1. Environmental Hazards and Human Health
Chapter 19
(see Bozeman video-
Health Impacts of Pollution)

2. Risks and Hazards
Risk is the possibility of suffering harm from a hazard that can cause injury, disease, economic loss or environmental damage.
Risk is expressed as a probability (Insurance actuary)
Risk assessment involves using data, hypotheses and models to estimate the probability of harm to human health, society, or the environment that may result from exposure to specific hazards
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3. Risk and Probability
Fig p. 410

4. Major Hazards There are 4 major types of hazards:
Cultural hazards- such as unsafe working conditions, smoking, poor diet, drugs, drinking, driving, criminal assault, unsafe sex and poverty
Chemical hazards from harmful chemicals in air, water, soil and food
Physical hazards- such as noise, fire, tornadoes, hurricanes, earthquakes, volcanic eruptions, floods and ionizing radiation
Biological hazards from pathogens, pollen and other allergens and animals, such as bees and poisonous snakes.
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5. Toxicology the study of the adverse effects of chemicals on health.
Toxicity - a measurement of how harmful a substance is; dependent on:
Dose - the amount of a potentially harmful substance that is ingested, inhaled, or absorbed through the skin
Age/ Body mass
Genetic makeup
Multiple chemical sensitivity (MCS)
Solubility and persistence of the chemical
Biomagnification
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6. Responses
Dose Response- the resulting type and amount of damage to health;
TWO types of responses:
acute effect: immediate or rapid harmful reaction, e.g., dizziness, rash, death;
chronic effect: permanent or long–lasting consequence, e.g., asthma, kidney damage, heart disease

7. Determining Toxicity 3 methods of determining toxicity:
Case reports: (usually to physicians) about health effects after exposure to a chemical
Epidemiology: involving studies of populations exposed to certain chemicals or diseases
Laboratory investigations: (usually with test animals/ Analysis of umbilical cord blood)
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8. Water pollutant levels Scientific measurements and modeling
Air pollutant levels
Soil/dust levels
Food pesticide levels
Nutritional health
Overall health
Scientific measurements and modeling
Lifestyle
Figure 17.13
Science: Estimating human exposure to chemicals and measuring their effects are very difficult because of the many and often poorly understood variables involved. Question: What three of these factors might make you more vulnerable to the harmful effects of chemicals?
Predicted level of toxicant in people
Personal habits
Metabolism
Genetic predisposition
Accumulation
Excretion
Lung, intestine, and skin absorption rates
Fig , p. 454

9. Scientists Use Live Lab Animals and Nonanimal Tests to Estimate Toxicity
LD50 is the median lethal dose = the kills 50% of animals amount of a chemical received that (usually rats or mice) in a test population (usually 60–200 animals) within a 14–day period.
Poison - legally defined as a chemical that has an LD50 of 50 milligrams or less per kilogram of body weight.

10. Hypothetical Dose-Response Curve Showing Determination of the LD50

11. Some Toxicity Ratings Table 9–1 p.414
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12. Dose–Response Curves
Dose–response curves show the adverse effects of various doses of a toxic agent on a test population by plotting harmful effect as a function of dose.
The left dose–response curve shows increasing harmful effects with dose, and no dose is considered safe.
The right example has a threshold, such that low doses are considered safe.
Fig.19–6
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13. Two Types of Dose- Response Curves

14. Chemical Hazards What are toxic vs. hazardous chemicals?
Toxic chemicals are generally defined as substances that are fatal to over 50% of test animals (LD50) at given concentrations.
Hazardous chemicals cause harm by
being flammable or explosive (e.g., gasoline);
irritating or damaging the skin or lungs (e.g., strong acids or alkalines such as oven cleaners);
interfering with or preventing oxygen uptake and distribution (e.g., carbon monoxide, CO);
inducing allergic reactions of the immune system (allergens).
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15. Potential Pathways on Which Toxic Chemicals Move Through the Environment

16. Biomagnification in a Food Chain

17. 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
Enters the food chain: biomagnification

18. Photo-chemical oxidation
WINDS
PRECIPITATION
WINDS
PRECIPITATION
Hg and SO2
Hg2+ and acids
Hg2+ and acids
Photo-chemical oxidation
Human sources
Elemental mercury vapor
(Hg)
Inorganic mercury and acids
(Hg2+)
Inorganic mercury and acids
(Hg2+)
Coal-burning plant
Incinerator
Deposition
Runoff of Hg2+ and acids
Deposition
Deposition
Large fish
Vaporization
Small fish
BIOMAGNIFICATION IN FOOD CHAIN
Zooplankton
Phytoplankton
Figure 17.A
Science: cycling of mercury in aquatic environments, in which mercury is converted from one form to another. The most toxic form to humans is methylmercury (CH3Hg+), which can be biologically magnified in aquatic food chains and webs. Some mercury is also released back into the atmosphere as mercury vapor.
Bacteria and acids
Elemental mercury liquid (Hg)
Oxidation
Inorganic mercury (Hg2+)
Organic mercury (CH3Hg+)
Bacteria
Settles out
Settles out
Settles out
SEDIMENT
Fig. 17-A, p. 450

19. 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 such as wind, solar cells, and hydrogen
Tax each unit of mercury emitted by coal-burning plants and incinerators
Convert coal to liquid or gaseous fuel
Figure 17.B
Ways to prevent or control inputs of mercury into the environment from human sources—mostly coal-burning power plants and incinerators. Question: Which four of these solutions do you think are the most important?
Require labels on all products containing mercury
Phase out use of mercury in batteries, TVs, compact fluorescent lightbulbs, and all other products unless they are recycled
Collect and recycle mercury-containing electric switches, relays, and dry-cell batteries
Fig. 17-B, p. 451

20. Mutagens, Teratogens, and Carcinogens
Mutagens are agents, chemicals and radiation, that cause random mutations, or changes in the DNA
- e.g., UV radiation; x-rays
Teratogens are agents (chemicals, radiation, or viruses) that affect embryo and cause birth defects;
e.g., PCBs, steroid hormones, heavy metals
Carcinogens are agents (chemicals, radiation, or viruses) that cause cancer;
over 100 types of cancer (depending on cells involved)
e.g., cigarette smoke.
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21. Mutagens

22. Teratogens – affect embryos

23. Hormonally active agents (HAAs)
Gender benders (hormone mimickers, or disruptors)
Thyroid disrupters
Phthlates “THAL-ates,”- group of chemicals used to soften and increase the flexibility of plastic and vinyl
flexible plastic and vinyl toys, shower curtains, food packaging, plastic wrap, detergents, plastic plumbing pipes, lubricants, medical tubing and fluid bags, vinyl flooring) *Prior to1999, U.S. manufacturers have used phthalates in baby pacifiers, soft rattles, and teething toys!
Disrupt endocrine system signaling pathways
Cancer

24. Hormone Disrupters DDT; Bisphenol A Fig.19-7
(Endocrine Disrupting Chemicals “EDC’s”)
DDT; Bisphenol A
Fig.19-7
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25. Bisphenol A Estrogen mimic
Found in many common products (baby bottles; hard, clear plastic products- reusable, water bottles)
Laboratory findings
Effects on human health
TED Talk – Toxic Baby
Should it be banned?

26. PCBs: Legacy from the Past
Class of chlorine-containing compounds
(PCB = Polychlorinated Biphenyl )
Oily liquids or solids that can enter the air as vapor
Were widely used as lubricants, hydraulic fluids, electrical insulators in transformers
Were used in paints, pesticides, fire retardants in fabrics, preservatives, adhesives.
Highly persistent.
Banned in 1979 in the U.S.
Fat soluble – Biomagnification
Banned, but found everywhere

27. Perfluorochemicals to add shine
Shampoo
Teddy bear
Clothing
Baby bottle
Perfluorochemicals to add shine
Some stuffed animals made overseas contain flame retardants and/or pesticides
Can contain perfluorochemicals
Can contain bisphenol-A
Nail polish
Perfluorochemicals and phthalates
Mattress
Flame retardants in stuffing
Perfume
Phthalates
Carpet
Padding and carpet fibers contain flame retardants, perfluorochemicals, and pesticides
Hairspray
Phthalates
Food
Some food contains bisphenol-A TV
Wiring and plastic casing contain flame retardants
Milk
Fat contains dioxins and flame retardants
Sofa
Figure 17.16
Some potentially harmful chemicals found in most homes. Most people have traces of these chemicals in their blood and body tissues. We do not know the long-term effects of exposure to low levels of such chemicals. (Data from U.S. Environmental Protection Agency, Centers for Disease Control and Prevention, and New York State Department of Health) Question: Does the fact that we do not know much about long-term harmful effects of these chemicals make you more likely or less likely to minimize your exposure to them? Why?
Frying pan
Foam padding contains flame retardants and perfluorochemicals
Nonstick coating contains perfluorochemicals
Fruit
Water bottle
Computer
Toys
Tennis shoes
Tile floor
Imported fruit may contain pesticides banned in the U.S.
Can contain bisphenol-A
Flame retardant coatings of plastic casing and wiring
Vinyl toys contain phthalates
Can contain phthalates
Contains perfluorochemicals, phthalates, and pesticides
Fig , p. 458

28. 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: Stockholm Convention- global treaty to ban or phase out the “Dirty Dozen” of toxic chemicals (Persistant Organic Pollutants “POPs”)

29. Physical Hazards (not in this chapter!)
Earthquakes are among various types of natural physical hazards. Other physical hazards include volcanoes and ionizing radiation.
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30. Preventing loss: understand where risk is high
Map of expected damage from earthquakes
Preventing loss:
understand where risk is high
establish building codes to regulate placement and design of buildings in high risk areas
determine if prediction is feasible.
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31. Cultural / Biological Hazards: The Global HIV/AIDS Epidemic
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
25 Million deaths, so far; alter country’s age structure

32. AIDS Is the Leading Cause of Death for Ages 15–49 Worldwide

33. Some Diseases Can Spread from One Person to Another
Nontransmissible disease – not capable of being passed to another
Infectious disease - transmitted via microorganisms in the air or water (Cholera, Malaria, TB)
Transmissible disease (contagious or communicable disease) – physical contact needed

34. The World’s Seven Deadliest Infectious Diseases Kill 12
The World’s Seven Deadliest Infectious Diseases Kill 12.5 Million People

35. 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
Figure 17.10
Solutions: ways to prevent or reduce the incidence of infectious diseases, especially in developing countries. Question: Which three of these approaches do you think are the most important?
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 , p. 447

36. Case Study: The Growing Global Threat from Tuberculosis
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

37. Tracking the Spread of Infectious Diseases to Humans from Other Animals
Ecological medicine
Human practices that encourage the spread of diseases from animals to humans
Emerging infections
HIV
SARS
West Nile virus
Lyme virus

38. Malaria—Death by Parasite-Carrying Mosquitoes
Caused by Plasmodium (PROTIST!) specifically carried by Anopheles mosquitoes
Spread
Symptoms
Malarial cycle

39. Case Study: Malaria—Death by Parasite-Carrying Mosquitoes (2)
Malaria on the rise since 1970
Drug resistant Plasmodium
Insecticide resistant mosquitoes
Effect of global warming
AIDS patients particularly vulnerable
Prevention of spread and current research

40. Global Outlook: Distribution of Malaria

41. A Boy in Brazil’s Amazon Sleeps Under an Insecticide-Treated Mosquito Net

42. Animation: HIV replication

43. Animation: Life cycle of plasmodium

44. ABC Video: Bird flu

45. ABC Video: Polio scare

46. ABC Video: The problem with pork

47. Comparative Risk Analysis: Most Serious Ecological and Health Problems