Bar soap vs liquid soap - The more eco-friendly choice

When it comes to bath time, consumers usually have two choices - bar vs liquid soap. While bar soap was the first to appear in the market, liquid soap has gained popularity over the years. When I was young, my family used bar soap as liquid soap was not as common back then. The switch to liquid soap can be attributed to reasons such as better hygiene and high moisturising capabilities.

Bar soap is claimed to be less hygienic than liquid ones as it is a hotbed for bacteria. From my online research, many articles supporting the use of bar soap stated that bacteria on bar soap do not transfer to the user's hand. However, these articles were all citing the same study by Heinze et al. (1988), where E. coli and P. aeruginosa inoculated on bar soap were not found on users' hands after washing. I searched for more studies which found that bar soap harboured more bacteria than liquid soap in general (Karbara et al. (1984) and McBride (1984)). Brook et al. (1993) and Afolabi et al. (2007) found that wet bar soap contained more bacteria than dry ones, and thus the type of soap containers used to store the bars is important as well. Hence, bacteria on bar soaps can be greatly reduced by keeping them dry and well-drained.

Since hygiene is no longer a big concern, we can now compare them based on environmental friendliness. Bar soap is made by adding lye (sodium hydroxide) to animal or plant fats, which are usually derived from palm or coconut oil. Liquid soap is usually formed from petroleum products by replacing the fatty acids with synthetic components.

Packaging: Bar soap uses lesser packaging while liquid soap is usually housed in large plastic bottles (which can be recycled).

Transport: Since liquid soap generally weighs more than bar soap, more fuel is required to transport them.

Usage: Some people have said that they tend to overestimate the amount of liquid soap needed to create sufficient lather, while others have stated that bar soap tends to become "mushy" over time and will thus get discarded before it is used up.

Ingredients: This is the interesting part. I compared the ingredients of two soaps I have at home - Kao White bar soap (stored in my wardrobe for its fragrance) and ON: THE BODY Lemon verbena body wash (the soap I am currently using).

Kao White bar soap

1. Sodium palmate: formed from the reaction of fatty acids from palm/coconut oil with sodium hydroxide i.e. saponification. Cleansing.

2. Sodium palm kernelate: formed from palm kernel oil and sodium hydroxide. Cleansing.

3. Water: just water

4. Palm acid and palm kernel acid: mixture of fatty acids. Hardness.

5. Glycerin: attracts and preserves water (humectant). Moisturising.

6. Sodium gluconate: natural preservative and chelating agent (to remove metal ions).

7. Sodium chloride: lowers the solubility of soap for preservation.

8. Etidronic acid: preservative and chelating agent.

9. Titanium dioxide: usually used for UV protection (no use in bar soaps), cause soap to have a white/opaque appearance.

10. PEG-6 (polyethylene glycol): polymers which can penetrate skin.

11. Pentasodium pentetate: prevents reaction among the compounds in the soap

12. BHT (butylated hydroxytoluene): preservative.

ON: THE BODY Lemon verbena body wash

1. Water

2. Sodium laureth sulfate: foaming agent. It has been linked to skin irritation, especially at high concentrations.

3. Glycerin

4. Cocamidopropyl betaine: cleansing. Produced from coconut oil and dimethylaminopropylamine. Linked to skin irritation and allergies. It is a potential environment toxin as well.

5. Sodium chloride

6. Potassium cocotate: derived from coconut oil. Cleansing.

7. Citrus medica limonum fruit extract: Fancy name for lemon

8. Lippia citriodoria flower and leaf extract: Lemon verbena. Claimed to have medicinal benefits.

9. Polyquaternium-7: anti-static agent.

10. Disodium cocoamphodiacetate: derived from coconut oil. Cleansing.

11. Lauryl hydroxysultaine: Cleansing.

12. PEG-40 hydrogenated castor oil: Cleansing and fragrant.

13. Caprylyl glycol: Moisturiser and preservative. Anti-microbial.

14. Ethylhexyl methoxycinnamate: usually used for UV protection. Also known as octinoxate. Toxic to coral reefs, like oxybenzone.

15. PEG-8

16. Buthylene glycol: skin penetration. Preservative. Fun fact: it is also found in construction materials.

17. 1,2-hexanediol: Solvent and humectant.

18. Citric acid: lowers pH. Found in bath bombs as well.

19. Sodium citrate: chelating agent.

20. Tetrasodium EDTA: chelating agent and preservative.

21. Sodium benzoate: preservative.

22. CI 19140: Tartrazine. Colourant. Derived from coal.

23. CI 42053: Fast green FCF. Colourant.

24. Fragrance

The body wash has twice the amount of ingredients as the bar soap. It seems like overkill when all a soap needs to do is to wash away some grime and dirt. Frankly, I wanted to throw out my liquid soap when researching its ingredients, especially when I came across octinoxate. Bar soap is derived from palm and coconut oil which are associated with extensive deforestation for plantations. However, as you can see, the liquid soap has many ingredients produced from coconut oil as well.

My conclusion is bar soap is more environmentally friendly than liquid soap. In addition, bar soap tends to be cheaper as well. If you have money to spare, you can opt for more eco-friendly soap choices, which are usually made from castile soap and other natural ingredients.