Environmental Hazards and Human Health

1

• Chapter 17
• Environmental Hazards and Human Health

2
Core Case Study Are Baby Bottles and Food Cans
Safe To Use? The BPA Controversy (1)

• Some synthetic chemicals act as hormone mimics
  and disrupt the human endocrine system
• Excess estrogen effects on males
• Feminization
• Smaller penis
• Lower sperm counts
• Presence of both male and female sex organs

3
Core Case Study Are Baby Bottles and Food Cans
Safe To Use? The BPA Controversy (2)

• BPA (bisphenol A)
• Estrogen mimic
• In polycarbonates and other hardened plastics
• Baby bottles and sipping cups
• Reusable water bottles
• Sports drink and juice bottles
• Microwave dishes
• Food storage containers
• Liners of most food and soft drink cans

4
Core Case Study Are Baby Bottles and Food Cans
Safe To Use? The BPA Controversy (3)

• BPA leaches into foods and drinks
• Even when containers not heated
• 93 of Americans older than 6 have BPA levels
  above the threshold level set by the EPA
• Higher in children and adolescents
• Risks for infants, children, adults

5
Baby Drinking from BPA Bottle
Fig. 17-1, p. 436
6
17-1 What Major Health Hazards Do We Face?

• Concept 17-1 We face health hazards from
  biological, chemical, physical, and cultural
  factors, and from the lifestyle choices they
  make.

7
Risks Are Usually Expressed as Probabilities

• Risk
• Probability of suffering harm from a hazard
• Probability vs. possibility
• Risk Assessment
• Risk Management

8
Science Risk Assessment and Risk Management
Fig. 17-2, p. 437
9
Risk Assessment
Risk Management
Comparative risk analysis
Hazard identification
How does it compare with other risks?
What is the hazard?
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 How much money should be
spent?
Consequences of risk What is the likely damage?
Fig. 17-2, p. 437
10
We Face Many Types of Hazards

• Biological
• Pathogen an organism that causes disease in
  other organisms
• Chemical
• Physical
• Cultural
• Lifestyle choices

11
17-2 What Types of Biological Hazards Do We Face?

• Concept 17-2 The most serious biological hazards
  we fade are infectious diseases such as flu,
  AIDS, tuberculosis, diarrheal diseases, and
  malaria.

12
Some Diseases Can Spread from One Person to
Another (1)

• Infectious disease
• Pathogen invades the body and multiplies
• Transmissible disease
• Contagious or communicable disease
• Infectious disease transmitted between people
• Flu, tuberculosis, measles

13
Some Diseases Can Spread from One Person to
Another (2)

• Nontransmissible disease
• Not caused by living organisms
• Heart disease, most cancers, diabetes
• Since 1950, death from infectious diseases have
  declined due to
• Better health care
• Better sanitation
• Antibiotics
• Vaccines

14
Infectious Diseases Are Still Major Health
Threats

• Infectious diseases spread through
• Air
• Water
• Food
• Body fluids
• Epidemics and pandemics
• Resistance of bacteria and insects to drugs and
  pesticides

15
Science Pathways for Infectious Diseases in
Humans
Fig. 17-3, p. 439
16
Pets
Livestock
Wild animals
Insects
Food
Water
Air
Fetus and babies
Other humans
Humans
Fig. 17-3, p. 439
17
Stepped Art
Fig. 17-3, p. 439
18
Major Causes of Death from Infectious Diseases in
the World, 2007
Fig. 17-4, p. 439
19
Disease (type of agent)
Deaths per year
Pneumonia and flu (bacteria and viruses)
3.2 million
HIV/AIDS (virus)
2.0 million
Tuberculosis (bacteria)
1.8 million
Diarrheal diseases (bacteria and viruses)
1.6 million
Hepatitis B (virus)
1 million
Malaria (protozoa)
900,000
Measles (virus)
800,000
Fig. 17-4, p. 439
20
Disease (type of agent)
Deaths per year
Stepped Art
Fig. 17-4, p. 439
21
Science Focus Genetic Resistance to Antibiotics
Is Increasing (1)

• Bacteria rapid reproduction, easily spread
• Overuse of antibiotics
• Overuse of pesticides

22
Science Focus Genetic Resistance to Antibiotics
Is Increasing (2)

• Methicillin-resistant Staphylococcus aureus
  (MRSA)
• Resistant to most antibiotics
• Symptoms of MRSA
• How will it be controlled?

23
Case Study The Growing Global Threat from
Tuberculosis

• One in ten will become sick with TB
• 1.8 million deaths each year, primarily in
  less-developed countries
• Why is tuberculosis on the rise?
• Not enough screening and control programs
• Genetic resistance to a majority of effective
  antibiotics
• Person-to-person contact has increased
• AIDS individuals are very susceptible to TB

24
Lung Tissue Destroyed by Tuberculosis
Fig. 17-5, p. 440
25
Individuals Matter Three College Students Have
Saved Thousands of Lives

• North Carolina State seniors
• Developed a device that can detect TB bacteria
  on a slide
• Very useful in less-developed countries

26
Viral Diseases and Parasites Kill Large Numbers
of People (1)

• Influenza or flu virus
• 1 Killer
• HIV
• 2 Killer
• Hepatitis B virus (HBV)
• 3 Killer
• Emergent diseases West Nile virus

27
Viral Diseases and Parasites Kill Large Numbers
of People (2)

• Viruses that move form animals to humans
• West Nile virus
• Ecological medicine
• Reduce chances of infection
• Wash your hands
• Avoid touching your face
• Avoid sick people

28
Science Focus Ecological Medicine How Humans
Get Infectious Diseases from Animals

• Ecological medicine
• Human practices that encourage the spread of
  diseases from animals to humans
• Emerging infections
• HIV
• Avian flu
• Hepatitis B
• Lyme virus

29
Case Study Global HIV/AIDS Epidemic (1)

• Acquired immune deficiency syndrome (AIDS)
• caused by human immunodeficiency virus (HIV)
• Many secondary infections
• No vaccine to prevent or cure AIDS
• Expensive drugslive longer

30
Case Study Global HIV/AIDS Epidemic (2)

• 25 million deaths, so far
• 1 killer globally of women 15-49
• Most prevalent in sub-Saharan Africa
• Life expectancy dropped from 62 to 47
• Alters age structure of population

31
Case Study Malaria The Spread of a Deadly
Parasite (1)

• Malaria
• Caused by Plasmodium sp. carried by Anopheles
  mosquitoes
• Tropical and subtropical regions
• Spread
• Symptoms
• Malarial cycle

32
Case Study Malaria The Spread of a Deadly
Parasite (2)

• Malaria on the rise since 1970
• Drug resistant Plasmodium
• Insecticide resistant mosquitoes
• Clearing of tropical forests
• AIDS patients particularly vulnerable
• Prevention of spread and current research

33
Global Outlook Distribution of Malaria
Fig. 17-6, p. 444
34
A Boy in Brazils Amazon Sleeps Under an
Insecticide-Treated Mosquito Net
Fig. 17-7, p. 445
35
We Can Reduce the Incidence of Infectious Diseases

• Good news
• Vaccinations on the rise
• Oral rehydration therapy
• Bad news
• More money needed for medical research in
  developing countries

36
Solutions Infectious Diseases
Fig. 17-8, p. 445
37
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
Require careful hand washing by all medical
personnel
Immunize children against major viral diseases
Provide oral rehydration for diarrhea victims
Conduct global campaign to reduce HIV/AIDS
Fig. 17-8, p. 445
38
17-3 What Types of Chemical Hazards Do We Face?

• Concept 17-3 There is growing concern about
  chemicals in the environment that can cause
  cancers and birth defects, and disrupt the human
  immune, nervous, and endocrine system.

39
Some Chemicals Can Cause Cancers, Mutations, and
Birth Defects

• Toxic chemicals
• Carcinogens
• Chemicals, types of radiation, or certain viruses
  the cause or promote cancer
• Mutagens
• Chemicals or radiation that cause mutations or
  increase their frequency
• Teratogens
• Chemicals that cause harm or birth defects to a
  fetus or embryo

40
Case Study PCBs Are EverywhereA 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
• Biomagnification
• Food chains and webs
• Banned, but found everywhere

41
Potential Pathways on Which Toxic Chemicals Move
Through the Environment
Fig. 17-9, p. 447
42
Atmosphere
Vegetation
Crops
Surface water
Humans
Animals
Surface water
Groundwater
Water table
Fish
Vegetation
Groundwater
Soil
Water table
Rock
Rock
Fig. 17-9, p. 447
43
Some Chemicals May Affect Our Immune and Nervous
Systems

• Some natural and synthetic chemicals in the
  environment can weaken and harm
• Immune system
• Nervous system
• Neurotoxins PCBs, arsenic, lead, some pesticides
• Endocrine system

44
Science Focus Mercurys Toxic Effects (1)

• Hg teratogen and potent neurotoxin
• Once airborne, persistent and not degradable
• 1/3 from natural sources
• 2/3 from human activities
• Enters the food chain biomagnification
• How are humans exposed?
• Inhalation vaporized Hg or particulates
• Eating fish with high levels of methylmercury
• Eating high-fructose corn syrup

45
Science Focus Mercurys Toxic Effects (2)

• Effects of Hg on humans
• Damage nervous system, kidneys, lungs
• Harm fetuses and cause birth defects
• Who is most at risk?
• Pregnant women
• 75 of exposure comes from eating fish

46
Solutions Mercury Pollution
Fig. 17-10, p. 449
47
Solutions
Mercury Pollution
Prevention
Control
Phase out waste incineration
Sharply reduce mercury emissions from
coal-burning plants and incinerators
Remove mercury from coal before it is burned
Label all products containing mercury
Switch from coal to natural gas and renewable
energy resources
Collect and recycle batteries and other products
containing mercury
Fig. 17-10, p. 449
48
Some Chemicals Affect the Human Endocrine System

• Glands that release hormones that regulate bodily
  systems and control sexual reproduction, growth,
  development, learning, behavior
• Hormonally active agents have similar shapes and
  bind to hormone receptors
• Gender benders
• Thyroid disruptors
• BPA?
• Phthalates in plastics

49
Hormones and Hormones Mimics or Blockers
Fig. 17-11, p. 449
50
Hormone
Estrogen-like chemical
Antiandrogen chemical
Receptor
Cell
Normal Hormone Process
Hormone Mimic
Hormone Blocker
Fig. 17-11, p. 449
51
Hormone
Estrogen-like chemical
Antiandrogen chemical
Receptor
Cell
Normal Hormone Process
Hormone Mimic
Hormone Blocker
Stepped Art
Fig. 17-11, p. 449
52
17-4 How Can We Evaluate and Deal with Chemical
Hazards?

• Concept 17-4A Scientists use live laboratory
  animals, case reports of poisonings, and
  epidemiological studies to estimate the toxicity
  of chemicals, but these methods have limitations.
• Concept 17-4B Many health scientists call for
  much greater emphasis on pollution prevention to
  reduce our exposure to potentially harmful
  chemicals.

53
Many Factors Determine the Harmful Health Effects
of a Chemical (1)

• Toxicology
• Toxicity dependent on
• Dose
• Age
• Genetic makeup
• Multiple chemical sensitivity (MCS)
• Solubility
• Persistence
• Biomagnification

54
Many Factors Determine the Harmful Health Effects
of a Chemical (2)

• Response
• Acute effect immediate or rapid
• Chronic effect permanent or long-lasting

55
Science Estimating Human Exposure to Chemicals
and Measuring Their Effects
Fig. 17-12, p. 452
56
Water pollutant levels
Soil/dust levels
Air pollutant levels
Food pesticide levels
Nutritional health
?
Scientific measurements and modeling
Overall health
Lifestyle
Predicted level of toxicant in people
Personal habits
Metabolism
Genetic predisposition
Accumulation
Excretion
Lung, intestine, and skin absorption rates
Fig. 17-12, p. 452
57
Case Study Protecting Children from Toxic
Chemicals

• Analysis of umbilical cord blood significance
• Infants and children more susceptible
• Eat, drink water, and breathe more per unit of
  body weight than adults
• Put their fingers in their mouths
• Less well-developed immune systems and body
  detoxification processes
• Fetal exposure may increase risk of autism,
  asthma, learning disorders

58
Scientists Use Live Lab Animals and Nonanimal
Tests to Estimate Toxicity (1)

• Mice and rats
• Systems are similar to humans
• Small, and reproduce rapidly
• Is extrapolation to humans valid?
• Dose-response curve median lethal dose (LD50)
• Nonthreshold dose-response model
• Threshold dose-response model

59
Scientists Use Live Lab Animals and Nonanimal
Tests to Estimate Toxicity (2)

• More humane methods using animals
• Replace animals with other models
• Computer simulations
• Tissue culture and individual animal cells
• Chicken egg membranes
• What are the effects of mixtures of potentially
  toxic chemicals?

60
Hypothetical Dose-Response Curve Showing
Determination of the LD50
Fig. 17-13, p. 453
61
100
75
50
Percentage of population killed by a given dose
25
LD50
0
0
2
4
6
8
10
12
14
16
Dose (hypothetical units)
Fig. 17-13, p. 453
62
Toxicity Ratings and Average Lethal Doses for
Humans
Table 17-1, p. 453
63
Science Two Types of Dose-Response Curves
Fig. 17-14, p. 454
64
Nonlinear dose-response
Linear dose- response
Effect
Dose
No threshold
Fig. 17-14a, p. 454
65
Effect
Threshold level
Dose
Threshold
Fig. 17-14b, p. 454
66
There Are Other Ways to Estimate the Harmful
Effects of Chemicals

• Case reports and epidemiological studies
• Limitations of epidemiological studies
• Too few people tested
• Length of time
• Can you link the result with the chemical?
• Cannot be used for new hazards

67
Are Trace Levels of Toxic Chemicals Harmful?

• Insufficient data for most chemicals
• We are all exposed to toxic chemicals
• Are the dangers increasing or are the tests just
  more sensitive?

68
Some Potentially Harmful Chemicals Found in Most
Homes
Fig. 17-15, p. 455
69
Shampoo Per?uorochemicals to add shine
Clothing Can contain per?uorochemicals
Teddy bear Some stuffed animals made overseas
contain flame retardants and/or pesticides
Baby bottle Can contain bisphenol A
Nail polish Perfluorochemicals and phthalates
Mattress Flame retardants in stuffing
Perfume Phthalates
Hairspray Phthalates
Carpet Padding and carpet fibers contain flame
retardants, perfluorochemicals, and pesticides
Food Some food contains bisphenol A
TV Wiring and plastic casing contain ?ame
retardants
Milk Fat contains dioxins and flame retardants
Sofa Foam padding contains flame retardants and
per?uorochemicals
Frying pan Nonstick coating contains
per?uorochemicals
Tile floor Contains per?uorochemicals,
phthalates, and pesticides
Computer Flame retardant coatings of plastic
casing and wiring
Fruit Imported fruit may contain pesticides
banned in the U. S.
Toys Vinyl toys contain phthalates
Tennis shoes Can contain phthalates
Water bottle Can contain bisphenol A
Fig. 17-15, p. 455
70
Stepped Art
Fig. 17-15, p. 455
71
Why Do We Know So Little about the Harmful
Effects of Chemicals?

• Severe limitations estimating toxicity levels and
  risks
• Only 2 of 100,000 chemicals have been adequately
  tested
• 99.5 of chemicals used in the United States are
  not supervised by government

72
Pollution Prevention and the Precautionary
Principle

• Those introducing a new chemical or new
  technology would have to follow new strategies
• A new product is considered harmful until it can
  be proved to be safe
• Existing chemicals and technologies that appear
  to cause significant harm must be removed
• 2000 global treaty to ban or phase out the dirty
  dozen persistent organic pollutants (POPs)
• 2007 REACH program in the European Union

73
Individuals Matter Ray Turner and His
Refrigerator

• 1974 Ozone layer being depleted by
  chlorofluorocarbons (CFCs)
• 1992 International agreement to phase out CFCs
  and other ozone-destroying chemicals
• Ray Turner citrus-based solvents to clean
  circuit boards

74
17-5 How Do We Perceive Risks and How Can We
Avoid the Worst of Them?

• Concept 17-5 We can reduce the major risks we
  face by becoming informed, thinking critically
  about risks, and making careful choices.

75
The Greatest Health Risks Come from Poverty,
Gender, and Lifestyle Choices

• Risk analysis
• Risk assessment
• Risk management
• Risk communication
• Greatest health risks
• Poverty
• Gender
• Lifestyle choices

76
Global Outlook Number of Deaths per Year in the
World from Various Causes
Fig. 17-16, p. 458
77
Cause of death
Annual deaths
Poverty/malnutrition/ disease cycle
11 million (150)
Tobacco
5.4 million (74)
Pneumonia and ?u
3.2 million (44)
Air pollution
2.4 million (33)
HIV/AIDS
2 million (27)
Diarrhea
1.6 million (22)
Tuberculosis
1.5 million (21)
Automobile accidents
1.2 million (16)
1.1 million (15)
Work-related injury and disease
1 million (14)
Malaria
Hepatitis B
1 million (14)
Measles
800,000 (11)
Fig. 17-16, p. 458
78
Comparison of Risks People Face in Terms of
Shorter Average Life Span
Fig. 17-17, p. 459
79
Hazard
Shortens average life span in the United States
by
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
Living lifetime near nuclear plant
10 hours
Fig. 17-17, p. 459
80
Case Study Death from Smoking (1)

• Most preventable major cause of suffering and
  premature death
• Premature death of 5.4 million per year globally
  and 442,000 in the United States
• Could be linked to increased dementia and
  Alzheimers disease
• Nicotine additive
• Effects of passive smoking (secondhand smoke)

81
Case Study Death from Smoking (2)

• How to reduce smoking
• Taxes
• Classify and regulate nicotine
• Bans on smoking in public places
• Education

82
Normal Lung and Emphysema Lung
Fig. 17-18, p. 459
83
Stepped Art
Fig. 17-18, p. 459
84
Annual Deaths in the U.S. from Tobacco Use and
Other Causes
Fig. 17-19, p. 460
85
Cause of Death
Deaths per Year
Tobacco use
442,000
Accidents
101,500 (33,960 auto)
Alcohol use
85,000
Infectious diseases
75,000 (15,000 from AIDS)
Pollutants/toxins
55,000
Suicides
30,600
Homicides
20,622
Illegal drug use
17,000
Fig. 17-19, p. 460
86
Stepped Art
Fig. 17-19, p. 460
87
Estimating Risks from Technologies Is Not Easy

• System reliability () Technological
  reliability () x Human reliability ()
• To err is human
  

88
Most People Do a Poor Job of Evaluating Risks

1. Fear
2. Degree of control
3. Whether a risk is catastrophic or chronic
4. Optimism bias
5. Want instant gratification without thinking of
   future harm

89
Several Principles Can Help Us to Evaluate and
Reduce Risk

• Compare risks
• Determine how much you are willing to accept
• Determine the actual risk involved
• Concentrate on evaluating and carefully making
  important lifestyle choices

90
Three Big Ideas

1. We face significant hazards from infectious
   diseases, malaria, and tuberculosis, and from
   exposure to chemicals that can cause cancers and
   birth defects, and disrupt the human immune,
   nervous, and endocrine systems.
2. Because of the difficulty in evaluating the harm
   caused by exposure to chemicals, many health
   scientists call for much greater emphasis on
   pollution prevention.

91
Three Big Ideas

1. Becoming informed, thinking critically about
   risks, and making careful choices can reduce the
   major risks we face.