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 dose2 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