Managing Risk

1
Chapter 17
Environmental Hazards and Human Health

• Managing Risk
• In the 21st Century

2
Chapter Overview Questions

• What types of hazards do people face?
• Biological- bacteria, viruses, protists, fungi,
  animal parasites
• Chemical- toxins, mutagens, teratogens,
  carcinogens
• Physical- fires, earthquakes, weather
• Cultural- driving, smoking, poor diet, crime,
  poverty, unsafe sex
• What types of disease (biological hazards)
  threaten people in developing countries and
  developed countries?

3
Chapter Overview Questions

• How can risks be estimated and recognized?
• Risk analysis (a potential career!)
• Risk assessment
• Comparative risk analysis (ranking risks)
• Risk management (making decisions)
• Risk communication (informing politicians the
  public)

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.
• Costs are starting to come down a bit

5
Core Case Study The Global HIV/AIDS Epidemic

• AIDS has reduced the life expectancy of
  sub-Saharan Africa from 62 to 40 47 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
HIV Positive
AIDS
Becoming Infected
Developing AIDS
Dying
42 million
4.9 million per year
3 million per year
7-10 yrs
(13,400 per day)
Eventually, all
Year 2005 data
7
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
8
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.

9
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 (disease-causing organisms)
• 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.

10
BIOLOGICAL HAZARDS DISEASE IN DEVELOPED AND
DEVELOPING COUNTRIES

• Nontransmissible Diseases- not caused by living
  organisms
• cannot spread from one person to another
• Transmissible a.k.a. Infectious Diseases- caused
  by living organisms such as bacteria and viruses
• can spread from person to person contagious

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Transmissible Disease

• Vectors Pathways for infectious disease in
  humans.

Next
12

Wild animals
Mosquitoes
Food
Livestock
Water
Air
Pets
Baby, Im A-L-L-L Clean!
Yeah.keep talkin
Fetus and babies
Vectors of Transmissible Diseases
Other humans
Humans
Fig. 18-4, p. 420
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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.

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Disease (type of agent)
Deaths per year
Flu and pneumonia (viruses bacteria)
3.2 million
HIV/AIDS (virus)
3.0 million
Malaria (protozoa)
2.0 million
Diarrheal diseases (viruses, bacteria, protozoa)
1.9 million
Tuberculosis (bacteria)
1.7 million
Hepatitis B (virus)
1 million
Measles (virus)
800,000
Fig. 18-5, p. 420
15
Case Study Growing Germ Resistance to Antibiotics

• Rapidly reproducing infectious bacteria are
  becoming genetically resistant to widely used
  antibiotics due to
• Overuse of antibiotics A 2000 study found that
  half of the antibiotics used to treat humans were
  prescribed unnecessarily (also, MOST are used in
  animal feed to hasten growth)
• Genetic resistance Spread of bacteria around the
  globe by humans overuse of pesticides which
  produce pesticide resistant insects that carry
  bacteria.

16
Case Study The Growing Global Threat from
Tuberculosis

• The highly infectious tuberculosis bacterium (TB)
  kills 1.7 million people per year and could kill
  25 million (total) people by 2020.
• Recent increases in TB are due to
• Lack of TB screening and control programs
  especially in developing countries due to
  expenses (half do not known they are infected)
• Drugs must be taken every day for 6-8 months
• Genetic resistance to the most effective
  antibiotics (symptoms disappear in in a few
  weeks, patients stop taking their medicine)

17
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, hastening viral evolution

18
Case Study- Flu Pandemics

• Common flu kills about 2 of those infected.
• Occasionally, flu strains develop that kill 80
  of those infected.
• 1918- Spanish Flu- killed 20-50 million worldwide
• 500,000 deaths in USA
• People woke up healthy, died by nightfall
• 1957- Asian Flu- killed 1-4 million people
• 1968- Hong Kong Flu- killed 1-4 million people

19
Case Study- Flu Pandemics

• Many health scientists believe that sooner or
  later, a potent flu pandemic will sweep the world
  again.
• Hastened by global air travel
• Could infect 25 of the worlds people and kill
  between 2 and 360 million people worldwide
• Worst-case, USA 1.9 million dead, 8.5 million
  hospitalized, 450 billion in economic losses,
  massive social economic disruption.
• H5N1- bird flu- deadly new strain of avian flu,
  related to 1918 flu
• So far, has not developed the ability to spread
  from humans to humans

20
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
21
Plasmodium is an infectious protozoan
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 Anopheles mosquito
Sporozoites penetrate liver and develop into
merozoites
Female mosquito injects Plasmodium sporozoites
into human host
Stepped Art
Fig. 18-7, p. 423
22
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
23
Case Study Malaria Death by Mosquito

• Columbia University economist Jeffrey Sachs-
  preventing malaria for one person costs 25 cents
  to 2.40 per year- This is probably the best
  bargain on the planet

Figure 18-6
24
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.
• Window screens bed nets
• Clear vegetation around houses
• Plant trees to soak up water in marshes
• Zinc Vitamin A supplements to increase
  resistance to malaria

25
Good News/ Bad News

• Good news- According to the WHO
• Global death rate from infectious diseases has
  dropped by 2/3 between 1970 2000
• Projected to continue to decrease
• Global immunizations of children have increased
  from 10 to 84 between 1971 2000
• Saves about 10 million lives per year

26
Good News/ Bad News

• Bad news- According to the WHO
• Only 10 of global medical research development
  money goes toward preventing infectious disease
  in developing countries
• Even though more people worldwide suffer from
  these diseases than all other diseases combined

27

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
28
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.

29
Case Study Ecological MedicineFruit Bats, Pig
Farms, and Japanese Encephalitis (Nipah Virus)
30
Case Study Ecological Medicine

• Malaysia, mid-1990s- clear forests for pig farms

• Displaced fruit bats a.k.a. flying foxes move
  into rafters of pig barns

• Bat droppings infected with Nipah Virus (Japanese
  encephalitis) drop into pig drinking water

• Virus spreads from pigs to keepers,
• killing 40 of human victims

• Outbreak contained 8 pig farms closed, 1 million
  pigs slaughtered disposed of

31
CHEMICAL RISKS

• Toxic Chemicals vs Hazardous Chemicals
• What is the difference?
• Toxic means poisonous, e.g. too much Tylenol
  damages your liver.
• Hazardous means harmful, e.g. fires floods
  are hazardous, but not toxic.

32
CHEMICAL RISKS

• A toxic (a.k.a. poisonous) 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 RISKS

• A hazardous chemical can harm humans or other
  animals because it
• Is flammable
• Is explosive
• An irritant
• Interferes with oxygen uptake, like CO (carbon
  monoxide)
• 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 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.

35
HAAs Hormonally Active Agents

• Molecules of certain synthetic chemicals have
  shapes similar to those of natural hormones and
  can adversely affect the endocrine system.

Next
36

Hormonally Active Agents (HAAs)
a.k.a. gender benders
Normal Hormone Process
Hormone Mimic
Hormone Blocker
Antiandrogen chemical
Hormone
Estrogenlike chemical
Receptor
Cell
Feminization Smaller penises Lower sperm
counts Hermaphroditism
Aluminum DDT Mercury PCBs Phthlates
Bisphenol A (BPA) Atrazine other herbicides
Fig. 18-9, p. 427
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.
• 15,000-22,000 people died
• Indian officials claim that simple upgrades could
  have prevented the tragedy.

38
TOXICOLOGY ASSESSING CHEMICAL HAZARDS

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

Figure 18-10
39
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 (age, size, gender,
  etc.)
• The effectiveness of the bodys detoxification
  systems.
• Ones genetic makeup.

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.

Next
41

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
42
TOXICOLOGY ASSESSING CHEMICAL HAZARDS

• Risk assessment expert Joseph V. Rodricks
• Toxicologists know a great deal about a few
  chemicals, a little about many, and next to
  nothing about most

43
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.

44
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.

45
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.

46
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.

47
Risk analysis
48
RISK ANALYSIS

• Scientists have developed ways to
• Evaluate and compare risks
• Decide how much risk is acceptable
• Find affordable ways to reduce it.

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49
Risk analysis

• Risk assessment (evaluating individual risks)
• Comparative risk analysis (ranking risks)
• Risk management (making decisions)
• Risk communication (informing politicians the
  public)

50

Comparative AVERAGE 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
51
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.

52
RISK ANALYSIS

• 2003 data

Figure 18-A
53
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.

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54

Cause of death
Annual deaths (Global)
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
55
Perceiving Risk

• Most of us are not good at evaluating risk!
• Most individuals evaluate the relative risk they
  face based on
• Fear
• Degree of control
• Optimism bias
• Whether risk is catastrophic.
• Instant gratification
• Unfair distribution of risk (NIMBY)
• Sometimes misleading information, denial, and
  irrational fears can cloud judgment.

56
RISK ANALYSIS

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

Figure 18-14
57

Shortens average life span in the U.S. by
Hazard
Poverty
710 years
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7.5 years
Smoking
610 years
Overweight (35)
6 years
Unmarried
also, Born Male
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
58
Becoming Better at Risk Analysis

• We can
• Carefully evaluate or tune out of the barrage of
  bad news covered in the media
• Compare risks
• Concentrate on reducing personal risks over which
  we have some control.

Figure 18-3
59
Becoming Better at Risk Analysis

• Read p. 464-465 Most People Do Not Know How
  and Several Principles
• Write one example of each of the five factors
  that cause people to mis-evaluate risk try to
  make at least two of your examples original.
• Briefly describe one personal risk that you
  probably overestimate and one that you probably
  underestimate.

Figure 18-3
60

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