Transcript Chp 17 Notes

MILLER/SPOOLMAN
LIVING IN THE ENVIRONMENT
17TH
Chapter 17
Environmental Hazards and
Human Health
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
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Feminization
Smaller penis
Lower sperm counts
Presence of both male and female sex organs
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
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
Baby Drinking from BPA Bottle
Fig. 17-1, p. 436
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.
Risks Are Usually Expressed as Probabilities
• Risk
• Probability of suffering harm from a hazard
• Probability vs. possibility
• Risk Assessment
• Risk Management
Science: Risk Assessment and Risk Management
Fig. 17-2, p. 437
We Face Many Types of Hazards
1. Biological:
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Pathogen: an organism that causes disease in other
organisms
2. Chemical
3. Physical
4. Cultural
5. Lifestyle choices
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.
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
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
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Better health care
Better sanitation
Antibiotics
Vaccines
Infectious Diseases Are Still Major
Health Threats
• Infectious diseases spread through
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Air
Water
Food
Body fluids
• Epidemics and pandemics
• Resistance of bacteria and insects to drugs and
pesticides
Science: Pathways for Infectious Diseases
in Humans
Fig. 17-3, p. 439
Major Causes of Death from Infectious Diseases
in the World, 2007
Fig. 17-4, p. 439
Science Focus: Genetic Resistance to
Antibiotics Is Increasing (1)
• Bacteria: rapid reproduction, easily spread
• Overuse of antibiotics
• Overuse of pesticides
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?
Case Study: The Growing Global Threat
from Tuberculosis
• One in ten will become sick with TB
• 1.8 million deaths each year, primarily in lessdeveloped 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
Lung Tissue Destroyed by Tuberculosis
Fig. 17-5, p. 440
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
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
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:
1. Wash your hands
2. Avoid touching your face
3. Avoid sick people
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
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HIV
Avian flu
Hepatitis B
Lyme virus
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 drugs—live longer
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
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
Case Study: Malaria — The Spread of a
Deadly Parasite (2)
• Malaria on the rise since 1970
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Drug resistant Plasmodium
Insecticide resistant mosquitoes
Clearing of tropical forests
AIDS patients particularly vulnerable
• Prevention of spread and current research
Global Outlook: Distribution of Malaria
Fig. 17-6, p. 444
A Boy in Brazil’s Amazon Sleeps Under an
Insecticide-Treated Mosquito Net
Fig. 17-7, p. 445
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
Solutions: Infectious Diseases
Fig. 17-8, p. 445
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.
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
Case Study: PCBs Are Everywhere—A
Legacy from the Past
• Class of chlorine-containing compounds
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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
Potential Pathways on Which Toxic Chemicals
Move Through the Environment
Fig. 17-9, p. 447
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
Science Focus: Mercury’s Toxic
Effects (1)
• Hg: teratogen and potent neurotoxin
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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?
1. Inhalation: vaporized Hg or particulates
2. Eating fish with high levels of methylmercury
3. Eating high-fructose corn syrup
Science Focus: Mercury’s 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
Solutions: Mercury Pollution
Fig. 17-10, p. 449
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
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Gender benders
Thyroid disruptors
BPA?
Phthalates in plastics
Hormones and Hormones Mimics or
Blockers
Fig. 17-11, p. 449
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.
Many Factors Determine the Harmful
Health Effects of a Chemical (1)
• Toxicology
• Toxicity dependent on
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Dose
Age
Genetic makeup
Multiple chemical sensitivity (MCS)
Solubility
Persistence
Biomagnification
Many Factors Determine the Harmful
Health Effects of a Chemical (2)
• Response
• Acute effect: immediate or rapid
• Chronic effect: permanent or long-lasting
Science: Estimating Human Exposure to
Chemicals and Measuring Their Effects
Fig. 17-12, p. 452
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
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
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?
Hypothetical Dose-Response Curve Showing Determination of
the LD50
Fig. 17-13, p. 453
Toxicity Ratings and Average Lethal Doses
for Humans
Table 17-1, p. 453
Science: Two Types of Dose-Response
Curves
Fig. 17-14, p. 454
There Are Other Ways to Estimate the
Harmful Effects of Chemicals
• Case reports and epidemiological studies
• Limitations of epidemiological studies
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Too few people tested
Length of time
Can you link the result with the chemical?
Cannot be used for new hazards
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?
Some Potentially Harmful Chemicals Found in
Most Homes
Fig. 17-15, p. 455
Chloroform
Source: Chlorine-treated water in
hot showers
Possible threat: Cancer
Para-dichlorobenzene
Source: Air fresheners,
mothball crystals
Threat: Cancer
1,1,1-Trichloroethane
Source: Aerosol sprays
Threat: Dizziness,
irregular breathing
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
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
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
Radon-222
Source: Radioactive soil
and rock surrounding
foundation, water supply
Threat: Lung cancer
Tobacco smoke
Source: Cigarettes
Threat: Lung cancer, respiratory
ailments, heart disease
Asbestos
Source: Pipe insulation, vinyl
ceiling and floor tiles
Threat: Lung disease, lung cancer
Carbon monoxide
Source: Faulty furnaces,
unvented gas stoves and
kerosene heaters,
woodstoves
Threat: Headaches,
drowsiness, irregular
heartbeat, death
Methylene chloride
Source: Paint strippers and thinners
Threat: Nerve disorders, diabetes
Stepped Art
Fig. 17-15, p. 455
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
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
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
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.
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
Global Outlook: Number of Deaths per
Year in the World from Various Causes
Fig. 17-16, p. 458
Comparison of Risks People Face in Terms of
Shorter Average Life Span
Fig. 17-17, p. 459
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
Alzheimer’s disease
• Nicotine: additive
• Effects of passive smoking (secondhand smoke)
Case Study: Death from Smoking (2)
• How to reduce smoking
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Taxes
Classify and regulate nicotine
Bans on smoking in public places
Education
Normal Lung and Emphysema Lung
Fig. 17-18, p. 459
Annual Deaths in the U.S. from Tobacco
Use and Other Causes
Fig. 17-19, p. 460
Estimating Risks from Technologies
Is Not Easy
• System reliability (%) = Technological reliability (%) x
Human reliability (%)
• To err is human…
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
Several Principles Can Help Us to Evaluate
and Reduce Risk
1. Compare risks
2. Determine how much you are willing to accept
3. Determine the actual risk involved
4. Concentrate on evaluating and carefully making
important lifestyle choices
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.
Three Big Ideas
3. Becoming informed, thinking critically about risks,
and making careful choices can reduce the major
risks we face.