Tag: surfactant

This week, we’re looking at the research surrounding Surfactants on Atopic Dermatitis. First a recap of eczema skin and its ‘compromised’ characteristics that warrant special care during skin cleansing.

The defective skin barrier in atopic dermatitis makes it:

–    Increased skin permeability

–    Increased transepidermal water loss

–    Increased bacterial colonization

–    Reduced antimicrobial peptides (AMP) expression, possibly resulting in higher incidences of infection

–    Elevated skin pH

The above makes eczema skin more prone to irritants and more vulnerable to the ‘harsh’ effects of surfactants, discussed last week:

• Alkalization –  Elevated skin pH has the impact of (i) reducing skin lipids (ii) allows for growth of harmful bacteria like staph bacteria and (iii) increases transepidermal water loss (TEWL)
• Damage to Skin Lipids
• Damage to Skin Cells
• Toxic to Skin Cells
• Irritation to Skin

Research on Surfactant Impacts on Eczema Skin

Much of the research focuses on certain surfactant ingredients, as below:

(I) Chlorhexidine Gluconate is the antiseptic for use on eczema skin as it causes the least atopic dermatitis skin lesions.

This is from a study examining the Effect of Hand Antiseptic Agents Benzalkonium Chloride, Povidone-Iodine, Ethanol, and Chlorhexidine Gluconate on Atopic Dermatitis in NC/Nga Mice. The four common antiseptic agents in hand sanitizers are:

Benzalkonium Chloride (BZK): A Cationic detergent with strong antiseptic activity, more gentle than that of ethanol-based BUT with reported contact dermatitis cases

Povidone-iodine (PVP-I) – Commonly use in mouthwash and in disinfection before surgery, low toxicity in humans BUT with reported contact dermatitis cases

Ethanol (Et-OH) – Broad antibacterial and antiviral spectrum BUT result in rough hands because of its strong defatting effect on the skin

Chlorhexidine gluconate (CHG) – Broad antibacterial spectrum AND with low incidences of contact dermatitis

(II) Reduce the use of Sodium Lauryl Sulphate (SLS)

In a study involving twenty volunteers with atopic dermatitis, it was found that repeated exposure to sodium lauryl sulphate and sodium hydroxide lead to a more pronounced impairment of the skin barrier function and significant transepidermal water loss.

SLS is a known skin irritant that damages the lipid barrier, causing inflammation and detachment of the skin layers (denaturation discussed last week).

(III) Reduce Cocamidopropyl Betaine (CAPB)

In another study involving 1674 patients, atopic dermatitis was associated with contact hypersensitivity to cocamidopropyl betaine (CAPB), but not to cocamide diethanolamide DEA or amidoamine. CAPB is an amphoteric surfactant, that is considered milder than SLS and a very common surfactant in many products. However, CAPB is cytotoxic, i.e. toxic to skin cells.

(IV) The Use of Hydrophobically modified polymers (HMPs)

The recent studies on surfactants are in agreement that for patients with skin conditions, a gentle liquid cleanser containing HMPs are more appropriate. Addition of cationic polymers to skin cleansers can further protect the skin and improve moisturization. To further improve cleanser mildness, adding hydrophobically modified polymers (HMPs) to cleansers make it less irritating to the skin. This is due to the formation of larger micelle of the surfactant, i.e. the larger the less likely to penetrate and remove skin lipids.

Above is similar to the care to note when cleansing baby skin, as well as what to use/ avoid to limit the harmful effects of surfactants on skin discussed in the previous two weeks. For all the posts in this Surfactant Skincare Series, see:

1. Surfactants and Functions
2. Cleansing Baby Skin
3. Impact on Skin

References

• Effect of the Hand Antiseptic Agents Benzalkonium Chloride, Povidone-Iodine, Ethanol, and Chlorhexidine Gluconate on Atopic Dermatitis in NC/Nga Mice. Research published on International Journal of Medical Sciences 2015
• Skin Barrier Integrity and Natural Moisturising Factor Levels After Cumulative Dermal Exposure to Alkaline Agents in Atopic Dermatitis Acta Derm Venereol, 2014
• Cutaneous delayed-type hypersensitivity in patients with atopic dermatitis: reactivity to surfactants. J Am Acad Dermatol. 2014 Apr
• Hydrophobically modified polymers can minimize skin irritation potential caused by surfactant-based cleansers Journal of Cosmetic Dermatology 4 December 2013

This month, we’re looking at surfactants – the chemical agents in cleansing products. It is important because while surfactants play an important cleansing function, they also potentially cause skin irritation. Last two weeks, we have understood:

1. Different groups of surfactants and their functions – Anionic, Cationic, Amphoteric and Non-ionic surfactants
2. What to Look out for when Cleansing Baby Skin – Discussion on the use of liquid cleanser being preferable to water, and what to look out for in the choice of liquid cleanser

Today, we’re looking more in-depth into how surfactants interact with skin and the potential harm to our skin.

Alkalization – The traditional soap is alkaline in nature (pH of 9 and above) and the alkalinity will increase the skin pH (which is of pH 4.6 to 5.6). Modifying the skin pH to more alkaline than it is supposed to be has the impact of (i) reducing skin lipids, including ceramides (ii) allows for growth of harmful bacteria like staph bacteria that thrives in a more alkaline environment and (iii) increases transepidermal water loss (TEWL). Alkaline soap is able to dissolve both fat and water-soluble components of skin. Synthetic cleansers are of varying pH and able to modify the pH of the cleansing product.

Damage to Skin Lipids – Surfactants are able to clean dirt and sebum that are oil-soluble. However, this property also means that surfactants may inadvertently solubilize the skin natural lipid membranes (ceramides). Stronger anionic surfactants like Sodium Lauryl Sulphate (SLS) enhances penetration into the skin and able to affect the deeper skin cells (skin lipids).

Damage to Skin Cells – During washing, the surfactants interact with the skin cells and collagen fibers and cause temporarily swelling and hyper-hydration. Once the water evaporates, there is destruction of the skin protein structures (known as denaturation) and leads to skin dryness, roughness, tightness and scaling. This is an adverse effect of anionic surfactant.

Toxic to Skin Cells – Known as cytotoxicity, surfactants can permeate skin cells and cause irreparable alteration. Certain surfactants such as benzalkonium chloride and cocamidopropyl betaine (CAPB) are known to be more cytotoxic than SLS.  CAPB is an amphoteric surfactant, a group of surfactant less irritating than anionic surfactant (SLS belongs to anionic group) but nonetheless can be cytotoxic. CAPB is also associated with allergic contact dermatitis.

Irritation to Skin – This is related to the duration of exposure, frequency, concentration and individual skin type. SLS is a known irritant that can cause skin inflammation (irritant contact dermatitis) and when combined with triclosan (an antibacterial and antifungal agent in products), can stay on the skin for hours/days. Amphoteric and nonionic surfactants are considered to be less irritating to skin. (Note: Skin irritation and cytotoxity are different concepts.)

What to Note when Choosing Cleansing Products

Based on the above surfactant interaction with skin, it follows that we ought to choose:

• Products close to the skin pH (even water is not, either neutral pH 7 or sometimes more alkali)
• It follows then to avoid soaps, which by nature are alkaline
• Avoid SLS, as it can penetrate, damage and irritant skin
• Avoid CAPB as it is cytotoxic
• Choose products with larger micelles as they do not penetrate the skin cells as much (product packaging may not indicate this information so it’s quite hard to know; look out for Polyethylene oxide (PEO)/ PEO Sorbitan Laurate which forms larger micelles in the surfactant or for the term Hydrophobically Modified Polymers (HMPs))
• Choose cleansing products that are moisturizing and moisturize right after washing
• Reduce washing for prolonged time and frequent washing
• Avoid alcohols, gels and alphahydroxy acids that can cause stinging
• Avoid perfume, benzoyl peroxide, preservatives, parabens, propylene glycol, lanolin, methylisothiazolinone and other top irritants in this post
• Avoid ingredients ending with sulfates

It is not easy to find a cleanser without any of the above-mentioned ingredient. For those with sensitive skin, it may be better to not wash as often and take care to choose a hypoallergenic product. Try to read the ingredient label of your product and be sure that the first few ingredients are at least not those in this post.

References

• The Infant Skin Barrier: Can We Preserve, Protect, and Enhance the Barrier? Dermatology Research and Practice Volume 2012
• Surfactants, skin cleansing protagonists Beauty Review
• Status of surfactants as penetration enhancers in transdermal drug delivery J Pharm Bioallied Sci. 2012 Jan-Mar; 4(1): 2–9
• The impact on skin depends on the surfactant concentration, the type of exposure, the duration of contact, and the individual response. Dermatology Research and Practice, Volume 2012

Last week, we briefly looked at the different types of surfactants and understand their functions. This week, we’re looking deeper into baby skin and the research around cleansing baby skin.

Baby Skin Structural Vulnerabilities

In the Skin Fact series, we’ve discussed much about baby skin structural differences. Below is a recap of certain baby skin characteristics that increase its vulnerability during skin cleansing:

Higher transepidermal water loss due to thinner stratum corneum – More vulnerable to water loss during bathing and skin barrier breakdown when there’s excessive friction (from over-washing or from rubbing skin when toweling dry).

High surface-area to volume ratio – along with a thinner stratum corneum and immature drug matebolism, make baby skin more vulnerable to harmful chemicals used during bathing

Less total lipids – make it vulnerable to further reduction of skin lipids lost during washing

Cleansing Baby Skin – Research on What’s Best

From a search on Pubmed for review articles on the research for baby skin cleansing, there’s actually not much research on it. From a 2009 European round table meeting, the consensus is:

1. Liquid cleansers in bathing are beneficial over water alone – Water cannot remove dirt, oil that can only be removed by oil. Prolonged washing with water dries the skin and depending on the pH of the water itself, it may be more alkaline than the natural pH of the skin.
2. Liquid cleanser are preferred, rather than soap which alters the skin pH and affect the skin lipids, increase skin drying and irritation – Learn more about soap and its impact on skin pH in the skin pH series. The pH of skin can affect its skin lipids, which (a lower skin lipids) in turn causes drying, itchiness and skin inflammation.
3. Liquid cleanser should be mild, non-irritating, non-stinging (especially to the eyes as babies may not be able to blink fast enough) and non-pH altering, and contains moisturizing function

For cleansing of baby’s skin, I’ve found two other articles that offer recommendation on what’s best for baby skin.

Apart from the three points above, additional points are:

4. Avoid Anionic Surfactants, these are those that cleanse very well but most irritating to skin, an easy way to identify them is to look out for those chemicals ending with Sulfates.

5. Choose those with large head groups and have the ability to form larger micelles. Surfactants organize into groups of molecules called micelles and generally the larger these micelles are, the less irritating the surfactant is. This is related to larger micelles being less able to penetrate the outer layer of skin (stratum corneum).

6. No preservatives is not best as bacterial growth can happen in such products

7. No scent does not mean no fragrance (potential irritant) is used, it can be one fragrance masking that of another.

Why Baby Skin needs Cleansing

Just like last week we asked the question ‘Why not just use water to clean?‘ (because 40% of dirt, oil can only be removed by oil), we also have to understand why baby skin needs cleansing. Baby skin has saliva, nasal secretions, urine, feces, germs and dirt which can potentially irritate the skin when left on the skin. It is also possible that both skin allergy and the body (ie food allergy) can develop from foods being left on the skin for too long. It is therefore important to clean baby skin. However, baby skin, given its structural vulnerabilities, should not be over-washed and to avoid using baby wipes on face or baby wipes that are non-hypoallergenic, especially those containing fragrance and MI.

Next week, I’d (make a brave) attempt to look into how surfactants affect skin and in particular, impact on eczema skin. It’s a very ‘chemical’ topic and not easy, so appreciate if there’s feedback to improve on the blog post, and share your best cleanser!

References

• Bathing and cleansing in newborns from day 1 to first year of life: recommendations from a European round table meeting
• The Infant Skin Barrier: Can We Preserve, Protect, and Enhance the Barrier?
• Update on Newborn Bathing (Medscape)