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Environmental Hazards and Human Health

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1 Environmental Hazards and Human Health
Chapter 17

2 Core Case Study: The Global HIV/AIDS Epidemic
Acquired immune deficiency syndrome (AIDS) caused by human immunodeficiency virus (HIV); many secondary infections In 2007, ~60,000 people in the US infected No vaccine to prevent or cure AIDS Expensive drugs—live longer, only 90% can afford 25 Million deaths, so far; alter country’s age structure

3 Lesions That Are a Sign of Kaposi’s Sarcoma

4 Global Outlook: Worldwide, AIDS Is the Leading Cause of Death for Ages 15–49
How AIDS can affect the age structure of a population. This figure shows the projected age structure of Botswana’s population in 2020 with and without AIDS

5 17-1 Risks Are Usually Expressed as Probabilities
Risk is the probability of suffering harm from a hazard that cause injury, disease, death, economic loss, or damage Probability (estimate of the likelihood ) and possibility (could happen) Risk Assessment Scientific process of using statistical methods to estimate how much harm a particular hazard can cause to human health Risk Management Involves deciding whether or how to reduce a particular risk

6 © 2004 Brooks/Cole – Thomson Learning
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 Air Pollution 2 months Drowning 1 month Comparison of risks people face, expressed in terms of shorter average life span. After poverty and gender, the greatest risk people face are mostly from the lifestyle choices they make. Individual responses some of these risks can vary with factors such as genetic variation, family medical history, emotional makeup, stress, and social ties and support. 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

7 We Face Many Types of Hazards
Five major types of hazards Biological: pathogens Chemical: harmful chemicals in air, water, soil Physical: fire, earthquakes, floods, storms Cultural: criminal assault, poverty, working conditions Lifestyle choices: smoking, drinking, eating too much, unsafe sex

8 17-2 Some Diseases Can Spread from One Person to Another
Nontransmissible disease Cardiovascular disease, cancer, asthma, diabetes Transmissible disease (contagious or communicable disease) Caused by a pathogen (bacteria, virus or parasite) that invades the body transmitted from one person to the next Flu, HIV, malaria, measles

9 Some Diseases Can Spread from One Person to Another
Since 1950, death from infectious diseases have declined due to Better health care Antibiotics Vaccines

10 Infectious Diseases Are Still Major Health Threats
Infectious diseases spread through Air Water Food Body fluids Epidemics (area or country) and pandemics (global) Resistance of bacteria and insects

11 Science Focus: Genetic Resistance to Antibiotics Is Increasing
Bacteria: rapid reproduction, easily spread Over use of antibiotics

12 Science Focus: Genetic Resistance to Antibiotics Is Increasing
Methicillin-resistant Staphylococcus aureus (MRSA)

13 Case Study: The Growing Global Threat from Tuberculosis
Effects ~9.2 million people per year Kills 1.7 million a year (84% in developing 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

14 Current tuberculosis epidemic
Deaths per 100,000 people <2.5 2.5-10 10-35 35-70 70-100 Current tuberculosis epidemic 100+ 3/25/2017

15 Some Viral Diseases Kill Large Numbers of People
Influenza or flu virus #1 Killer Transmission HIV #2 Killer Antiviral drugs

16 Some Viral Diseases Kill Large Numbers of People
Global strategy to slow down the spread of HIV Reduce the number of new infections Concentrate on those most likely to spread HIV Free testing Education for prevention Provide free or low-cost drugs Research

17 Some Viral Diseases Kill Large Numbers of People
Hepatitis B virus (HBV) #3 Killer Mode of transmission Viruses that move form animals to humans West Nile virus Severe acute respiratory syndrome (SARS) Reduce chances of infection: Wash your hands

18 Case Study: Malaria—Death by Parasite-Carrying Mosquitoes
Malaria on the rise since 1970 Drug resistant Plasmodium Insecticide resistant mosquitoes Effect of global warming AIDS patients particularly vulnerable

19 The Life Cycle of malaria
Anopheles mosquito (vector) in aquatic breeding area eggs adult larva pupa The Life Cycle of malaria 1. Female mosquito bites infected human, ingesting blood that contains Plasmodium gametocytes 4. Parasite invades blood cells, causing malaria and making infected person a new reservoir 2. Plasmodium develops in mosquito 3/25/2017 3. Mosquito injects Plasmodium sporozoites into human host

20 Malaria Malaria 3/25/2017 Endemic in more than 100 countries.
Caused by four protozoa species. 270–500 million new cases and 1 million deaths per year. Malaria 3/25/2017

21 We Can Reduce the Incidence of Infectious Diseases
Good news Vaccinations on the rise Oral rehydration therapy- only a few cents per person Used to prevent dehydration million deaths from dehydration million deaths from dehydration Bad news More money needed for medical research in developing countries

22 3/25/2017 Disease (type of agent) Deaths per year Pneumonia and flu
(bacteria and viruses) 3.2 million HIV/AIDS (virus) 3.0 million Diarrheal diseases (bacteria and viruses) 1.9 million Tuberculosis (bacteria) 1.7 million Each year the world’s seven deadliest infectious diseases kill about 12.6 million people- most of them poor people in developing countries. This amounts to about 34,500 mostly preventable deaths every day. Malaria (protozoa) 1 million Hepatitis B (virus) 1 million Measles (virus) 3/25/2017 800,000

23 17-3 Some Chemicals Can Cause Cancers, Mutations, and Birth Defects
Toxic chemicals Carcinogens- cause cancer Mutagens- change in DNA Teratogens- causes harm or birth defects to a fetus

24 Case Study: PCBs Are Everywhere—A Legacy from the Past
Class of chlorine-containing compounds polychlorinated biphenyls Very stable Nonflammable Break down slowly in the environment Travel long distances in the air Fat soluble Biomagnification Food chains and webs Banned in 1976, but found everywhere Toxic effects such as endocrine disruption and neurotoxicity are also associated with other compounds within the group. PCBs were used as coolants and insulating fluids (transformer oil) for transformers and capacitors, especially in components of early fluorescent light fittings and electrical transformers, and as plasticizers in paints and cements, stabilizing additives in flexible PVC coatings of electrical wiring and electronic components, pesticide extenders, cutting oils, reactive flame retardants, lubricating oils, hydraulic fluids, sealants (for caulking in schools and commercial buildings[7]), adhesives, wood floor, paints, de-dusting agents, water-proofing compounds, casting agents, vacuum pump fluids, fixatives in microscopy, surgical implants, and in carbonless copy paper.

25 Some Chemicals May Affect Our Immune, Nervous, and Endocrine Systems
Some natural and synthetic chemicals in the environment can weaken and harm Immune system Are weakened arsenic, methyl mercury, dioxins Nervous system PCBs, methyl mercury, arsenic, lead, and certain pesticides Endocrine system Aluminum, atrazine, DDT, mercury, PCBs, bisphenol A

26 Science Focus: Mercury’s Toxic Effects
Hg: teratogen and potent neurotoxin Once airborne, persistent and not degradable 1/3 from natural sources 2/3 from human activities Coal-burning power plants, waste incinerators, chemical manufacturing plants, Enters the food chain: biomagnification

27 Science: Cycling of Mercury in Aquatic Environments

28 Science Focus: Mercury’s Toxic Effects
2007: Hg hotspots identified New England, New York, Nova Scotia How are humans exposed? Inhalation: vaporized Hg or particulates of inorganic salts Eating fish with high levels of methylmercury Effects of Hg on humans Brain damage in fetuses and young children Lower IQ, poor school performance Harm the heart, kidneys and immune system in adults

29 Science Focus: Bisphenol A
Estrogen mimic Found in many common products Water and baby bottles, food- containers and dental fillings Laboratory findings 94 studies by independent labs found numerous adverse health effects from low level exposure 12 studies funded by chemical industry found no adverse effects Effects on human health Brain damage, prostate disease, early puberty, reduced sperm count, hyperactivity, decrease sex drive in males, obesity

30 17-4 Many Factors Determine the Harmful Health Effects of a Chemical
Toxicology Study of harmful effects of chemicals on humans Toxicity measures how harmful a substance is in causing injury, illness, or death to a living organism dependent on Dose Age Genetic makeup Multiple chemical sensitivity (MCS) Solubility and persistence of the chemical Water soluble (move throughout environment) Oil or fat soluble (accumulate in tissue) Biomagnification

31 Bioaccumulation and Biomagnifications
DDT in fish-eating birds (ospreys) 25 ppm DDT in large fish (needle fish) 2 ppm DDT in small fish (minnows) 0.5 ppm DDT in zooplankton 0.04 ppm Bioaccumulation and biomagnification. DTT is a fat-soluble chemical that can accumulate in the fatty tissues of animals. In food chains or webs, the accumulated DDT can be biologically magnified in the bodies of animals at each higher tropic level. This diagram shows that the concentration of DDT in the fatty tissues of organisms was biomagnified about 10 million times in this food chain in an estuary near long Island Sound in New York. If each phytoplankton organism takes up from the water and retains one unit of DDT, a small fish eating thousands of zooplankton ( which feed on the phytoplankton) will store thousands of units of DDT in its fatty tissue. Then each larger fish that eats 10 of the smaller fish will ingest and store tens of thousands of units, and each bird (or human) eats several large fish will ingest hundreds of thousands of units. Black dots represent DDT, and arrows show small loses of DDT through respiration and excretion. DDT in water ppm, Or 3 ppt Bioaccumulation and Biomagnifications 3/25/2017

32 Typical variations in sensitivity to a toxic chemical
© 2004 Brooks/Cole – Thomson Learning Typical variations in sensitivity to a toxic chemical Number of individuals affected Very sensitive Majority of population Very insensitive Typical variations in sensitivity to a toxic chemical within a population, mostly because of differences in genetic makeup. Some people are very sensitive to small doses of a toxin (left) and others are very insensitive (right). Most people fall between these two extremes. 20 40 60 80 Dose (hypothetical units) 3/25/2017

33 Many Factors Determine the Harmful Health Effects of a Chemical
Response The damage to health resulting from exposure to a chemical Acute effect Immediate or rapid reaction Dizziness or nausea to death Chronic effect Permanent or long- lasting consequences Kidney or liver damage

34 Scientists Use Live Lab Animals and Nonanimal Tests to Estimate Toxicity
Dose-response curve: median lethal dose (LD50) The dose that can kill 50% of the animals in a test population within an 18- day period. Nonthreshold dose-response model Any dosage causes harm that increase with dosage Threshold dose-response model A threshold dose must be reached before any detectable harmful effects occur Can the data be extrapolated to humans?

35 LD50 3/25/2017 100 75 Percentage of population killed by a given dose
2 4 6 8 10 12 14 16 Dose (hypothetical units) 3/25/2017

36 © 2004 Brooks/Cole – Thomson Learning
Nonlinear dose-response Linear dose-response Effect Effect Threshold level Dose Dose No threshold Threshold 3/25/2017

37 Table 9-1 Toxicity Ratings and Average Lethal Doses for Humans
Supertoxic Extremely toxic Very toxic Toxic Moderately toxic Slightly toxic Essentially nontoxic LD50 (milligrams per kg of body weight)* Less than 0.01 Less than 5 5–50 50–500 500–5,000 5,000–15,000 15,000 or greater Average Lethal Dose† Less than 1 drop Less than 7 drops 7 drops to 1 teaspoon 1 teaspoon to 1 ounce 1 ounce to 1 pint 1 pint to 1 quart More than 1 quart Examples Nerve gases, botulism toxin, mushroom toxins, dioxin (TCDD) Potassium cyanide, heroin, atropine, parathion, nicotine Mercury salts, morphine, codeine Lead salts, DDT, sodium hydroxide, sodium fluoride, sulfuric acid, caffeine, carbon tetrachloride Methyl (wood) alcohol, ether, Phenobarbital, amphetamines (speed), kerosene, aspirin Ethyl alcohol, Lysol, soaps Water, glycerin, table sugar *Dosage that kills 50% of individuals exposed †Amounts of substances in liquid form at room temperature that are lethal when given to a 70.4-kg (155-pound) human

38 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 Chicken egg membranes What are the effects of mixtures of potentially toxic chemicals?

39 Reality 2% of chemicals in use have been tested
99.5% of used chemicals not regulated 3/25/2017

40 Some Potentially Harmful Chemicals Found in Most Homes

41 Are Trace Levels of Toxic Chemicals Harmful?
We do not know

42 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 (POPs)

43 POPs – The Dirty Dozen

44 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

45 17-5 The Greatest Health Risks Come from Poverty, Gender, and Lifestyle Choices
Risk analysis Greatest health risks Poverty Gender Lifestyle choices

46 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 3 million (41) HIV/AIDS 2.1 million (29) Diarrhea 1.9 million (26) Tuberculosis 1.7 million (23) Automobile accidents 1.2 million (16) Figure 17.18 Global outlook: number of deaths per year in the world from various causes (Concept 17-5). Numbers in parentheses give these deaths in terms of the number of fully loaded 200-passenger jet airplanes crashing every day of the year with no survivors. Because of sensational media coverage, most people are misinformed about the largest annual causes of death. Question: Which three of these items are most likely to shorten your life span? (Data from World Health Organization) Work-related injury and disease 1.1 million (15) Malaria 1 million (14) Hepatitis B 1 million (14) Measles 800,000 (11) Fig , p. 461

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

48 Case Study: Death from Smoking (1)
Most preventable major cause of suffering and premature death Nicotine: additive Effects of passive smoking (secondhand smoke)

49 Case Study: Death from Smoking (2)
How to reduce smoking Taxes Ban Classify and regulate nicotine Education

50 Cause of Death in US Deaths Tobacco use 442,000 Accidents
101,500 (43,450 auto) Alcohol use 85,000 Infectious diseases 75,000 (17,000 from AIDS) Pollutants/toxins 55,000 Figure 17.20 Annual deaths in the United States from tobacco use and other causes in Smoking is by far the nation’s leading cause of preventable death, causing more premature deaths each year than all the other categories in this figure combined. (Data from U.S. National Center for Health Statistics, the Centers for Disease Control and Prevention, and the U.S. Surgeon General) Suicides 30,600 Homicides 20,622 Illegal drug use 17,000 Fig , p. 463

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