1. Unit 9: Environmental Health and Toxicology
Section 1: Risks and Hazards

2. Central Case Study: Poison in the Bottle
Bisphenol A (BPA) – Used to make hard plastic found in utensils, baby bottles, laptops, toys, etc.
Leaches into food, water, air, and human bodies
93% of Americans currently have it in their body
Only a low dose required to have negative effects
Linked to Cancer, nerve damage, and miscarriages
Mimics the hormone estrogen
Conflicting information regarding health risk
Many countries banned use in baby bottles
U.S. FDA rejected a ban on its use in 2012

3. RISKS AND HAZARDS
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: (lifestyle choices) such as smoking, poor diet, unsafe sex, drugs, unsafe working conditions, and poverty.

4. BIOLOGICAL HAZARDS
Diseases not caused by living organisms cannot spread from one person to another (nontransmissible disease), while those caused by living organisms such as bacteria and viruses can spread from person to person (transmissible or infectious)
Bacteria: single-celled, prokaryotic organisms
Notable bacterial diseases: cholera, Tuberculosis, bubonic plague, anthrax, food poisoning, gonorrhea, strep throat, etc.
Viruses: small, infectious agent that replicates itself using the living cells of other organisms
Notable viral diseases: common cold, small pox, Ebola, influenza, rabies, measles, HIV, herpes

5. BIOLOGICAL HAZARDS
Antibiotics used against bacteria (antivirals CAN work against viruses, but usually do not)
Bacteria are developing genetic resistance to antibiotics
We are starting to see “superbugs” in different bacterial species

6. Transmissible Disease
Pathway for infectious disease in humans.

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

8. The Growing Global Threat from Tuberculosis
The highly infectious tuberculosis (TB) kills 1.7 million people per year and could kill 25 million people 2020.
Recent increases in TB are due to:
Lack of TB screening and control programs especially in developing countries due to expenses.
Genetic resistance to the most effective antibiotics.

10. VIRAL DISEASES
Flu, HIV, and hepatitis B viruses infect and kill many more people each year then highly publicized West Nile, SARS, and Ebola viruses.
The influenza virus is the biggest killer virus worldwide.
Pigs, chickens, ducks, and geese are the major reservoirs of flu.
As they move from one species to another, they can mutate and exchange genetic material with other viruses.

11. VIRAL DISEASES
HIV is the second biggest killer virus worldwide. Five major priorities to slow the spread of the disease are:
Quickly reduce the number of new infections to prevent further spread.
Concentrate on groups in a society that are likely to spread the disease.
Provide free HIV testing and pressure people to get tested.
Implement educational programs.
Provide free or low-cost drugs to slow disease progress.

12. Malaria – Death by Mosquito
Malaria kills about 2 million people per year
Caused by parasitic protozoans
Get into blood stream and cause cells to burst
Major problem in tropical regions

13. Preparation for LD50 Lab – Friday
Practice in performing a serial dilution

14. Pre Lab Definitions: (Fill these in on your lab paper)
Serial: In a series, order or interval. Measured steps.
Dilution: Water down
Pipette: “Little pipe” for moving and measuring liquids.
Serial dilutions reduce the concentration of a sample in small steps or fractions.

15. Lab: Fill in the instructions as we go along. Read each step carefully.
1. Label test tubes 1, 2, 3, 4.

16. Lab: Fill in the instructions as we go along. Read each step carefully.
1. Add 10 mL of water to test tube 1.
2. Add 3 drops of methylene blue to test tube 1. (mix) – use paper towel over mouth of tube as methylene blue WILL dye your skin
3. Transfer 1 mL of water from test tube 1 to test tube 2.

17. Lab: Fill in the instructions as we go along. Read each step carefully.
4. Add 9 mL of water
5. Pipette 1 mL of water from test tube 2 to test tube 3.
6. Add 9 mL of water
7. Pipette 1 mL of water from test tube 3 to test tube 4.
8. Add 9 mL of water

18. The Basics of Toxicology
Toxicology – the science that examines effects of poisonous substances
Toxicity – the degree of harm a substance can inflict
Toxicant – poison; toxic substance
Environmental toxicology – deals with toxic substances that come from or are discharged into the environment

19. CHEMICAL HAZARDS
A hazardous chemical can harm humans or other animals because it:
Is flammable
Is explosive
An irritant
Interferes with oxygen uptake
Induce allergic reactions.

20. 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 hormones into the bloodstream; help regulate the body.

21. Dose-Response Studies
LD50- lethal dose that kills 50% of the individuals
ED50- effective dose that causes 50% of the animals to display the nonlethal effect

23. Synergistic Interactions
Sometimes, when a person is exposed to more that one risk at a time, the risk can compound and become worse
Ex: the health impact of a carcinogen such as asbestos can be much higher if an individual also smokes tobacco.

24. Case Study: A Black Day in Bhopal, India
The world’s worst industrial accident occurred in 1984 at a pesticide plant in Bhopal, India.
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
Indian officials claim that simple upgrades could have prevented the tragedy.

25. Stockholm Convention
In 2001, a group of 127 nations gathered in Stockholm, Sweden, to reach an agreement on restricting the global use of some chemicals
12 chemicals were to be banned, phased out, or reduced
These include DDT, PCBs, and certain chemicals that are by-products of manufacturing processes.

26. TOXICOLOGY: ASSESSING CHEMICAL HAZARDS
Children are more susceptible to the effects of toxic substances because:
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. Cause of death Annual deaths 11 million (75) 5 million (34)
Poverty/malnutrition/ disease cycle
Tobacco
5 million (34)
Pneumonia and flu
3.2 million (22)
Air pollution
3 million (21)
HIV/AIDS
3 million (21)
Malaria
2 million (14)
Diarrhea
1.9 million (13)
Tuberculosis
1.7 million (12)
Figure 18.13
Global outlook: number of deaths per year in the world from various causes. Numbers in parentheses give these deaths in terms of the number of fully loaded 400-passenger jumbo jets crashing every day of the year with no survivors. Because of sensational media coverage, most people have a distorted view of 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)
Car accidents
1.2 million (8)
Work-related injury & disease
1.1 million (8)
Hepatitis B
1 million (7)
Measles
800,000 (5)

28. Shortens average life span in the U.S. by
Hazard
Shortens average life span in the U.S. 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
Figure 18.14
Global outlook: comparison of risks people face, expressed in terms of shorter average life span. After poverty and gender, the greatest risks people face come mostly from the lifestyle choices they make. These are merely generalized relative estimates. Individual responses to these risks can differ because of factors such as genetic variation, family medical history, emotional makeup, stress, and social ties and support. QUESTION: Which three of these items are most likely to shorten your life span? (Data from Bernard L. Cohen)
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
Lifetime near nuclear plant
10 hours