Eating PCBs from Lake Ontario:
A Clicker Case on Science and the Media
Eric Ribbens, Western Illinois University
1
Jill
Jill wiped away a tear as she sat down on the couch.
The home pregnancy kit she had just used clearly
indicated that she was not pregnant.
“Why?” she wondered. “I
just want a baby!”
Jill and Steve had been
trying to get pregnant for
over three years now
without success.
2
She turned on the radio…
The announcer’s voice boomed out:
“Do fish from Lake Ontario prevent pregnancy?
Study says yes! Women who eat fish from Lake
Ontario are more likely to have menstruation
problems, take longer to get pregnant, and may
have altered levels of estrogen. So, if you forgot
to take the pill... just eat some fish!”
3
The announcer moved on to another topic,
after cracking a joke about how fishermen
were going to disappear because they
couldn’t have babies.
Jill began to cry. It was those fish, it
had to be those fish. She was going
to dig through the freezer, throw all
the fish away, and break Steve’s
fishing rods!
She stormed into their bedroom
and collapsed on their bed,
sobbing.
4
Steve
Steve ambled into the
bedroom from the bathroom,
where he had been shaving, to
find Jill sobbing on the bed.
“What’s wrong, honey?” he
asked, cuddling her. In
between sobs, Jill told him
what the radio announcer
had said.
5
Another Perspective
“That doesn’t sound right”, Steve thought. He
grabbed his bedside copy of the Lake Ontario
Sport Fisherman magazine and flipped through
to a page summarizing
recent news related to
the Great Lakes. “Isn’t
this the same study?”
Steve thought? He read:
6
Another Study Proves
Lake Ontario Fish Are Safe To Eat
“Not only is it a great thrill to catch a big fish out of Lake
Ontario, but now scientists have also shown the fish really
are safe to eat. Some environmentalists have been worrying
that PCB contamination in
Lake Ontario might get into
the big finnies. Although
PCBs are some of the most
stable chemicals around,
some people worry that
they might affect
reproduction.”
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Lake Ontario Fish Safe
“Even though PCB levels in Lake Ontario have been
decreasing, some UB researchers tracked women who eat
fish from the lake. And the news is indeed reassuring.
Menstrual cycles were a mere 12 hours shorter, and the
amount of fish ingested had no significant effect on the
time it took to become pregnant.
So ladies, get your spatula out! These fish are fun to
catch... and good to eat!”
8
Steve read the article to Jill. After hearing it, Jill was
completely confused. Which story was right? She picked
up the phone and dialed her best friend’s number.
Laura was a nurse who worked for a pediatrician. They
had gone to school together, dated together, and now
they exercised together and dreamed of children
together.
“Laura!” Jill cried. “Did you hear that
maybe I can’t get pregnant because of
those fish Steve keeps catching!” Laura
firmly replied: “Calm down Jill, and tell
me the whole story. I read about that
study too, and it doesn’t sound that
bad to me!”
9
Three Versions
• Get together in small groups and quickly
decide (each version is on the handout):
What the radio broadcast says?
What the magazine article says?
What the news release says?
• Think in terms of the three people: Jill (trying
to get pregnant), Steve (Jill’s husband), Laura
(Jill’s friend).
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What Should Laura Do?
Imagine you are Laura. Jill is coming over, and
you need to explain this to her and help her
figure out what to do. What would you say? In
particular, does this study really show that Jill’s
problems with getting pregnant could be due to
the fish she eats?
11
CQ#1: What would you tell Jill?
A. PCBs in the fish she ate are preventing her
from getting pregnant.
B. It’s safe to eat fish out of Lake Ontario.
C. You can’t tell whether it’s safe or not.
D. It may be unsafe, but the news story is
vague.
12
In small groups
• What was the research question for the study
headed by Germaine Buck?
• What was the research question for the study
headed by Pauline Mendola?
13
CQ#2: Both of these studies were
interested in:
A. Women’s reproductive health.
B. Showing fish in Lake Ontario are dangerous
to eat.
C. How many PCBs are in Lake Ontario fish.
D. Why fishermen don’t have many children.
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Research Question
• Dr. Buck:
– Effects of PCBs on
the time it takes to
get pregnant.

• Dr. Mendola:
– Effects of PCBs on
menstrual cycles.
Both studies used the New York Angler Cohort.
15
In small groups
• What questions do you think they asked the
participants in the time-to-pregnancy study?
Describe the data collected by this study.
• What questions do you think they asked
participants in the menstrual cycle study?
16
CQ#3: One big problem with Dr.
Buck’s study is:
A. Expecting women to remember how long
they have eaten fish from Lake Ontario.
B. Expecting women to remember how long
they have been trying to get pregnant.
C. Assuming that if you are not on birth control
then you are trying to get pregnant.
D. They didn’t ask any questions of the men.
17
CQ#4: One big problem with Dr.
Mendola’s study is:
A. Women will think the questions were
intrusive and won’t answer honestly.
B. It didn’t randomly assign women to eat fish
vs. no fish.
C. The researchers didn’t ask how many fish
these women ate.
D. It’s unclear how precise women were
expected to be: Hours? Days? Weeks?
18
Dr. Buck’s Study
• 874 women trying to get pregnant.
• Telephone interviews:
– Trying to become pregnant? Did you?
– If so, how many cycles before becoming
pregnant? (If not, then what???)
• Fish consumption data:
– Do you eat Lake Ontario fish?
– How many years have you eaten Lake Ontario
fish?
19
Dr. Mendola’s Study
• 2,223 women,
• Survey data:
– Length of menstrual cycle,
– Regularity of menstrual cycle,
• Fish consumption data:
– Do you eat Lake Ontario fish?
– How many years?
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Look at the statistical significances
reported:
• Dr. Buck’s study: “Researchers found a small
conception delay for women who ate fish, but
the effect was not statistically significant.”
• Dr. Mendola’s study: Nothing reported (the
wording “results” implies statistical
significance?).
21
CQ#5: What does it mean when someone
says an effect is statistically insignificant?
A. There is a good chance the effect doesn’t
really exist, based on your data.
B. Your data is wrong, and you need to redo
your experiment.
C. Your hypothesis was written poorly. Go back
to the hypothesis and redesign the project.
22
CQ#6: What kind of study were these?
A. Comparative
B. Controlled
C. Can’t tell
23
Types of Experimental Designs
• Comparative
– Find a set of comparable
things already in
existence.
– Measure existing things.
Compare results to
predicted results from
hypothesis.
• Controlled
– Set up experiment. Don’t
let anything vary except
the parameter you are
studying
– Measure resulting
“things.” Compare
results to predicted
results from hypothesis.
24
Small group work
This was a comparative study, not a
controlled study. What are the advantages of
the controlled approach as compared to the
comparative approach? What are the
disadvantages?
25
In small groups
What did the researchers determine about
the relationship between PCB consumption
and the amount of time it takes to become
pregnant?
26
CQ#7: Women who ate fish…
A.
B.
C.
D.
E.
Are less likely to get pregnant.
Take longer to get pregnant.
Get pregnant more quickly.
Don’t seem to be affected.
Are more likely to have twins.
27
In small groups
What did the researchers determine about the
relationship between PCB consumption and
the menstrual cycle?
28
Menstrual Cycle Results
• 1.1 days shorter if eat fish >1x / month.
• 1.3 days shorter if eat lots of fish.
• 0.5 days shorter for both if regular menstrual
cycles.
29
CQ#8: Was the radio description valid?
A. Yes, the radio broadcast got the story right.
B. No, the radio broadcast got the story wrong.
C. We can’t tell.
30
CQ#9: Was the magazine description
valid?
A. Yes, the magazine got the story right.
B. No, the magazine got the story wrong.
C. We can’t tell.
31
CQ#10: Was the news release valid?
A. Yes, the news release got the story right.
B. No, the news release got the story wrong.
C. We can’t tell.
32
In small groups
The researchers didn’t find all that much, so
why did they do it? Isn’t it a colossal waste of
money to investigate something and not get
decent results?
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CQ#11: If you think the researchers didn’t
find all that much, why did they do it? Isn’t
it a colossal waste of money to investigate
something and not get decent results?
A. It is a big waste of time: NSF shouldn’t fund
research that doesn’t produce significant
results.
B. That’s how research goes: you don’t know
the results before you do them, and results
of no effect also tell us something about the
hypothesis.
34
In small groups
What should Jill do? What would you do
if you were Jill? (Yes, I know you guys
don’t plan to get pregnant …
so what would you want
your wife to do?)
35