Environmental Hazards and Human Health

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Environmental Hazards and Human Health

• Chapter 17

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17-1 What Major Health Hazards Do We Face?

• Concept 17-1 People face health hazards from
  biological, chemical, physical, and cultural
  factors, and from the lifestyle choices they
  make.

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Science Risk Assessment and Risk Management
Fig 17-3
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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 such as smoking, poor diet,
  unsafe sex, drugs, unsafe working conditions, and
  poverty.

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Using Risk Assessment(Benefit/Cost Analysis)

• Benefits gt Risks,
• then behavior or process should continue
• Benefits lt Risks,
• then behavior or process should not continue.
• Every behavior or process involves RISK.

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17-2 What Types of Biological Hazards Do We Face?

• Concept 17-2 In terms of death rates, the most
  serious infectious diseases are flu, AIDS,
  diarrheal diseases, malaria, and tuberculosis
  most of these deaths occur in developing
  countries.

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Core Case Study The Global HIV/AIDS Epidemic

• Acquired immune deficiency syndrome (AIDS) caused
  by human immunodeficiency virus (HIV) many
  secondary infections
• No vaccine to prevent or cure AIDS
• Expensive drugslive longer
• 25 Million deaths, so far alter countrys age
  structure

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Global Outlook Worldwide, AIDS Is the Leading
Cause of Death for Ages 1549
Fig 17-2
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Some Viral Diseases Kill Large Numbers of People

• Global strategy to slow down the spread of HIV
• Reduce the number of new infections
• Concentrate on those most likely to spread HIV
• Free testing
• Education for prevention
• Provide free or low-cost drugs
• Research

United Nations HIV/AIDS
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Major Causes of Death in the World and in the
United States in 2005
Fig 17-3
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Growing Germ Resistance to Antibiotics

• Rabidly producing infectious bacteria are
  becoming genetically resistant to widely used
  antibiotics due to
• Genetic resistance Spread of bacteria around the
  globe by humans, overuse of pesticides which
  produce pesticide resistant insects that carry
  bacteria. Methicillin-resistant Staphylococcus
  aureus (MRSA)
• Overuse of antibiotics A 2000 study found that
  half of the antibiotics used to treat humans were
  prescribed unnecessarily.

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Science Pathways for Infectious Diseases in
Humans
Fig 17-5
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The Worlds Seven Deadliest Infectious Diseases
Kill 12.5 Million People
Fig 17-6
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Malaria Death by Mosquito

• Malaria kills about 2 million people per year and
  has probably killed more than all of the wars
  ever fought.

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Global Outlook Distribution of Malaria
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A Boy in Brazils Amazon Sleeps Under an
Insecticide-Treated Mosquito Net
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Infectious Disease Control

• Here are some link to International and U.S.
  organizations that deal with disease control
• UNICEF
• WHO World Health Organization
• CDC Center for Disease Control
• Department of Health Human Services
• NIH National Institute of Health

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Solutions Infectious Diseases, Ways to Prevent
or Reduce Their Occurrence
Fig 17-10
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17-3 What Types of Chemical Hazards Do We Face?

• Concept 17-3 There is growing concern about
  chemicals that can cause birth defects and
  cancers and disrupt the human immune, nervous,
  and endocrine systems.

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CHEMICAL HAZARDS

• A toxic chemical can cause temporary or permanent
  harm or death.
• Mutagens are chemicals or forms of radiation that
  cause or increase the frequency of mutations in
  DNA.
• Teratogens are chemicals that cause harm or birth
  defects to a fetus or embryo.
• Carcinogens are chemicals or types of radiation
  that can cause or promote cancer.

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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.

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Case Study PCBs Are EverywhereA Legacy from the
Past

• Class of chlorine-containing compounds
• Very stable
• Nonflammable
• Break down slowly in the environment
• Travel long distances in the air
• Fat soluble
• Biomagnification
• Food chains and webs
• Banned, but found everywhere

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Potential Pathways on Which Toxic Chemicals Move
Through the Environment
Fig 17-10
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Some Chemicals May Affect Our Immune, Nervous,
and Endocrine Systems

• Some natural and synthetic chemicals in the
  environment can weaken and harm
• Immune system
• Nervous system
• Endocrine system
• Hormonally active agents (HAAs)
• Gender benders
• Thyroid disrupters

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Hormones and Hormones Mimics or Blockers
Fig 17-12
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Science Focus Bisphenol A

• Estrogen mimic
• Found in many common products - Plastics
• NIEHS link to info

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Science Focus Mercurys Toxic Effects

• Hg teratogen and potent neurotoxin
• Once airborne, persistent and not degradable
• 1/3 from natural sources
• 2/3 from human activities
• Enters the food chain biomagnification

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Science Cycling of Mercury in Aquatic
Environments
Fig 17-A
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SOLUTIONS
Mercury Pollution
Prevention
Control
Phase out waste incineration
Sharply reduce mercury emissions from
coal-burning plants and incinerators
Remove mercury from coal before it is burned
Tax each unit of mercury emitted by coal-burning
plants and incinerators
Switch from coal to natural gas and renewable
energy resources such as wind, solar cells, and
hydrogen
Convert coal to liquid or gaseous fuel
Require labels on all products containing mercury
Phase out use of mercury in batteries, TVs,
compact fluorescent lightbulbs, and all other
products unless they are recycled
Collect and recycle mercury-containing electric
switches, relays, and dry-cell batteries
Fig. 17-B, p. 451
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17-4 How Can We Evaluate and Deal with Chemical
Hazards?

• Concept 17-4A Scientists use live laboratory
  animals, non-animal tests, case reports of
  poisonings, and epidemiological studies to
  estimate the toxicity of chemicals, but these
  methods have limitations.
• Concept 17-4B Many health scientists call for
  much greater emphasis on pollution prevention to
  reduce our exposure to potentially harmful
  candidates.

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Many Factors Determine the Harmful Health Effects
of a Chemical

• Toxicity dependent on
• Dose
• Frequency of exposure
• Age
• Genetic makeup the effectiveness of the bodys
  detoxification systems
• Multiple chemical sensitivity (MCS)
• Solubility and persistence of the chemical
• Biomagnification
• Response
• Acute effect
• Chronic effect

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TOXICOLOGY ASSESSING CHEMICAL HAZARDS

• Typical variations in sensitivity to a toxic
  chemical within a population, mostly because of
  genetic variation.

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Science Estimating Human Exposure to Chemicals
and Measuring Their Effects
Fig 17-13
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Hypothetical Dose-Response Curve Showing
Determination of the LD50
Fig 17-14
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Toxicity Ratings and Average Lethal Doses for
Humans
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Science Two Types of Dose-Response Curves
Fig 17-15
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Toxicity Ratings
LD50 is the dose at which 50 of the population
die
Household product risk Dept Health Human
Services
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Toxicology and Risk Assessment Careers

• Society of Toxicology
• Environmental Health and Toxicology
• EPA risk assessment
• Risk Management Careers

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TOXICOLOGY ASSESSING CHEMICAL HAZARDS

• Under existing laws, most chemicals are
  considered innocent until proven guilty, and
  estimating their toxicity is difficult,
  uncertain, and expensive.
• Federal and state governments do not regulate
  about 99.5 of the commercially used chemicals in
  the U.S.

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TOXICOLOGY ASSESSING CHEMICAL HAZARDS

• Some scientists and health officials say that
  preliminary but not conclusive evidence that a
  chemical causes significant harm should spur
  preventive action (precautionary principle).
• Manufacturers contend that wide-spread
  application of the precautionary principle would
  make it too expensive to introduce new chemicals
  and technologies.

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Some Potentially Harmful Chemicals Found in Most
Homes
Fig 17-16
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17-5 How Do We Perceive Risks and How Can We
Avoid the Worst of Them?

• Concept 17-5 We can reduce the major risks we
  face if we become informed, think critically
  about risks, and make careful choices.

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Comparative Risk Analysis Most Serious
Ecological and Health Problems
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Stepped Art
Fig. 17-17, p. 461
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Global Outlook Number of Deaths per Year in the
World from Various Causes
Fig 17-18
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Comparison of Risks People Face in Terms of
Shorter Average Life Span
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Annual Deaths in the U.S. from Tobacco Use and
Other Causes in 2004
Fig 17-20
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RISK ANALYSIS

• Estimating risks from using many technologies is
  difficult due to unpredictability of human
  behavior, chance, and sabotage.
• Reliability of a system is multiplicative
• If a nuclear power plant is 95 reliable and
  human reliability is 75, then the overall
  reliability is (0.95 X 0.75 0.71) 71.

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Characteristics of Risk(Factors on Right
Increase Perception of Riskiness)
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Using Risk Assessment(Benefit/Cost Analysis)

• Benefits gt Risks,
• then behavior or process should continue
• Benefits lt Risks,
• then behavior or process should not continue.

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Becoming Better at Risk Analysis

• We can carefully evaluate or tune out of the
  barrage of bad news covered in the media, compare
  risks, and concentrate on reducing personal risks
  over which we have some control.

Fig 17-3