Mustela. The skin care specialist for babies and mothers-to-be.
The sun and children’s skin
Expert file
The sun and children’s
skin: preparing for
the future today
The sun emits radiation which penetrates into the skin. It provokes biological reactions that can be both beneficial and harmful to the body from the moment exposure to its rays is not carried out in moderation.
It is now recognised that solar radiation can cause skin cancer, something which is becoming more and more frequent to the point of becoming a real public health problem. Skin cancer is closely connected to excessive exposure to the sun, in particular during childhood.
Children’s skin is more fragile than that of an adult: it is less able to defend itself against the harmful effects of the sun and for many years keeps a "memory" of all the sunburn it has endured. Childhood is thus a key period of sun protection.
By using sun protection products adapted to children’s immature skin and adopting a “reasonable” attitude towards the sun, parents play a major role in their children’s present and future.
Doctor Clarence de Belilovsky, Dermatologist
Contents
The sun’s rays
The visible effects of the sun on the skin
The invisible effects of the sun on the skin
The particularities of children’s skin in the sun
Sun creams: chemical filters or mineral screens?
Sunburn Protection Factors (SPF)
The qualities of sun protection creams for children
The sun’s rays
Among the solar radiation which reaches the Earth, one can distinguish three types of rays which have an effect on the body:
• Visible rays (that which can be seen by the human eye),
• Infrared (IR),
• And ultraviolet (UV): A (UVA) and B (UVB).
The ozone layer stops the UV rays whose length is less than 290 nanometres (UVC) and the shortest UVB rays (280-290 nm).
The different rays
The effects of the rays, whether beneficial or harmful, vary according to their wavelength, their energy and how deep they penetrate into the skin.
The longer the wavelength, the deeper it penetrates into the skin. This explains why the UVA rays penetrate deeper than the UVB rays.
The importance of UVA rays
Until recently we were only interested in UVB, the most energetic rays responsible for sunburn. Then studies showed that UVA rays play a significant role.
Indeed, their energy is not as powerful but:
• The skin receives virtually 1000 times more UVA rays than UVB rays on it during the course of the day. UVA rays represent 98% of UV rays and UVB rays only 2%.
• UVA rays are constant throughout the day whereas UVB rays are at maximum strength at noon but very weak in the morning and evening.
• The proportion of UVA rays received is virtually constant throughout the course of the year as opposed to the UVB rays which are more intense in the summer and weaker in winter.
Hence, the latest sun protection recommendations advise using products that are active against UVA, UVB and infrared rays.
The decrease in the ozone layer
This is a cause for great concern because it lets through more UVB rays which reach our skin.
The sun we receive on our skin varies according to various factors
• Season: in July in the northern hemisphere the risk of getting sunburnt from UVB rays is 100 greater than in winter.
• Latitude: the sun’s intensity is at its maximum at the equator where the rays shine vertically and thus have a shorter journey through the ozone layer.
• Altitude: the quantity of UVB rays increases by 4% every time you move 300 metres upwards. This partly explains the major risk of sunburn in the mountains.
• Time of day: in the morning and the evening the sun’s rays are oblique and cross the ozone layer more between 11 am and 2 pm when UVB sunlight is at its maximum.
• Clouds: according to their thickness and their altitude, they can filter the UV rays a little but it is still possible to get sunburnt when the sky is overcast.
• The nature of the ground: reflective powers vary according to whether there is snow (85%), sand (17%), water (5%) or grass (3%). Hence the mountains accumulate every danger with more UVB rays and more reflection on the snow.
• Water: this reflects UV rays up to 20%, hence a risk of sunburn even under the water.
The visible effects of the sun
on the skin
The sun’s rays initiate favourable biological reactions, the main one being the synthesis of vitamin D. This vitamin stimulates the metabolism of calcium and promotes bone growth. The sun also acts on the morale (prevention of seasonal depression).
Nevertheless, solar radiation can induce harmful biological effects. Fortunately the skin has a natural biological defence system which moves into action after only a few days exposure to the sun: thickening of the skin’s stratum corneum and melanogenesis, responsible for tanning.
Tanning and sun protection: inequalities
Melanogenesis is the skin’s pigment (melanin) synthesis process under the effect of the sun.
It calls upon 2 types of pigments:
• Brown-black pigments or eumelanin,
• Red pigments or phaeomelanin.
The distribution of these pigments according to each individual is variable, creating true "phototypes", which means to say an aptitude to tan or redden with more or less ease:
Phototype
Hair
Skin Tone
I
II
III
IV
V
VI
Red
Fair
Light brown
Mid-brown
Dark brown
Black
Milky white
Fair
Fair matt
Matt
Matt
Black
Freckles
+++
++
+
0
0
0
Sunburn
Constant ++
Constant +
Frequent
Rare
Exceptional
Absent
Tan
0
Slight tan
Light or dark tan
Dark
Very dark
Black
The tanning mechanism is one of the skin’s defence processes under the action of ultraviolet rays, which causes overall or partial darkening of the exposed areas. It is due to progressive manufacturing of the skin’s natural pigment, melanin. This is why the tan appears gradually after exposure.
During the first hours following exposure: two types of phenomena may appear according to the length and intensity of exposure and the subject’s phototype:
• The calorific effect due to the infrared rays can lead to sunstroke (with dizziness and headache), or even "heat stroke" (with acute dehydration with confusion and disorientation). This occurs especially in children.
• The epidermis can be burnt by UVB rays and partially by UVA rays, provoking "sunburn".
• UVA rays provoke slight tanning of the skin, a temporary protective measure of the skin.
After several years: repeated exposure to the sun without suitable effective protection leads to deterioration of the skin cells:
• UVA rays speed up skin ageing and initiate the destruction of the skin’s elasticity.
• UVB rays, with the help of the UVA rays, induce skin cancer via a photo-carcinogenesis mechanism.
One can distinguish the epitheliomas, which appear in the form of little round white or pink-coloured elevated areas or persistent scabs, and the malignant melanomas appearing on healthy skin or from a change in a mole.
To catch these melanomas at an early stage you need to be attentive to any moles that change in appearance or shape, colour or thickness and do not hesitate to go and see a doctor.
The invisible effects of the sun
on the skin
Well beyond the visible effects on the skin, the sun presents unsuspected dangers by altering the skin in-depth at two levels: cellular DNA and the cutaneous immune system.
In order to eliminate abnormal cells our body is equipped with a defence system composed of the protein P53 and Langerhans’ cells. But beware, overexposure to the sun can inactivate these defence processes.
DNA lesions and protein P53
Harmful UV rays provoke DNA lesions. These lesions activate the cellular defence and repair mechanisms that get protein P53 to intervene:
• If the damage is not too serious, protein P53 enables the DNA to be repaired. If damage proves to be irreparable, P53 initiates cell death with the formation of sunburn cells.
• Over time and continued sun exposure, protein P53 can mutate and become ineffective. There is thus a proliferation of abnormal cells. This leads to skin cancer.
Photo-Immuno-Suppression (PIS) and Langherans’ cells
Langherans’ cells are epidermal cells which, acting like sentries for the skin, spot the foreign elements or cancerous cells and trigger their elimination by the immune system.
UV irradiation acts on Langerhans’ cells by reducing their number and altering their functioning.
Altered or inhibited, the Langerhans’ cells can no longer play their role of recognition and rejection of abnormal cells. One talks about immunosuppression, leading to the accumulation of damaged cells, which initiates photo-carcinogenesis (skin cancer).
• The dermis is immature until the age of 3 years, it is thinner than that of an adult and the fibres of collagen and elastin are in the middle of maturation. If too many UV rays penetrate into this compartment of the skin, they will disturb its normal growth.
• The sebaceous glands are immature until the age of 7 years. Children’s skin thus tends to be on the dry side, lacking the lipids that form an effective barrier. The sun only makes things worse.
• Lastly, the sweat glands are immature until the age of 3 years. In the event of prolonged exposure to strong heat, these glands are incapable of producing a sufficient amount of sweat to eliminate the stored-up energy: this is when you get heat stroke which can be extremely serious with acute dehydration and obligatory hospitalisation.
The particularities of
children’s skin in the sun:
immaturity and memory
Children’s skin is immature, in the middle of forming,
and requires special protection.
• In the epidermis, the pigmentation cells (melanocytes) are less abundant and not very pigmented until the infant is one year old and are thus a lot less efficient than those of an adult. They are immature like the protective immune system cells (Langerhans’ cells) and thus much more sensitive to UV rays. There is less cellular cohesion hence the rays can penetrate more easily. For these reasons the skin is more sensitive to UV rays.
Children’s skin is more exposed to the sun
Childhood is the greatest period of exposure to the sun (playing outside, school holidays, etc.). By the age of 18 you have received virtually 50% of the sun exposure of your whole life. The annual doses are 2 to 3 times those of an adult. We also know that strong exposure for a short period of time is more serious than the same exposure during the rest of your life.
Children’s skin has a memory
It stores up for the long term any childhood sun damage that is responsible for visible damage at adulthood. UV rays provoke a small amount of damage to the skin’s cellular DNA. This damage accumulates over the long term, is gradually less well repaired and the cells may become cancerous. This is why adding DNA protection to sun screens represents a major progress in protecting children’s skin.
Studies show that too much exposure to the sun during childhood, in particular frequent painful sunburn, could represent a factor of risk in getting a melanoma as an adult. The risk also increases proportionately with the number of moles.
The effectiveness of children’s sun protection
Studies show that protecting your child gives results once they reach adulthood. One study specifies that if you regularly apply a sun protection cream with SPF 15 during childhood and adolescence you reduce the risk of skin cancer at adulthood by 60%.
Sun protection:
chemical filters, mineral screens
or organo-mineral screens?
• Based on their composition, chemical filters only absorb certain wavelengths of the sun’s rays. There are, overall, specific chemical filters for UVA rays and others for UVB. To get good protection with a broad spectrum, it is necessary to combine several filters.
• On the other hand, mineral and organo-mineral screens are inert powders which remain on the surface of the skin, protect it against UVA and UVB rays and do not cause an allergic reaction. For these reasons, these screens are used in preference in very high protection products for babies, as well as children prone to an allergic reaction to chemical UV filters.
Sunburn Protection Factors (SPF)
• For UVB, rays, the SPF determines the strength of protection against sunburn.
The SPF, calculated by laboratory tests, is the ratio between the intensity required to provoke redness on a given area with cream and the intensity required to provoke redness on a given area without cream. In practical terms, a cream with SPF 10 lets through 1/10th of the UV rays responsible for sunburn which corresponds to a 90% protection. SPF 50 lets through 1/50th of the UV rays and thus ensures a 98% protection.
But be careful:
• The SPF is not a measure of the amount of sun exposure and thus SPF 50 does not authorise you to stay in the sun 50 times longer than without protection.
• SPFs are only assessed for a maximum of 2 hours. Hence the cream must be regularly reapplied.
Why are higher and higher SPF indexes being recommended?
Because we realize that in practice consumers do not apply a sufficient quantity of cream and they do not reapply it often enough either. Hence SPF 25 applied in too small a quantity may provide the protection of a cream with SPF 5.
• For the UVA rays: take care not to neglect protecting against UVA rays. Effectively a product with a high UVB protection factor could lead you to believe that it is possible to remain longer in the sun without getting sunburnt whereas UVA protection that is too weak would leave the UVA rays the possibility of increasing their harmful and invisible effects.
Protection against UVA rays should be at least equal to one third of the protection against UVB rays.
It is essential to use complete sun protection against UVB and UVA rays.
The qualities of a sun protection cream for children
1. Protection on the surface.
Effectiveness against sunburn and the cumulative effects of the sun: high SPF (30 minimum).
• Broad spectrum: UVB, UVA, infrared,
• Fixation to the stratum corneum to avoid penetration into the skin: with mineral and organo-mineral screens.
2. Protection in-depth.
• Protection of the genome (cellular DNA),
• Fight against photo-immuno-suppression.
3. Resistance to water.
4. Resistance to the sun and heat (photostability).
5. Perfect tolerance certified by specific tests.
6. Fragrance-free.
How do you choose the right sunburn
protection factor?
The strength of the cream should be chosen according to skin type (phototype) and type of sunlight. For the latter, a UV-index was recently established. It defines the strength of UV rays according to geographical location, month and hour. It helps you choose the appropriate protection.
UV-index
1 and 2
How do you choose the right SPF?
Essential preventive measures
3 and 4
5 and 6
7 and 8
9 and 10
Strength of
the sun
Weak
Moderate
Strong
Very strong
Extreme
Exposure time
before sunburn,
fair skin
> 1 hour
40 minutes
30 minutes
20 minutes
15 minutes
According to Dr M. Jeanmougin
The majority of recommendations were established for adults with SPFs varying from 6 to 50+ according to the UV-index and their skin type. For children, it would be wise to use strong protection automatically, irrespective of skin type (SPF 30+ at least). Children with fair skin should use the same SPF throughout the entire holiday period. Those with matt skin can progressively use weaker SPFs according to the type of sunlight (maximum or moderate).
Essential preventive measures
Even today children’s sun protection is insufficient. In France, 33% of children and 62% of teenagers are too exposed in relation to their skin type. In Australia, half of all babies get sunburn. In addition, good habits fall to the wayside: the number of children who get sunburn between the ages of 1 and 2 years doubles; 50% drop in protective clothing between the ages of 1 and 6 years.
1. Do not expose your child directly to the sun; sunburn is dangerous.
2. Avoid any exposure between noon and 4 pm.
3. Use sun protection tailored to your child’s skin.
In the event of inevitable exposure, apply a sun protection product specifically for babies/children. Reapply frequently in an adequate amount and each time after going in the water.
Choose a high factor (at least SPF 30 up to SPF 50+), depending on the sunshine intensity and their skin type, and protection against UVA and UVB rays.
Give preference to hypoallergenic, fragrance-free, alcohol-free formulas that are free from artificial colourings and based on mineral and organo-mineral screens for optimal safety. Do not forget to protect sensitive and highly exposed areas (forehead, cheekbones, nose, and lips).
4. Apply protection before exposure to the sun...
...before going to the beach, for skiing lessons or for a walk. Apply a thick layer of the product: a texture that is visible on application will help you to spread it better.
Reapply an adequate amount at least every 2 hours during exposure and each time after going in the water.
As soon as possible, teach your child to spread their cream themselves, over their arms to begin with, for example.
5. Protect your child even in the shade, under a parasol or in cloudy weather (more than 80% of UV rays pass through the clouds).
6. Choose suitable clothing.
A wide-brimmed hat for the park and the beach alike!
A simple T-shirt made of thick cotton to provide better protection against UV rays.
Sunglasses: your child’s eyes are fragile and wearing unsuitable sunglasses may lead to irreversible lesions: look for the EC standard, choose category 3 or 4 and a style that provides good coverage. A mask is essential when skiing.
7. Avoid the traps.
Wind and water are refreshing...but beware: UV rays can still penetrate!
Water, snow, tarmac, sand... and even grass reflect UV rays: protect your child under all circumstances.
8. Give them something to drink regularly.
Your child must keep regularly hydrated. Give them something to drink, even if they do not feel thirsty; this is essential to prevent heat stroke... and it’s a good habit to adopt throughout your life!
9. Look after your sun care products.
Close the tube or spray properly, do not leave them lying in direct sunlight and never reuse a product that has already been opened the following year.