toxicology

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Author:
kamato
ID:
177728
Filename:
toxicology
Updated:
2012-10-15 16:56:33
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environ
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Description:
environmental toxicology
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  1. Paracelsus
    • all substances are poison, the right dose ..
    • -contributer to dose response relationship
    • -founder of modern toxicology
    • -notion of target organ
  2. toxicology is the study of
    • adverse effects of chemicals on living organisms
    • -study of how xenobiotics (chemical compounds) affect biological systems
  3. toxicologist
    investigates the adverse effects of chemicals including their celluar, biochemical, and molecular mechanisms of action and asesses the probablity of their occurance.
  4. Classification levels of environmental hazards to health (5)
    • 1. human body
    • 2. genes-control organ develp and function
    • 3. germ cells-involve reproduction
    • 4. somatic cells-all other parts of the body
    • 5. cells may grow in an organ in uncontrollable ways.
  5. Cancer
    2 main agents induce cancer

    • 1. viral infection (onocogenic viruses Hep C and HPV)
    • 2. environmental agents (certain chemicals)
  6. Toxic Chemicals
    # chemical in common use world-wide
    ___ to ___ chemicals/year
    exposures: (3)
    esistence: (4)
    -related to #2 cause of death-cancer (environmental exposures)
    • 80, 0000 chemicala in common use world-wide
    • 200___ to 2000 new chemicals/year
    • exposures: (3) at home wor,k environment
    • esistence: (4) in the food, air, soil, water
    • related to #2 cause of death-cancer (environmental exposures)
  7. Classification of toxic chemicals is based on 
    (5)
    • 1. molecular structure
    • 2. physical characteristics
    • 3. sources
    • 4. end uses
    • 5. toxic properties
  8. 2 types of classification
    type I--
    type II--
    • type I- (a-e) based on combo of physical and chemical prop, toxic effects and use (toxic chemicals, fibers and dust) 
    • type II- (a-g) mechanisms of toxicity(carcinogens, neurotoxins, mutagens, allergens)
  9. cancer
    unregulated growth of cells
  10. tumor
    a clump of cancer cells
  11. mutation
    an alteration in the DNA of the germ cells.
  12. mutagen
    a substance that causes a mutation
  13. carcinogens
    the agents believed to cause cancer
  14. poison
    any agent capable of producing a deleterious response in a biological system
  15. toxic substance
    any substance whose physiological action is harmful to health
  16. synergism
    the combined effect of the two chemical is greater than the sum of the...
  17. toxin
    refers to a toxic substance made by living orgaisms including reptiles, insects, plants and microorganisms
  18. toxicity
    the degree to which something is posionous-related to physical and chemical properties.
  19. examples of toxins
    (5)
    • 1.bacteria-botulinum
    • 2. fungi-myco
    • 3. algae-phyco
    • 4. plants- phyto
    • 5. animals-zoo toxins
  20. toxicants
    toxic substances that are man-made
  21. Adverse health impacts of toxic exposure
    (3) 
    1. no exposure...
    2. key factors: 
    3. not all... 
    • 1. unless exposed to toxic substances no toxic effect on human health
    • 2. Key factors: manifestation and magnitude
    • 3. not all exposure will lead to a toxic manifestation
  22. fields within toxicology
    • 1. regulatory
    • 2. forensic
    • 3. clinical
    • 4. environmental
    • 5. reproductive
    • 6. developmental
  23. environmental toxicology
    • examines how environmental exposures to chemical pollutants may present risks to biological organisms, particularly animals, birds, and fish 
    • -production, fate and effect of the natural and synthetic pollutants in the environment
  24. sources of harzdous chemicals
    • manufactured
    • natural
    • unintentionally produced
  25. hazardous chemical in nature
    • poisonous materials
    • toxic plants
    • volcanoes
    • animal sting/bite
  26. manufactured intentionally
    • essential for a specific application
    • large category
  27. produced unintentionally
    • 1. unwanted material-byproducts
    • 2. generated in many industrial processes
    • 3. impurity in starting materials 
    • 4. side reaction of complex chemical pathways
  28. factors affecting the toxicity of toxic substances
    • route of entry
    • dose
    • duration
    • susceptibility
    • possible synergistic effects
  29. routes of exposure (4)
    • gastrointensina tract
    • respitotory system
    • contact with surface skin
    • injection into blood stream (blood transplant)
  30. point of entry effects and systemic distribution
    • 1.absorb-skin-irritation-into circulatory system, 
    • 2. ingestion-mouth and stomach-irriation-circulatory system via biliary-hepatic system distribution
    • 3. inhalation-lungs-irritation, particulate, entrapment-alveolar space-through capillaries, circulatory system
  31. ways of describing a dose
    (7)
    e
    a
    a
    t
    e
    i
    b
    • 1. exposure dose-amt encountered in envir
    • 2. absorbed-(avail internal organs)
    • 3. administered
    • 4. total-adding individ dose
    • 5. external-aquired by contact-
    • 6. internal-portion that is internalized
    • 7. biologically effective
  32. lethal dose LD50
    • the doase mg/kg of body weight causing death in 50% of animals
    • -used to compare chemicals
  33. dose-response relationship
    correlative relationship bw the charactertistics of exposure to chemicals and the spectrum of effects caused by the chemical
  34. duration of exposure terms
    • acute-o-24hrs
    • subacute-less than one month
    • subchronic-1-3 month
    • chronic-3 plus
  35. direct adverse effects of exposure to chemicals
    • 1. local effects-damage at the site where a chemicals first comes into contact with the body (cell replacement)
    • 2. systemic effects-generalized distribution of the chemical throughout the body by the bloodstream to internal organs (damage to enzyme system)
    • 3. target organ effects-some chemical may confine their effects to specific organs (DNA damage)
  36. latency
    time period bw initial exposure and measureable response
  37. effects of chemical mixtures
    (4 types of effects) 
    • additive
    • synergism
    • potentiation (2 chemical bring it out)
    • antagonism
  38. biological tests for toxicity: 
    test subjects (3 types) 
    • subjects used for testing
    • 1. volunteers
    • 2. animals exposed purposively (in vitro)
    • 3. cells derived from human, animal or plant sources.
  39. testing for toxicity
    (6) 
    • 1.often difficult to determine
    • 2. use eipdemiology
    • 3. immunobiological test
    • 4. lab test with animal model, cell culcture
    • 5. ames test
    • 6. ecological risk assessment
  40. Enzyme Linked Immunosorbant Assay ELISA
    -ids the presence of absense of toxins in the environment
  41. ames test
    • -1970
    • mutagen test-if it can grow in the environment it may be a mutagent
  42. ecological risk assessment
    it is:
    process (3) 
    • qualitative/quantitative appraissal for actual or potential effect of a contaminant chemical on wildlife
    • 1. problem formulation
    • 2. analyis
    • 3. risk characterization
  43. risk assessment is...
    qualitative or quantitative estimation of the likelihood of adverse effects that may resuls from exposure to specified health hazards or from the absence of beneficial influence.
  44. Process of Risk Assessment
    • 1. hazard id
    • 2. dose-response relationship
    • 3. exposure assessment-id populations exposed, examines roots, magntitude and frequency)
    • 4. risk characterization -estimates number of excess unwarranted health events expected at diff time intervals at each level of exposure
  45. Risk management
    action orientted to control toxic chemicals
    (5 strategies)
     
    • 1. exposure standards
    • 2. requirements for pre-market testing
    • 3. recalls of toxic products
    • 4. banning hazardous materials
    • 5. develop, eval, and implementation of regulatory options, aimed at risk reduction.
  46. disposal of toxic chemicals
    • 1. incineration
    • 2. dumping
    • 3. land filling
    • 4. land application
    • 5. deep-well injection

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