1. Risk, Toxicology, and Human Health
Chapter 11
Risk, Toxicology, and Human Health

2. Chapter Overview Questions
What types of hazards do people face?
What types of disease (biological hazards) threaten people in developing countries and developed countries?
What chemical hazards do people face?
How can risks be estimated and recognized?

3. 14_11.JPG
Figure 14-11
Title:
Synthetic chemicals take many routes in traveling through the environment.
Caption:
Although humans take in only a tiny proportion of these compounds, and although many compounds are harmless, humans—particularly babies—receive small amounts of toxicants from many sources.
Notes:
Keywords:
environmental health, toxicology, toxicants, air pollution, groundwater, streams, rivers, soils, crops, croplands, agriculture, farms, farming, pesticides, urbanization, city, cities

4. 14_02a.jpg Figure 14-02a Title: Death and disease. Caption:
Infectious diseases are the second-leading cause of death worldwide, accounting for over one-quarter of all deaths per year (a). Data are for 2004, from World Health Organization.
Notes:
Keywords:
environmental health, epidemiology, health, diseases

5. 14_15.JPG
Figure 14-15
Title:
Our perceptions of risk do not always match the reality of risk.
Caption:
Listed here are several leading causes of death in the United States, along with a measure of the risk each poses. Risk is measured in days of lost life expectancy, that is, the number of days of life lost by people suffering the hazard, spread across the entire population—a measure commonly used by insurance companies. By this measure, one common source of anxiety, airplane accidents, poses 20 times less risk than home accidents, over 50 times less risk than auto accidents, and over 200 times less risk than being overweight. Data from Cohen, B Catalog of risks extended and updated. Health Physics 61:
Notes:
Keywords:
environmental health, epidemiology, diseases, risks, assessments, management

6. 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.

7. 14_01a.jpg
Figure 14-01a
Title:
Environmental health hazards can be divided into four types.
Caption:
The sun's ultraviolet radiation is an example of a physical hazard (a). Excessive exposure increases the risk of skin cancer.
Notes:
Keywords:
sunlight, electromagnetic radiation, health, diseases

8. 14_04.JPG
Figure 14-04
Title:
Asbestos was widely used in insulation and other products.
Caption:
A cause of lung cancer and asbestosis, the substance has now been removed from many buildings in which it was used. Its removal poses risks as well, however, and removal workers must wear protective clothing and respirators.
Notes:
Keywords:
environmental health, toxicology, toxicants

9. 14_01b.jpg
Figure 14-01b
Title:
Environmental health hazards can be divided into four types.
Caption:
Chemical hazards (b) include both artificial and natural chemicals. Much of our exposure comes from household chemical products, such as pesticides that some people apply to their lawns.
Notes:
Keywords:
environmental health, toxicology, toxicants, pesticides

10. 14_05.JPG
Figure 14-05
Title:
Synthetic chemicals, such as those in household products, are everywhere around us in our everyday lives.
Caption:
Some of these compounds may potentially pose environmental or human health risks.
Notes:
Keywords:
environmental health, toxicology, toxicants

11. Cost of Avoiding Risk

12. 14_SBS01-02.JPG Figure 14-SBS01-02 Title:
Effects of bisphenol-A on cell division.
Caption:
During normal cell division (a), chromosomes align properly. Exposure to bisphenol-A causes abnormal cell division (b), whereby chromosomes scatter and are distributed improperly and unevenly between daughter cells.
Notes:
Keywords:
environmental health, toxicology, toxicants, teratogens

13. 14_T02.JPG
Table 14-T02
Title:
Estimated numbers of chemicals in commercial substances during the 1990s.
Caption:
Data from Harrison, P., and F. Pearce AAAS Atlas of Population and Environment. Berkeley, CA: University of California Press.
Notes:
Keywords:
environmental health, toxicology, toxicants

14. 14_09.JPG Figure 14-09 Title: Atrazine may affect frogs. Caption:
According to research by Tyrone Hayes of the University of California at Berkeley, frogs may suffer reproductive abnormalities from exposure to the best-selling herbicide atrazine. Industry-backed scientists have disputed the findings.
Notes:
Keywords:
environmental health, toxicology, toxicants, endocrine disruptors, hormones

15. 14_10a.jpg Figure 14-10a Title: Sperm counts and testicular cancer.
Caption:
Research in 1992 synthesized the results of 61 studies that had reported sperm counts in men from various localities since The data were highly variable but showed a significant decrease in human sperm counts over time (a). Many scientists have hypothesized that this decrease may result from exposure to endocrine-disrupting chemicals in the environment. (a) Data from Carlsen, E., et al Evidence for decreasing quality of semen during the last 50 years. British Medical Journal 305: , as adapted by Toppari, J., et al Male reproductive health and environmental xenoestrogens. Environmental Health Perspectives 104 (Suppl 4):
Notes:
Keywords:
environmental health, toxicology, toxicants, endocrine disruptors, hormones

16. 14_10b.jpg Figure 14-10b Title: Sperm counts and testicular cancer.
Caption:
Some have also hypothesized that endocrine disruptors could be behind an increased incidence of testicular cancer (b). (b) Adami, H.O., et al Testicular cancer in nine northern European countries. International Journal of Cancer 50:
Notes:
Keywords:
environmental health, toxicology, toxicants, endocrine disruptors, hormones, diseases

17. 14_08a.jpg
Figure 14-08a
Title:
Many endocrine-disrupting substances mimic the structure of hormone molecules.
Caption:
(a) Normal hormone binding.
Notes:
Keywords:
environmental health, toxicology, toxicants, endocrine disruptors, hormones, receptors

18. 14_08b.jpg
Figure 14-08b
Title:
Many endocrine-disrupting substances mimic the structure of hormone molecules.
Caption:
(b) Hormone mimicry.
Notes:
Keywords:
environmental health, toxicology, toxicants, endocrine disruptors, hormones, receptors

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

20. 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.

21. TOXICOLOGY: ASSESSING CHEMICAL HAZARDS
Under existing laws, most chemicals are considered innocent until proven guilty.
Federal and state governments do not regulate about 99.5% of the commercially used chemicals in the U.S.

22. TOXICOLOGY: ASSESSING CHEMICAL HAZARDS
Some scientists abide by the Precautionary Principle
Manufacturers contend that following the Precautionary Principle is too expensive.

23. 14_12.JPG Figure 14-12 Title: Global distillation. Caption:
In a process called global distillation, pollutants that evaporate and rise high into the atmosphere at lower latitudes, or are deposited in the ocean, are carried toward the poles by atmospheric currents of air and oceanic currents of water. For this reason, polar organisms take in more than their share of toxicants, despite the fact that relatively few synthetic chemicals are manufactured or used near the poles.
Notes:
Keywords:
environmental health, toxicology, toxicants, air pollution, atmosphere, winds, oceans, surface currents

24. 14_01c.jpg
Figure 14-01c
Title:
Environmental health hazards can be divided into four types.
Caption:
Biological hazards (c) include other organisms that transmit disease. Some mosquitoes are vectors for certain pathogenic microbes, including those that cause malaria.
Notes:
Keywords:
health, infectious diseases

25. BIOLOGICAL HAZARD: DISEASE
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)

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

27. 14_02b.jpg Figure 14-02b Title: Death and disease. Caption:
Six types of diseases—respiratory infections, AIDS, diarrhea, tuberculosis (TB), malaria, and childhood diseases such as measles—account for 80% of all deaths from infectious disease (b). Data are for 2004, from World Health Organization.
Notes:
Keywords:
environmental health, epidemiology, health, diseases

28. 14_03a.jpg Figure 14-03a Title: West Nile virus. Caption:
In the map (a), colors show the year that West Nile virus was first detected within each state. The disease spread westward across the country in less than 5 years. Data from Centers for Disease Control and Prevention.
Notes:
Keywords:
environmental health, epidemiology, infectious diseases

29. Chapter 20
Section 2 Biological Hazards
Lyme Disease Risk

30. Disease (type of agent) Deaths per year
Pneumonia and flu (bacteria and viruses)
3.2 million
HIV/AIDS (virus)
3.0 million
Malaria (protozoa)
2.0 million
Diarrheal diseases (bacteria and viruses)
1.9 million
Figure 18.5
Global outlook: the World Health Organization estimates that each year the world’s seven deadliest infectious diseases kill 13.6 million people—most of them poor people in developing countries. This amounts to about 37,300 mostly preventable deaths every day. QUESTION: What three things would you do to reduce this death toll? (Data from the World Health Organization)
Tuberculosis (bacteria)
1.7 million
Hepatitis B (virus)
1 million
Measles (virus)
800,000
Fig. 18-5, p. 420

31. 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

32. A Model of Increase in Malaria Risk Due to Climate Change
Chapter 20
Section 2 Biological Hazards
A Model of Increase in Malaria Risk Due to Climate Change

33. 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

34. 14_01d.JPG
Figure 14-01d
Title:
Environmental health hazards can be divided into four types.
Caption:
Cultural or lifestyle hazards (d) include the decisions we make about how to behave, as well as the constraints forced on us by socioeconomic factors. Smoking is a lifestyle choice that raises one's risk of lung cancer and other diseases considerably.
Notes:
Keywords:
health, diseases

35. Water pollutant levels
Air pollutant levels
Soil/dust levels
Food pesticide levels
Nutritional health ?
Mathematical measurements & modeling
Overall health
Lifestyle
Figure 18.11
Science: estimating human exposure to chemicals and their effects is very difficult because of the many and often poorly understood variables involved. QUESTION: Which three of these factors do you think make you more vulnerable to the harmful effects of chemicals?
Predicted level of toxicant in people
Personal habits
Metabolism
Genetic predisposition
Accumulation
Excretion
Lung, intestine & skin absorption rates
Fig , p. 431

36. An increasing dose has a greater effect
Dose-Response Curve

37. Very sensitive Very insensitive
Number of individuals affected
Very sensitive
Majority of population
Very insensitive
Figure 18.10
Science: typical variations in sensitivity to a toxic chemical within a population, mostly because of differences in genetic makeup. Some individuals in a population are very sensitive to small doses of a toxin (left), and others are very insensitive (right). Most people fall between these two extremes (middle). QUESTION: Approximately where do you fall on this curve for most chemicals?
Dose (hypothetical units)
Fig , p. 430

38. 14_14a.jpg Figure 14-14a Title: Dose-response curves. Caption:
In a classic linear dose-response curve (a), the percentage of animals killed or otherwise affected by a substance rises with the dose. The point at which 50% of the animals are killed is labeled the lethal-dose-50, or LD50. Go to Graph It! at or on the student CD-ROM.
Notes:
Keywords:
environmental health, toxicology, toxicants, lethal doses, responses, curves, thresholds

40. 14_14b.jpg Figure 14-14b Title: Dose-response curves. Caption:
For some toxic agents, a threshold dose (b) exists, below which doses have no measurable effect. Go to Graph It! at or on the student CD-ROM.
Notes:
Keywords:
environmental health, toxicology, toxicants, lethal doses, responses, curves, thresholds

41. RISK ANALYSIS
Annual deaths in the U.S. from tobacco use and other causes in 2003.
Figure 18-A

42. Shortens average life span in the U.S. by
Hazard
Shortens average life span in the U.S. by
Poverty
7–10 years
Born male
7.5 years
Smoking
6–10 years
Overweight (35%)
6 years
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
Figure 18.14
Global outlook: comparison of risks people face, expressed in terms of shorter average life span. After poverty and gender, the greatest risks people face come mostly from the lifestyle choices they make. These are merely generalized relative estimates. Individual responses to these risks can differ because of factors such as genetic variation, family medical history, emotional makeup, stress, and social ties and support. QUESTION: Which three of these items are most likely to shorten your life span? (Data from Bernard L. Cohen)
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
Fig , p. 436

43. Epidemiology
The map below shows the location of cases of mercury poisoning in Virginia. Patterns point scientists toward areas of mercury poisoning.

45. Bioaccumulation – the increasing concentration of a toxin in an organisms body over its lifetime.

47. Perceiving Risk
Most individuals evaluate the relative risk they face based on:
Degree of control.
Fear of unknown.
Whether we voluntarily take the risk.
Whether risk is catastrophic.
Unfair distribution of risk.

48. 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.

49. Toxicity: How Dangerous Is It?
Almost any chemical be harmful if taken in, or ingested, in large enough amounts.
A dose is the amount of a harmful substance to which a person is exposed.
The damage to health from exposure to a given dose is the response.

50. 14_IGD01.JPG Figure 14-IGD01 Title:
Hypothetical risk distributions for individuals using an estrogenic sunscreen to prevent skin cancer.
Caption:
Schlumpf, M., et al In vitro and in vivo estrogenicity of UV screens. Environmental Health Perspectives 109:
Notes:
Keywords:
environmental health, toxicology, toxicants, endocrine disruptors, hormones, diseases, sunscreens, risks, assessments, management

51. Setting Concentration Standards for Wildlife and Humans
Let’s say that an LC50 study on arsenic (a poisonous element) is conducted using small fish. It is discovered that the LC50 is 50,000 ug/L (50 mg/L). What should the standards be?

52. The Standard for Wildlife
The Standard for Wildlife is set at one-tenth of the LC50 or LD50.
50,000 ug/L divided by 10 = 5,000 ug/L (5 mg/L)
of arsenic.

53. The Standard for Humans
The Standard for Humans is set at one-hundredth of the LC50 or LD50.
50,000 ug/L divided by 100 = ug/L (0.5 mg/L)
of arsenic.

54. 50,000 ug/L divided by 1000 = 50 ug/L (0.05 mg/L)
Usually an extra safety factor of 10 is incorporated into standards for humans
The extra safe Standard for Humans is set at one-thousandth of the LC50 or LD50.
50,000 ug/L divided by 1000 = ug/L (0.05 mg/L)
of arsenic.

55. Risk Analysis Risk Assessment – determining the level of risk
Risk Acceptance – ranking risks and determining what level of risk is acceptable
Risk Management – developing a plan to manage and reduce the risk
Risk Policy Implementation – creating laws and policies to protect society

56. 14_16.JPG Figure 14-16 Title: Risk assessment. Caption:
The first step in addressing the risk of an environmental hazard is risk assessment, a process of quantifying the risk of the hazard and comparing it to other risks. Once science identifies and measures risks, then risk management can proceed. In this process, economic, political, social, and ethical issues are considered in light of the scientific data from risk assessment. The consideration of all these types of information is designed to result in policy decisions that minimize the risk of the environmental hazard.
Notes:
Keywords:
environmental health, toxicology, toxicants, risks, assessments, management

57. Hazard identification Comparative risk analysis
Risk Assessment
Risk Management
Hazard identification
Comparative risk analysis
What is the hazard?
How does it compare with other risks?
Risk reduction
How much should it be reduced?
Probability of risk
How likely is the event?
Risk reduction strategy
How will the risk be reduced?
Figure 18.3
Science: risk assessment and risk management.
Consequences of risk
Financial commitment
What is the likely damage?
How much money should be spent?
Fig. 18-3, p. 419

58. Environmental Effects on Health
Section 1 Pollution and Human Health
Environmental Effects on Health
Chapter 20

59. The End

60. Ecological Medicine and Infectious Diseases
Mostly because of human activities, infectious diseases are moving at increasing rates from one animal species to another (including humans).
Ecological (or conservation) medicine is devoted to tracking down these connections between wildlife and humans to determine ways to slow and prevent disease spread.

61. Case Study: Malaria – Death by Mosquito
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.

62. 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.

63. 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.

64. Case Study: A Black Day in Bhopal, India
The world’s 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.
15,000-22,000 people died
Indian officials claim that simple upgrades could have prevented the tragedy.

65. 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.

66. 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.

67. 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

68. Comparative Risk Analysis Most Serious Ecological and Health Problems
High-Risk Health Problems • Indoor air pollution • Outdoor air pollution • Worker chemical exposure
• Pollutants 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 in surface waters
Figure 18.12
Science: comparative risk analysis of the most serious ecological and health problems according to scientists acting as advisers to the EPA. Risks under each category are not listed in rank order. QUESTION: Which two risks in each of the high-risk problems do you think are the most serious? (Data from Science Advisory Board, Reducing Risks, Washington, D.C.: Environmental Protection Agency, 1990)
Low-Risk Ecological Problems • Oil spills • Groundwater pollution • Radioactive isotopes • Acid runoff to surface waters • Thermal pollution
Fig , p. 433

70. 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%.

71. Cause of Death Deaths 442,000 Tobacco use 101,500 (43,450 auto)
Accidents
85,000
Alcohol use
75,000 (16,000 from AIDS)
Infectious diseases
Pollutants/toxins
55,000
Figure 18.A
Annual deaths in the United States from tobacco use and other causes in Smoking is by far the nation’s leading cause of preventable death, causing more premature deaths each year than all the other categories in this figure combined. (Data from U.S. National Center for Health Statistics and Centers for Disease Control and Prevention and U.S. Surgeon General)
30,600
Suicides
20,622
Homicides
17,000
Illegal drug use
Fig. 18-A, p. 435

72. 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

73. Cause of death Annual deaths 11 million (75) 5 million (34)
Poverty/malnutrition/ disease cycle
Tobacco
5 million (34)
Pneumonia and flu
3.2 million (22)
Air pollution
3 million (21)
HIV/AIDS
3 million (21)
Malaria
2 million (14)
Diarrhea
1.9 million (13)
Tuberculosis
1.7 million (12)
Figure 18.13
Global outlook: number of deaths per year in the world from various causes. Numbers in parentheses give these deaths in terms of the number of fully loaded 400-passenger jumbo jets crashing every day of the year with no survivors. Because of sensational media coverage, most people have a distorted view of the largest annual causes of death. QUESTION: Which three of these items are most likely to shorten your life span? (Data from World Health Organization)
Car accidents
1.2 million (8)
Work-related injury & disease
1.1 million (8)
Hepatitis B
1 million (7)
Measles
800,000 (5)
Fig , p. 435

74. RISK ANALYSIS
Comparisons of risks people face expressed in terms of shorter average life span.
Figure 18-14

75. 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