Environmental Hazards and Human Health

1
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 books e-resources page at
  www.thomsonedu.com 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 Kaposis sarcoma (above).

Figure 18-1
7
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.

8
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)

9
Transmissible Disease

• Pathway for infectious disease in humans.

Figure 18-4
10

Wild animals
Mosquitoes
Food
Livestock
Water
Air
Pets
Fetus and babies
Other humans
Humans
Fig. 18-4, p. 420
11
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
12

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
Tuberculosis (bacteria)
1.7 million
Hepatitis B (virus)
1 million
Measles (virus)
800,000
Fig. 18-5, p. 420
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.
• Overuse of antibiotics A 2000 study found that
  half of the antibiotics used to treat humans were
  prescribed unnecessarily.

14
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.

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.
• 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.

17
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.

18
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
19

Female mosquito bites infected human, ingesting
blood that contains Plasmodium gametocytes
Merozoites enter bloodstream and develop into
gametocytes causing malaria and making infected
person a new reservoir
Plasmodium develop in mosquito
Sporozoites penetrate liver and develop into
merozoites
Female mosquito injects Plasmodium sporozoites
into human host.
Fig. 18-7, p. 423
20
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
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
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.

23

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
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
24
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.

25
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.

26
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.

27
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.
• Nervous system brain, spinal cord, and
  peripheral nerves.
• Endocrine system complex network of glands that
  release minute amounts of hormones into the
  bloodstream.

28
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
29

Normal Hormone Process
Hormone Mimic
Hormone Blocker
Antiandrogen chemical
Hormone
Estrogenlike chemical
Receptor
Cell
Fig. 18-9, p. 427
30
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.
• 15,000-22,000 people died
• Indian officials claim that simple upgrades could
  have prevented the tragedy.

31
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 bodys detoxification
  systems.
• Ones genetic makeup.

32
TOXICOLOGY ASSESSING CHEMICAL HAZARDS

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

Figure 18-10
33

Number of individuals affected
Majority of population
Very sensitive
Very insensitive
Dose (hypothetical units)
Fig. 18-10, p. 430
34
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
35

Water pollutant levels
Air pollutant levels
Soil/dust levels
Food pesticide levels
Nutritional health
?
Mathematical measurements modeling
Overall health
Lifestyle
Predicted level of toxicant in people
Personal habits
Metabolism
Genetic predisposition
Accumulation
Excretion
Lung, intestine skin absorption rates
Fig. 18-11, p. 431
36
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.

37
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.

38
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.

39
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.

40
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.

41
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
42

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
Low-Risk Ecological Problems Oil spills
Groundwater pollution Radioactive isotopes
Acid runoff to surface waters Thermal pollution
Fig. 18-12, p. 433
43
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.

44
RISK ANALYSIS

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

Figure 18-A
45

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
55,000
Pollutants/toxins
30,600
Suicides
20,622
Homicides
17,000
Illegal drug use
Fig. 18-A, p. 435
46
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
47

Cause of death
Annual deaths
11 million (75)
Poverty/malnutrition/ disease cycle
5 million (34)
Tobacco
3.2 million (22)
Pneumonia and flu
3 million (21)
Air pollution
3 million (21)
HIV/AIDS
2 million (14)
Malaria
1.9 million (13)
Diarrhea
1.7 million (12)
Tuberculosis
1.2 million (8)
Car accidents
Work-related injury disease
1.1 million (8)
1 million (7)
Hepatitis B
800,000 (5)
Measles
Fig. 18-13, p. 435
48
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.

49
RISK ANALYSIS

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

Figure 18-14
50

Shortens average life span in the U.S. by
Hazard
Poverty
710 years
Born male
7.5 years
Smoking
610 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
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
10 hours
Lifetime near nuclear plant
Fig. 18-14, p. 436
51
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
52

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?
Financial commitment
Consequences of risk
How much money should be spent?
What is the likely damage?
Fig. 18-3, p. 419