|Lecture Notes:: 19 January
© R. Paselk 2008
- Chem 451 is part of a three course group designed to provide
an introduction to toxicology for students in chemistry and the
natural resources and life sciences. Chem 451, Biochemical Toxicology,
looks at what happens to toxins inside organisms, how toxins
get into organisms and how they are eliminated. Chem 450, Chemical
Concepts in Toxicant Behavior, looks at how toxins move through
the environment, and how they are modified in the environment;
finally, Chem 433, Chromatography, is a laboratory course focused
on the most important techniques for the isolation and analysis
of organic compounds.
- Chem 451 and Chem 450 are both seminar courses. In each the
instructor lectures for the first 10 weeks or so to provide a
basic background in the subject area. The last five weeks or
so consists then of student presentations. For Biochemical Toxicology
the seminars will focus on what happens to a toxin or toxin family
inside organisms. It is not acceptable to report on toxins
in the environment in this course, save that for Chem 450. Seminars
should "bring us up-to-date." That is they should focus
on a topic of current interest with a current literature. I expect
to see references published within the past few months, as well
as earlier literature as appropriate.
- Because of our intimate class size this semester I have some extra time slots and what I am contemplating is discussing topics of current interest. With this in mind if you have nothing you see that excites you in terms of toxicology email me or suggest it in other ways and perhaps we'll give it a shot. Examples might include:
- Local groups were very upset about the emissions from the pulp mill - are these emissions worrisome?
- Dow-Corning lost a law suit and paid out billions of dollars for damage caused by silicon breast implants why is this now widely seen as a miscarriage of justice?
- Should veterans who served in Viet Nam be compensated for injuries they credit to "agent orange"?
- Is organic food less toxic?
- Many other topics could be listed.
- Grading will be based on a midterm exam, a final exam and
your seminar. The questions will be provided in advance for both
exams. Past questions are currently posted on our web site as
examples. You can assume that most of these questions will remain
unchanged, but I may add questions or modify them slightly. The
questions will become "finalized" at least one week
before each exam. The exam will then consist of a selection from
the questions (i.e. 3 or 4 for the midterm). I expect that you
will have researched out and outlined the questions in advance.
I recommend you attempt a "practice exam" to make sure
you have sufficient time to write your essays (12-15 minutes
What is toxicology?
- It has been defined as "The science that defines the
limits of safety of chemical agents." Thus we are concerned
with the quantitative affects of chemicals. Note that all
chemicals are toxic in extreme concentration. For example, we
require oxygen within a range of concentration - too little and
we suffocate, too much and we are poisoned. We also must be concerned
with acute (brief and severe) versus chronic (long term) affects.
For example, lead and mercury tend to be stored in the body,
so low level concentrations in the environment will have no immediate
effect, but long term can be extremely damaging.
- Toxicology is also referred to as the science of poisons.
It is often considered as a subset of Pharmacology (the science
of drugs), and is most often taught in the US in pharmacology
departments. (Actually, we might consider Pharmacology a subset
of Toxicology since all drugs are also poisons!)
- Toxicology is obviously of great interest in that it deals
with the many hazardous substances in the environment, both natural
and "un-natural." As such there is also a lot of public
interest and politics involved with the study and dissemination
of toxicological information.
Biochemical Toxicology focuses
on the way in which chemicals and organisms interact, including
- Uptake: how do chemicals enter an organism;
- Distribution: where do chemicals go in the organism's
body after uptake (for example non-polar organic molecules tend
to deposit in fat and reside there for some time);
- Variations in response: there are frequently tremendous
differences in the toxicity of a given compound in different
species of organisms (dioxin is extremely toxic to female guinea
pigs, much less so for many other organisms), and we also can
see large variations of response between individuals of a single
- Kinetics: describes how the concentrations of a chemical
change vs. time within an organism and thus when and for how
long a given exposure may result in a toxic dose;
- Metabolism: describes how organisms modify chemicals.
Generally toxins are detoxified and modified to increase their
solubility and elimination, but this is not an intelligent
system, so sometimes non-toxic substances become toxic!
- Types of responses: does a toxin inhibit an enzyme,
cause genetic damage, bind to a receptor, alter a membranes integrity,
cause cancer, etc.
Last modified 1 January 2010
© RA Paselk 2008