is devoted to tracking down these connections between wildlife and humans to determine ways to slow and prevent disease spread. 25. CHEMICAL HAZARDS

A toxic chemical can cause temporary or permanent harm or death.

• Mutagensare chemicals or forms of radiation that cause or increase the frequency of mutations in DNA.

26. Teratogensare chemicals that cause harm or birth defects to a fetus or embryo.

27. Carcinogensare chemicals or types of radiation that can cause or promote cancer. 28. CHEMICAL HAZARDS

A hazardous chemical can harm humans or other animals because it:

• Is flammable

29. Is explosive

30. An irritant 31. Interferes with oxygen uptake 32. Induce allergic reactions. 33. Effects of Chemicals on the Immune, Nervous, and Endocrine Systems

Long-term exposure to some chemicals at low doses may disrupt the bodys:

• Immune system : specialized cells and tissues that protect the body against disease and harmful substances.

34. Nervous system : brain, spinal cord, and peripheral nerves.

35. Endocrine system : complex network of glands that release minute amounts of hormones into the bloodstream. 36. 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 37. Case Study:A Black Day in Bhopal, India

The worlds 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.

38. 15,000-22,000 people died

39. Indian officials claim that simple upgrades could have prevented the tragedy. 40. TOXICOLOGY: ASSESSING CHEMICAL HAZARDS

Factors determining the harm caused by exposure to a chemical include:

• The amount of exposure (dose).

41. The frequency of exposure.

42. The person who is exposed. 43. The effectiveness of the bodys detoxification systems. 44. Ones genetic makeup. 45. TOXICOLOGY: ASSESSING CHEMICAL HAZARDS

Typical variations in sensitivity to a toxic chemical within a population, mostly because of genetic variation.

Figure 18-10 46. 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 47. Fig. 18-11, p. 431 Water pollutant levels Air pollutant levels Soil/dust levels Food pesticide levels Nutritional health Overall health Mathematical measurements & modeling ?Lifestyle Predicted level of toxicant in people Personal habits Genetic predisposition Metabolism Accumulation Excretion Lung, intestine& skin absorption rates 48. 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.

49. They are exposed to toxins when they put their fingers or other objects in their mouths.

50. Children usually have less well-developed immune systems and detoxification processes than adults. 51. TOXICOLOGY: ASSESSING CHEMICAL HAZARDS

Under existing laws, most chemicals are consideredinnocent 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.

52. 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.

53. Some health scientists contend that regulators should assume children at a risk 100 times that of adults. 54. 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 ).

55. Manufacturers contend that wide-spread application of the precautionary principle would make it too expensive to introduce new chemicals and technologies. 56. How Would You Vote? Should we rely more on the precautionary principle as a way to reduce the risks from chemicals and technologies?

• a. No. Assuming that every chemical or technology is a serious health or environmental threat will lead to wasteful over-regulation, high costs and hinder the development of critically needed pesticides, plastics, and other commercial products.

57. b. Yes. Preventing the commercialization of harmful chemicals and technologies is better than dealing with the high costs of medical treatments and environmental damage.

58. RISK ANALYSIS

Scientists have developed ways to evaluate and compare risks, decide how much risk is acceptable, and find affordable ways to reduce it.

Figure 18-12 59. Fig. 18-12, p. 433 Comparative Risk Analysis Most Serious Ecological and Health ProblemsHigh-Risk Health Problems Indoor air pollution Outdoor air pollution Worker chemical exposurePollutants in drinking water Pesticide residues on food Toxic chemicals in consumer products High-Risk Ecological Problems Global climate change Stratospheric ozone depletion Wildlife habitat alteration & destruction Species extinction, loss of biodiversity Medium-Risk Ecological Problems Acid deposition Pesticides Airborne toxic chemicals Toxic chemicals, nutrients, and sediment insurface waters Low-Risk Ecological Problems Oil spills Groundwater pollution Radioactive isotopes Acid runoff to surface waters Thermal pollution 60. RISK ANALYSIS

Estimating risks from using many technologies is difficult due to unpredictability of human behavior, chance, and sabotage.

Reliability of a system is multiplicative:

• If a nuclear power plant is 95% reliable and human reliability is 75%, then the overall reliability is (0.95 X 0.75 = 0.71) 71%.

61. RISK ANALYSIS

Annual deaths in the U.S. from tobacco use and other causes in 2003.

Figure 18-A 62. RISK ANALYSIS

Number of deaths per year in the world from various causes. Parentheses show deaths in terms of the number of fully loaded 400-passenger jumbo jets crashing every day of the year with no survivors.

Figure 18-13 63. Fig. 18-13, p. 435 Cause of death Annual deaths Poverty/malnutrition/ disease cycle 11 million(75) Tobacco 5 million(34) Pneumonia and flu 3.2 million(22) Air pollution 3 million(21) HIV/AIDS Malaria 2 million(14) Diarrhea 1.9 million(13) Tuberculosis 1.7 million(12) Car accidents 1.2 million(8) Work-related injury & disease 1.1 million(8) Hepatitis B 1 million(7) Measles 800,000(5) 3 million(21) 64. Perceiving Risk

Most individuals evaluate the relative risk they face based on:

• Degree of control.

65. Fear of unknown.

66. Whether we voluntarily take the risk. 67. Whether risk is catastrophic. 68. Unfair distribution of risk. Sometimes misleading information, denial, and irrational fears can cloud judgment. 69. RISK ANALYSIS

Comparisons of risks people face expressed in terms of shorter average life span.

Figure 18-14 70. Fig. 18-14, p. 436 Shortens average life span in the U.S. by Hazard Poverty Born male Smoking Overweight (35%) Unmarried 5 years Overweight (15%) 2 years Spouse smoking 1 year Driving 7 months Air pollution 5 months Alcohol 5 months Drug abuse 4 months Flu 4 months AIDS 3 months Drowning 1 month Pesticides 1 month Fire 1 month Natural radiation 8 days Medical X rays 5 days Oral contraceptives 5 days Toxic waste 4 days Flying 1 day Hurricanes, tornadoes 1 day Lifetime near nuclear plant 10 hours 6 years 6 10 years 7.5 years 710 years 71. Becoming Better at Managing Risk

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