1. What are you most scared of?
Shark attack
Motorcycling
Snakebite
Smoking
Driving
Airplane crash

2. What are you most scared of?
Shark attack – 1 in 281 million
Motorcycling – 1 in 50 participants
Snakebite – 1 in 56 million
Smoking – 1 in 300 participants by age 65
Driving – 1 in 6,700
Airplane crash – 1 in 9 million

3. What are you most scared of?
Fireworks discharge
Lightning
Gunshot
Earthquake
Car accident

4. Your chance of dying from . . .
Fireworks discharge – 1 in 386,766
Lightning – 1 in 84, 079
Gunshot – 1 in 6,309
Earthquake – 1 in 148,756
Car accident – 1 in 66
Statistics from National Safety Council

5. Chapter 10: Risk, Toxicology, & Human Health

6. What is risk?
Risk – possibility of suffering harm from a hazard

7. Impacts of risks on humans
Mortality
Morbidity
Loss of quality of life
Loss of work days
Property damage

8. Examples of Cultural Hazards
Smoking
Poor Diet
Poverty
Unsafe sex

9. Examples of Chemical Hazards
Air
Water
Soil
Food

10. Examples of Physical Hazards
Fires
Earthquakes
Volcanic eruptions
Floods
Tornadoes
Hurricanes

11. Examples of Biological Hazards
Pathogens
Pollen
Allergens
Animals

12. Quantitative Measures of Risk
Probabilities - a mathematical statement about the likelihood of harm
Can be expressed in three ways:
1:100
1/100
“One in one hundred”

13. Quantitative Measures of Risk
Ex: 1:6,210 - risk of dying from alcohol
(1 person in 6,210 people will die of alcohol related illness)
The bigger the bottom number (denominator) the less the chance
Ex: chance of winning Power Ball lottery: about 1 in 80,000,000
Ex: chance of laughing at with Mr. Strogen today: about 1 in 3

14. “The dose makes the poison”
Toxicology
Dose – the amount of a substance that a person has in their body
Can be:
Ingested
Inhaled
Injected
Absorbed
“The dose makes the poison”

15. Sensitivity to Toxins
The amount of damage (response) is related to the dose you get
Response is related to age, gender, and genetic makeup

16. Toxicology Solubility - what can the chemical dissolve in?
Water-soluble toxins
Oil/Fat-soluble toxins
Which do you think is generally “better” for the health of an organism?
Water is “better” since it can be diluted
Fats aren’t good since chemicals can gather in body fat of animals

17. Toxicology Persistence - how long a chemical stays in the environment
Roundup (kills plants) breaks down in 24 h when exposed to light
DDT (kills insects) breaks down in 2 to 15 years

18. Toxicology
Chemical interactions - two (or more) factors together can have a greater effect than each by themselves
Being exposed to asbestos (insulation) and smoking give you a 400 times greater chance of lung cancer + =

19. Toxicology Bioaccumulation chemicals stored in organs (fat) of animals
Biomagnification
chemicals are passed to each member of the food chain
large amounts in animals at top of chain

20. Case Study – DDT Dichlorodiphenyltrichloroethane
Used as an insecticide beginning in the 1940s, primarily in tropical areas of the world with malaria and typhus
Highly effective at killing insects
WHO estimates that its use has saved 25 million lives

21. Case Study – DDT
1962, Rachel Carson wrote Silent Spring, which described the negative effects of pesticides, like DDT:
Cancer in humans
Thinner egg shells, reproductive problems, and death in birds
Carson was concerned with the widespread spraying of chemicals, especially since we didn’t fully understand its effects on the environment or humans

22. Case Study – DDT Silent Spring resulted in a public outcry to ban DDT
1972, banned in the US
2004, banned worldwide (some exemptions)
Often cited as the beginning of the “environmental movement”

23. DDT Discussion
Should DDT be banned everywhere in the world? Should there be exemptions?
Should a product, like DDT, be allowed if it saves human lives while harming wildlife?

25. STEPS TO MEASURE RISK 1. Problem Identification
Scientific or public concerns about harm from a particular substance often initiate the problem identification process.
Evidence is gathered by:
Animal studies
Test tube studies
Comparison studies – the properties of the substance are compared with substances known to be harmful.

26. STEPS TO MEASURE RISK 2. Exposure Assessment
Estimates how much of a substance a population inhales, ingests, or absorbs through the skin (aka the “dose”)
Some of the factors we must consider are:
How long people have been exposed
Whether the exposure was continuous or intermittent
How they were exposed – inhalation, ingestion, or absorption through the skin

27. STEPS TO MEASURE RISK 3. Toxicity Assessment
Toxicity assessments estimate how much of a substance does what kind of harm
The toxicity assessment step looks at how much of a substance causes what kind of harm to humans.
Toxicity to humans is not usually measured directly by intentionally exposing people, for obvious ethical reasons.

28. Toxicity Assessment
An interesting animal study concerning the artificial sweetener saccharin
Animal studies indicated that saccharine caused bladder cancer in animals. In 1977, the FDA proposed a ban on its use.
Studies later reveled that the doses given to animals were the equivalent of a human drinking 100 cans of soda a day. Human tests never linked saccharine to human cancer because the way that saccharine gave cancer to rats does not happen in humans.
Saccharine was taken off the FDA’s possible cancer list in 2000, after 25 years of needless worry.
Worry is still around today.

29. Toxicity Assessment - Poisons
Poisons – materials that kill at a very small dose (50 milligrams or less per kilogram of weight)
The LD50 (lethal dose) is the amount that kills 50% of a test population in a given time.

30. Toxicity Assessment -Poisons
The LD50 of this chemical is 7.
Look along the blue curve. The dose that kills 50% is the LD50.

31. STEPS TO MEASURE RISK Toxicity Ratings

32. Risk Assessment vs. Risk Management
Risk Assessment “What is the hazard?”
Risk Management “How can the risk be minimized?”