1. Risk, Toxicology, and Human Health
G. Tyler Miller’s
Living in the Environment
14th Edition
Chapter 19

2. Key Concepts to Chapter 19
Types of hazards people face
Defining and measuring toxicology
Types and measurement of chemical hazards
Types and effects of biological hazards
Risk estimation, management, and reduction

3. Annual death rates in the U.S. in 2003.

4. Sections 1 and 2 Key Concepts
What is risk? What are the major types of hazards?
What determines if a chemical is hazardous?
What are the basic principles of toxicology?
Can a little bit of pollution actually be good for you?
How good are estimates of toxicity?

5. Risk, Probability and Hazards
Risk: is the possibility of suffering a harm from a hazard that can cause injury, disease, death, economic loss, or environmental damage.
Risk Assessment: the scientific process of estimating harm a particular hazard may cause.
Risk Management: deciding whether or not to reduce a risk and at what cost.

6. What is risk? Risk is expressed in probabilities.
Example: “The lifetime risk of developing lung cancer is 1 in 250 from smoking a pack a day”
Plane crash: 1 in 10 million
Lightning: 1 in 1.4 million
House Fire: 1 in 200

7. Risk and Probability Risk Risk assessment Risk management Probability
Fig p. 410

8. Hazards: Types of Risk
Cultural hazards: working conditions, diet, driving,
unsafe sex, poverty, etc..
Physical hazards: fire, tornado, volcanic eruption,
earthquake, etc..
Chemical hazards: harmful chemicals in the air,
water, soil and food. Example: DDT or PCBs
Biological hazards: pathogens (bacteria, virus,
parasites), pollen, animals, plants.

9. Which type of hazard do these fit into?

10. Toxicology Toxicity Dosage Bioaccumulation Biomagnification Synergism
Fig p. 411
Toxicity
Dosage
Bioaccumulation
Biomagnification
Synergism
Response
Acute effect
Chronic effect
Fig p. 411

11. TOXICOLOGY: Assessing Chemical Hazards
Toxicity: measure of how harmful a substance is in causing injury, illness, or death to living organisms.
FACTORS AFFECTING TOXICITY:
1) Dose: the amount of substance ingested, inhaled or absorbed.

12. Factors Affecting Toxicity
2) Age of individual
3) Immune System (detoxification)
4) Genetic Makeup
5) Length and frequency of exposure

13. Factors Affecting Harm Caused By A Substance
Solubility (water soluble move through environment easily)
2) Fat Soluble (can accumulate in body tissue and cells)
3) Persistence (how long before it breaks down)
Bioaccumulation
Biomagnifications

14. Factors Affecting Harm Caused By A Substance
4) Chemical interactions
For instance: workers exposed to asbestos increase risk of long cancer by 20 times, if they smoke also 400 times.
Response: they type of damage (acute vs. chronic)

15. Principles of Toxicology
Any synthetic or natural chemical can be harmful if ingested in large enough quantity.
THE DOSE MAKES THE POISON
Critical questions: what is the lowest level that will cause harm?

16. Principles of Toxicology
Trace amounts of chemicals in the environment may or may not be harmful.
Some say they are not, look at life expectancy over last several centuries.
Some say they are, look at cancer rates and say it is hard to know long-term impacts.

17. Poisons
Median lethal dose (LD50): at what dosage does the toxin kill 50% of animals (usually mice or rats)
Fig p. 413

18. Principles of Toxicology
How do scientists determine toxicity:
Epidemiologic case studies
Animal Testing (usually with control groups)
Computer modeling

19. Dose-Response Curves Dose-response Nonthreshold Threshold
Fig p. 414

20. Principles of Toxicology
How good are the estimates of toxicology?
There are serious limitations to all these types of studies.
Therefore, most allowable limits are set well below estimated harmful levels.

21. Sections 1 and 2 Review
What is risk? What are the major types of hazards?
What determines if a chemical is hazardous?
What are the basic principles of toxicology?
Can a little bit of pollution actually be good for you?
How good are estimates of toxicity?

22. Section 3: Chemical Hazards
What are toxic and hazardous chemicals?
What are some possible impacts from chemical hazards?
Are hormonally active agents a human health threat?
Why do scientists no so little about the impacts of chemicals on human health?
Is pollution prevention the answer?

23. What are toxic and hazardous chemicals?
Toxic Chemical: a chemical through that can cause temporary or permanent harm or death.
Hazardous Chemical: can harm humans because it is flammable or explosive.

24. Types of Toxic Agents Mutagen: causes changes to ones DNA.
Teratogens: chemicals that cause birth defects to fetus or embryo. (alcohol)
Carcinogens: cause cancer (growth of cancerous tumors)

25. Impacts of Chemicals on Humans
Chemicals may also impact:
Immune system (arsenic, dioxin)
Nervous System (neurotoxins, brain, spinal cord, etc.)
Endocrine System (levels of hormones)

26. Hormonally Active Agents
Exposure to low level certain synthetic chemicals may disrupt a bodies hormone levels
Endocrine disrupters or hormonally active agents
So called, gender benders

27. Establishing Guilt Is Difficult
Under current laws, most chemicals are considered innocent until proven guilty.
“Toxicologist know a great deal about a few chemicals, a little about many, and nothing about most.”

28. Establishing Guilt Is Difficult
U.S. National Academy of Sciences estimates that only 10% of the 80,000 chemicals in commercial use have been tested for toxicity.
Why?
Not required (considered innocent)
Lack of funds, personnel, facilities
Expensive
Difficult to test interactions

29. Pollution Prevention Model
Where do we go from here?
We do not know much about all of the chemicals inside us, around us
Eliminating them mean other problems
Some say Pollution Prevention,

30. Pollution Prevention Model
Precautionary Principle: where there is plausible, but incomplete scientific evidence of significant harm we need to take action to reduce the risk.
“Better Safe Than Sorry”

31. Pollution Prevention Model
First: new chemical technologies would be considered harmful until studies say otherwise.
Second: existing chemicals that appear to be harmful would be removed from use.
EU close to adopting this type of approach.

32. Review Chapter 19 Section 3
What are toxic and hazardous chemicals?
What are some possible impacts from chemical hazards?
Are hormonally active agents a human health threat?
Why do scientists no so little about the impacts of chemicals on human health?
Is pollution prevention the answer?

33. Chemical Hazards Hazardous chemicals Mutagens Teratogens Carcinogens
Neurotoxins
Hormonally active agents
Precautionary principle

34. Section 4: Biological Hazards
What are nontransmissible and transmissible diseases?
Case studies: 1) Germ resistance to antibiotics, 2) Global Tuberculosis Epidemic, 3) HIV and AIDS Threat, 4) Malaria Comeback, 5) Bioterrorism: A Growing Threat, 6) Solutions: How can we reduce the Incidence of Infectious Diseases?

35. Transmittable and Nontransmittable Diseases
Nontransmissible: caused by something other than a living organism and does not spread from person to person. (cancer, diabetes, etc.)
Transmissible: caused by living organisms and can spread from person to person. (bacteria, virus, parasite)

36. Transmittable and Nontransmittable Diseases
According to WHO: 30% of deaths are nontransmissible and 26% transmissible IDs and 12% nontransmissibe cancers.

37. Transmittable and Nontransmittable Diseases
Good News: Since 1950, ID death rates fallen dramatically.
Bad News: Bacteria resistance growing and insects becoming immune to pesticides.

38. Biological Hazards: Diseases
Nontransmissible disease
Fig p. 425
Transmissible disease
Pathogens
Vectors
Tuberculosis
HIV/AIDS
Malaria

43. TB Kills 1.7 million people per year.

46. Reducing Infectious Diseases
Fig p. 426

47. Bioterrorism Possible targets: air, water, and food Inexpensive
Fairly easy to produce biological agents
Recombinant DNA techniques
Refer to Fig p. 427

48. Case Studies Jigsaw
1) Germ resistance to antibiotics, 2) Global Tuberculosis Epidemic, 3) HIV and AIDS Threat, 4) Malaria Comeback, 5) Bioterrorism: A Growing Threat, 6) Solutions: How can we reduce the Incidence of Infectious Diseases?

49. Section 19-5 Risk Analysis Goals

50. Risk Analysis Risk analysis Comparative risk analysis
System reliability
Risk management
Risk perception

51. Risk Analysis
Fig p. 428