Transcript Lifestyle Choices Game

Environmental Hazards and
Human Health
Chapter 17
17.1
Risks Are Usually Expressed as
Probabilities
 Risk – probability of
suffering harm from
a hazard that can
cause injury,
disease, death,
economic loss, or
damage
• Gives likelihood of
such an event
Possible…or Probably?
 Possibility: it may
happen
 Example: It is
possible that a
smoker can get lung
cancer.
 Probability: estimate
for the likelihood of
an event
 Example: The
lifetime probability
of developing lung
cancer from smoking
one pack of
cigarettes per day is
1 in 250.
Risks Are Usually Expressed as
Probabilities
 Risk Assessment –using
statistical methods to estimate
how much harm a particular
hazard can cause to human
health or the environment
 Risk Management –
deciding whether or how to
reduce a particular risk to a
certain level and at what cost.
Science: Risk Assessment and Risk
Management
Sensational News
 Most people are not good at
understanding and comparing risk…
• American’s worry about getting avian
flu
• By mid-2008 had killed no one
• Most American’s don’t get vaccinated
for the common flu
• Contributes to the deaths of 36,000
Americans each year
We Face Many Types of Hazards
 Foods high in
cholesterol or fat content
 Lying out in the sun or
going to a tanning salon
 Living in a hurricaneprone area
 How serious are the
risks we face, and do the
benefits of certain
activities outweigh the
risks?
Five major types of hazards
 Biological: pathogens (bacteria, viruses, parasites,
protozoa, and fungi)
 Chemical: harmful chemicals in air, water, soil, and food
 Physical: fire, earthquakes, volcanic eruptions, floods,
and storms
 Cultural: unsafe working conditions, unsafe highways,
criminal assault, and poverty
 Lifestyle choices: smoking, eating too much, drinking
too much alcohol, and having unsafe sex
Your Turn!
 Lifestyle Choices Game
Lifestyle Choices Game
 Rules:
• Water in cup represents your BODILY FLUIDS!
• You are at a party where you are allowed to
exchange bodily fluids…
• Exchange: Pour all liquid in one cup into
another, then pour half back in first cup
• Only exchange fluids a total of three times
• Do NOT exchange fluids with the same person
more than once
Lifestyle Choices Game
 OH NO…!
• One person in the room is infected with
influenza and does not know it…
• Flu test: indicator will turn the liquid in their cup
bright pink if they have the virus in their fluids
Lifestyle Choices Game
 Round 2 –You determine the rules…peer
pressure?
17.2
Some Diseases Can Spread from One
Person to Another
 Nontransmissible disease – doesn’t spread from
person to person
• Ex. Cardiovascular disease
• Risk increases with age…
 Infectious disease – caused by pathogen that invades
the body
• Ex. Flu, HIV, TB
 Transmissible disease (contagious or
communicable disease) – infectious disease that
spreads from person to person
Global Outlook: Worldwide, AIDS Is the
Leading Cause of Death for Ages 15–49
Major Causes of Death in the World and
in the United States in 2005
Leading cause of death is
cardiovascular disease…
 Since 1950, death from infectious diseases have
declined due to
• Better health care
• Antibiotics
• Vaccines
 Disability-adjusted life years (DALYs) – measure of
total disease burden in a population
• Assesses amount of ill health (includes premature
death and disability)
• Controversial because difficult to evaluate the
severity of various disabilities
Infectious Diseases Are Still Major
Health Threats
 Infectious diseases
spread through
•
•
•
•
Air
Water
Food
Body fluids
 Epidemics – large
scale outbreak in a
country
 Pandemics – global
epidemic
Science: Pathways for Infectious
Diseases in Humans
The World’s Seven Deadliest Infectious
Diseases Kill 12.5 Million People
Some Viral Diseases Kill Large
Numbers of People
 Influenza or flu virus
• #1 Killer
• Transmission
 HIV
• #2 Killer
• Antiviral drugs
 HBV
• #3 Killer
• Similar Transmission as HIV
Science Focus: Genetic Resistance to
Antibiotics Is Increasing
 Bacteria: rapid
reproduction, easily
spread
 Over use of antibiotics
 Over use of pesticides
 Methicillin-resistant
Staphylococcus aureus
(MRSA)
Video Clip
 Alien Invaders
17.3 and 17.4
Energy Pyramid Review
•
•
•
•
Which level has the most energy?
Which level has the most organisms?
Which level has the least organisms?
Which level has the least energy?
Solution?
 dichloro-diphenyltrichloroethane
• DDT
27
DDT
 DDT was invented in
the 1940’s and
viewed as:
• Miracle for farmers
• Safe
28
DDT
 Arial crop sprayers
were used to spray
tons of DDT on crops
across the U.S
29
DDT Victim?
 Scientists discovered
that DDT was
concentrated in the bald
eagle
• How?
 DDT affected the eagle’s
ability to reproduce
30
Biomagnification
 The increase in
concentration of an
element or
compound, such as
the pesticide DDT,
that occurs in a food
chain
Some Chemicals Can Cause Cancers,
Mutations, and Birth Defects
 Toxic chemicals – cause
temporary or permanent
harm or death to humans
and animals
• Carcinogens – substances
that promote cancer
• Mutagens – substances that
cause mutations in DNA
(genetic  inheritable)
• Teratogens – chemicals that
cause harm or birth defects
to a fetus or embryo
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
Some Chemicals May Affect Our Immune,
Nervous, and Endocrine Systems
 Hormonally active agents (HAAs)
• Gender benders – effects on sexual
development and reproduction
• Thyroid disrupters – cause growth, weight,
brain, and behavioral disorders
 Phthlates (“thall-eights”) – chemicals used to
soften PVC plastic used in toys, blood storage
bags, and medical tubes
• Birth defects, liver damage, premature
breast development, immune suppression,
etc.
Many Factors Determine the Harmful
Health Effects of a Chemical
 Toxicology – study of the harmful effects of
chemicals on humans and other organisms
 Toxicity dependent on
• Dose – amount of a harmful chemical that a
person has ingested, inhaled, or absorbed
through the skin
• Age
• Genetic makeup
• Multiple chemical sensitivity (MCS)
• Solubility and persistence of the chemical
• Biomagnification
Many Factors Determine the Harmful
Health Effects of a Chemical
 Response
• Acute effect – immediate or rapid harmful
reaction to an exposure
• Chronic effect – permanent or long-lasting
consequence
Science: Estimating Human Exposure to
Chemicals and Measuring Their Effects
Case Study: Protecting Children from
Toxic Chemicals
 Analysis of umbilical cord blood: significance
• 287 chemicals detected (180 carcinogenic, 217
neurological damage)
 Children face a risk 10 times higher than that
faced by adults…why?
Case Study: Protecting Children from
Toxic Chemicals
 Infants and children more susceptible to the
toxic effects of chemicals than adults
1. Eat, drink, and breathe more per unit of body
weight than adults
2. Put their fingers in their mouths
3. Less well-developed immune systems and
body detoxification processes
Scientists Use Live Lab Animals and
Nonanimal Tests to Estimate Toxicity
 Dose-response curve: median lethal dose
(LD50) - Dose that can kill 50% of the animals
in a test population within an 18 day period
Scientists Use Live Lab Animals and
Nonanimal Tests to Estimate Toxicity
 Nonthreshold dose-response model – any dose
causes damage
 Threshold dose-response model – a threshold
dosage must be reached before any detectable harm
Toxicity Ratings and Average Lethal
Doses for Humans
Scientists Use Live Lab Animals and
Nonanimal Tests to Estimate Toxicity
 Animal Testing: Can the data be extrapolated
to humans?
Scientists Use Live Lab Animals and
Nonanimal Tests to Estimate Toxicity
 More humane methods using animals
 Replace animals with other models
• Computer simulations
• Tissue culture and individual animal cells
 What are the effects of mixtures of potentially
toxic chemicals?
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?
Can not be used for new hazards
Food for thought…
 “Toxicologists know a great deal about a few
chemicals, a little about many, and next to
nothing about most.”
• ~Joseph V. Rodricks (risk assessment expert)
 10% of 100,000 registered synthetic chemicals
in commercial use have been screened for
toxicity
Your Turn!
 LD50 Toxicity Analysis
17.5
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.
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
Some Potentially Harmful Chemicals
Found in Most Homes
Comparative Risk Analysis: Most
Serious Ecological and Health Problems
The Greatest Health Risks Come from
Poverty, Gender, and Lifestyle Choices
 Risk analysis – identifying hazards and
evaluating their associated risks, ranking risks,
determining options and making decisions
about reducing the risk.
 Greatest health risks
• Poverty
• Gender
• Lifestyle choices
Global Outlook: Number of Deaths per
Year in the World from Various Causes
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
Estimating Risks from Technologies
Is Not Easy
 System reliability = Technological reliability x
Human reliability
 To err is human
Most People Do Not Know How to
Evaluate Risks
 Fear
 Degree of control
 Whether a risk is catastrophic
 Optimism bias
 Unfair distribution of risks
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