Does Fluoride Affect the Survival Rate of Daphnia?

Researched by Jillian H.
2000-01

 

PURPOSE

The reason for my experiment was to determine if the amount of fluoride affects the survival rate of Daphnia.

I became interested in this idea when the CNN news said, "There is too much fluoride in our water, which might cause medical problems."  So, I decided to test it.

The information gained from this experiment will help people realize how much fluoride to use for human health reasons.

HYPOTHESIS

My hypothesis is that 0.01% of fluoride will kill the Daphnia. 

I base my hypothesis on The World Book Encyclopedia 1998, which stated, "The level most commonly used in fluoridated water is 1ppm."  One ppm is the same as 0.0001%.

EXPERIMENT DESIGN

The constants in this study were: 

  • the type of Daphnia
  • amount of water 
  • temperature of the water
  • amount of Daphnia tested on in a group
  • place where the Daphnia were being tested 
  • amount of light 
The manipulated variable was the amount of fluoride. 
 

The responding variable was the number of Daphnia that died in a certain amount of time. 
 

To measure the responding variable I used a microscope to determine if the Daphnia were alive, based on a visible heartbeat. 

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MATERIALS
 
QUANTITY ITEM DESCRIPTION
1.111% Fluoride
400 mL Water
200 Daphnia
1  Microscope
5 Petri Dish

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PROCEDURES
 

1. Gather materials.
2. Have 5 groups of Daphnia with 20 in each group. 
3. Put each Daphnia group in their own petri dish.
4. Put 40 mL of water in the petri dishes.
5. Put 1% amount of fluoride in the A group
6. Check the Daphnia under the microscope right away, then every15 minutes until 1 hour to see if the heart is still beating. 
7. Put .1 % of fluoride in the B group.
8. Check the Daphnia under the microscope right away, then every 15 minutes until 1 hour to see if the heart is still beating.
9. Put .01 % of fluoride in the C group.
10. Check the Daphnia under the microscope right away, then every 15 minutes until 1 hour to see if the heart is still beating.
11. Put .001% of fluoride in the D group
12. Check the Daphnia under the microscope right away, then every 15 minutes until 1 hour to see if the heart is still beating.
13. Put no fluoride in the E group (Control group). 
14. Repeat steps 3-13 one more time.
15. See how much fluoride is safe for Daphnia survival

RESULTS

The original purpose of this experiment was to determine if the amount of fluoride affects the survival rate of Daphnia.

The results of the experiment were that .01 % of fluoride is safe for Daphnia survival. 

See the table and graphs.
 

CONCLUSION

My hypothesis was that .01% of fluoride would kill the Daphnia.

The results indicate that this hypothesis should be rejected.

Because of the results of this experiment, I wonder if this amount of fluoride would affect shrimp, fish, or small mammals.

If I were to conduct this project again I would 

1. Use more Daphnia in each test
2. Conduct more trials 
3. Use more concentrations of fluoride

 
 
RESEARCH REPORT







INTRODUCTION
 Fluoride is used to protect teeth.  It is commonly used in toothpaste and water. It prevents tooth decay so dentists and hygienists use it for preventative reasons.  It’s especially good for children because it prevents cavities from being formed. 
 

FLUORIDE
 Fluoride comes from a rock called fluorite. It is most commonly found in food, water, soil, and rocks. It is used in toothpaste and most drinking water.  Almost 61% of Americans today drink fluoridated water.  In America eight of the fifty states passed laws to have fluoride in their drinking water. In ten other states more than 90% of the population have fluoride in their drinking water. 
 

EFFECTS OF FLUORIDE
 Fluoride is good for your teeth, because it prevents tooth decay.  But, it is bad for your  bones, tendon muscle, skin, cartilage, lungs, kidneys, and your trachea.  It can confuse your immune system so it starts to attack your bodies tissue. It also can enlarge tumor growth rate in cancer victims. 
 

FLUORITE
 Fluorite is a rock that contains fluoride.  It is commonly found in limestone, dolomites, and other igneous rocks.  Fluorite is most popular for its many colors, which are purple, blue, green, yellow, brown, pink, and rose.  It earns its reputation as "The Most Colorful Mineral in the World." Some fluorite has two or more colors mixed in one.  The outside crystal is one color then the inside crystal is another and so on.  Fluorite is also fluorescent.  Even the word "Fluorescent" comes from fluorite. Some fluorite is thermoluminescence, which means it glows when heated. 
 

DAPHNIA

 Daphnia are micro-organisms that live in bodies of water, such as lakes, swamps, oceans, etc.  They are part of the Crustacean family.  A Daphnia’s heart is oval and large, so you can see its heart beating very easily.  You can see their heart right through their body wall.  The Daphnia’s body is laterally compressed.  Anterior head, middle thorax, and posterior abdomen are the Daphnia’s three main body parts.  Their thorax and abdomen are enclosed in a carapace, which their head extends in front of it.   The head is bent which makes their body smoothly round.  They also have a pair of large eyes on the top of their head.  Daphnia have a mouth which is located on the head, which you can’t see. 
The Daphnia swim with a jerky motion.  They use their stroking action to move upward, which they need to do to get oxygen from the air.  Daphnia make a good test organism because they are prolific and because body functions can be viewed through the clear carapace.  The difference in females and males are the female has a smaller antenna than the male.  You are more likely to have a female than a male.  The females have two types of eggs, winter eggs and summer eggs.  Winter eggs are hatched with fertilization, while summer eggs are hatched without fertilization. 
 

SUMMARY
 Fluoride is commonly used in toothpaste and water.  Dentists use it to prevent tooth decay and cavities from being formed.
 
BIBLIOGRAPHY

Appelman, Evan H. "Fluorine," The World Book Encyclopedia.  1999. Vol. 7 pp. 306.

"Daphnia." [Online] Available http://daphnia.com/daphnia.html, Jan. 5,2001

Environmental News Network. "Daphnia evolve into pollution eaters." [Online] Available http://www.cnn.com/NATURE/99/01/pollution.eaters.enn/index.html, October 1, 1999.

Epstein, Bruce A. "The Doctor’s Office." [Online] Available http://www.allkids.org/Articles/fluoride.html, Jan. 26, 2001.

Fox, Richard. "Daphnia Magna." [Online] Available http://www.science.lander.edu/rsfox/daphnia.html, Dec. 3,2001.

Groth, Edward III. "Fluoridation," The World Book Encyclopedia. 1995. Vol.7 pp. 305-306.

Hileman, Gette. "Fluoridation," Academic American Encyclopedia. 1998. Vol. 8 pp. 187.

Journal of Chemical Physics.  "Fluoride-Worse Than We Thought." [Online] Available http://westonaprice.org/, May 25, 1999.
 

ACKNOWLEDGEMENTS

First of all I would like to thank my parents, for helping me get all my equipment, do my experiment, and encouraging me to do the project.  I would also like to thank Mrs. Hughes, a hygienist, for lending me the fluoride I needed for my experiment.  The last person I would like to thank would have to be Mr. Newkirk who stayed after school to help me with finishing my project.  Without these people's help, I wouldn’t have been able to finish my science project.
 

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