Hypothesis

We hypothesize if we test multiple soap brands including ones that focus on skincare and fragrance such as Dove or as opposed to antibacterial soaps, then more bacterial cultures will grow in the fragrance and skincare-focused products. We conclude and believe in this hypothesis due to our research showing that different fragrance and skin care usage soaps contain more harmful chemicals and scents opposed to higher cleansing properties, which anti-bacterial soaps seem to be more focused on.

This topic is something that has been persistently on our minds since the coming of the pandemic. During the pandemic, a lot of stress was put on citizens to properly sanitize and wash their hands. Even the Ottawa public health saying that it was the number 1 one way to protect and control against the spread of disease and germs. Drawing from this, I realized that there are so many different soap brands and types that as a consumer, it is hard to know what is the best option. In addition, it is hard to decide which brands are telling the truth or which ones are stretching it. Therefore, we have always assumed that brands labeled as moisturizers and fragrance products are less effective as if overused sanitizers which are labeled as the most effective germ killers can dry out and cause damage to the skin. Because of this, I assume that brands make the trade-off of effectiveness to a gentler soap product. 

 

Research

There are many things to look into before experimenting with the validity of soap products, we needed to thoroughly understand what we were testing and how it works, and here is what we found:

How do soaps do their cleansing job?

Fat and oils — Soap can be created by using many animal fats and oils, and it is one of the most crucial parts of the saponification process. Some examples of these are vegetable oil and coconut oil.

Alkali — Alkali are included due to their unique reaction with fats and oils. In liquid soap, potassium hydroxide (KOH) is used for this reaction, but sodium hydroxide (NaOH) is the most optimal option in solid soaps.

Saponification — The alkali reacts with the fats and oils, breaking them into soap and glycerine molecules these are called surfactants. Surfactants have a hydrophilic or water-attracting head (polar) and a hydrophobic (nonpolar) water-repelling tail. The hydrophobic tail attracts grease dirt and oils, whereas the hydrophilic head allows the soap to be soluble in water.

Micelle formation — When soap is added to water, it separates into two parts: COO and Na+ions. The hydrophilic part is the COO, which is present in the water, and Na+ ions stick to the oils in the solution. If you add a surfactant like soap or detergent, the emulsion of water and oil becomes more stable. Water is attracted to the hydrophilic end of the soap, while nonpolar particles are attracted to the hydrophobic end. This results in the creation of a micelle as the hydrophobic tails point inward and the hydrophilic heads point outward, creating a sphere trapping dirt and oils inside.

Rinsing — As the hydrophilic ends point outwards, the micelle structure can easily be washed off your hands and down the drain.

Ingredients in soaps that harm human health:

Triclosan and Triclocarban are ingredients often used in soaps as they are very antibacterial. But these chemicals can cause lung, ear and eye irritation. Unfortunately, Triclosan and Triclocarban are also linked to bacterial resistance and weakening of the immune system.

Parabens are common preservatives in soap, but they cause skin irritation, hormone and reproductive organ distribution and can cause many types of cancer.

Fragrance, perfume, or natural fragrance can all be bad in your soaps. Products don't need to elaborate on what is in the scent, meaning that the soap could have synthetic fragrances or irritating ingredients.

Surfactants:

Surfactants are substances that lower the surface tension of two liquids or a liquid and a solid. Surfactants perform many uses such as emulsifiers, wetting agents, foaming agents, and dispersants in coatings. This allows surfactants to be used in everything from shampoo to ski waxes. The main differences in surfactants are their charges whether positive, negative, neither, or both, it is a defining factor. There are four different types of surfactants.

1. Nonionic 

Characteristics of nonionic surfactants include no charges at all and are commonly used as emulsifiers between oil and water.

Examples include polysorbate, which is an emulsifier in pharmaceutical products. Sorbitan is used for manufacturing food and healthcare products for their dispersing and wetting properties. PEGs (polyethylene glycol), are used in cosmetic pharmaceutical and consumer care products. Pluronic or poloxamer, has various uses.

Nonionic surfactants are most commonly used for stabilizing oil-in-water (w/o) or water-in-oil (o/w) emulsions. Nonionic surfactants do not have an ionizable group. They are less reactive to changes in the pH of a solution and amounts of electrolytes. They also have fewer interactions with cell membranes than cationic and anionic surfactants. All of these factors are why nonionic surfactants are sensitive to skin, especially as fewer interactions with skin cells lead to less irritation and reduced chemical reactions caused by electrolytes and pH mediums. This type of surfactant can be commonly seen in oral products and parenteral drugs.
 

2. Anionic

Characteristics of anionic surfactants include, a strong positive charge, they are very effective but harsh, lathering well, and being commonly found to irritate if overused.

Examples include soaps and sodium lauryl sulfate, commonly used in household cleaners, and sometimes seen in detergents. Lastly, sodium stearate is most commonly used in hand soaps and is used in many of the soaps we tested.

Anionic surfactants contain negatively charged functional heads, these can be sulfonate, phosphate sulfate, and carboxylates. Alkyl sulfates are a special type of anionic surfactant. Alkyl sulfates include an organic alcohol that is combined with sulfuric acid or a sulfate that is then neutralized with a base. The reason that anionic surfactants are used in hand soap is due to the negative charge that they produce when ionized, the negative charge in the head attracts positively charged particulate soils like clay. Despite this, they are not as effective as other surfactants, and are not good at emulsifying oily soils.

 

3. Cationic

Characteristics of cationic surfactants include, a strong negative charge, extremely harsh and often cause irritation, they are seen in anti-static products (fabric softeners, hair conditioners etc.) and disinfectants.

Examples include citrimonium bromide which is seen in antiseptics, polyquaternium-10 which is seen in hair conditioners, adogen which is used in industrial cleaners, and many more.

Cationic surfactants have a positively charged head. They are often used in industrial and household cleaning items, as their pH value is below 7. Specifically, they are seen in antifungal and antimicrobial products. Their positive charge also allows them to be extremely useful in anti-static products. If you mix cationic and anionic surfactants they will fall out of the solution and no longer be effective, however cationic and non-ionic surfactants are compatible and are typically used together in products.

4. Amphoteric

Characteristics of amphoteric surfactants include their dual charge, their reaction based on the pH of the solution it is in, their mildness, and their quite low amounts of foam production.

Some examples of amphoteric surfactants are cocamidopropyl betaine, which is a detergent used in cosmetics and shampoos, and alkylbetaine which is used in cosmetic products exclusively conditioner for hair and body.

Amphoteric surfactants have a dual-charged hydrophilic head. It contains both positive and negative charges that cancel one another out creating a total charge of zero, this is referred to as zwitterionic. Amphoteric surfactants are very sensitive to pH levels in the solution they are put into. When amphoteric surfactants are put in an alkyl solution, they will act more as an anionic surfactant. Although, when they are put in an acidic solution, they will behave like a cationic surfactant.

Variables: 

When performing this experiment, we had to ensure that the results of our experiment were consistent.

Bacteria: 

We decided to use hockey gloves, as they would create an even layer of bacteria on our skin. We left the gloves in a room-temperature space for two hours before drawing bacteria. Furthermore, we left the bacteria on our skin for 5 minutes before washing.

Water: 

We used the same sink and made sure to use approximately room-temperature water. We rinsed for 5 seconds before and after applying soap.

Wash: 

We decided to do 5 upward strokes of soap starting from the base of our wrists to the tips of our fingers rotating approximately 20 degrees each time to cover the entire hand, we made sure to spread our fingers 1 centimetre apart. We repeated this on both sides of our hands, applying light pressure.  

Swab: 

We decided that the best place to do this was on one hand because the action of one scrubbing the other could contribute to cleaning itself. We decided to use the right hand and swab at the base joint of our fingers in a slightly curved line across the back. Then we swabbed three times across and back-rotated at 90 degrees and did it one more time.

The black line is where we swabbed

<------- Petri Dish

Soap: We also realized that solid and liquid soaps may be more or less effective, so we tested both.

Petri dishes: We made sure to put the dishes once coated with bacteria in the same environment for the same amount of time, as it could affect which cultures are able to grow.

 

Materials:

• Petri dishes, with a thin layer of nutrient agar at the bottom. 2 per soap brand
• A source of bacteria
• Q-tips or cotton swabs, one for every petri dish
• At least 2 different brands of soap, one that is heavy-duty and one that is fragrance focused
• A source of clean water
• A pair of hands
• Sharpie
• Masking tape
• Possibly a spray bottle
• An incubator, homemade or store-bought

Procedure

Step 1: Gathering of Bacteria

Take your bacteria source and lightly press the object against one hand for 30 seconds, if you are working with a fabric, dampen slightly before performing, and do 5

 squirts of water. Make sure to wait 5 minutes before moving forward.

 

Step 2: Washing

Take your soap, if it is liquid put two pumps at your wrist, if bar soap then rinse it underwater for 2 seconds using the hand not being used for the test. Spread your fingertips 1 centimetre apart. Then lightly rub it in, starting from the wrist toward the tip of your thumb then rotate your stroke towards your palm 15 degrees, for the next upward rub. Make sure to take your soap off your hand and bring it back to your wrist to start the next stroke. Stroke upwards 5 times on the palm of your hand.  We then rinsed the hand underwater for 3 seconds.

Step 3: Drying

Pat a clean towel on your hand 4 times lightly. Use a different place on the towel or a completely different one when testing the different soaps.

 

Step 4: Swabbing 

Take the hand that you have used in all the previous testing. Using a cotton swab take a sample from where the first finger joint is to the next, it will be a slightly curved line at the top of your palm that you are swabbing. Do not continue the swab to the thumbs joint, only use the other four fingers. Do this once across, then again back 2 times in total. Next, swab 3 times across and back from the side of the petri dish. Then turn it 90 degrees and repeat it once more.

Step 5: labelling

Put a piece of masking tape on the lid of each petri dish, using a sharpie, label it according to what soap was used.

 

Step 6: Incubation

For incubation, we used a homemade contraption. We created it by putting small holes in a cardboard box and then putting it onto a heating vent in Zach’s house after we placed a blanket onto that to trap the air.

 

Observations:

January 30

Today was the final day before we are going to conclude the experiment and we noticed some of the dishes have started to grow a bright yellow bacteria cultures that are found in ivory and method dishes. Side from this the smell has become stronger and more disgusting. 

January 28

Today I noticed that method is growing alot of yellow cultures alike to the home made soap solution. Although aside front this not much has changed.

January 27

Today much of the trends in the growth stayed the same and everything progressed at a similar rate.Although we have been starting to notice that the dishes are starting to reate a very strong and disgusting odour, it smelled a lot like mold.

January 26

Today showed some interesting results, Ivory has only grown 4 bacteria cultures and is looking like it is going to be most if not one of the most effective brands that we have tested. Aside from this we also saw alot of growth in dove compared to previous days and if it follows this trend we believe it will be one of the less effective than the average.

January 25

Today followed similar trends to yesterday's results, however the homemade soap is growing yellow bacteria culture while most of the other brands aside from method have white or light grey colouring. 

January 24

Today yielded the first results. It has been 2 days since we started the incubation of the dishes and the growth has been lots of growth. The incubation process has also been working effectively. Some of the dishes have been growing lots, especially soft soap and dial antibacterial. But both dove and ivory have been quite effective so far, and we believe it may have to do with the fact that they are both bar soaps.

​​​

Observations:

Deciding on what Petri dishes collected the most bacteria proves to be a challenge, due to how we didn't possess a spectrophotometer or microscope to count and identify the colonies of the bacteria. To solve this issue, we decided to use a survey to display how others think and react to the different Petri Dish samples. 17 subjects were asked which soap was most effective and least effective. 

Most Effective:                                         Least Effective:

Anti-Bacterial: 0                                       Antibacterial: 9

Ivory: 9                                                     Ivory: 0

Dove: 2                                                    Dove: 0

Method: 0                                                 Method: 2

Soft Soap: 0                                             Soft Soap: 4

Base:0                                                      Base: 4

Homemade: 4                                           Homemade: 0

 

Analysis:

Using the results of the experiment, we can see that the most effective was the ivory soap and the least effective was the dial antibacterial soap. However, this is surprising to us as the antibacterial soap was labeled as being more effective. We looked deeper into each soap's composition to find out why this was the result.

 

Ivory

 

Ingredients include Sodium Tallowate And/Or Sodium Palmate, Water, Sodium Cocoate, Sodium Palm Kernelate, Glycerin, Sodium Chloride, Fragrance, Coconut Acid, Palm Kernel Acid, Tallow Acid, Palm Acid, Tetrasodium.

 

This soap includes several surfactants such as sodium Cocoate and/or Sodium Palm Kernelate. These ingredients are also focused on hand care and controlling the viscosity of the soap solution.

 

The rest of the ingredients in ivory hand soap serves the purpose of hand care and fragrance. 

 

Dove

 

Ingredients include, Sodium Lauroyl Isethionate, Stearic Acid, Lauric Acid, Sodium Oleate, Water, Sodium Isethionate, Sodium Stearate, Cocamidopropyl Betaine, and Fragrances 

 

The main cleansing agent in dove soap is Sodium Lauroyl Isethionate, alongside a few others such as Sodium Stearate, and Cocamiopropyl betaine. Sodium Lauroyl Isethionate is an extremely mild anionic surfactant that serves many uses in cosmetic products for this reason. 

 

These soap brands are direct competitors in the soap market. The differences in surfactant use also show a little bit of what these brands are more focused on and how they advertise themselves to consumers. 

 

Soft Soap

 

Ingredients include Sodium Laureth Sulfate, Cocamidopropyl Betaine, Sodium Chloride, Cocamide MEA, Sodium Salicylate, Glycol Stearate, Sodium Benzoate, Citric Acid, Tetrasodium EDTA, Sodium Sulfate.

 

The main cleaning agent in Softsoap is sodium Laureth Sulfate. This also works alongside Cocamidopropyl Betaine. Although Sodium Laureth Sulfate is a milder anionic surfactant and Cocamidopropyl Betaine is also very mild and is used for skincare and fragrance alongside its cleansing properties.

 

Method

Ingredients include, Sodium Lauryl Sulfate, Cocamidopropyl Betaine, Decyl and Lauryl Glucoside, Fragrance Oil Blend, Sodium Citrate, Sodium Chloride, Aloe Vera Gel, vitamin E, Glycerin, Color and Methylisothiazolinone 

 

The main cleaning ingredient in method soap is Sodium Lauryl Sulfate, in addition, it also includes Cocamidopropyl Betaine. These two main cleansers are very similar to those in Dove and Soft soap, however method and Soft soap the two liquid soap brands performed less effectively than Dove. This finding leads us to believe that bar soaps may be more effective than liquid.

 

Conclusions:

 

In this experiment, we were trying to identify if brands that have advertised themselves as skincare and fragrance products can have comparable results to brands that advertise themselves as antibacterial and heavy-duty. Through our testing, the results were surprising to us. The best soap brand in our testing was Ivory. This was not a surprise however as we bought this soap brand to compare it to Dove as they are both bar soaps but with different types of advertising. However, the results of retaining the Dial antibacterial brand were very surprising to us, as it was deemed to be the least effective due to our survey results. However, according to the Food and Drug Association, there are also health concerns relating to the ingredient triclosan, and it was one of the ingredients that we researched that are possibly dangerous. Along with this, the FDA says that there is not enough true evidence that antibacterial soaps are more effective than regular soaps. Antibacterial soaps are similar to other soap brands, however, they are ingredients to kill and stop the replicating of the bacteria. The reason that we believe the antibacterial soap that we tested was less effective is the amount of time we gave it to work. Even sanitizers need to be left on the skin for 30 seconds to reach their maximum effectiveness, they are often left for even longer. I believe the antibacterial soap performed poorly compared to other soaps because other brands focused more on their surfactants that would wash the bacteria away. The antibacterial soap we tested focused more on ingredients that would stay on your hands and prevent the spread of bacteria. However, throughout this experiment, there were some limitations that we ran into throughout the way. One of the limitations that we ran into was not owning a microscope. This prevented us from taking a closer look at the bacteria that each dish grew, this would have allowed us to figure out which ingredients allowed what types of bacteria to grow. Another limitation that we ran into was with the homemade soap. With the homemade soap solution, we ran into the issue of viscosity being far to low. We thought of the idea of putting the solution in s foam bottle. However, we did not want the soap to go into a dirty container or one that had other soap residue left behind, as it could have tainted the results. These findings show that not all soap products are as they advertise themselves and that it is important to look closely into brands that directly enter or touch your body as they may be harmful or ineffective. In conclusion, our hypothesis was rejected as the soap brands that we tested did not all follow the trend of fragrance and hand care products being less effective than antibacterial and cleansing-focused brands. 

 

n/a

*See Conclusion*

Justify the statement the cleansing action of soap is due to emulsification and micelle formation. 

https://www.bellevuecollege.edu/wp-content/uploads/sites/140/2014/06/Exp4_Soap_and_detergents.pdf 

https://fontanacandlecompany.com

Human Surfactant Use Throughout History: Unveiling the Origins. 

Classifying Surfactants for use in coatings formulation 

Anionic Surfactant - an overview | ScienceDirect Topics

An Easy Guide to Understanding How Surfactants Work | IPC.  

healthywomen.org/content/blog-entry/whats-hiding-your-soap-four-toxic-ingredients-avoid

We acknowledge our parents, who supervised and maintained safety regarding our expirement, along with giving us questions about our project, helping us think outside of the box and encouraging us to build up on our project. A special thanks to our amazing science and math teacher, Mrs. Price, who guided us and many others towords the goal of our finished product through assignments and activities. And thanks to all the creators and volanteers who helped make this brilliant Calgay Youth Science Fair the exquisite project it is.