MILLERSPOOLMAN LIVING IN THE ENVIRONMENT 17 TH Chapter

MILLER/SPOOLMAN LIVING IN THE ENVIRONMENT 17 TH Chapter 17 Environmental 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 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

Risk Assessment Hazard identification What is the hazard? Probability of risk How likely is the event? Risk Management Comparative risk analysis How does it compare with other risks? Risk reduction How much should it be reduced? 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? Fig. 17 -2, p. 437

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

Pets Livestock Wild animals Insects Food Water Air Fetus and babies Other humans Humans Stepped Art Fig. 17 -3, p. 439

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 lessdeveloped 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 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

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 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 Fig. 17 -8, p. 445

17 -2 questions 1) Distinguish between infectious disease and transmissible disease. 2) In terms of death rates what are the 4 most infectious diseases? 3) How can we reduce threat of malaria?

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

Atmosphere Vegetation Crops Surface water Humans Animals ater w e ac Surf Vegetation Fig. 17 -9, p. 447

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

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 Switch from coal to natural gas and renewable energy resources Label all products containing mercury Collect and recycle batteries and other products containing mercury Fig. 17 -10, p. 449

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

Hormone Estrogen-like chemical Antiandrogen chemical Receptor Cell Normal Hormone Process Hormone Mimic Hormone Blocker Fig. 17 -11, p. 449

Hormone Estrogen-like chemical Antiandrogen chemical Receptor Cell Normal Hormone Process Hormone Mimic Hormone Blocker Stepped Art Fig. 17 -11, p. 449

17 -3 Questions 1) Distinguish between Mutagens, teratogens, and carcinogens. 2) Describe threats of mercury on the human body. 3) How can we reduce the risk of mercury’s harmful affects?

17 -4 How Can We Evaluate and Deal with Chemical Hazards? • Concept 17 -4 A 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 -4 B 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

Soil/dust levels Water pollutant levels Air pollutant levels Food pesticide levels Nutritional health ? Scientific measurements and modeling Overall health Lifestyle Predicted level of toxicant in people Personal habits Genetic predisposition Metabolism Accumulation Excretion Lung, intestine, and skin absorption rates Fig. 17 -12, p. 452

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 (LD 50) • 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?

Percentage of population killed by a given dose 100 75 50 25 LD 50 0 0 2 4 6 8 10 Dose (hypothetical units) 12 14 16 Fig. 17 -13, p. 453

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

Nonlinear doseresponse Effect Linear doseresponse Dose No threshold Fig. 17 -14 a, p. 454

Effect Threshold level Dose Threshold Fig. 17 -14 b, p. 454

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?

Chloroform Source: Chlorine-treated water in hot showers Possible threat: Cancer Para-dichlorobenzene Source: Air fresheners, mothball crystals Threat: Cancer 1, 1, 1 -Trichloroethane Source: Aerosol sprays Threat: Dizziness, irregular breathing Tetrachloroethylene Source: Dry-cleaning fluid fumes on clothes Threat: Nerve disorders, damage to liver and kidneys, possible cancer Formaldehyde Source: Furniture stuffing, paneling, particleboard, foam insulation Threat: Irritation of eyes, throat, skin, and lungs; nausea; dizziness Styrene Source: Carpets, plastic products Threat: Kidney and liver damage Nitrogen oxides Source: Unvented gas stoves and kerosene heaters, woodstoves Threat: Irritated lungs, children's colds, headaches Benzo-α-pyrene Source: Tobacco smoke, woodstoves Threat: Lung cancer Particulates Source: Pollen, pet dander, dust mites, cooking smoke particles Threat: Irritated lungs, asthma attacks, itchy eyes, runny nose, lung disease Radon-222 Source: Radioactive soil and rock surrounding foundation, water supply Threat: Lung cancer Tobacco smoke Source: Cigarettes Threat: Lung cancer, respiratory ailments, heart disease 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 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

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 HIV/AIDS 2. 4 million (33) 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 -16, p. 458

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 Fig. 17 -17, p. 459

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

Stepped Art Fig. 17 -18, p. 459

Coal-fired electricity 286% Synthetic oil and gas produced from coal 150% Coal 100% 92% Tar sand Oil 86% 58% Natural gas Nuclear power fuel cycle Geothermal 17% 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.