Posted: 06/20/2011
For a long time, we have considered
the barrier function of full-term infants’ skin equivalent to adults.
However, there also is the perception that baby skin is soft, delicate,
sensitive, fragile, and in need of special care. Which perspective is
really true?
Both views to some extent are true. The skin of a full-term newborn has remarkable structural and functional competence at birth and does approach adult skin after a period of adjustment to the dry, extra-uterine environment.
However, recent closer examination of the skin in healthy infants and young children through noninvasive methods for studying the skin microstructure in vivo has revealed differences from adult skin.
Just like many other organ systems in infants, skin development in children continues during the early years of life, and with certain skin structures such as sebaceous glands, does not reach full adult function until adolescence.
Important for pediatric health care providers to understand are the implications that the structural and functional difference in the skin of infants and young children have for skin care recommendations in this population. Important implications of these differences include:
- Infants and young children are at
greater risk for disruption of the barrier function, toxicity, and
development of contact irritation or allergy because:
- Water handling properties differ—infant skin has higher water content, and it absorbs and loses water faster
- Infant skin has significantly lower amounts of natural moisturizing factor (NMF) in the stratum
- Infant stratum corneum is thinner (on average 30% thinner), and the infant suprapapillary epidermis is on average 20% thinner
- Infant corneocytes and granular layer keratinocytes are smaller possibly due to high cell turnover rates
- Newborns lack the acid mantle, which is formed during the first month of life. This is important for the barrier function of the stratum corneum by stabilizing intercellular lipids and retaining skin hydration as well as control of microbial colonization on the skin surface. Water, soaps, and some cleansers can disrupt this mantle in infants and young children making it more alkaline and potentially altering skin microflora, increasing TEWL, all resulting in the loss of effective barrier function
- Delayed full functioning of melanocytes, thinner stratum corneum, and smaller skin cells all place infants and young children at enhanced risk of skin damage from UV light exposure, It is believed that the groundwork for later skin cancer is laid in childhood
What is the best way to clean a child’s skin? I have often read and heard that bathing in water only is the safest as well as an effective way to cleanse the skin of infants and young children. Is this true?
Washing the skin with water alone provides insufficient cleansing and removal of unwanted material such as fecal enzymes, urine components, and other water-insoluble skin surface impurities.
The alkaline pH of water has been demonstrated to increase to skin surface pH for extended periods of time after exposure. Water that has high mineral content can impair skin barrier function while not adequately cleaning the skin. A note of caution here is necessary. Not all methods of cleansing the skin are alike.
Soaps, detergents, and some cleansers can also temporarily raise skin pH and be quite irritating and drying. Fortunately, new skin cleanser technology has produced cleansers that have less total surfactant and larger micelles with a pH below 7.0 for less aggressive but effective cleansing. These types of skin cleanser are available as liquids (gels and body wash) and not as solid bars. They also tend to foam less when applied to the skin.
Skin cleansers for use in infants and young children with these qualities along with minimal dyes and fragrances will provide safe, mild, gentle, effective cleansing.
Application of a moisturizing cream immediately after bathing to areas of the skin that tend to be dry or inflamed may also enhance the skin barrier function.
A study out of Germany that tested the impact of various skin care regimens on the skin barrier function of healthy full-term neonates demonstrated that bathing with a pH 5.5 wash gel followed by skin cream application showed lower transepidermal water loss and greater hydration of the stratum corneum than did bathing with water alone or bathing with wash gel.
They also demonstrated that neither the use of the wash gel or the cream delayed the development of the skin acid mantle during the first 8 weeks of life.
Should children be bathed daily?
How often a child should bathe varies a great deal depending on circumstances.
The frequency of bathing needs to take into account the child's’ age, the weather, and what they are exposed to from the environment.
For very young infants, bathing every 2–3 days is quite adequate along with spot cleansing as needed though out the day for the diaper area, face, hands, and neck folds.
(for tropical climates - this may not be adequate because of sweating - dr tanpohtin)
Older children may need daily bathing if they have been playing outside, wearing sunscreen, or very active in public areas.
During winter months, less frequent bathing may help to reduce dry skin from lower humidity from dry indoor heating.
Long baths as well as the use of bubble baths or bath additives with dyes and perfumes should be avoided because these increase the skin pH and cause dryness and irritation.
The ideal is a 15-minute or less bath in plain bath water using a mild cleanser with a pH of 7 or less. Mild cleansers may be used for spot cleansing as well. Apply skin cream as needed for skin dryness.
I have been receiving questions from parents in my office about the safety of preservatives in skin care products for their children. How do you recommend responding to these types of questions?
Many parents express concern because of things they have read or heard related to possible human health threats from ingredients in skin care products. Claims of inadequate testing for safety and possible risks to consumers are rampant on the Internet and in popular literature. This information alleges that industry practices related to safety testing are flawed, that there is little government oversight, and that cosmetics contain cancer-causing chemicals and other toxic ingredients. As health care providers, we must be able to adequately answer their concerns with sound scientific data where available and to educate parents on how ingredients are tested and regulated.
The absence or inadequate use of preservatives in personal care products that are applied to the skin can yield them highly susceptible to contamination by bacteria and/or fungi. This is especially true for products with high water content. Oil-based products, on the other hand, are at lower risk and therefore tend to contain smaller amounts or no preservatives at all.
The microflora of the skin itself that is easily introduced into the skin care product can contaminate it. Products stored in jars where the hand is repeatedly dipped in to retrieve the contents are the most susceptible to this type of contamination. These organisms thrive and grow in the dark moist environments of skin care products if nothing is present to inhibit this growth. Common contaminating microorganisms include Pseudomonas aeruginosa, S aureus, and Candida albicans. Skin care products can also become contaminated during the manufacturing process.
Preservatives in personal care products have a safety history that encompasses thousands of products used over decades by millions of consumers. There are no documented reports linking the use of a personal care product preservative and serious human disease. Even contact allergy to these ingredients has been reported in a very small percentage of users (approximately 6% of general population has a cosmetic-related contact allergy). In contrast, the absence of preservatives is clearly associated with contaminated products and the risk of skin infection. Prior to legislation in the United States restricting the sale of contaminated products, the US FDA found that 20% of a sample of personal care products on the market was contaminated.
The cosmetic industry has the primary responsibility to ensure that all ingredients, preservatives, and co-formulants used in skin care products are safe for their intended uses. The FDA has regulatory oversight of and authority over the cosmetic industry, including the banning or restriction of ingredients for safety reasons. In addition, the Cosmetic Ingredient Review (CIR), an independent scientific review board, critically evaluates chemical ingredients used in cosmetics and publishes its findings in the peer-reviewed literature.
As with many medications and other chemicals in our environment, the adage “It is the dose that makes the poison” (Paracelsus, 16th century) is appropriate with preservatives as well. Many of the health-related allegations about cosmetic ingredients are based on the results of high-dose laboratory testing in animals, not human testing. The ideal is to use the lowest concentrations of preservatives that provide the desired result, thereby reducing exposure. The safety and efficacy of multiple preservatives in combination each in low concentration over single preservatives in higher concentrations is well documented. Researchers are continually working to develop even safer preservative systems.
With the current evidence available to us, the benefit of using preservatives appears to outweigh any potential risks. However, we must remember that there are very few certainties in medicine. The cosmetic industry needs to be encouraged to publish more toxicity studies and safety evaluations and use the lowest concentrations of preservatives needed for efficacy. The longer preservatives are used without ill effects, the more confident we can be that preservatives are indeed safe.
Is there such a thing as a healthy tan?
A tan in actuality is a sign of skin damage. When the skin is exposed to UV light, the UV rays affect the DNA of epidermal cells and dermal fibroblasts, resulting in genotoxic and oxidative effects. In response, a protective mechanism in the skin is called into action where the existing melanin in the skin oxidizes and melanocytes produce new melanin, resulting in tan. The level of susceptibility will vary depending on the child’s skin type and how quickly they sunburn as well as how easily they tan. Children are even more susceptible than adults to this DNA-damaging effect due to lower levels of protective melanin present in the skin (melanocytes do not become fully functional until into the 2nd year of life), a thinner stratum corneum, and a higher surface area:body mass ratio.
A recent study out of England looked at healthy Caucasian babies suggesting that UVR-induced skin changes and associated photodamage can begin as early as the first summer of life before melanocytes have become fully functional. Additionally, it is believed that prior to the age of 18 years, children receive much of their lifetime-accumulated sun exposure. Chronic UV light exposure is associated with nonmelanoma skin cancer and head/neck melanomas. Several epidemiologic studies also suggest that the skin of young children may be especially vulnerable to early intense UV light exposure that leads to blistering sunburns and has been associated with trunk melanomas.
Increasingly, the skin is being recognized as playing an important role in the body’s immune response. Exposure to UV light can modulate this immune response and result in a level of immunosuppression. Transgenic mice studies have demonstrated that exposure to solar-simulated radiation in the neonatal period can reduce epidermal Langerhans cells and potentially compromise skin immune system development. Whether infants and young children are similarly susceptible is not clear at this point, but further study is definitely needed in this area.
What advice should I be giving parents regarding sun protection for their children?
We have made progress in educating the public about sun exposure risks. However, sun protection practices for children still remain suboptimal. On any summer weekend in the United States, 7% to 13% of American children become sunburned, and the incidence for the summer season ranges from 29% to 83%. Remember that children of any skin type can sunburn if the UV light dose is high enough. Recommendations for sun protection are available from the AAP, American Academy of Dermatology (AAD), and the American Cancer Society (ACS) and they include:
- Sun avoidance: Avoiding suntanning and sunburn is especially necessary for infants less than 6 months of age. Keep babies away from direct sun exposure. For older infants and young children, time outdoor activities to avoid periods of peak sun exposure. Use lightweight but tightly woven clothing and hats to cover skin, and provide shaded play areas. Extra caution should also be used around reflective surfaces such as water, snow, and sand that can reflect up to 85% of the UV light
- Apply and reapply sunscreen: In infants and young children, use sunscreens that have the lowest possibility for skin penetration, irritation, and allergy. Since babies often rub their eyes and put their hands in their mouths, exposure through this route must also be considered. For children 6 months of age and younger, the AAP recommends sun avoidance but states that sunscreen may be applied to small areas of skin uncovered by clothing and hats
We have made progress spreading the news that sun protection is necessary for children. However, we still have a long way to go in actually implementing these practices and establishing them as health habits.
No comments:
Post a Comment