Assessing Toxic Risk
Student worksheet
Your name:
1
Your group members’ names:
Chapter 1: The dose makes the poison
1. Can any chemical be toxic? If not, why? If so, when?
2. Are natural chemicals safer than synthetic (man-made) chemicals? Why or why not?
3. How do we know whether a chemical is toxic?
4. Vitamin D has a lower LD50 than acetylsalicylic acid (the active ingredient in aspirin).
Which chemical is more toxic? Why?
5. What is chronic toxicity? How does it differ from acute toxicity?
6. Opinion question: Is animal testing necessary? Justify your answer.
Toxicity calculations (from p. 13 in your book; show your work here):
1. Your weight in kilograms=
2. The average lethal dose of caffeine for a human your size=
3. How many cups of coffee would it take to kill an average person of your size?
A. If you drank one cup of coffee per day for that number of days, would you probably die
from an overdose of caffeine? Why or why not?
B. If you could drink exactly that number of cups of coffee in one sitting, would you be
guaranteed to die? Why or why not?
C. What is the most important assumption that we make when we use LD50s to estimate
lethal doses for humans?
Assessing Toxic Risk
Student worksheet
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Chapter 2: From data to standards
1. Which is used to set safe drinking water standards: acute toxicity or chronic toxicity?
Why?
2. Are all groups of people equally sensitive to contaminants? Give an example of a factor
that might increase a person’s sensitivity.
3. How much uncertainty is involved in setting drinking water standards?
a. List some sources of uncertainty.
b. Would it be possible to collect enough scientific data to eliminate this
uncertainty? Why or why not?
Chapter 3: What’s the risk?
1. What two pieces of information are necessary for assessing chemical risk? Why are these
two things important?
Chapter 4: Ecological risks
1. What type of organism is more likely to suffer from exposure to chemicals: herbivores or
top carnivores? Why?
2. What is degradation? Do all chemicals experience degradation at the same rate? List
some ways a chemical could be degraded in the environment.
Chapter 5: Using bioassays for environmental research
1. Compare and contrast the procedures for finding out whether a chemical is safe for the
environment vs. the procedures for finding out whether it is safe for human consumption.
2. What is the difference between LD50 and TC50?
Assessing Toxic Risk
Student worksheet
Vocabulary
toxicity
dose
exposure
response
bioassay
dose/response bioassay
LD50
TC50
acute effects
chronic effects
uncertainty factor
chemical risk (give equation)
degradation
bioaccumulation
biomagnifications
treatment
control
independent variable
dependent variable
replicates
3
Assessing Toxic Risk
Student worksheet
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Take notes to prepare for your poster. Your poster should include:
1. Title. Try to make it catchy, but not too catchy (must contain some information about
what you are testing).
2. Introduction
a. What do you already know about your chemical? Do some research on the uses
and toxicity of your chemical.
b. What organism are you using? Give some very basic information on why you are
using it.
3. Hypothesis. Will your chemical be toxic to your organism? At what dose?
4. Procedure. Describe exactly what you did. Take lots of notes on this!
Assessing Toxic Risk
Student worksheet
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5. Graphs. Using the graphs in your worksheets as an example, plot your results. Make
sure the axes are labeled so that anyone walking up to the poster would be able to
understand what your results are, without reading anything!
6. Results. What do your graphs say?
7. Conclusions about hypothesis. If your results allow you to, talk about the toxicity of this
chemical to your organism.
8. Discussion
a. Were you able to answer your hypothesis? Or did your methods not allow you to
really test it?
b. If you did this study again, what would you do differently? What would you keep
the same?
c. What does this experiment tell you about the environmental impact of using this
chemical? Refer to information (if you can find it) about how prevalent use of the
chemical is, and how abundant it is in the environment.
d. What new questions did this experiment make you wonder about? Would you
like to make any new comparisons, test new concentrations, or look at other
organisms?
e. Make any other comments about the implications of your study.