A look at the physiology and particular requirements of very young skin and suggests ways of formulating suitable products for the youngest users of personal care products
A study in Illinois, US, showed that the average 1 month old baby was bathed four times weekly and shampooed thrice weekly and has 8+/-3 products applied, with a resultant exposure to 48+/-18 different chemicals.[1] The first questions when formulating cosmetic products specifically for babies and young children is how does their skin differ from that of adults? What problems are generally confined to young skin? What special precautions are required in the cosmetic treatment of young skin?
A baby’s skin is dramatically different to that of an adult and a baby’s skin changes as he or she gets older. A newborn doesn’t have fully developed sweat glands, the skin is much thinner, has more collagen and is more elastic. Pores are smaller and the absence of hair reduces a baby’s natural defence against environmental stresses. The pH of the skin of a newborn baby is 6.34 but this reduces to pH 4.95 within four days.[2] Microbial colonisation of skin begins immediately after birth and the acid pH assists in the growth of non-pathogenic bacteria that ideally grow in a state of equilibrium that is protective against pathogenic organisms.[3]
Babies need a lot of cleansing; alkaline soaps can affect the acid mantle, while neutral soaps and other cleansing aids can cause dryness of the stratum corneum and irritancy. Bathing with cleansing aids should be confined to two or three times weekly, with only warm water used at other times. To counteract skin dryness lubricating emollients may be used but these may contribute to skin dryness and also upset the natural skin flora so should only be used if the skin is excessively dry. Diaper dermatitis, or nappy rash, is a common problem caused by the excessive wetness and alkaline pH within the nappy but according to Lund[2] the prime cause is faecal contact, which must be minimised by frequent changing and the use of a barrier cream with high zinc oxide content is recommended. The one produced by Johnson & Johnson comprises 13% zinc oxide in an emulsion of paraffinum liquidum, dimethicone, lanolin and petrolatum.
A problem when formulating products for the very young is the high skin surface to body weight ratio, which means that there is an increased risk of toxicity through percutaneous absorption. Formulating for mildness is an obvious requirement and Boots insists that its products intended for use by children less than seven years old are formulated in accordance with Boots’ hypoallergenic criteria. These include a restricted positive list of preservatives, sunscreens and colours. Essential oils cannot be used, the use of herbal extracts is restricted and perfumes must contain only minimal quantities of allergens. Skin testing must be performed on a minimum of 50 subjects.
Despite concerns about problems caused by inhalation, baby powders are in common use. The majority comprise lightly fragranced talc but approximately 25% of the market uses modified zea mays (corn) starch with tricalcium phosphate. The world’s best selling baby oil is fragranced paraffinum liquidum. Gelled oils are also popular and comprise paraffinum liquidum gelled with hydrogenated butylene/ethylene/styrene copolymer and hydrogenated ethylene/propylene/styrene copolymer. They may also contain tocopheryl acetate and a botanical extract plus fragrance.
Shampoos account for a significant share of baby care product sales and the main concern is to avoid eye sting. The pH should be close to neutral and the solution isotonic to tears. The principal surfactants are non-ionic or amphoteric and there are a number available. A Caucasian child’s hair is usually very fine and as it grows it becomes very prone to tangle so the inclusion of a conditioning aid is useful. An abstract of Patent USP 50019299 appears on page 51 of this issue of SPC and it describes the ingredients used to create a conditioning shampoo or cleanser based on amphoteric and non-ionic surfactants and containing a silicone compound as a detangling aid.
Baby massage has been practised for thousands of years, particularly in India and China, but more recently it has been adopted in the west and promoted by mainstream practitioners. Bonding between mother and baby is one aspect, but what is more important is the fact that it is very helpful in calming and relaxing the baby, helping it to nod off to sleep easily. Other benefits include improving the skin, strengthening limbs, stretching and making limbs more mobile. Many maternity wards in hospitals now run baby massage courses for parents.
As the baby becomes a child it may bathe and foam baths are offered to increase its enjoyment. However they can cause problems such as urethritus and vulvovaginitis and should carry a warning statement. In the US it is mandatory for children’s foam baths to be labelled: ‘Caution - Use only as directed. Excessive use or prolonged exposure may cause irritation to skin and urinary tract. Discontinue use if rash, redness, or itching occurs. Consult your physician if irritation persists. Keep out of reach of children except under adult supervision.’
Protecting children from sunburn is an obvious precaution. As mentioned previously, Boots has a more restricted list than those allowed by EU legislation and to achieve the high SPF preferred for the young the use of titanium dioxide and zinc oxide is probably necessary. US Patent 60067896 reviewed on page 51 of this issue describes a novel sunscreen product that combines sun protection and colour marking that enables a user to visualise when the product needs to be re-applied.
Dry skin is not uncommon in children, particularly in northern winters, and it manifests itself in many forms, from a slight roughness and lack of elasticity to atopic dermatitis, eczema and psoriasis. Moisturising lotions based on mild emulsifiers are preferred.
Of major concern when a child starts school is infestation by head lice. The third patent review in this issue describes a blend of essential oils as an insect repellent, that deters head lice.
Formulations considerations
Having identified market requirements the first task for the formulator is to design suitable basic products and then to please the marketing department by adding various extra ingredients to confer unique selling points.
Suggested additives for cleansing products include ColaLipid C [INCI: Cocamidopropyl phosphatidyl PG-dimonium chloride], from Colonial Chemical Inc (Clarient in the UK). This is a coconut oil derived phospholipid that displays a broad range of functional attributes including gentle cleansing and foaming properties, anti-irritation effects when combined with anionic surfactants, unusually high substantivity, long-lasting skin conditioning and broad spectrum antimicrobial activity. A similar material is available as Arlasilk Phospholipid PTM [INCI: Myristamidopropyl PG-dimonium chloride phosphate] from Uniqema/Croda that offers ultimate mildness and broad spectrum antimicrobial enhancement and can be utilised to minimise preservative requirements and to develop self-preserved systems.
Building on the friendly bacteria concept heavily promoted for some foodstuffs, Gova Ingredients (Adina in the UK) supplies Biolin, a mixture of inulin and alpha-glucan oligosaccharide described as a cosmetic that promotes growth of friendly skin bacteria, which then can overwhelm harmful bacteria. For example, Candida albicans is typically found in warm, moist places such as the nappy area and can flourish, causing irritated skin, but Biolin ensures favourable conditions and maintains a flora mainly to the disadvantage of Candida albicans.
Inulin is extracted from chicory and it is also the basis of materials from Orafti (Adina) and Inutec H25 is said to have hair conditioning properties equivalent to cationic conditioners but it is nonionic, biodegradable and extremely mild.
To impart detangling properties into shampoos requires the presence of silicone compounds and/or cationic conditioning aids. Biosil Basics’ Cocosil [INCI: Cetrimonium laureth-12 succinate (&) PEG-7 dimethicone] and BioPlex Cetylsil S [INCI: Cetyl triethylmonium dimethicone PEG-8 succinate] each offer a combination of both. The complex of a quaternary compound and a carboxy silicone result in a significant reduction of irritation. They are substantive to hair and are clear in surfactant systems.
Mild surfactants are the prime requirement for baby and children’s cleansers and shampoos; alkyl polyglucosides are popular in this regard. Colonial Chemical supplies a number of sulfonated alkyl polyglucosides that are derived from renewable resources. An example is Poly(sodium decylglucosides hydroxypropyl sulfonate) and these anionic surfactants exhibit low or no irritation to skin and eyes, are biodegradable, build foam and viscosity in surfactant formulations and are mild enough for baby wipes.
Mackanate DC-100 [INCI; Disodium PEG-12 dimethicone sulfosuccinate] from McIntyre Group (Chemlink in the UK) is a sulfosuccinate derived from water soluble silicone copolymers resulting in an extremely mild, water soluble, anionic sulfosuccinate recommended for hair and skin care products. When blended with other, more irritating anionic surfactants, it has a mollifying effect on their eye irritation properties.
Arch Personal Care (Adina) offers a range of mild foaming peptides ideal for baby cleansers. The current range includes non-animal derived Foam-Soy C and Foam-Wheat C and has recently introduced foaming silk peptide. Foaming polypeptides are highly functional fatty acid derivatives of hydrolysed proteins and amino acids based on marine collagen, soy and wheat. They have the ability to reduce irritation associated with surfactants such as sodium lauryl sulfate and alpha-olefin sulfonate. The presence of the protein base provides a protective colloid function, coating skin and hair and augmenting their natural barrier functions.
Petrolatum is commonly used as a barrier on the very young but many consumers are looking for non-petroleum-based materials. Zenolatum, Zenitech (Adina) is a high molecular weight naturally derived polymer from castor oil that may be used as a natural alternative to petrolatum. It is a condensation polymer of castor oil, succinic acid, isostearic acid and hydrogenated castor oil. Other vegetable derived alternatives to petrolatum include Natural Wax Jelly, a vegetable wax and oil blend from Strahl & Pitsch (Cornelius).
For massaging babies the use of the Versagel range of products from Penreco is suggested. These are clear gelled oil systems and are widely used in baby oils to prevent splashing and increase viscosity. Jojoba Glaze from Desert Whale Jojoba Company is gelled jojoba oil, which can be used for similar types of product. Gilugels are a range of gelled emollients from BK Giulini Chemie that also find application in this area be be be.
Inhalation problems have made talc and other baby powders less desirable for many users and a suggested alternative is the so-called liquid talc. In their simplest form they may not be much more than a modified corn starch and a suspending agent such as xanthan gum in water or aqueous-ethanol. However, for added emolliency and improved effect they may include esters and active additives.
Suggested additives for moisturising emulsions include Biosil EFA [INCI: Linoleic acid, linolenic acid (&) tocopherol], an essential fatty acid complex offering an easy to use blend of materials said to be essential for healthy looking skin. Biosil EFA is based on Omega-6 linoleic acid and Omega-3 linolenic acid, the only long chain fatty acid which the body needs but cannot synthesise. Another suitable additive from Biosil Technolgies (Paroxite in UK) is Biosil Basics SMC, a mix of Aloe barbadensis leaf extract, hydrolysed wheat protein, phytic acid, triticum vulgar (wheat) germ oil, Simmondsia chinensis (jojoba) seed oil, sorbitol, tocopherol and hydrolysed algin plus six plant extracts. This is claimed to increase moisture balance and retention in the skin and look very impressive on the product label.
From Kitozyme (Adina) we have Kiosmetine-CG [INCI: Chitin, beta-glucan], a high purity natural biopolymer providing excellent skin moisturising, barrier repair and enhancement of the skin’s own defence system. This would be ideal for use on chapped skin and for protection against environmental aggressions. Colloidal oat protein available from S. Black is also designed for use in skin care products for irritated or very dry skin and is suitable for young children.
To suit almost any of the products aimed at the baby and pre-teen market Cosmetochem suggests Herbalmilks. These are described as plant derived emulsifier systems incorporating plant oils and extracts that are PEG-free and do not contain parabens. There is an extensive list of combinations including honey and almond, macadamia and fig and cotton and white lily. Resplanta Cotton [INCI: glycereth-8 cotton oil esters] is a water soluble emollient with solubilising properties obtained by the ethoxylation of cotton oil glycerides. Lipemul 2020 from Lipotec (S. Black) has the ability to form a matrix in water-based systems which can entrap perfume oils then give slow release to ensure a long-lasting fragrance.
For the young and very young, mild emulsifiers are as important for body lotions as mild surfactants are for cleansing aids. Emulium Kappa [INCI: Candelilla/jojoba/rice bran polyglyceryl-3 esters, glyceryl stearate, cetearyl alcohol (&) sodium stearoyl lactylate] from Gattefossé is a multifunctional emulsifier from natural resources. Emulsions made using it are said to be sensory, versatile and highly stable and the cushion textures obtained to be unique, infinitely soft and sensually voluptuous. Other PEG-free emulsifiers available include the Montanov range from Seppic and Olivem 1000 from B&T Srl.
Finally many material suppliers provide information specific to baby and child care products. The Baby Care Review presentation by Symrise covers the products used pre-natal and post-natal for the mother and has many suggested formulations for baby care and reviews clothes and lifestyle products for mother and child.
References
1. Cetta F, Lambert G, Newborn chemical exposure from OTC skin care products, Clin. Pediatr, 286-9 (1991)
2. Lund C, Newborn Skin Care, Cosmetic Dermatology, Martin Dunitz, London, 349 (1994)
3. Holbrook K, A histological comparison of infant and adult skin, Neonatal skin structure and function, Marcel Dekker, New York, p3-31 (1982)
