13e environmental science 14e - lecture.siit.tu.ac.th
TRANSCRIPT
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ENVIRONMENTAL SCIENCE
13e
14e
15e
CHAPTER 14:
Environmental Hazards
and Human Health
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Fig. 14-1, p. 344
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Core Case Study: BPA
Controversy (2) • Bisphenol A, an estrogen (Female hormone)
mimic
• Found in hardened Polycarbonate plastics
– Baby bottles
– Sipping cups
– Reusable water bottles
– Sports drink and juice bottles
– Microwave dishes
– Food storage containers
– Nearly all canned food liners
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Core Case Study: BPA
Controversy (3)
• 93% of Americans have BPA in their
bodies
• Controversy over health risk
– Human health
– Fetuses
– Infants
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Fig. 14-2, p. 344
14-1 What Major Health
Hazards Do We Face?
• Concept 14-1 People face health hazards
from biological, chemical, physical, and
cultural factors, and from the lifestyle
choices they make
• Risk - Probability
Risk assessment
Risk management
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Fig. 14-3, p. 345
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Major Types of Hazards
• Biological
• Chemical
• Physical
• Cultural
• Lifestyle
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14-2 What Types of Biological
Hazards Do We Face?
• Concept 14-2 The most serious
infectious diseases are flu, AIDS,
tuberculosis, diarrheal diseases, and
malaria.
• Nontransmissible diseases
• Transmissible (infectious) disease
– Pathogens
• Epidemic*
• Pandemic**
* A large-scale outbreak of an
infectious disease in an area or
country.
** A global epidemic
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Humans
Fetus and babies
Other humans
Water AirInsectsWild animalsLivestockPets Food
Stepped Art
Fig. 14-4, p. 348Pathways for infectious disease in humans.
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Fig. 14-5, p. 348
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Case Study: the Tuberculosis
Threat (1)
• TB spreading rapidly
• 1 in 3 infected; 5-10% will eventually
develop it
• 2008: 9.3 million active cases
– Poor countries in Asia and Africa
– ~ 1.6 million will die
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Case Study: the Tuberculosis
Threat (2)
• Inadequate screening
• Increased resistance to antibiotics
• Increased person-to-person contacts
• Inadequate treatment
• Multidrug resistant TB
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Science Focus:
Growing Resistance to Antibiotics
• High bacterial reproductive rate
• Genetic resistance
• Global travel
• Widely use of pesticides (cause an increase of
disease-transmitting species i.e. mosquitoes that resistance to
pesticides that once helped to control their populations)
• Overuse of antibiotics
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Resistance geneTransfer from
antibiotic drug
(produce from weak
bacteria)
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Most Deadly Viral Diseases
1. Influenza/flu
2. HIV – AIDS (27 million deaths, 1981-
2008)
3. Hepatitis B
4. Other viruses
– West Nile fever
– SARS (Severe acute respiratory distress
syndrome)
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Case Study: HIV/AIDS
Epidemic (1)
• Acquired immune deficiency
syndrome
• Human immunodeficiency virus
• Spread by
– Unsafe sex
– Sharing needles
– Infected mother to child
– Exposure to infected blood
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Case Study: HIV/AIDS
Epidemic (2)
• Living with AIDS 2008
– 33 million worldwide
– 2/3 in sub-Saharan Africa
– 1 million in the U.S.
– 2.7 million new cases
• 27 million deaths, 1981-2008
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Case Study: Malaria
• 1 in 5 at risk
• Parasite spread by mosquitoes
• Kills 2700 people per day, mostly in
Africa
• Mosquito nets for beds
• Spray homes with DDT
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Merozoites enter
bloodstream
and develop into
gametocytes
causing malaria
and making
infected person
a new reservoir
Sporozoites
penetrate liver
and develop
into merozoites
Female mosquito injects
Plasmodium sporozoites
into human host.
Plasmodium
develop in
mosquito
Female mosquito bites
infected human, ingesting
blood that contains
Plasmodium gametocytes
Fig. 14-7, p. 351
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Fig. 14-6, p. 350
Distribution of malaria. About 40% of the world’s population
lives in areas in which malaria is prevalent.
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Fig. 14-8, p. 351
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Fig. 14-9, p. 352
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14-3 What Types of Chemical
Hazards Do We Face?• Concept 14-3 There is growing concern
about chemicals that can cause cancer
and birth defects and disrupt the human
immune, nervous, and endocrine systems.
• Toxic chemicals
• Carcinogens
• Mutagens
• Teratogens (are chemicals that cause harm or birth
defects to a fetus or embryo)
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Chemical Hazards
• Immune system disruptors
• Neurotoxins
• Hormonally active agents (HAA) can
mimic hormones. Exposure to low levels of HAAs can impair
reproductive systems and sexual development and cause physical
and behavioral disorders.
– DDT, PCBs, atrazine, aluminum, mercury,
BPA, PCBs
– Males of many species becoming more
feminine
– BPA of special concern
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• Some chemicals such as As, methyl-Hg, and
dioxins can weaken the human immune system
and leave the body vulnerable to attacks by
allergens and infectious bacteria, viruses, and
protozoa.
• PCBs, Pb, methyl-Hg, As, and pesticide can
harm the human nervous system (brain, spinal
cord, and peripheral nerves) and cause
behavioral changes, learning disabilities,
retardation, attention deficit disorder, paralysis,
and death.
Chemical Hazards
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• Low exposure of BPA causes a brain damage,
prostrate disease, breast cancer, early puberty,
reduced sperm count, impaired immune
function, type 2 diabetes, hyperactivity,
increased aggressiveness, impaired learning,
increased addiction to drugs such as
amphetamines, decreased sex drive in males.
Chemical Hazards
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Fig. 14-10, p. 353
Atmosphere
Vegetation
Surface water
Vegetation
HumansAnimals
Crops
Soil
Potential pathways on
which toxic chemicals move through
the living and nonliving environment
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Science Focus: Mercury (1)
• Nerve and organ damage
• Birth defects
• Natural sources
• Human activities
– Coal burning
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Science Focus: Mercury (2)
• Humans exposed through
– Inhaling vaporized mercury and mercury
compounds
– Contaminated fish
– High fructose corn syrup
• 30,000 to 60,000 U.S. newborns likely have
reduced IQ
• Need to end coal burning and waste
incineration
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Fig. 14-A, p. 354
Control
Sharply reduce mercury emissions
from coal-burning plants and
incinerators
Heavily tax each unit of mercury
emitted by coal-burning plants and
incinerators
Require labels on all products
containing mercury
Collect and recycle mercury-
containing electric switches, relays,
compact fluorescent lightbulbs, and
dry-cell batteries
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
Solutions
Mercury Pollution
Prevention
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14-4 How Can We Evaluate
Chemical Hazards?• Concept 14-4A Scientists use live
laboratory animals, case reports of
poisonings, and epidemiological studies to
estimate the toxicity of chemicals, but
these methods have limitations.
• Concept 14-4B We can reduce the major
risks we face by becoming informed,
thinking critically about risks, and making
careful choices.
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Determining Chemical Safety
• Toxicology
• Toxicity is a measure of how harmful a substance is.
• Dose
The effects of a particular chemical can
also depend upon by several factors i.e.
• Water and fat soluble toxins
• Persistence
• Biological magnification
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The concentrations
of some potential
toxins in the
environment
increase as they
pass through the
successive
trophic levels of
food chains and
webs.
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Type and Severity of Health
Damage
• Response – dose dependent
– Acute effect
– Chronic effect
Table 14-1, p. 357
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Case Study: Protecting Children
from Toxic Chemicals
• Toxic chemicals in newborns’ blood
• Infants and children more susceptible
– Increased intake of air, water, food for
their body weights
– Put contaminated objects in their
mouths
– Less-developed immune systems
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Estimating Toxicity
• Test on live animals
• Dose-response curve
– Lethal dose
– Median lethal dose (LD50)
• Extrapolation from data
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Fig. 14-12, p. 360
Tennis shoesCan containphthalates
ToysVinyl toyscontainphthalates
ComputerFlame retardantcoatings of plasticcasing and wiring
Water bottleCan containbisphenol-A
FruitImported fruit maycontain pesticidesbanned in the U.S.
SofaFoam padding containsflame retardants andperfluorochemicals
TVWiring and plastic casingcontain flame retardants
CarpetPadding and carpet fiberscontain flame retardants,perfluorochemicals, andpesticides
MattressFlame retardants in stuffing
Baby bottleCan containbisphenol-A
ClothingCan containperfluorochemicals
Teddy bearSome stuffed animalsmade oversees containflame retardants and/orpesticides
ShampooPerfluorochemicalsto add shineNail polish
Perfluorochemicalsand phthalates
PerfumePhthalates
HairsprayPhthalates
FoodSome food containsbisphenol-A
MilkFat contains dioxinsand flame retardants
Frying panNonstick coating containsperfluorochemicals
Tile floorNonstick coating containsperfluorochemicals,phthalates, and pesticides
Some potentially harmful chemicals found in most homes.
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Protection against Harmful
Chemicals
• Pollution prevention
• Precautionary principle
• Ban of 12 Persistent organic
pollutants (POPs) or the dirty dozen
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14-5 How Do We understand Risks and
How Can We Avoid the Worst of Them?
• Concept 14-5 We can reduce the
major risks we face by becoming
informed, thinking critically about
risks, and making careful choices.
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Evaluating Risks (1)
• Risk analysis (risk assessment)
• Comparative risk analysis
• Risk management
• Risk communication
• Poverty – the greatest risk
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Fig. 14-3, p. 345
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Evaluating Risks (2)
• Risks from lifestyles
– Don’t smoke
– Lose excess weight
– Eat healthy foods
– Exercise regularly
– Little or no alcohol
– Avoid excess sunlight
– Practice safe sex
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Measles
Hepatitis B
Work-relatedinjury and disease
Malaria
Automobile accidents
Tuberculosis
Diarrhea
HIV/AIDS
Air pollution
Pneumonia and flu
Tobacco
Poverty/malnutrition/disease cycle
Cause of death
Annual deaths
11 million
(150)5.4 million (74)
3.2 million (44)
2.4 million (33)
2 million (27)
1.6 million (22)
1.5 million (21)
1.2 million (16)
1.1 million (15)
1 million (14)
1 million (14)
800,000 (11)
Fig. 14-13, p. 361
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Fig. 14-15, p. 364
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Fig. 14-15, p. 364
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Cause of Death Deaths
442,000
101,500 (43,450 auto)
85,000
75,000 (16,000 from AIDS)
55,000
30,600
20,622
17,000Illegal drug use
Homicides
Suicides
Pollutants/toxins
Infectious
diseases
Alcohol use
Accidents
Tobacco use
Fig. 14-16, p. 364
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Estimating Risks
from Technologies
• System reliability (%)
= Technological reliability x Human
reliability
• Difficulties in estimating reliability
• Perceived risk vs. actual risk
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Improving Risk Evaluation
• Compare risks
• Determine how much risk you are
willing to accept
• Determine the actual risk involved
• Concentrate on evaluating and
carefully making important lifestyle
choices
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Three Big Ideas from This
Chapter1. We face significant hazards from infectious
diseases 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.
3. Becoming informed, thinking critically about risks,
and making careful choices can reduce the major
risks we face.
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THE END