LULAC Ford PAS Science Corps
The Case of the Killer Cola:
What’s It Like to Be a Health Toxicologist?
LEADER GUIDE
LULAC Ford PAS Science Corps: The Case of the Killer Cola
Leader Guide
The Case of the Killer Cola: What’s It Like to
Be a Health Toxicologist?
Overview
In 2001, a young woman arrived at an Australian hospital suffering from weight loss,
muscle weakness, vomiting, and diarrhea. The doctors quickly assessed her condition
and found that her potassium level was acutely low and that she had both liver and
muscle damage. Their findings led them to believe that she had been exposed to a toxic
substance. When questioned about her diet, she reported that she consumed in excess
of 8 liters of cola (that’s almost 34 cans) per day! Armed with this information, the
doctors realized that the young woman was suffering from acute caffeine overdose.
They were able to rid her of her symptoms by rehydrating her and helping her withdraw
from the caffeine. In today’s session, participants observe the behavior of California
blackworms (Lumbriculus variegatus) in a control condition, and then note how their
behavior changes after exposure to several potential toxins, including caffeine. The
teams that make the most thorough and detailed observations will earn a Science Corps
Star.
Materials Needed
Before You Teach
For the whole group:
 Deep container (such as a tank) for
holding worms
 Narrow rubber bands
 Applicator sticks or coffee stirrers
 Scissors
 Electrical tape
 Containers for preparing,
measuring, and storing stock
solutions
 Bunsen burner or hot plate







Glass stirring rod
Distilled water
Pipette (that measures ml)
80-proof vodka (for ethanol)
Vivarin® (for caffeine)
Cigarettes of regular length and
strength (for nicotine)
Strainer or filter
InTOXICating!
For each participant:
 Copy of RM 1: Too Much Energy?
Watch Them Squirm
For each participant:
 Copy of RM 2: Toxicants and California Blackworms
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
For each team of participants:
 9 observation chambers (small,
clear containers, such as weighing
dishes or Petri dishes, that allow at
least a 1-cm depth for solutions)
 8 labels
 2 large beakers
 Distilled water
 20–25 California blackworms
For the whole group:
 Recovery container for
blackworms







Leader Guide
1 Serological pipette (10 ml) with a
pump
4 probes (see Before You Teach)
Filter paper
4 disposable plastic pipettes (with
tips cut off) or eyedroppers
2 plastic spoons
Stopwatch or other timer
A way or place to dispose of the
toxicants
Wrapping It Up
For each participant:
 Copy of RM 3: Family Letter
Before You Teach

Purchase California blackworms (Lumbriculus variegatus) at a local tropical fish
store or order them from Carolina Biological Company (800-334-5551). You can
order a culture of about 40–50 worms (catalog # 141720) or a culture kit that
includes 40–50 worms plus a tank and food for breeding more worms.

Determine which, if any, field trips or speakers you will arrange for this session
(see Possible Field Trips and Speakers on page 10).

Make copies of required RMs.

Make 4 probes for each team by cutting a 2½ cm piece of a narrow rubber band
and then taping it to the end of an applicator stick or coffee stirrer. Use electrical
tape to attach the rubber band to the stick. About half the rubber band should
hang from the end of the stick.

Practice transferring the worms from one container to another. Though directions
are provided, it’s best to try it yourself so you can become comfortable doing it
and demonstrating the procedure for the participants. Try using the different tools
so that you can decide on the best technique for participants to use when
transferring worms. Serological pipettes (10 ml) with pumps work well because of
their large capacity and ease in sucking up worms for transfer.

Solution preparation: Participants can prepare the solutions if you think they
can follow directions carefully and are proficient at measuring volume. It is ideal
to have a few participants make the stock and the toxicant solutions before the
session. However, if you plan on having participants make the solutions during
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
Leader Guide
the session, you should prepare the stock solutions ahead of time in order to
have enough time for the worm experiment. For each set of solutions, make the
stock solution first and then use it to make the toxicant solutions. Use ONLY
distilled water for the control and toxicant solutions.
o Ethanol: Do not use denatured ethanol, methanol, or isopropyl alcohol.
Vodka is recommended because it is clear and nearly odorless. To
prepare the stock solution of ethanol, measure out 100 ml of 80-proof
vodka (40% ethanol) and add enough distilled water to bring the solution
volume to 400 ml (10% ethanol). Use this stock solution to prepare the
following solutions:
Low: To 5 ml of stock solution, add enough distilled water to bring the
final solution volume to 200 ml (0.25% ethanol)
Medium: To 50 ml of stock solution, add enough distilled water to
bring the final solution volume to 200 ml (2.5% ethanol)
High: Measure out 200 ml of stock solution (10% ethanol)
o Caffeine: Use Vivarin rather than NoDoz® tablets, which contain mint
flavoring. To prepare the stock solution of caffeine, place two Vivarin
tablets (a total of 400 mg caffeine) in a flask and add distilled water to
bring the solution volume to 400 ml. Heat while frequently stirring to
dissolve the tablets. Gently break any tablets that don’t dissolve by
tapping them with a glass rod while the solution is being heated. Do not let
the solution boil. Use this stock solution to prepare the following solutions:
Low: To 16 ml of stock solution, add enough distilled water to bring the
final solution volume to 200 ml (8% caffeine)
Medium: To 66 ml of stock solution, add enough distilled water to
bring the final solution volume to 200 ml (33% caffeine)
High: Measure out 200 ml of stock solution (100% caffeine)
o Nicotine: Use any regular length and strength cigarette (not menthol,
100’s, or ultralights). To prepare the stock solution of nicotine, stir the
tobacco from two cigarettes (a total of 2.2 mg nicotine) into 500 ml of very
warm distilled water, and allow the mixture to stand for 15–20 minutes.
Strain or filter the solution. (You will lose about 50 ml of solution through
straining.) This process makes about 450 ml (0.011 mg/ml). Use this stock
solution to prepare the following solutions:
Low: To 10 ml of stock solution, add enough distilled water to bring the
final solution volume to 200 ml (0.06% nicotine)
Medium: To 50 ml of stock solution, add enough distilled water to
bring the final solution volume to 200 ml (0.3% nicotine)
High: Measure out 200 ml stock solution (1.1% nicotine)
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
Leader Guide
Activities/Procedures
InTOXICating! [Whole Group]
1. Have participants read Too Much Energy? (RM 1). Ask them the following
questions:
 How does caffeine affect the human body? Caffeine blocks adenosine and wards
off feelings of sleepiness. If used in excess, caffeine can cause diarrhea,
vomiting, delirium, convulsions, and a host of other issues.
 What other toxins or poisons do you know about? Answers will vary but may
include alcohol, nicotine, arsenic, cyanide, lead, and insecticides.
2. Explain to participants that in this session they will conduct a controlled experiment
that involves exposing California blackworms (a water worm) to three toxicants—
ethanol, nicotine, and caffeine. Ask participants what they know about these three
substances and their effects on humans.
Watch Them Squirm [Teams]
1. Distribute the activity sheet Toxicants and California Blackworms (RM 2) and
have participants carefully look it over.
2. Before participants start the procedure, go over the following guidelines:
 Use only the full-length
worms that are uniform in
After participants have exposed the worms to
color. Worms that are dark
the toxicants and started timing, they may
with lighter sections have
send one person at a time to observe, compare,
recently undergone
and contrast another team’s worms with their own
regeneration and should not
worms. Remind them that the other team may be
be used.
testing the same or a different toxicant.
 Use care in handling the
worms so as not to fragment them.
 To transfer worms from a deep container, use the Serological pipette with a
pump. When the worms are in a shallow container, use a disposable plastic
pipette or eyedropper for moving them by squeezing the bulb, tilting the pipette or
eyedropper to one side so that the opening faces one end of the worm, and
letting go of the bulb to draw up the worm.
 The worms should only be “probed” with the probes your leader gives you—
never use the tip of the pipette or eyedropper.
 Distinguish the anterior end of the worm from the posterior end. The anterior end
is blunter and more darkly pigmented and moves first.
 Worms will clump into a ball when they are disturbed. If the worms are in a
clump, it’s easy to move them from one container to another using a spoon. To
unclump them, participants should probe the worms or gently water them with the
pipette.
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
Leader Guide
What’s Going On?
In this activity, teams expose blackworms to solutions of toxicants (ethanol,
caffeine, and nicotine) at different concentrations. Teams then compare worm
activity in the control (plain distilled water) and the toxicant solutions in
order to determine the effects of the toxicants on the worms. “Normal”
behavior is described in the table below.
Observation Recording
Behavior
Clumping
Swimming
Crawling
Other
Description of “normal” behavior
The worms will entangle themselves around one another to form a
“tumbleweed”-like ball. They do this when they are stressed after
being moved from one container to another. After they have
calmed down (which may take a few hours or a whole day), they
will separate.
If the worm’s posterior end is touched by the probe, the worm will
swim forward in a corkscrew fashion, alternating clockwise and
counterclockwise. If the worm is probed on the anterior end, it will
coil and reverse its position. Both these movements are quite rapid,
and it may take some time to note the differences.
Whether probed on the anterior or posterior end, the worms will
move by peristaltic crawling (successive waves of muscle
contractions) in the opposite direction.
The worms generally like to crawl around on the bottom of the
container. When relaxed, they will stick their posteriors straight up.
In the ethanol solution, the worms will be less likely to clump and will
become quite inactive as the concentration increases. In the highest
concentration, they may straighten out their middles but curl their ends. Their
anterior area will be more affected. The worms may need to be probed
several times to stimulate a response. They will have less skill in swimming,
although they will still be able to crawl. They should begin to recover in 15
minutes after being removed from the low and medium solutions. However,
for the worms in the high solution, recovery might take two days or more.
In the caffeine solution, the worms will become very active as the
concentration increases, and will show a greater sensitivity to probing. At the
low concentration, they may try to clump. At the high concentration, they
may first curl in a ball and then stretch out. After being removed from the
low and medium concentrations, some recovery should be seen within around
15 minutes, and all worms should fully recover within 24 hours.
In the nicotine solution, the worms may twitch and curl their tails. In the high
concentration, paralysis will occur—the worms will stretch out and just float
in the water. After removal from the lower concentration, there should be
some recovery within 15 minutes, and all worms should recover within 24
hours of being removed from the toxicant solutions.
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
Leader Guide
Wrapping It Up [Whole Group]
1. Gather the group together and ask each team to share a summary of its
observations of the worms’ behavior when exposed to different levels of the toxicant.
Record teams’ observations on the board or a piece of paper, using a chart like the
one below:
Team #
Ethanol
Caffeine
Nicotine
High
Medium
Low
Control
2. Ask participants the following questions:
 Compare and contrast the behaviors of the worms at the highest concentrations
of the different toxicants. Are there differences in the worms’ behavior depending
on the kind of toxicant? In ethanol, the worms display little or no movement and
no response when probed. In caffeine, the worms are active initially but settle
down later, curling and stretching out. In nicotine, the worms at first show no
movement but then jerk and twitch in response to probing.
 How did the concentration of the toxicant solution affect the worms’ behavior? At
low concentrations, the worms behave virtually the same as the ones in the
control. There are noticeable differences in the behavior of the worms at the high
concentrations and fewer differences at the medium concentrations.
3. Ask teams the following:
 This was an “acute” test, meaning that the worms were only exposed to a
toxicant for a short period of time. But in real-life situations, worms and other
living things, including people, are exposed to small amounts of toxicants for long
periods of time. How might you design an experiment to test the effect of
“chronic” exposure, which means low doses over a long period of time? You
might begin by exposing the worms to the lowest concentration used in this
experiment, as well as exposing them to even lower concentrations. Since the
exposure needs to be chronic, the experiment would last over a much longer
period of time (months or even years). The exposure could be constant or
periodic. Periodic exposure—meaning that the worms are given some recovery
time between exposures—would be more representative of “real life” exposure.
 The investigation that you did was a controlled experiment. What was the
control? Why is a control necessary in a scientific experiment? The control was
the set of blackworms whose behavior was observed but to which no toxicant
was applied—the blackworms in only distilled water. A control is necessary to be
able to determine what is “normal” so we can compare and determine deviations
from normality.
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
Leader Guide
4. If time allows, you might go over the questions from the participants’ activity sheets.
 Did all of your worms (at each concentration) demonstrate the same behavior?
Assume that one worm demonstrated normal behavior and the other four
demonstrated abnormal behavior. How would you explain this? No, all of the
worms at each concentration did not demonstrate the same behavior. This can
be explained by variability, or differences, between the worms, such as
differences in genetics, age, health, or size.
 Can the results of your tests be applied to humans or other vertebrates? Why or
why not? Not directly. Effects can only be extrapolated from an experimental
system to another system if the two types of systems can be shown to be
sufficiently similar in relevant characteristics and behavior. Worms are far from
being similar to humans!
 Analyze your data, based on what you learned from your investigation and your
answers to the questions above. What conclusions can you draw from your
results? Answers will vary depending on the toxicant used.
5. The teams that make the most thorough and detailed observations will earn a
Science Corps Star.
6. At the end of the session, hand out copies of the Family Letter (RM 3) and tell
participants to share their experiences during this session with their families.
Background Information
Toxins
Toxins are chemicals that, when present at high enough levels, affect the health of an
organism. All chemicals have the potential to cause harm. It is the amount of the
chemical an organism comes into contact with that determines its toxicity. Even water
can be toxic when ingested in too great a quantity over a short time period.
“Exposure” refers to the first contact with the toxin. Once exposed, the route by which
the toxin enters the body and the pathway it then follows is an important consideration:
Did the person or organism breathe in the substance, swim in it, or drink it? Knowing the
route allows a toxicologist to determine what organs or tissues in the body will primarily
be affected. The system that the toxin harms is known as the “target.” This system can
be a cell, process, or organ. How the toxin harms the normal functioning of that system
is called its “mechanism of action.”
Exposure to Toxins
There are several key factors to consider regarding an organism’s exposure to a toxin.
The duration, or length, of the exposure is a major factor. “Acute exposure” means that
an organism is exposed to a toxin for a relatively short time. “Chronic exposure” means
that an organism is consistently exposed to a toxin for a relatively long time. Merely
visiting a house with a high level of radon (a natural radioactive gas that can cause lung
cancer) would mean acute exposure; actually living in it would mean chronic exposure.
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
Leader Guide
The amount of the toxin is another important factor. In general, the greater the dose of
the toxin, the greater the harm it causes. Some toxins cause no biological harm at low
doses and only cause harm at a certain point. Other toxins always cause great harm,
regardless of the size of the dose.
How the toxin enters the body can also determine its effect on the person or organism.
Inhaling is the fastest route into the body, ingesting is slower than inhaling, and
absorption through the skin is slower still.
Other relevant factors in terms of toxicity include the person’s age, general health, and
previous exposure, as well as other substances in the person’s body that could interact
with the toxin.
Toxins that remain in the body can become more concentrated as organisms move up
the food chain. This accumulation of toxins is called “bioaccumulation.” Bioaccumulation
begins with a small organism ingesting or absorbing a toxin; that organism is then one
of many eaten by a larger predator, which is then one of many eaten by yet another
predator, and so on. Bioaccumulation typically begins in a plant and then moves from a
plant eater to a meat eater. Eventually a higher organism—such as a bird—will eat
enough of the organism with the toxic buildup—such as bugs that have eaten plants
sprayed with a toxic pesticide—that the bioaccumulation can cause harm.
Testing for Toxins
All chemicals are toxic to some organism. Toxicologists use a risk assessment process
to determine how toxic a substance is to a given population—in other words, what is the
probability of one or more health problems if the population is exposed to a specific
amount of that toxin?
To determine whether a substance is toxic, researchers collect a variety of data. They
look at epidemiological and toxicological studies, which examine short-term and longterm exposure to the toxin. If the toxin is found to be harmful in some way, researchers
then try to pinpoint the range—at what level of exposure does the toxin begin to cause
harm? What level is acceptable? Researchers often conduct these tests on animals and
then extrapolate the reaction of the animals to how humans might respond.
What Does a Health Toxicologist Do?
Health toxicology is a broad area that generally focuses on toxins that can affect human
health. This area of study includes looking at the amount of a substance that can cause
harm, the effects of the substance, its pathway in the body, and the risk of certain
chemicals. Health toxicologists can specialize in multiple fields, including biology,
chemistry, and microbiology. Professionals in this field might work for companies that
want to ensure that their products are not toxic, government agencies that monitor
toxins, or research organizations that study the effects of and treatments for various
toxins. A career in health toxicology typically requires a minimum of a bachelor’s
degree. The majority of professionals in the field typically hold a more advanced degree,
with education that can continue into a post-doctoral degree.
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
Leader Guide
Possible Field Trips and Speakers
The following are suggestions for field trips and speakers related to this session.
Possible questions for participants to pose are included for each field trip and speaker.
You should also guide participants in creating their own questions.
1. Visit a poison control center (go to http://www.aapcc.org/findyour.htm to find the
nearest center). Possible questions:
 What are some common household poisons?
 What are the signs of a person being poisoned? What’s the first thing one should
do to help that person?
 What kinds of jobs or careers are there in the field of toxicology?
2. A doctor, nurse, or medical student in the area may be a speaker. Ask the person to
focus the discussion on the effects of caffeine, alcohol, and nicotine on the human
body. Possible questions:
 How does one determine what “moderate consumption” of each of these
substances is?
 How are these substances similar to and different from one another?
 How can these substances become addictive?
3. A forensic medical examiner in the area may be a speaker. Contact a local police
station to find out if it has a forensic lab that includes examining for toxins. Possible
questions:
 What’s an example of a case that could involve poisons or toxins?
 How do you examine a body or crime scene for poisons and toxins?
 What kind of education or training did you receive to enter this profession? What
advice would you give to a young person who’s interested in this profession?
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
Leader Guide
References
InTOXICating!
RM 1: Too Much Energy?
ABC News Radio. (August 6, 2001). Caffeine toxicity. Health Minutes by Norman Swan.
Retrieved April 13, 2006, from
http://www.abc.net.au/health/minutes/stories/s341707.htm.
ABC Radio National. (August 6, 2001). Cola consumption & energy drinks. The Health
Report. Retrieved April 13, 2006, from
http://www.abc.net.au/rn/talks/8.30/helthrpt/stories/s342149.htm.
Canadian Institutes of Health Research. (n.d.). How drugs affect neurotransmitters. The
Brain from Top to Bottom. Retrieved April 13, 2006, from
http://www.thebrain.mcgill.ca/flash/i/i_03/i_03_m/i_03_m_par/i_03_m_par_cafeine.ht
ml.
Erowid. (February 8, 2000). Caffeine effects. The Vaults of Erowid. Retrieved April 13, 2006,
from http://www.erowid.org/chemicals/caffeine/caffeine_effects.shtml.
Neuroscience for Kids. (n.d.). Caffeine. Retrieved April 13, 2006, from
http://staff.washington.edu/chudler/caff.html.
Watch Them Squirm
Drewes, C. (September, 2004). Lumbriculus variegatus: A biology profile. Retrieved April 19,
2006, from http://www.eeob.iastate.edu/faculty/DrewesC/htdocs/Lvgen4.htm.
RM 2: Toxicants and California Blackworms
Drewes, C. (September, 2004). Lumbriculus variegatus: A biology profile. Retrieved April 19,
2006, from http://www.eeob.iastate.edu/faculty/DrewesC/htdocs/Lvgen4.htm.
Southwest Environmental Health Sciences Center. (1996–2004). California blackworms
curriculum. Retrieved March 24, 2006, from
http://coep.pharmacy.arizona.edu/curriculum/blackworms/pdf/nic_bwrm.pdf.
Wrapping It Up
Southwest Environmental Health Sciences Center. (2001). Toxicity testing with California
blackworms: Nicotine. Retrieved March 24, 2006, from
http://coep.pharmacy.arizona.edu/curriculum/blackworms/pdf/nic_bwrm.pdf.
Background Information
Toxins
Agency for Toxic Substances and Disease Registry. (November 17, 2005). A toxicology
curriculum for communities trainer’s manual. Retrieved December 6, 2005, from
http://www.atsdr.cdc.gov/training/toxmanual/modules/3/lecturenotes.html.
Conklin, S. (2000). Some basic principles of toxicology. Retrieved December 6, 2005, from
http://www.toxicology.org/AI/FA/toxenrich_basic.pdf.
Environmental Protection Agency. (n.d.). Water quality: Tick tock toxins. Retrieved
December 6, 2005, from
http://www.epa.gov/ORD/NRMRL/Pubs/625R02009/pdf36.pdf.
©Ford Motor Company Fund, 2005. Do not copy without permission.
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
Leader Guide
Norton, A. (December, 2005). Even low levels of common toxins may be a danger.
Retrieved December 6, 2005, from
http://www.planetark.com/dailynewsstory.cfm/newsid/33159/story.htm.
What Does a Health Toxicologist Do?
Biological Research for Animals and People. (2001). Career rap: Toxicologist. Retrieved
December 6, 2005, from http://www.biorap.org/br7toxic.html.
Society of Toxicology. (2005–2006). Resource guide to careers in toxicology. Retrieved
December 6, 2005, from http://www.toxicology.org/AI/APT/careerguide.asp.
Pictures and Images
All pictures and images in this session were taken from Microsoft Office Clip Art
(http://office.microsoft.com/clipart/default.aspx?lc=en-us).
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
RM 1
Too Much Energy?
In 2001, a young woman came to the Royal Adelaide
Hospital in Australia complaining of muscle weakness,
diarrhea, weight loss, and nausea. Doctors initially
thought that she might be suffering from a condition
called muscular dystrophy—an auto-immune disease
that causes muscle inflammation—or the aftermath of a
viral infection. Doctors examining her found that while
she was able to get into a squatting position, she could
not return to a standing position without help. They
ordered blood tests and found that her body’s potassium
level was dangerously low (probably because of the
prolonged diarrhea). Tests showed that she had also
sustained liver and muscle damage. After ruling out the
muscle diseases they had initially thought were the cause, doctors’ suspicions turned to
environmental toxins, such as heavy metals. To determine what she might have been
exposed to, doctors asked the young woman about her daily routine. When she
revealed that she consumed 8 liters of cola (that’s about 34 cans) a day, her doctors
were amazed.
Doctors rushed to determine the caffeine content in the cola. They found
that the amount of caffeine the woman regularly ingested was toxic and had
led to all of her symptoms. Because of her low potassium levels, she was in
great danger of having a fatal heart arrhythmia (a condition in which the
heart beats incorrectly, often leading to death). The woman was hospitalized
and given fluids and potassium replacement. She eventually recovered and
was discharged from the hospital.
Caffeine is a drug that causes central nervous system stimulation. Caffeine “works” by
binding to receptors of adenosine (a natural chemical that slows down neural activity
and causes sleepiness) in the brain and preventing adenosine from binding. With
caffeine present, nervous system activity increases. Caffeine overdose can lead to
feelings of anxiety, restlessness, sleep disturbances, delirium, diarrhea, vomiting, and
convulsions. Caffeine can also cause lethal heart arrhythmia.
Caffeine is a toxicant that can be misused and lead to health problems or death. Other
commonly used toxicants include ethanol (alcohol) and nicotine, both of which can also
lead to severe health problems and even death.
Challenge: In today’s session, you will investigate the effect of three toxicants—ethanol
(alcohol), caffeine, and nicotine—on the California blackworm, a small worm that lives in
ponds. Using your existing knowledge about these three toxicants, how do you think
each will affect the worms’ swimming and crawling behavior? The teams that make the
most thorough and detailed observations will earn a Science Corps Star.
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
RM 2
Toxicants and Blackworms
What happens to California blackworms when they are exposed to toxicants, such as
alcohol, caffeine, and nicotine? How do they react?
Materials
 9 observation chambers
 8 labels
 2 large beakers
 Distilled water
 20–25 California blackworms
 At least 1 Serological pipette (10 ml)
with a pump






4 probes
Filter paper
4 disposable plastic pipettes (with
tips cut off) or eyedroppers
2 plastic spoons
Toxicant solutions
Stopwatch or other timer
Procedure
1. Circle the toxicant your team has been assigned to test:
ethanol
caffeine
nicotine
2. Label 8 observation chambers as follows: Control, Low, Medium, High, WaterControl,
Water1, Water2, Water3.
Distilled
3. Arrange your dishes as shown at right.
Water
Toxicant
4. Using a beaker of distilled water, fill the Control,
WaterControl, Water1, Water2, and Water3 dishes with
Water3
High
distilled water.
Water2
Medium
5. Use the Serological pipette or spoon to place 20–25
Water1
Low
worms in another beaker containing distilled water.
6. Use the Serological pipette to place approximately 5–6
WaterControl
Control
worms apiece in the dishes labeled WaterControl, Water1,
Water2, and Water3.
Worm Moving Tips
7. Observe the worms, and write a description of
their “normal” behaviors in the Observation
 Let the worms clump, then scoop up
Recording Chart below.
as many worms as possible with a
spoon or pipette. Try not to transfer
 In the “Clumping” row, note whether the
any liquid into the new container (you
worms tend to clump together in a ball.
don’t want to dilute the toxicant).
 To explore “Swimming” behavior, use
 A Serological pipette with a pump is
probes to touch the anterior end (which is
ideal for transferring worms from a
deep container into a shallow one. To
blunter and more darkly pigmented) of
use a pipette, squeeze the bulb, tilt
each worm and observe its movement.
the pipette so that the opening faces
Then touch the posterior end and again
one end of the worm, and let go of
observe the movement. Note whether all
the bulb.
the worms exhibit the same behavior or if
there are differences in their behavior.
 To examine “Crawling” behavior, first put a piece of moistened filter paper in a
clean observation chamber, then use a pipette or eyedropper to transfer one or
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
RM 2
two worms to the chamber. Remove all excess water. Probe each worm first on
its anterior end and then on its posterior end.
8. In the “Other” row, note any other “normal” behaviors you observe.
Observation Recording Chart
Behavior
Description of “Normal” Behavior
Clumping
Swimming
Crawling
Other
9. How do you think each of the three toxicants will affect the worms’ behavior? Record
your hypotheses in the table below.
Toxicant
Hypothesized Behavior
Ethanol
(alcohol)
Caffeine
Nicotine
10. Add your assigned toxicant solutions to the corresponding dishes to a depth of 1 cm.
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
RM 2
11. Familiarize yourself with the activity level ratings in the table below. Note that a
rating of 0 means “No Activity,” a 5 means “Normal” behavior, and a 10 means “Very
Active.” Your task is to determine a swimming activity rating at each time interval
that the worms are exposed to the toxicant. Any additional observations (clumping,
curling, straightening, etc.) should be recorded in the Worm Data Table on page 4.
Activity Rating Scale:
No Activity
0
Swimming
Behavior
Activity
Rating
(circle a
number)
Control
Normal
3
Very Active
5
Low
7
10
Medium
High
0 min.
0 min.
0 min.
0 min.
0 3 5 7 10
0 3 5 7 10
0 3 5 7 10
0 3 5 7 10
3 min.
3 min.
3 min.
3 min.
0 3 5 7 10
0 3 5 7 10
0 3 5 7 10
0 3 5 7 10
6 min.
6 min.
6 min.
6 min.
0 3 5 7 10
0 3 5 7 10
0 3 5 7 10
0 3 5 7 10
10 min.
10 min.
10 min.
10 min.
0 3 5 7 10
0 3 5 7 10
0 3 5 7 10
0 3 5 7 10
12. Decide who in your group will be responsible for the following tasks (some of you will
have more than one task):

Timer (1 person): Keep track of the time intervals—0, 3, 6, and 10 minutes.

Worm Movers (up to 4 people): Move the worms to and from their containers
(that is, from WaterControl to Control, Water1 to Low, Water2 to Medium, and
Water3 to High).

Data Collector (1 person): Record the Observers’ reports in the Worm Data
Table.

Observers (4 people, 1 for each dish): Observe the behavior of the worms
once they’ve been moved from the distilled water dishes to the toxicant and
control dishes, and report the activity rating, clumping behavior, and any other
observations to the Data Collector.
13. Transfer the worms (as close to the same time as possible), and start the clock
immediately.
14. Observe and record the worms’ behavior at 0, 3, 6, and 10 minutes. In between
observations, you can send one person to observe other teams’ worms. For
instance, if you visit another team who’s using the same toxicant, do its worms
behave similarly to your team’s worms? If you visit a team who’s using a different
toxicant, do its worms behave differently from your team’s worms?
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
RM 2
Worm Data Table
Toxicant:
Observed Behavior During Recovery
Observed Behavior During Exposure
Control
0 min.
0 min.
3 min.
3 min.
6 min.
6 min.
10 min.
10 min.
High
0 min.
0 min.
Conc*:
3 min.
3 min.
6 min.
6 min.
10 min.
10 min.
Medium
0 min.
0 min.
Conc:
3 min.
3 min.
6 min.
6 min.
10 min.
10 min.
Low
0 min.
0 min.
Conc:
3 min.
3 min.
6 min.
6 min.
10 min.
10 min.
*
Conc stands for Concentration; you’ll fill this in later.
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
RM 2
15. After the exposure time has ended, transfer your worms back to the dishes labeled
WaterControl, Water1, Water2, and Water3. Try not to transfer any toxicant solution with
the worms. Note their behavior at 0 minutes.
16. Observe the worms again at 3, 6, and 10 minutes, and record any observations.
17. Your leader will tell you how to dispose of the toxicants.
Data Summary
Color in the squares up to the activity level for each indicated time.
Swimming Activity Levels for Toxicant
Activity Level
10
7
5
3
0
0
3
6
10
Control
0
3
6
10
0
Low
3
6
10
0
Medium
3
6
10
High
Complete your Worm Data Table with the following information on toxicant
concentrations, and then answer the questions below.
Toxicant Concentrations
Ethanol
Caffeine
Nicotine
Low
0.25%
0.08 mg/ml
0.00055 mg/ml
Medium
2.5%
0.33 mg/ml
0.00275 mg/ml
High
10%
1.0 mg/ml
0.011 mg/ml
1. Did all of your worms (at each concentration) demonstrate the same behavior?
Assume that one worm demonstrated normal behavior and the other four
demonstrated abnormal behavior. How would you explain this?
2. Can the results of your tests be applied to humans or other vertebrates? Why or why
not?
3. Analyze your data, based on what you have learned from your investigation and
your answers to the questions above. What conclusions can you draw from your
results?
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LULAC Ford PAS Science Corps: The Case of the Killer Cola
RM 3
Family Letter
Dear Family of __________________________________,
This week, the Science Corps “How We Work” unit, The Case of the Killer Cola,
focused on the story of a young woman who overdosed on caffeine. Your child took on
the role of a health toxicologist and investigated the effect of such toxicants as alcohol,
caffeine, and nicotine on California blackworms.
There are several activities you might do with your child to help your child continue to
explore health and toxicology, for example:

Search the Internet for information on caffeine, nicotine, and alcohol and their health
effects (or borrow a book on these topics from the library) to learn more about how
toxic agents affect the body.

Grow two identical plants. Water one of the plants normally. For the other, add a
small amount of a toxic chemical (perhaps something from your cleaning cabinet—
make sure that you carefully dispose of the toxin-filled water!). Over the next few
days and weeks, observe what happens to the plant that has been given the toxin.

Read books or search the Internet to find information about the toxins contained in
everyday household items (such as electronic equipment). What happens to these
toxins if they are not disposed of properly?
Thank you, and please feel free to contact me with any questions!
_______________________________________
Science Corps Leader
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