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Chapter 8: Environmental Health and Toxicology

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Title: Chapter 8: Environmental Health and Toxicology


1
Chapter 8 Environmental Health and Toxicology
By Anna Blum and Maggie Ellis
2
Environmental Health
  • Environmental Health-focused on factors that
    cause disease, including elements of the natural,
    social, cultural, and technological world in
    which we live
  • Ever since Silent Spring, focus on discharge,
    movement, fate, and effects of synthetic chemical
    toxins
  • Risks come from
  • Toxins
  • Radiation
  • Infectious Agents
  • Trauma
  • Pollution

3
The Global Disease Burden is Changing
  • Disease burden calculated in terms of DALYs
  • Chronic conditions now affect poor as well as
    affluent because people live longer
  • Causes By 2020
  • Heart disease to be leading cause of global
    disease
  • Global cancer rates will increase by 50
  • Psychiatric and neurological conditions will
    increase from 10 to 15 (Depression expected to
    be the second largest cause of all years lived
    with disability worldwide)
  • Chronic obstructive lung diseases expected to
    increase

4
Things That Kill You (part 1)
  • Heart disease number one killer, kills women more
    than men
  • Suicide is the fourth largest cause of female
    deaths
  • Smoking predicted to be single biggest cause of
    death worldwide

5
Infectious Diseases Are Scary
  • Communicable diseases responsible for about 1/3
    of all disease-related mortality
  • 11 million children under 5 die annually due to
    infectious diseases
  • Most of these deaths could be eliminated through
    better nutrition, clean water, improved
    sanitation, and inexpensive inoculations

6
More Infectious Diseases
  • Malaria- 515 million cases each year, 1 million
    people die
  • Spreading as climate changes expands mosquito
    habitats
  • Emergent diseases-those not previously known or
    have been absent for at least 20 years
  • SARS
  • Avian Flu
  • H1N1
  • Ebola
  • West Nile Virus
  • AIDS/HIV

7
Case Study Chronic Wasting Disease
  • Chronic Wasting Diseasedeer and elk populations
    in North America
  • Caused by strange prion protein
  • One of a family of irreversible, degenerative
    neurological diseases known as transmissible
    spongiform encephalopathies (TSE) including mad
    cow
  • Canadian government spending 65 million to fight
    CWD
  • Cattle imported from Canada found to have TSE in
    2004
  • Worry about it spreading to humans, as of yet no
    one in the US has died

8
Causes of Emergent Disease
  • Environmental change stresses biological systems
  • Cut down forests
  • Drain wetlands
  • Invasive species introduced by humans
  • Increased human incursion into wilderness
  • Increased consumption of wild species allows
    diseases to jump barriers---3/4 of all emerging
    diseases are zoonotic, or shared by animals and
    humans
  • Climate change allows animals to expand their
    range

9
Increasing Resistance to Antibiotics and
Pesticides is
  • Partially through natural selection and ability
    to evolve rapidly
  • Mutated bacteria that are resistant live and
    multiply via natural selection
  • Partially through human tendency to use control
    measures aimlessly
  • DDT spread everywhere, so that some were only
    minimally exposedencouraged natural selection
    and the survival of resistant

10
Antibiotics, Farming, and Disease
  • More than half of the antibiotics used in the US
    each year are fed to livestock
  • These antibiotics and hormones are excreted in
    urine and feces
  • Spread on land or water where they evolve into
    supervirulent pathogens
  • At least half of the 100 million antibiotic doses
    prescribed to humans each year are unnecessary or
    wrongimproper disposal or use can lead to
    illness

11
Toxicology
  • Study of toxins (poisons) and their effects on
    living systems
  • Damage or kill living organisms because they
    react with cellular components to disrupt
    metabolic functions
  • Toxins harmful even in dilute concentrations

12
Ecotoxicology
  • All toxins hazardous, but not all hazardous
    materials are toxic
  • Some materials are hazardous because they are
    flammable, explosive, etc.
  • Environmental Toxicologyecotoxicology, deals
    with the interactions, transformation, fate, and
    effects of natural and synthetic chemicals in the
    biosphere, including individual organisms,
    populations, and whole ecosystems

13
How Do Toxins Affect Us?
  • Allergens Antigens
  • Immune system depressants
  • Endocrine disrupters
  • Sick building syndrome
  • poor indoor air quality may
  • cost USA 60 billion in sick
  • days and reduced productivity

14
Teratogens
  • Chemicals or other factors that specifically
    cause abnormalities during embryonic growth and
    development
  • Example Fetal alcohol syndrome- a cluster of
    symptoms including craniofacial abnormalities,
    developmental delays, behavioral problems, and
    mental defects that last throughout a childs
    life
  • Even on drink during pregnancy puts a child at
    risk
  • By some estimates, between 300,000 and 600,000
    children born every year in the US are exposed in
    the womb to unsafe levels of mercury
  • Effects include reduced intelligence, ADD, and
    behavioral problems, costing 8.7 billion
    annually

15
Carcinogens
  • Substances that cause cancer
  • According to the American Cancer Society, ½ males
    and 1/3 females will have some sort of cancer in
    their lifetime
  • Debate over environment vs. lifestyle
  • According to the EPA, 200 million US residents
    live in combined lifetime cancer risk form
    environmental carcinogens exceeds 1 in 100,000 or
    ten times the acceptable risk

16
Diet Affects Health
  • Strong correlation between cardiovascular disease
    and the amount of salt and animal fat in ones
    diet
  • Fruits, vegetables, whole grains, complex carbs,
    and dietary fiber have a positive affect
  • Vitamins A,C, and E, substances produced in
    cruciferous vegetables, and selenium seem to have
    anticancer effects
  • Every year in the US 300,000 deaths are linked to
    obesity
  • 1/3 of US children may become diabetic unless
    people start eating less and exercising more,
    increased risk (1/2) for Black and Hispanic
    children

17
Case Study Poisoning Bhopal
  • December 3rd, 1984
  • Bhopal, central India,
  • Noxious gas methylisocyanate (MIC), a component
    of pesticide Temik, made at the Union Carbide
    plant in Bhopal.
  • Water had gotten into tank and it exploded,
    sending MIC throughout the city
  • 15,000 died instantly 800,000 suffered medical
    problems
  • More than 20 years after the catastrophe, no one
    punished and most of the 470 million paid by
    Union Carbide has yet to be distributed

18
Solubility
  • Solubility is important in determining how, when,
    and where a toxic material will move to the site
    of action
  • Water soluble compounds move widely and rapidly
    and have ready access to most cells
  • Oil or fat soluble compounds generally need a
    carrier to move but can easily penetrate cells
  • more likely to accumulate and be stored in lipid
    deposits for years

19
Exposure Susceptibility
  • Airborne toxins generally cause more ill health
  • Toxins also enter through food, water, skin
    contact
  • Largest exposure for toxins
  • are found in industrial settings
  • Condition of being timing
  • of exposure influence toxicidty

20
Bioaccumulation Biomagnification
  • Cells have mechanisms for bioaccumulation
  • allows them to accumulate nutrients and essential
    materials but also leaves the risk of absorbing
    bad toxins
  • Bioaccumulation
  • Biomagnification When the toxic burden of a
    large number of organisms at a lower trophic
    level is accumulated and concentrated by a
    predator in a higher tropic level

21
Persistence
  • Some chemical compounds are unstable and degrade
    rapidly so their concentrations decline quickly
    after release
  • Others are more persistent and last for a few
    centuries
  • cause more problems and unexpected effects

22
Things That Kill You (part 2)
  • PBDEs are in textiles, upholstery, and plastic.
    They effect behavioral nervous system
    development
  • PFOs and PFOA/C8s are found in nonstick,
    water-proof, stain-resistant products and
    everywhere. Literally.
  • cause liver damage, cancer, reproductive and
    developmental problems in rats kill pet birds
  • Phthalates are found in cosmetics, deodorants,
    and many plastics
  • cause kidney and liver damage,
  • cancer in rats endocrine hormone
  • disrupters that cause reproductive
  • abnormalities and decreased
  • fertility/quality of sperm

23
Things That Kill You (part 3)
  • Perchlorate is a waterborne containment left over
    from propellants and rocket fuels it pollutes
    water used to water crops.
  • Disrupts adult metabolism and childhood
    developments
  • BPA is in polycarbonate plastic.
  • Causes abnormal chromosome numbers, aneuploidy
    (the leading cause of mental retardations and
    miscarriages)
  • Atrazine is a widely used herbicide
  • Causes birth defects, abnormal development

24
Interactions!
  • Antagonistic reactions interfere with the effects
    or stimulate the breakdown of other chemicals
  • Additive reactions occur together in exposure
  • Synergism An interaction in which one substance
    exacerbates the effects of another

25
Degradation Excretion
  • Enzymes process waster products and environmental
    poisons to reduce their toxicity
  • can make chemicals more dangerous by breakdown
    ones that should not be broken down
  • Factors that affect post reproduction stages
    usually don't effect reproductive success or
    exert selective pressure
  • Excretion reduces the effects of
  • waste products and environmental toxins by
  • eliminating them from the body

26
Repair
  • Our skin and organ linings have high cellular
    reproduction rates to replace injured cells
  • Chance that cells will lose normal growth
    controls and create a tumor and irritants will be
    turned into carcinogens

27
Why Lab Animals Die
  • Because we test toxins on them!
  • Expensive, time-consuming, painful to animals
  • takes hundreds of animals, years of work,
    thousands of dollars for one text
  • however, most accurate and reliable data
  • more human toxicity tests are being developed
  • Problems
  • differences in sensitivity in members of a
    population
  • unrelated species can react very differently to
    same toxin

28
Acute versus Chronic
  • Acute effects
  • Chronic effects
  • Usually difficult to detect
  • the specific health risks
  • because of other factors
  • Different toxicity levels for everything
  • Just because they are detectable doesn't mean
    you'll die

29
Risky Business
  • Risk The possibility of something undesirable
    will happen as a result of exposure to a hazard
  • Risk assessment The scientific process of
    estimating the threat hazards pose to health
  • Includes risk identification, dose response
    assessment, exposure appraisal risk
    characterization

30
Why We Do Stupid Things (part 1)
  • People downplay certain risks and emphasize
    others that suit their agenda
  • Tolerate risks that we choose and
  • object those we don't
  • Have difficulty understanding and
  • believing probabilities
  • Personal experiences can be misleading
  • Exaggerated view of our ability to control fate
  • Media gives a biased perspective of things
  • Irrational fear or mistrust of new technology

31
Why We Do Stupid Things (part 2)
  • Most people will tolerate a higher probability of
    an event if the harm caused by it is low
  • If we enjoy or find an activity profitable, we
    will ignore the risks
  • Perception of risks based on whether they are
    known or unknown, we are in control of the
    outcome or not, and how bad the results can be

32
Things That Keep You Alive
  • It is difficult to separate the effects of
    different hazards and evaluate their risks
    accurately
  • When setting standards for environmental toxins,
    consider
  • combined effect of exposure to many different
    areas of damage
  • different sensitivities of members of the
    population
  • effects of chronic and acute exposure
  • how does it affect our overall environment?
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