Risk, Toxicology, and Human Health

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Risk, Toxicology, and Human Health
G. Tyler Millers Living in the Environment 14th
Edition Chapter 19
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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

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

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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.

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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

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Risk and Probability

• Risk

• Riskassessment

• Riskmanagement

• Probability

Fig. 19-2 p. 410
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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.

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Which type of hazard do these fit into?
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Toxicology
Fig. 19-4 p. 411

• Toxicity

• Dosage

• Bioaccumulation

• Biomagnification

• Synergism

• Response

• Acute effect

• Chronic effect

Fig. 19-3 p. 411
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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.

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Factors Affecting Toxicity

• 2) Age of individual
• 3) Immune System (detoxification)
• 4) Genetic Makeup
• 5) Length and frequency of exposure

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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

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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)

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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?

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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.

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Poisons

• Median lethal dose (LD50) at what dosage does
  the toxin kill 50 of animals (usually mice or
  rats)

Fig. 19-5 p. 413
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Principles of Toxicology

• How do scientists determine toxicity
• Epidemiologic case studies
• Animal Testing (usually with control groups)
• Computer modeling

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Dose-Response Curves

• Dose-response

• Nonthreshold

• Threshold

Fig. 19-6 p. 414
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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.

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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?

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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?

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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.

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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)

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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)

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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

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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.

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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

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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,

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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

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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.

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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?

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Chemical Hazards

• Hazardous chemicals

• Mutagens

• Teratogens

• Carcinogens

• Neurotoxins

• Hormonally active agents

• Precautionary principle

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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?

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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)

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Transmittable and Nontransmittable Diseases

• According to WHO 30 of deaths are
  nontransmissible and 26 transmissible IDs and
  12 nontransmissibe cancers.

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Transmittable and Nontransmittable Diseases

• Good News Since 1950, ID death rates fallen
  dramatically.
• Bad News Bacteria resistance growing and insects
  becoming immune to pesticides.

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Biological Hazards Diseases

• Nontransmissible disease

Fig. 19-13 p. 425

• Transmissible disease

• Pathogens

• Vectors

• Tuberculosis

• HIV/AIDS

• Malaria

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TB Kills 1.7 million people per year.
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Reducing Infectious Diseases
Fig. 19-15 p. 426
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Bioterrorism

• Possible targets air, water, and food
• Inexpensive
• Fairly easy to produce biological agents
• Recombinant DNA techniques

Refer to Fig. 19-16 p. 427
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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?

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Section 19-5 Risk Analysis Goals
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Risk Analysis

• Risk analysis

• Comparative risk analysis

• System reliability

• Risk management

• Risk perception

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Risk Analysis
Fig. 19-17 p. 428