1. Environmental Hazards and Human Health
Chapter 18
Environmental Hazards and Human Health

2. Risk is a measure of the likelihood that you will suffer harm from a hazard.
We can suffer from:
Biological hazards: from more than 1,400 pathogens.
Chemical hazards: in air, water, soil, and food.
Physical hazards: such as fire, earthquake, volcanic eruption…
Cultural hazards: such as smoking, poor diet, unsafe sex, drugs, unsafe working conditions, and poverty.
RISKS AND HAZARDS

3. Types of diseases:
nontransmissible disease- Diseases not caused by living organisms cannot spread from one person to another
Heart disease, emphysema, asthma,
transmissible or infectious-while those caused by living organisms such as bacteria and viruses can spread from person to person
Flu, HIV, Malaria, Lyme, Hepatitis B

4. Transmissible Disease
Pathway for infectious disease in humans.
Figure 18-4

5. Transmissible Disease
WHO estimates that each year the world’s seven deadliest infections kill 13.6 million people – most of them the poor in developing countries.
Figure 18-5

6. WHO reported in 2005- 42 million (1.1 mill US) had HIV
No vaccine
Drugs are limited among poor
How does HIV affect humans?
Where did AIDS come from?
&m=
aids-epidemic
HIV/AIDS EPIDEMIC

7. Core Case Study: The Global HIV/AIDS Epidemic
AIDS has reduced the life expectancy of sub- Saharan Africa from 62 to 47 years – 40 years in the seven countries most severely affected by AIDS.
News on AIDS
How does this age structure affect the economics of this country?
Figure 18-2

8. Should developed and developing nations mount an urgent global campaign to reduce the spread of HIV and to help countries afflicted by the disease?
a. No. A global AIDS campaign could divert attention and resources from efforts to combat other serious threats.
b. Yes. The disease is decimating the populations and destroying the economies of many developing countries.
How Would You Vote?

9. Case Study: The Growing Global Threat from Tuberculosis
Recent increases
in TB are due to:
Lack of TB screening and control programs
Genetic resistance to the most effective antibiotics.
Population growth, urbanization, air travel
More AIDS which weakens immune system

10. Most Dangerous Viral Diseases
Flu, HIV, and hepatitis B viruses infect and kill many more people each year then highly publicized West Nile and SARS viruses.
1918 Spanish Flu
ted
Hepatitis B is a virus that attacks your liver which is your natural filter of toxins
Most Dangerous Viral Diseases

11. Case Study: Malaria – Death by Mosquito
Malaria kills about 2 million people per year and has probably killed more than all of the wars ever fought.
Figure 18-7

13. Reducing Chances of Malaria
Spraying insides of homes with low concentrations of the pesticide DDT greatly reduces the number of malaria cases.
Draining swamps
Insecticides
Sleep nets/screen doors
Drugs to victims
Reducing Chances of Malaria

14. Growing Germ Resistance
Rabidly producing infectious bacteria are becoming genetically resistant to widely used antibiotics due to:
Genetic resistance: Spread of bacteria around the globe by humans, overuse of pesticides which produce pesticide resistant insects that carry bacteria.
Overuse of antibiotics: A 2000 study found that half of the antibiotics used to treat humans were prescribed unnecessarily.

15. More infectious diseases…
E.Coli
Salmonella
Lyme
More infectious diseases…

16. 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 18.8
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?
Careful hand washing by all medical personnel
Immunize children against major viral diseases
Oral rehydration for diarrhea victims
Global campaign to reduce HIV/AIDS
Fig. 18-8, p. 424

17. A toxic chemical can cause temporary or permanent harm or death.
Mutagens are chemicals or forms of radiation that cause or increase the frequency of mutations in DNA.
Ex. Radiation exposure, sunlight
Teratogens are chemicals that cause harm or birth defects to a fetus or embryo.
Ex. Pregnant women drinking alcohol
Carcinogens are chemicals or types of radiation that can cause or promote cancer.
Ex. Cigarette smoke, Arsenic
CHEMICAL HAZARDS

18. Effects of Chemicals on the Immune, Nervous, and Endocrine Systems
Long-term exposure to some chemicals at low doses may disrupt the body’s:
Immune system: specialized cells and tissues that protect the body against disease and harmful substances.
Nervous system: brain, spinal cord, and peripheral nerves.
Endocrine system: complex network of glands that release minute amounts of hormones into the bloodstream.

19. Chemical Toxin
Effect on Human body
Arsenic and dioxins
Weaken immune system
PCBs, methyl mercury, pesticides
Nervous system
DDT, PCBs, atrazine
Endocrine system- hormones
Phthalates
Birth defects, liver damage

20. Effects of Chemicals on the Immune, Nervous, and Endocrine Systems
Molecules of certain synthetic chemicals have shapes similar to those of natural hormones and can adversely affect the endocrine system.
Figure 18-9

21. Bhopal, India
The world’s worst industrial accident occurred in 1984 at a pesticide plant.
An explosion at Union Carbide pesticide plant in an underground storage tank released a large quantity of highly toxic methyl isocyanate (MIC) gas.
15,000-22,000 people died and there are still people suffering today

22. TOXICOLOGY: ASSESSING CHEMICAL HAZARDS
Factors determining the harm caused by exposure to a chemical include:
The amount of exposure (dose).
The frequency of exposure.
The person who is exposed.
The effectiveness of the body’s detoxification systems.
One’s genetic makeup.

23. Helpful vocab. Related to harm on a individual caused by a substance
Solubility- fat soluble substances (nonpolar) accumulate in cells
Persistence- resist breaking down
Bioaccumulation- molecules absorb and store in specific organs/tissues
Biomagnification- as you move up the food chain/web there is more of the toxin
Helpful vocab. Related to harm on a individual caused by a substance

24. Who toxins affect…
Typical variations in sensitivity to a toxic chemical within a population, mostly because of genetic variation.
Figure 18-10

25. How do we reduce the harmful effects of toxins?
Break down and excrete
Enzymes repair damaged DNA
Cells reproduce and replace damaged areas
How do we reduce the harmful effects of toxins?

26. What are children more susceptible to toxins?
Children breathe more air, drink more water, and eat more food per unit of body weight than adults.
They are exposed to toxins when they put their fingers or other objects in their mouths.
Children usually have less well-developed immune systems and detoxification processes than adults.

27. TOXICOLOGY: ASSESSING CHEMICAL HAZARDS
Under existing laws, most chemicals are considered innocent until proven guilty, and estimating their toxicity is difficult, uncertain, and expensive.
Federal and state governments do not regulate about 99.5% of the commercially used chemicals in the U.S.

28. Prevention vs. Reaction
Some scientists and health officials say that preliminary but not conclusive evidence that a chemical causes significant harm should spur preventive action (precautionary principle).

29. RISK ANALYSIS
Scientists have developed ways to evaluate and compare risks, decide how much risk is acceptable, and find affordable ways to reduce it.
Figure 18-12

30. Annual deaths in the U.S. from tobacco use and other causes in 2003.
RISK ANALYSIS
Figure 18-A

31. RISK ANALYSIS
Number of deaths per year in the world from various causes. Parentheses show deaths in terms of the number of fully loaded 400- passenger jumbo jets crashing every day of the year with no survivors.
Figure 18-13

32. Becoming Better at Risk Analysis
We can carefully evaluate or tune out of the barrage of bad news covered in the media, compare risks, and concentrate on reducing personal risks over which we have some control.
Becoming Better at Risk Analysis
Figure 18-3

33. Environmental Changes and Diseases
Global Warming warmer temps for more mosquitos survivingMalaria
Deforestation bats Nipah virus and pigs humans
Deforestation less fox more mice  more ticks Lyme
Environmental Changes and Diseases