17THMILLER/SPOOLMAN

LIVING IN THE ENVIRONMENT

Chapter 17Environmental 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• 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

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 analysisHazard 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

Science: Pathways for Infectious Diseases in Humans

Fig. 17-3, p. 439

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 AirInsectsWild animalsLivestockPets Food

Stepped Art

Fig. 17-3, p. 439

Major Causes of Death from Infectious Diseases in the World, 2007

Fig. 17-4, 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

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 hands2.Avoid touching your face3.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

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

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 victimsConduct 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

Potential Pathways on Which Toxic Chemicals Move Through the Environment

Fig. 17-9, p. 447

Fig. 17-9, p. 447

Atmosphere

CropsVegetation

Surface water HumansAnimals

Surface water

Vegetation

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 particulates2. Eating fish with high levels of methylmercury3. 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

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

Hormones and Hormones Mimics or Blockers

Fig. 17-11, p. 449

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

Science: Estimating Human Exposure to Chemicals and Measuring Their Effects

Fig. 17-12, p. 452

Fig. 17-12, p. 452

Water pollutant levelsSoil/dust levels Air pollutant levels

Food pesticide levels

Nutritional health

Overall health Scientific measurements and modeling

?

Lifestyle

Predicted level of toxicant in peoplePersonal habits

Genetic predisposition

MetabolismAccumulationExcretion

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?

Hypothetical Dose-Response Curve Showing Determination of the LD50

Fig. 17-13, p. 453

Fig. 17-13, p. 453

100

75

50

25

Perc

enta

ge o

f pop

ulati

on k

illed

by

a gi

ven

dose

LD50

00 2 4 6 8 10 12 14 16

Dose (hypothetical units)

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

Fig. 17-14a, p. 454

Nonlinear dose-response

Linear dose- response

Effec

t

Dose

No threshold

Fig. 17-14b, p. 454

Effec

t

Threshold level

Dose

Threshold

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?

Some Potentially Harmful Chemicals Found in Most Homes

Fig. 17-15, p. 455

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 perfluorochemicalsNail polish

Perfluorochemicals and phthalates

Baby bottle Can contain bisphenol A

Mattress Flame retardants in stuffingPerfume

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

AsbestosSource: Pipe insulation, vinylceiling and floor tilesThreat: Lung disease, lung cancer

Carbon monoxideSource: Faulty furnaces,unvented gas stoves andkerosene heaters,woodstovesThreat: Headaches,drowsiness, irregularheartbeat, death

Methylene chlorideSource: Paint strippers and thinnersThreat: Nerve disorders, diabetes

Tobacco smokeSource: CigarettesThreat: Lung cancer, respiratoryailments, heart disease

Radon-222Source: Radioactive soiland rock surroundingfoundation, water supplyThreat: Lung cancer

Benzo-α-pyreneSource: Tobacco smoke,woodstovesThreat: Lung cancer

StyreneSource: Carpets,plastic productsThreat: Kidney andliver damage

FormaldehydeSource: Furniture stuffing,paneling, particleboard,foam insulationThreat: Irritation of eyes,throat, skin, and lungs;nausea; dizziness

TetrachloroethyleneSource: Dry-cleaningfluid fumes on clothesThreat: Nerve disorders,damage to liver andkidneys, possible cancer

Para-dichlorobenzeneSource: Air fresheners,mothball crystalsThreat: Cancer

ChloroformSource: Chlorine-treated water inhot showersPossible threat: Cancer

1,1,1-TrichloroethaneSource: Aerosol spraysThreat: Dizziness,irregular breathing

Nitrogen oxidesSource: Unvented gasstoves and keroseneheaters, woodstovesThreat: Irritated lungs,children's colds,headaches

ParticulatesSource: Pollen, petdander, dust mites,cooking smoke particlesThreat: Irritated lungs,asthma attacks, itchyeyes, 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

Global Outlook: Number of Deaths per Year in the World from Various Causes

Fig. 17-16, p. 458

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)

Comparison of Risks People Face in Terms of Shorter Average Life Span

Fig. 17-17, p. 459

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

Normal Lung and Emphysema Lung

Fig. 17-18, p. 459

Stepped Art

Fig. 17-18, p. 459

Annual Deaths in the U.S. from Tobacco Use and Other Causes

Fig. 17-19, p. 460

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.

Three Big Ideas

3. Becoming informed, thinking critically about risks, and making careful choices can reduce the major risks we face.