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Effectiveness of Non-Alcohol |
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Researched by Dalainee
V. |
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Purpose
The purpose of this experiment was to compare the effectiveness of alcohol-based and non-alcohol based hand sanitizers in killing bacteria.
I became interested in this idea while walking around the Central Washington State Fair with my mother and saw Germ-X hand sanitizer dispensers outside the animal barns. The dispensers said that Germ-X's formula could kill 99.99% of the germs on your hands. I wondered if their statement was actually true, and if the active ingredient, 62% ethyl alcohol, was the best ingredient to use.
The information gained from this experiment could affect companies that manufacture hand sanitizers. It would also help users of hand sanitizers including: parents, medical workers, food service employees, and those who rent outhouses.
Hypothesis
My first hypothesis was that the 62% ethyl alcohol based hand sanitizer would be more effective in killing bacteria than the non-alcohol based hand sanitizer.
My second hypothesis was that the non-alcohol based hand sanitizer would kill more bacteria than water alone.
My third hypothesis was that the 70% isopropyl alcohol would have more effectiveness in killing bacteria than the 62% ethyl alcohol based hand sanitizer.
I based my first hypothesis on Dr. Sally Bloomfield’s statement, "Alcohol-based hand sanitizer provides an effective alternative in situations where soap and water are not available. Based on their safety and lack of antimicrobial resistance, alcohol-based hand sanitizers are appropriate for use in consumer settings."
I based my second hypothesis on the Texas Products Lake Palestine Hand Sanitizer advertisement that stated, “This natural Alcohol Free hand sanitizing gel uses Tea Tree and other essential oils to eliminate germs and bacteria without stripping the skin of essential oils and sebum, which act as natural protective barriers against bacterial infection.”
I based my third hypothesis on the logic that the isopropyl alcohol is 70% alcohol; where as the 62% ethyl alcohol based hand sanitizer has ingredients to soften the effect of dry skin, which I think will also soften the alcohol’s effect on killing bacteria.
Experiment Design
The constants in this study were:
- The purchase date of hand sanitizers and isopropyl alcohol
- The amount of hand sanitizer used
- The amount of time washing the hands
- The motion used to wash the hands
- The water’s temperature
- The time in between washing hands and taking the sample
- The template material
- The type of swab used for sampling bacteria
- The area on hands where sample was taken
- Size of the area where sample was taken
- Method of applying bacteria from swab to blood agar plates
- The type and size of blood agar plate
- The area on the blood agar plate where bacteria was applied
- The time the bacteria grew in the 35ºC incubator
- The method used to measure results
The manipulated variable was the type of cleanser.
The responding variable was the number of colonies visible on blood agar plates after incubation.
To measure the responding variable, I counted the bacterial colonies growing on the blood agar plates, using the naked eye in white light.
Materials
| Quantity |
Item Description |
| 1 |
Lab
Coat |
| 12 |
Subjects |
| 1 |
Stop
Watch |
| 1 |
Bottle
of Germ-x Hand Sanitizer |
| 1 |
Bottle
of Lake Palestine Hand Sanitizer |
| 1 |
Bottle
of 70% Isopropyl Alcohol |
| 1 |
Incubator |
| 48 |
Templates |
| 48 |
Sterile
Swabs |
| 6 |
Pairs
of Gloves |
| 1 |
Autoclave |
| 48 |
Swab
Containers |
| 1 |
Black
Sharpie |
| 3 |
Syringes |
| 1 |
Carrying
Case |
| 5 |
Ziploc
Bags |
| 48 |
Blood
Agar Plates |
Procedures
I. Start of the Experiment
a) Collect the
signed permission forms from the
volunteers
b) Obtain materials
c) Sterilize templates
d) Gather the subjects
b) Obtain materials
c) Sterilize templates
d) Gather the subjects
II. Taking the Unsanitized Sampling
a) Place the
sterile template on the subject’s right
hand for the “unsanitized” sample
b) Swab the subject’s right hand on the palm with the sterile swabs (upward-downward motion, then right to left motion, five times each)
c) Label one of the containers, using the black pen, with subject’s number (in Roman numerals), which hand it is (R for right, and L for left), and “Un” for unsanitized sample (Example: I, L, Un)
d) Put the swab into the labeled container
e) Throw away template
f) Place a sterile template on subject’s left hand
g) Swab the subject’s left hand with sterile swab, using original motion
h) Put swab in the labeled container
i) Repeat II a-h for the rest of the subjects’ hands
b) Swab the subject’s right hand on the palm with the sterile swabs (upward-downward motion, then right to left motion, five times each)
c) Label one of the containers, using the black pen, with subject’s number (in Roman numerals), which hand it is (R for right, and L for left), and “Un” for unsanitized sample (Example: I, L, Un)
d) Put the swab into the labeled container
e) Throw away template
f) Place a sterile template on subject’s left hand
g) Swab the subject’s left hand with sterile swab, using original motion
h) Put swab in the labeled container
i) Repeat II a-h for the rest of the subjects’ hands
III. Lake Palestine Hand Sanitizer Sampling
a)
Teach the motion the subjects use for washing
their hands (5 seconds on the top of the hand, 5 seconds on the palm,
and 5 seconds in between the fingers, using the tips of the other
hand’s fingers)
b) Have the first three subjects wash their right hands with the Lake Palestine Hand Sanitizer, using the syringe and stopwatch to measure the amount of hand sanitizer and the time spent washing
c) Place the sterile swabbing template over the palm of the right hand
d) Take the sample with the sterile swab, using original motion
e) Throw away template
f) Repeat step II c-d, except use “LP” instead of “Un” (Example: I, R, LP)
g) Repeat steps III b-f, but with the left hand
b) Have the first three subjects wash their right hands with the Lake Palestine Hand Sanitizer, using the syringe and stopwatch to measure the amount of hand sanitizer and the time spent washing
c) Place the sterile swabbing template over the palm of the right hand
d) Take the sample with the sterile swab, using original motion
e) Throw away template
f) Repeat step II c-d, except use “LP” instead of “Un” (Example: I, R, LP)
g) Repeat steps III b-f, but with the left hand
IV. Germ-X Hand Sanitizer Sampling
a) Repeat steps
III a-g, except use Germ-X hand
sanitizer and label containers with “P” instead of “LP’ or “un”
(Example: I, R, P)
V. 70% Isopropyl Alcohol Sampling
a) Repeat steps
III a-g, except use 70% isopropyl
alcohol and label containers with “IA” (Example: I, R, IA)
VI. Tap Water Sampling
a) Repeat steps
III a
b) Have the subjects wash their hands, with the class’ sink for tap water, using the original motions
c) Repeat III c-g, but use tap water and label containers with “TW”
(Example: I, R, TW)
b) Have the subjects wash their hands, with the class’ sink for tap water, using the original motions
c) Repeat III c-g, but use tap water and label containers with “TW”
(Example: I, R, TW)
VII. Incubating the Bacteria Samples
a) Take the
samples to the hospital laboratory
b) Transfer the bacteria to the blood agar plates by rubbing the swab samples, right to left, 3 times, while rotating the plate 45 degrees, eight times
c) Label plates with the same label the swab container had, using the black pen
d) Incubate the sample bacteria for 48 hours at 35°C
e) Return to the hospital laboratory after 48 hours
f) Take the blood agar plates out of the incubator
b) Transfer the bacteria to the blood agar plates by rubbing the swab samples, right to left, 3 times, while rotating the plate 45 degrees, eight times
c) Label plates with the same label the swab container had, using the black pen
d) Incubate the sample bacteria for 48 hours at 35°C
e) Return to the hospital laboratory after 48 hours
f) Take the blood agar plates out of the incubator
VIII. Measuring and Comparing the Results
a) Count the
number of bacterial colonies (with the
naked eye under white light) from the right hand subject plates, record
results using the labeled initials
b) Repeat step VIII a, but with the left hand subject plates
c) Sterilize the blood agar plates and other equipment (using the autoclave)
d) Compare the results
b) Repeat step VIII a, but with the left hand subject plates
c) Sterilize the blood agar plates and other equipment (using the autoclave)
d) Compare the results
Results
The original purpose of this experiment was to compare the effectiveness of alcohol-based and non-alcohol based hand sanitizers in killing bacteria.
The results of the experiment were that there was a large difference in the reduction of bacteria for the four cleansers. The 70% isopropyl alcohol had the most reduction, at 88% of the bacterial content killed. The 62% ethyl alcohol had the second most reduction, at 83%. The tap water had the second least reduction, at 27%. The non-alcohol based hand sanitizer had the least reduction, at 15%.
See the table and graph below.
Conclusion
My first original hypothesis was that the 62% ethyl alcohol based hand sanitizer would be more effective in killing bacteria than the non-alcohol based hand sanitizer.
The results indicate that this hypothesis should be accepted, because the 62% ethyl alcohol based hand sanitizer reduced 83% of the bacterial content on the subjects’ hands, which is more than the 15% the non-alcohol based hand sanitizer did.
My second original hypothesis was that the non-alcohol based hand sanitizer would kill more bacteria than water alone.
The results indicate that this hypothesis should be rejected, because non-alcohol based hand sanitizer only reduced 15% of the colonies on the subjects’ hand, while the tap water reduced 27%.
My third original hypothesis was that the 70% isopropyl alcohol would have more effectiveness in killing bacteria than the 62% ethyl alcohol based hand sanitizer.
The results indicate that this hypothesis should be accepted, because the 70% isopropyl alcohol reduced 88% of the bacteria, and the 62% ethyl alcohol based hand sanitizer reduced 83% of the hand sanitizer. This difference is too close, so more research needs to be done.
After thinking about the results of this experiment, I wonder if there would be any significant difference on the reduction of bacterial content between ethyl and isopropyl alcohol of the same percentage.
If I were to conduct this project again, I would include dry rubbing as one of my control groups. The rubbing of the subjects’ hands could decrease bacterial content. I would also test more subjects to have more trials. Furthermore, I would have compared more cleansers.
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Through the years, humans have used various substances to clean their hands and keep the risk of sickness at bay. The early items include mud, sand and water. Later, bar soaps, foam soaps and liquid soaps were used. Today there are hygienic wipes, alcohol based hand sanitizers and alcohol/water-free hand sanitizer. Though we have natural defenses against bacteria, hand washing increases those defenses. Hand Washing
Many people do not realize the importance of washing their hands. Those who do often do not wash them properly. There are many effective methods for washing hands. All involve washing the palm, in between the fingers, and on the top. The pressure and amount of soap are also very important. Children are often taught that if you sing “Happy Birthday” or “The Alphabet Song” while washing your hands, that when the song ends, that is enough time. Washing well takes time. Soap
The earliest records of hand washing are from Egypt in 1500 BC. These
records mention soap. The records were enscripted on medical documents
that described combining animal and vegetable grease. The soap was not
like the soap we use today, but still a method of sanitation. It
was used not only for hygienic reasons, but for curing skin diseases
also. Making soap was a smelly affair, and a household chore.The modern way to make soap is to mix sodium hydroxide (lye) with water and add oil (olive oil and coconut oil are popular choices). Soap molecules tend to be long. One end attaches to water. The other end attaches to grease and dirt. This allows filth on the hands to be washed away. Soap was originally named after Mount Sapo (according to Roman myth). Soap was discovered as an accident. Mount Sapo was a place where the ancient Romans would sacrifice their animals. The tallow (melted animal fat) left on the stones mixed with rain, and was washed down the mountain to the clay soil on the side of Tiber River. The women found the clay mixture while washing and thought it was a very effective cleaner. The Germans and Gauls also used soap, though to dye their hair red. Bacteria
Bacteria are large groups or clumps of a bacterium, a single celled organism. Thanks to their reproductive rate, there are uncountable numbers of bacteria in the world. There could be uncountable numbers on your kitchen table. Classification
There are many classifications for bacteria. Among them are the different shapes, the types of groups, whether they are gram positive or gram negative, and aerobic or anaerobic. Microbiology has transformed from a simple study of “animalcules” to complex revisions, tests, and classifications. Shapes
Bacilli, cocci, spirella, and vibros are the four different shapes of
bacteria. Bacilli are rod shaped, cocci are spherical, spirella are
spiral, and vibros are comma shaped. The singular of bacilli is
“bacillus.” The singular of cocci is “coccus.” Spirella and
vibros’ names are both singular and plural.Groups
Diplo, strepto, and staphylo are the three different groupings. Diplo
means pairs, strepto means chain, and staphylo means clusters/clumps. A
staphylococcus group is actually hundreds of cocci bacteria clustered
together. By combining the two words, “staphylo” and “coccus”, together
they form a specific meaning.Gram’s Stain
Han Christian Joachim Gram, the creator of Gram’s stain, was a Danish
medical worker. Gram’s stain was created in 1844. Gram’s solution is
created out of 1 part iodine, 2 parts potassium iodine, and 300 parts
water. The method of the staining is:1. Stain with gentian violet (made of methyl deritave of parasoniline) 2. Apply Gram’s solution If the bacterium selected becomes blue, then it is gram positive, but if the bacterium is decolorized, then the bacterium is gram negative. Bacteria are categorized by whether they are gram negative or gram positive. Aerobic and Anaerobic
Aerobic and anaerobic bacteria are two very important classifications
of bacteria. Aerobic bacteria require oxygen to live. Most anaerobic
bacterium cannot abide oxygen. Anaerobic bacteria are very dangerous.
Some live near the core of the earth. They also live in deep wounds of
animals, particularly humans, where no oxygen can reach them.Spores Some spores can resist very high temperatures. But if a spore is in danger, it releases botulin from its body. Botulin is a fatal food poison, found mostly in spore-containing cans in home kitchens. Reproduction
A single bacterium can produce millions of other bacteria in less than
24 hours. The basic reproduction method is to eat, grow, and split.
This type of reproduction is called “binary fission.” An easier phrase
that biologists use to describe it is “cell multiplication.” Another
way they reproduce is to mix DNA (deoxyribo nucleic acid) between two
bacteria and have a “baby.” This method is called “conjugation.”History Robert Hooke
Robert Hooke, an English scientist, was the first discoverer of
microscopes. He was born in the Isle of Wight and was educated at
the University of Oxford. Hooke made the first microscope, however
crude, in 1665. He was an assistant to Robert Boyle, an English
physicist. Hooke was also the first person in the world to actually
experience the examination of cells. He first looked through the
microscope at a cork (made from dead wood) from a wine bottle, and saw
millions of tiny little cubicles, which he connected to the cells the
monks used in the monastery. Though he did not understand the cells’
significance, Hooke is still a very important part of microbiological
history.Antoni van Leeuwenhoek
Around the same time, Antoni van Leeuwenhoek, a Dutch assistant working
at a cloth shop in Delft, Holland, created one of the best and most
beautiful microscopes of his time. The microscope only had one lens.
Leeuwenhoek had never even heard of the scientific discovery by Robert
Hooke.Although Leeuwenhoek was an assistant at a cloth store, he was fascinated by lenses. His hand made “glasses” far surpassed the ability of late 17th century microscopes. His “glasses,” when held up to the eye, could magnify 300 times, which was around the strength of being able to see a pinhead. Louis Pasteur
Louis Pasteur was born on December 27, 1822 in Dole, France. Louis’
father was a tanner. Soon after Pasteur was born, their family moved to
Arbois, France. He earned a doctorate in 1847 at École Normale,
Paris, France. Pasteur created the method of pasteurization to kill
bacteria in milk.Robert Koch
Robert Koch was born at Klausthal-Zellerfeld, Hanover, Germany on
December 11, 1843. Koch enrolled at the University of Göttingen in
186University of Göttingen in 1862. He studied botany, physics,
and mathematics. Koch, after graduation, became a medical careerist for
an institute of mentally challenged children, and a brief occupancy at
Hamburg General Hospital. After that, he used his wide range of
interests to make his first major project.Koch made a huge discovery for microbiology in the 1800’s. He established the fact that Bacillus anthracis caused anthrax in animals. He taught trainers how to isolate the bacteria so the animal would have a chance of living. Julius Petri
Julius Petri was the assistant to Robert Koch. Petri created what we
call Blood Agar Plates, but used to be called Petri Dishes. Blood Agar Plates are shallow glass dishes. They are made out of a gelatin-like liquid created out of seaweed called agar and sheep blood. Alcohol
Isopropyl and ethyl alcohol are the main ingredients for a successful
alcohol based hand sanitizer. Isopropyl
Though isopropyl alcohol is called rubbing alcohol, not many companies
use it in hand sanitizers. Isopropyl alcohol is also called
isopropanol. Isopropyl alcohol has heavier molecules than ethyl. The
chemical formula for isopropanol is CH3CH2CH2OH.Ethyl
Ethyl, called ethanol, is highly popular for companies that manufacture
hand cleansers. The chemical formula for ethanol is CH3CH2OH. Ethyl
alcohol is also formed in alcoholic beverages like beer or wine as well
as being used in automotive gasohol.Summary
Humans have natural defenses against bacteria, but washing your hands
increases those defenses. We have created various substances keep the
risk of sickness at bay. Sand, mud and water are earlier ersatz
cleaners. Bar soaps, foam soaps, and liquid soaps were created later.
Now, we use hygienic wipes, alcohol based hand sanitizers and
alcohol/water free hand sanitizers. |
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Bakalar, Nicholas. Where The Germs Are Canada: John Wiley & Sons Inc. 2003 pp.1-4, 6-15, 20-21, 227. Ernst, Rachel. “The Effect of Four Incubation Temperatures on Three Types of Bacteria” Selah School District 2005. <http://www.selah.k12.wa.us/SOAR/SciProj2005/RachelE.html> Facklam, Howard and Margery. Bacteria Canada: Fitzhenry & Whiteside Ltd. 1995 pp.7-9. Garland E. Allen and Randy Bird. “Koch, Robert” Encarta Deluxe 2005 CD-ROM 1993-2004. Garland E. Allen and Randy Bird. “Pasteur, Louis” Encarta Deluxe 2005 CD-ROM 1993-2004. Garza, Marisol. “Bacterial Content of Water Bottles” Selah School District 2004. <http://www.selah.k12.wa.us/SOAR/SciProj2004/MarisolG.html> “Gram’s Stain” Encarta Deluxe 2001 CD-ROM 1993 “History” The Soap and Detergent Association <http://www.sdahq.org/cleaning/history> “Hooke, Robert” Encarta Deluxe 2005 CD-ROM 1993-2004 “Ignition Temperatures” Encarta Deluxe 2005 CD-ROM 1993-2004 “Leeuwenhoek, Antoni van” Encarta Deluxe 2005 CD-ROM 1993-2004 Pitman, Simon. “Vi-Jon Laboratories defends anti-bacterial sanitizers” <http://www.cosmeticsdesign.com/news/ng.asp?n=63702-vi-jon-laboratories-triclocan-anti-bacterial-sanitizer> Silverstein, Virginia and Dr.Alvin and Robert. Monernans & Protists Canada: Fitzhenry and Whiteside Ltd. pp.1-20 “Types of Alcohol” Encarta Deluxe 2005 CD-ROM 1993-2004 Smith, Sarah. “The Effect of Clorox on the Bacterial Content on Bathroom Door Handles” Selah Science Projects 2004 <http://www.selah.k12.wa.us/SOAR/SciProj2005/SarahS.html> Taylor, Sonia. “Which Waterless Hand Sanitizer Is Most Effective in Killing Bacteria?” Selah School District 2002 <http://www.selah.k12.wa.us/SOAR/SciProj2002/SoniaT.html> Tierno, Philip M. The Secret Life of Germs: observations and lesson from a microbe hunter New York: Pocket Books, 2001 pp.1-4 Wane, Jennifer. “Does Antibacterial Hand Soap Kill More Bacteria than Non-Antibacterial Hand Soap?” Selah Science Projects 2004 <http://www.selah.k12.wa.us/SOAR/SciProj2004/JenniferW.html> |
Acknowledgements
I would like to thank the following people for helping make my project possible:
• My mother for helping through the year and buying me my materials
• My father for cutting the templates for the swabbing process in my experiment
• Marie Clark for supervising the laboratory part of my experiment. She really made a huge difference in my understanding and in my experiment.
• Mrs. McPherson for supervising the school part of my experiment
• Mr. Newkirk for correcting my errors in my report and for giving me the opportunity to work in SOAR
• My sister for telling me to put effort into my mind map
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