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Risk, Toxicology, and Human Health

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Risk, Toxicology, and Human Health G. Tyler Miller s Living in the Environment 14th Edition Chapter 19 Key Concepts to Chapter 19 Sections 1 and 2 Key Concepts What ... – PowerPoint PPT presentation

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Title: Risk, Toxicology, and Human Health


1
Risk, Toxicology, and Human Health
G. Tyler Millers 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
  • Riskassessment
  • Riskmanagement
  • Probability

Fig. 19-2 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
Fig. 19-4 p. 411
  • Toxicity
  • Dosage
  • Bioaccumulation
  • Biomagnification
  • Synergism
  • Response
  • Acute effect
  • Chronic effect

Fig. 19-3 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. 19-5 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. 19-6 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. 19-13 p. 425
  • Transmissible disease
  • Pathogens
  • Vectors
  • Tuberculosis
  • HIV/AIDS
  • Malaria

39
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43
TB Kills 1.7 million people per year.
44
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46
Reducing Infectious Diseases
Fig. 19-15 p. 426
47
Bioterrorism
  • Possible targets air, water, and food
  • Inexpensive
  • Fairly easy to produce biological agents
  • Recombinant DNA techniques

Refer to Fig. 19-16 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. 19-17 p. 428
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