Transcript chapter17 - Kevinflint.org

Environmental Hazards and
Human Health
Chapter 17
17-1 What Major Health Hazards
Do We Face?
 Concept 17-1 People face health hazards from
biological, chemical, physical, and cultural
factors, and from the lifestyle choices they make.
Science: Risk Assessment and Risk
Management
Fig 17-3
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.
Using Risk Assessment
(Benefit/Cost Analysis)
1. Benefits > Risks,
then behavior or process should continue
2. Benefits < Risks,
then behavior or process should not continue.
Every behavior or process involves RISK.
17-2 What Types of Biological Hazards
Do We Face?
 Concept 17-2 In terms of death rates, the most
serious infectious diseases are flu, AIDS,
diarrheal diseases, malaria, and tuberculosis;
most of these deaths occur in developing
countries.
Core Case Study: The Global
HIV/AIDS Epidemic
 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
 25 Million deaths, so far; alter country’s age
structure
Global Outlook: Worldwide, AIDS Is the
Leading Cause of Death for Ages 15–49
Fig 17-2
Some Viral Diseases Kill Large
Numbers of People
 Global strategy to slow down the spread of HIV
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Reduce the number of new infections
Concentrate on those most likely to spread HIV
Free testing
Education for prevention
Provide free or low-cost drugs
Research
United Nations HIV/AIDS
Major Causes of Death in the World and
in the United States in 2005
Fig 17-3
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. Methicillin-resistant Staphylococcus
aureus (MRSA)
• Overuse of antibiotics: A 2000 study found that
half of the antibiotics used to treat humans were
prescribed unnecessarily.
Science: Pathways for Infectious
Diseases in Humans
Fig 17-5
The World’s Seven Deadliest Infectious
Diseases Kill 12.5 Million People
Fig 17-6
Malaria – Death by Mosquito
 Malaria kills about
2 million people
per year and has
probably killed
more than all of
the wars ever
fought.
Global Outlook: Distribution of Malaria
A Boy in Brazil’s Amazon Sleeps Under
an Insecticide-Treated Mosquito Net
Infectious Disease Control
 Here are some link to International and U.S.
organizations that deal with disease control:
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UNICEF
WHO – World Health Organization
CDC – Center for Disease Control
Department of Health & Human Services
NIH – National Institute of Health
Solutions: Infectious Diseases, Ways to
Prevent or Reduce Their Occurrence
Fig 17-10
17-3 What Types of Chemical Hazards
Do We Face?
 Concept 17-3 There is growing concern about
chemicals that can cause birth defects and
cancers and disrupt the human immune,
nervous, and endocrine systems.
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.
CHEMICAL HAZARDS
 A hazardous chemical can harm humans or
other animals because it:
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Is flammable
Is explosive
An irritant
Interferes with oxygen uptake
Induce allergic reactions.
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 17-10
Some Chemicals May Affect Our Immune,
Nervous, and Endocrine Systems
 Some natural and synthetic chemicals in the
environment can weaken and harm
• Immune system
• Nervous system
• Endocrine system
• Hormonally active agents (HAAs)
• Gender benders
• Thyroid disrupters
Hormones and Hormones Mimics
or Blockers
Fig 17-12
Science Focus: Bisphenol A
 Estrogen mimic
 Found in many common products - Plastics
 NIEHS link to info
Science Focus: Mercury’s Toxic
Effects
 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
Science: Cycling of Mercury in Aquatic
Environments
Fig 17-A
SOLUTIONS
Mercury Pollution
Prevention
Phase out waste incineration
Remove mercury from
coal before it is burned
Switch from coal to natural
gas and renewable energy
resources such as wind,
solar cells, and hydrogen
Convert coal to liquid or
gaseous fuel
Phase out use of mercury in
batteries, TVs, compact
fluorescent lightbulbs, and all
other products unless they are
recycled
Control
Sharply reduce mercury
emissions from coal-burning
plants and incinerators
Tax each unit of mercury
emitted by coal-burning
plants and incinerators
Require labels on all
products containing mercury
Collect and recycle mercurycontaining electric switches,
relays, and dry-cell batteries
Fig. 17-B, p. 451
17-4 How Can We Evaluate and Deal with
Chemical Hazards?
 Concept 17-4A Scientists use live laboratory
animals, non-animal tests, 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
candidates.
Many Factors Determine the Harmful
Health Effects of a Chemical
 Toxicity dependent on
• Dose
• Frequency of exposure
• Age
• Genetic makeup = the effectiveness of the body’s detoxification
systems
• Multiple chemical sensitivity (MCS)
• Solubility and persistence of the chemical
• Biomagnification
 Response
• Acute effect
• Chronic effect
TOXICOLOGY: ASSESSING CHEMICAL
HAZARDS
 Typical variations
in sensitivity to a
toxic chemical
within a
population, mostly
because of
genetic variation.
Science: Estimating Human Exposure to
Chemicals and Measuring Their Effects
Fig 17-13
Hypothetical Dose-Response Curve
Showing Determination of the LD50
Fig 17-14
Toxicity Ratings and Average Lethal
Doses for Humans
Science: Two Types of DoseResponse Curves
Fig 17-15
Toxicity Ratings
LD50 is the dose at which 50% of the population die
Household product risk Dept Health & Human Services
Toxicology and Risk Assessment Careers
 Society of Toxicology
 Environmental Health and Toxicology
 EPA – risk assessment
 Risk Management Careers
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.
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.
Some Potentially Harmful Chemicals
Found in Most Homes
Fig 17-16
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 if we become informed, think critically
about risks, and make careful choices.
Comparative Risk Analysis: Most Serious
Ecological and Health Problems
Stepped Art
Fig. 17-17, p. 461
Global Outlook: Number of Deaths per
Year in the World from Various Causes
Fig 17-18
Comparison of Risks People Face in
Terms of Shorter Average Life Span
Annual Deaths in the U.S. from Tobacco
Use and Other Causes in 2004
Fig 17-20
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%.
Characteristics of Risk
(Factors on Right Increase Perception of Riskiness)
Voluntary
Involuntary
Driving a car
Breathing air polluted by a factory
Natural
Man Made
Radon in basement
Industrial chemicals
Familiar
Exotic
Household cleaners
Genetically engineered organism
Chronic
Catastrophic (Acute)
Routine small releases of chemicals from a
facility
Large release of chlorine gas from a plant
Visible Benefits
No Visible Benefits
Dying hair
Incinerator effluents
Controlled by Individuals
Controlled by others
Driving
Industrial pollution
Fair
Unfair
Using Risk Assessment
(Benefit/Cost Analysis)
1. Benefits > Risks,
then behavior or process should continue
2. Benefits < Risks,
then behavior or process should not continue.
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.
Fig 17-3