1. Environmental Hazards and Human Health
Chapter 18
Environmental Hazards 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. Updates Online
The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at to access InfoTrac articles.
InfoTrac: Report Shows 2005 to Be 'Least Bad Year' of AIDS Epidemic. Lawrence K. Altman. The New York Times, May 31, 2006 pA6(L).
InfoTrac: Concern Grows Over Increase In Diabetes Around World. Marc Santora. The New York Times, June 11, 2006 pA27(L).
InfoTrac: Push for New Tactics as War on Malaria Falters. Celia W. Dugger. The New York Times, June 28, 2006 pA1(L).
The National Academies: Genetically Altered Bacteria Could Block Malaria Transmission
Science Daily: Study Shows Promise For Simplified Treatment Of HIV Infection
The Gates Foundation

4. 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.
There is no vaccine for HIV – if you get AIDS, you will eventually die from it.
Drugs help some infected people live longer, but only a tiny fraction can afford them.

5. 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

6. Core Case Study: 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

7. Core Case Study: Mercury’s Toxic Effects
All mercury compounds are toxic
One third in the atmosphere comes from natural sources
Human activities provide the rest
Two main human exposures
Fish contaminated with mercury
Inhalation of vaporized mercury
Greatest risk is brain damage

8. Many coal-burning factories and power plants release toxic mercury and other air pollutants into the atmosphere.
p. 440

9. Figure 17-1: Gloved hands hold a fish contaminated with mercury (left)
Figure 17-1: Gloved hands hold a fish contaminated with mercury (left). Fish are contaminated with mercury in many lakes, including this one in Wisconsin (right).
Fig. 17-1, p. 442

10. Figure 17-11 Mercury poisoning has eroded pockets of tissue in this human brain
Fig , p. 455

11. Mercury in Utah http://www.ksl.com/?nid=148&sid=10121605

12. 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.

13. 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)

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

15. 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

16. (bacteria and viruses) 3.2 million
Disease
(type of agent)
Deaths per year
Pneumonia and flu
(bacteria and viruses)
3.2 million
HIV/AIDS (virus)
2.1 million
Diarrheal diseases (bacteria and viruses)
1.9 million
Tuberculosis (bacteria)
1.7 million
Figure 17-4: Global outlook: The World Health Organization has estimated that the world’s seven deadliest infectious diseases killed about 10 million people per year—most of them poor people in less-developed countries (Concept 17-2). This averages about 27,400 mostly preventable deaths every day. Question: How many people, on average, die prematurely from these diseases every hour?
Malaria
(protozoa)
1 million
Hepatitis B
(virus)
1 million
Measles
(virus)
800,000
© Cengage Learning 2015
Stepped Art
Fig. 17-4, p. 445

17. 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.

18. The genetically resistant bacteria start multiplying d.
A group of bacteria, including genetically resistant ones, are exposed to an antibiotic c.
The genetically resistant bacteria start multiplying d.
Eventually the resistant strain replaces the strain affected by the antibiotic b.
Most of the normal bacteria die
Figure 17-A Genetic resistance: (a) A population of bacteria is exposed to an antibiotic, which (b) kills all individuals except those possessing a trait that makes them resistant to the drug. (c) The resistant bacteria multiply and eventually (d) replace all or most of the nonresistant bacteria.
Normal bacterium
Resistant bacterium
Fig. 17-A, p. 447

19. 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.

20. Figure 17-5: The colorized red areas in this chest X-ray show where TB bacteria have destroyed lung tissue.
Fig. 17-5, p. 445

21. Figure 17-6: Estimated rates of occurrence of TB throughout the world in 2009.
Fig. 17-6, p. 446

22. 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.

23. 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.

24. How Would You Vote?
To conduct an instant in-class survey using a classroom response system, access “JoinIn Clicker Content” from the PowerLecture main menu for Living in the Environment.
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.

25. Figure 17-B This deer tick can carry the Lyme disease bacterium from a deer or mouse to a human.
Fig. 17.B, p. 450

26. Case Study: Malaria – Death by Mosquito
Malaria kills about 2 million people per year and has probably killed more than all of the wars ever fought.
Figure 18-7

27. Stepped Art Female mosquito bites infected human,
ingesting blood that contains Plasmodium
gametocytes
Merozoites enter blood-stream and develop into gametocytes causing malaria and making
infected person a new reservoir
Plasmodium
develops in
mosquito
Sporozoites penetrate liver
and develop into merozoites
Female mosquito injects Plasmodium sporozoites into human host
Stepped Art
Fig. 18-7, p. 423

28. 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

29. 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.

30. Solutions Infectious Diseases
Increase research on tropical diseases and vaccines
Reduce poverty
Decrease malnutrition
Improve drinking water quality
Reduce unnecessary use of antibiotics
Educate people to take all of an antibiotic prescription
Reduce antibiotic use to promote livestock growth
Figure 18.8
Solutions: ways to prevent or reduce the incidence of infectious diseases, especially in developing countries. QUESTION: Which three of these approaches do you think are the most important?
Careful hand washing by all medical personnel
Immunize children against major viral diseases
Oral rehydration for diarrhea victims
Global campaign to reduce HIV/AIDS
Fig. 18-8, p. 424

31. 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.

32. 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.

33. 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.

34. 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.

35. 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

36. Figure 17-15: Individuals matter: You can reduce your exposure, and that of any children you care for, to hormone disrupters. Questions: Which three of these steps do you think are the most important ones to take? Why?
Fig , p. 458

37. 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.

38. 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.

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

40. 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

41. 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.

42. 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.

43. EPA Website

44. Case Study: PCBs Are Everywhere – A Legacy from the Past
Class of chlorine-containing compounds
Very stable
Nonflammable
Break down slowly in the environment
Travel long distances in the air
Fat soluble
Ends up in food chains and webs
Banned, but found everywhere

45. Water table Fish Soil Water table
Atmosphere
Vegetation
Crops
Surface water
Humans
Animals
Surface water
Groundwater
Water table
Fish
Vegetation
Figure 17-10: PCBs and other persistent toxic chemicals can move through the living and nonliving environment by a number of pathways.
Soil
Groundwater
Water table
Rock
Rock
© Cengage Learning 2015
Fig , p. 454

46. 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.

47. Case Study: Protecting Children from Toxic Chemicals
Analysis of umbilical cord blood
180 chemicals found that cause cancers in humans or animals
Infants and children more susceptible
Less well-developed immune systems and body detoxification processes
Fetal exposure may increase risk of autism, asthma, learning disorders

48. Figure 17-14 The surfaces of many soft plastic products can contain phthalates.
Fig , p. 458

49. Chloroform
Source: Chlorine-treated water in
hot showers
Possible threat: Cancer
Para-dichlorobenzene
Source: Air fresheners,
mothball crystals
Threat: Cancer
Tetrachloroethylene
Source: Dry-cleaning
fluid fumes on clothes
Threat: Nerve disorders,
damage to liver and
kidneys, possible cancer
Formaldehyde
Source: Furniture stuffing,
paneling, particleboard,
foam insulation
Threat: Irritation of eyes,
throat, skin, and lungs;
nausea; dizziness
1,1,1-Trichloroethane
Source: Aerosol sprays
Threat: Dizziness,
irregular breathing
Styrene
Source: Carpets,
plastic products
Threat: Kidney and
liver damage
Nitrogen oxides
Source: Unvented gas
stoves and kerosene
heaters, woodstoves
Threat: Irritated lungs,
children's colds,
headaches
Carbon monoxide
Source: Faulty furnaces,
unvented gas stoves and
kerosene heaters,
woodstoves
Threat: Headaches,
drowsiness, irregular
heartbeat, death
Benzo-α-pyrene
Source: Tobacco smoke,
woodstoves
Threat: Lung cancer
Particulates
Source: Pollen, pet
dander, dust mites,
cooking smoke particles
Threat: Irritated lungs,
asthma attacks, itchy
eyes, runny nose,
lung disease
Tobacco smoke
Source: Cigarettes
Threat: Lung cancer, respiratory
ailments, heart disease
Radon-222
Source: Radioactive soil
and rock surrounding
foundation, water supply
Threat: Lung cancer
Asbestos
Source: Pipe insulation, vinyl
ceiling and floor tiles
Threat: Lung disease, lung cancer
Figure 17-19: A number of potentially harmful chemicals are found in many homes. Questions: Does the fact that we do not know much about the long-term harmful effects of these chemicals make you more likely or less likely to minimize your exposure to them? Why?
Methylene chloride
Source: Paint strippers and thinners
Threat: Nerve disorders, diabetes
Stepped Art
Fig , p. 462

50. 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.

51. Percentage of population killed by a given dose
Figure This hypothetical dose-response curve illustrates how scientists can estimate the LD50, the dosage of a specific chemical that kills 50% of the animals in a test group. Toxicologists use this method to compare the toxicities of different chemicals.
LD50
Dose (hypothetical units)
Fig , p. 460

52. Table 17.1, p. 461

53. Figure Scientists use two types of dose-response curves to help them estimate the toxicity of various chemicals. The linear and nonlinear curves in the graph on the left apply if even the smallest dosage of a chemical has a harmful effect that increases with the dosage. The graph on the right applies if a harmful effect occurs only when the dosage exceeds a certain threshold level.
Fig , p. 461

54. How Would You Vote?
To conduct an instant in-class survey using a classroom response system, access “JoinIn Clicker Content” from the PowerLecture main menu for Living in the Environment.
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.
b. Yes. Preventing the commercialization of harmful chemicals and technologies is better than dealing with the high costs of medical treatments and environmental damage.

55. 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

56. 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%.

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

58. Figure There is a startling difference between normal human lungs (left) and the lungs of a person who died of emphysema (right). The major causes of emphysema are prolonged smoking and exposure to air pollutants.
Fig , p. 467

59. 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

60. CONSIDER THIS. . .
CAMPUS SUSTAINABILITY Pollution Prevention at Pomona
p. 464

61. 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.
Sometimes misleading information, denial, and irrational fears can cloud judgment.

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

63. Number of people (% of world’s population)
Lack of access to
Number of people (% of world’s population)
Adequate
sanitation facilities
2.6 billion (37%)
Enough fuel for
heating and cooking
2 billion (28%)
Electricity
2 billion (28%)
Adequate health care
1.1 billion (15%)
Adequate housing
1 billion (14%)
Figure 17-21: These are some of the harmful effects that result from living in poverty. Questions: Which two of these effects would be the most harmful for you? Why?
Enough food for good health
925 million (13%)
Clean
drinking water
880 million (12%)
Fig , p. 466

64. 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

65. Unsafe working conditions, unsafe highways, criminal assault, and poverty are all examples of _____ hazards.
biological
chemical
natural
cultural

66. Which organism works by invading a cell, taking over its genetic machinery to replicate, and then spreading throughout a body?
bacteria
parasite
virus
pathogen

67. The biggest killer caused by a virus is _____.
HIV
influenza
West Nile
malaria

68. What is illustrated in the figure below?
genetic resistance
pandemic
toxicity
threshold dose-response

69. In your opinion, is vaccination a suitable way to slow or eradicate the spread of infectious disease?
Yes, vaccination has been proven effective.
No, much still needs to be learned about the use of vaccination.