Some Basic Principles of Toxicology
Toxicology Enrichment Materials
Teacher's Notes
This exercise
asks students to relate their own personal experiences to the principles
of toxicology. It also asks them to come up with several of their own
examples. Thus, this exercise is ideal for groups of 3 to 4 students.
There are no reference materials necessary, though the list of Toxicology
Terms might be helpful. Finally, there are no right or wrong answers!
(This should make grading easy!)
What follows is a list of possible student responses
to the questions and some discussion of those responses. These can be
used to lead a class discussion of answers.
Name
several poisons...
Students may think of air pollutants, cyanide, rat
poisons, pesticides (insecticides, herbicides, etc.), drugs (pharmaceutical
and drugs of abuse), household cleaning products and others.
Describe
the target and/or mechanism...
Students will probably not be able to answer this
question for most toxicants. However, if prompted, they may realize that
substances like bleach or other strong acids and bases are directly corrosive
to tissue. They may also know that some insecticides are toxic to the
nervous system or that chemotherapeutic agents kill cells (cancer cells
plus healthy cells) directly.
Name
a drug or chemical...
Bacteria-antibiotics (for bacterial infections)
Fungi-fungicides (for athlete's foot, or for agricultural purposes)
Plant-herbicides (weed killers)
Animals-rodenticides (rat poisons)
Restate
this famous quote...
Answers will vary.
How
could water be toxic?
Students should recognize that water is harmful in
a drowning situation. In other words, too much water exposed to the wrong
part of the body (lungs) is quite harmful.
Safe
substances harmful?
Answers will vary, but students should begin to understand
the importance of circumstances like "too much" and "in the wrong place."
Xenobiotics...
Answers will vary, but students should begin to realize
that they are exposed to many, many xenobiotics every day. Pollutants
in the air, additives in food, medications, cosmetics, etc., even food
itself. Plants contain many compounds that are foreign to mammalian metabolism.
Routes...
Inhalation-nasal passages, airways, lungs
Touch-skin
Ingestion-mouth, gut, liver
Injection-muscle, blood stream
Details of exposure...
Students should come up with several of the
following.
Site (where?)
Duration (how long?)
Frequency or rate (how often?)
Concentration and total volume (how much?)
Mixed with anything else?
Acute
vs. chronic significance...
Either answer is okay, but students should begin to
realize that though they hear more in the media about acute exposures,
chronic exposures may be equally or more harmful to populations. Acute
exposures like that described may kill off a large number of animals all
at once, but the survivors will be able to repopulate. Chronic exposure
may not kill as many animals, but may interfere with their reproduction.
It is more difficult for a population to recover from this type of problem.
Graphs...
 
Adverse responses...
Most students will not have experienced
any, and this should tell them something about the doses they received.
(Too low to observe adverse reactions.)
Ban
peanuts?
This is an extreme example. Students are not expected
to think peanuts should be banned, though it should get them thinking
about risk factors in public health and what is the responsibility of
the food producer vs. the food consumer.
Learned...
The goal is students begin to think of the effects
of various chemicals in one unifying theme of toxicology.
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