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
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
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
Fig. 17-2, p. 437
Risk Assessment Risk Management
What is the hazard? How does it compare with other risks?
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?
Consequences of risk What is the likely damage?
Financial commitment How much money should be spent?
Comparative risk analysis Hazard identification
We Face Many Types of Hazards
1. Biological: • 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 • Better health care
• Better sanitation
• Antibiotics
• Vaccines
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
Fig. 17-3, p. 439
Pets Livestock Wild animals Insects Food Water Air
Fetus and babies
Other humans Humans
Humans
Fetus and babies
Other humans
Water Air Insects Wild animals Livestock Pets Food
Stepped Art
Fig. 17-3, p. 439
Fig. 17-4, p. 439
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
Disease
(type of agent) Deaths per year
Pneumonia and flu
(bacteria and viruses) 3.2 million
HIV/AIDS (virus) 2.1 million
Diarrheal diseases
(bacteria and viruses) 1.9 million
Tuberculosis
(bacteria) 1.7 million
Malaria
(protozoa) 1 million
Hepatitis B
(virus) 1 million
Measles
(virus) 800,000 Stepped Art
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 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
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 • 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 • Drug resistant Plasmodium
• Insecticide resistant mosquitoes
• Clearing of tropical forests
• AIDS patients particularly vulnerable
• Prevention of spread and current research
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
Fig. 17-8, p. 445
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
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
• 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
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 • 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
Fig. 17-10, p. 449
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
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
Fig. 17-11, p. 449
Hormone Estrogen-like chemical Antiandrogen chemical
Receptor
Cell
Normal Hormone Process
Hormone Mimic Hormone Blocker
Hormone Estrogen-like chemical Antiandrogen chemical
Receptor
Cell
Normal Hormone Process Hormone Mimic Hormone Blocker
Stepped Art
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 • 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
Fig. 17-12, p. 452
Water pollutant levels Soil/dust levels
Air pollutant levels
Food pesticide levels
Nutritional health
Overall health Scientific measurements and modeling
?
Lifestyle
Predicted level of toxicant in people Personal habits
Genetic predisposition
Metabolism
Accumulation
Excretion
Lung, intestine, and skin absorption rates
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?
Fig. 17-13, p. 453
100
75
50
25
Pe
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nta
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f p
op
ula
tio
n k
ille
d b
y a
give
n d
ose
LD50
0
0 2 4 6 8 10 12 14 16
Dose (hypothetical units)
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
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?
Fig. 17-15, p. 455
Shampoo Perfluorochemicals to add shine
Teddy bear Some stuffed animals made overseas contain flame retardants and/or pesticides
Clothing Can contain perfluorochemicals Nail polish
Perfluorochemicals and phthalates
Baby bottle Can contain bisphenol A
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 flame retardants
Milk Fat contains dioxins and flame retardants
Sofa Foam padding contains flame retardants and perfluorochemicals
Frying pan Nonstick coating contains perfluorochemicals
Tile floor Contains perfluorochemicals, phthalates, and pesticides
Fruit Imported fruit may contain pesticides banned in the U. S.
Water bottle Can contain bisphenol A
Computer Flame retardant coatings of plastic casing and wiring
Toys Vinyl toys contain phthalates
Tennis shoes Can contain phthalates
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
Tobacco smoke Source: Cigarettes Threat: Lung cancer, respiratory ailments, heart disease
Radon-222 Source: Radioactive soil and rock surrounding foundation, water supply Threat: Lung cancer
Benzo-α-pyrene Source: Tobacco smoke, woodstoves Threat: Lung cancer
Styrene Source: Carpets, plastic products Threat: Kidney and liver damage
Formaldehyde Source: Furniture stuffing, paneling, particleboard, foam insulation Threat: Irritation of eyes, throat, skin, and lungs; nausea; dizziness
Tetrachloroethylene Source: Dry-cleaning fluid fumes on clothes Threat: Nerve disorders, damage to liver and kidneys, possible cancer
Para-dichlorobenzene Source: Air fresheners, mothball crystals Threat: Cancer
Chloroform Source: Chlorine-treated water in hot showers Possible threat: Cancer
1,1,1-Trichloroethane Source: Aerosol sprays Threat: Dizziness, irregular breathing
Nitrogen oxides Source: Unvented gas stoves and kerosene heaters, woodstoves Threat: Irritated lungs, children's colds, headaches
Particulates Source: Pollen, pet dander, dust mites, cooking smoke particles Threat: Irritated lungs, asthma attacks, itchy eyes, runny nose, lung disease
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
Fig. 17-16, p. 458
Cause of death Annual deaths
Poverty/malnutrition/ disease cycle 11 million (150)
Tobacco 5.4 million (74)
Pneumonia and flu 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)
Work-related injury and disease
1.1 million (15)
Malaria 1 million (14)
Hepatitis B 1 million (14)
Measles 800,000 (11)
Fig. 17-17, p. 459
Hazard Shortens average life span in the United States by
Poverty 7–10 years
Born male 7.5 years
Smoking 6–10 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
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
• Taxes
• Classify and regulate nicotine
• Bans on smoking in public places
• Education
Fig. 17-19, p. 460
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
Coal-fired
electricity 286%
Synthetic oil and
gas produced
from coal
150%
Coal 100%
Tar sand 92%
Oil 86%
Natural gas 58%
Nuclear power
fuel cycle 17%
Geothermal 10% Stepped Art
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.