Photoprotective Products
As presented, exposure to solar ultraviolet radiation can seriously damage skin. As well as aesthetic damage linked to premature skin aging, it also carries the risk of skin cancer. The problem is made worse by the fashion for sunbathing in summer in certain cultures. In winter, skiing can also lead to high UV exposure.
Photoprotection - protection of the skin from UVR - has an important role for all skins.
SPF
The ability of a sunscreen product to absorb radiation is defined by its sun protection factor (SPF). The SPF of a product is determined by measuring the time it takes to develop skin redness (erythema) to a known amount of radiation. This time is termed the minimum erythema dose (MED). The MED for a product containing sunscreen can be measured against one without, on the same area of skin. Suppose, for example, that:
| MED with sunscreens | = 300 secs |
| and | |
| MED without sunscreens | =20 secs |
| then | |
| the SPF of this product | = 300/20 |
| = 15. |
An SPF of, say, 15 is no guarantee, however, that one can stay in the sun 15 times longer than when not wearing a sunscreen.
Sunscreens
The regular, daily use of modern cosmetic products can potentially be very important for the long-term health of the skin. Among the most useful ingredients are sunscreens, which block ultraviolet radiation absorption by the skin, either wholly or in part. (Clothing, hats and sunglasses can all act as effective sunscreens.) The many formulations that are on sale include lotions, creams, pastes and gels, and rely on either chemical or physical agents for their protective action.
Sun Protection: Some Guidelines
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Sun damage is cumulative. All the doses of ultraviolet radiation (UVR) received by the skin, large or small, add up: the total dose leads to skin wrinkling, altered pigmentation and skin cancer.
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There is no such thing as a 'healthy tan'. Tanning is a response to skin injury by UVR.
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Avoid sun exposure between the hours of 10 a.m. to 3 p.m. Plan outdoor activities for the early morning or late afternoon.
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Wear Protective clothing,wear a hat and apply sunscreen to any remaining unprotected skin.
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Apply sunscreens even on overcast days.Although UVR is less intense on overcast days.
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Beware of sun exposure at high altitudes. In the mountains there is less atmosphere to absorb UVR, and therefore the risk of sunburn is greater.
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UVR is strongest near the equator, where the sun's rays strike the earth most directly.
- UVR is reflected by sand, concrete and snow, and reflected UVR adds to the total exposure. Because UVR is reflected and scattered, sitting in the shade does not necessarily protect from sunburn.
- Although sun beds emit mostly UVA, over-exposure can still cause sunburn, and their use enhances skin aging and the risk of skin cancer.
- People at high risk for skin cancer (persons with skin types I and II, outdoor workers, and persons with a history of skin cancer or a photosensitivity) should use sunscreens daily, and should never 'sunbathe'.
- Keep babies out of the sun. Begin using sunscreens on children as soon as they learn to walk, and then allow sun exposure with moderation.
- Teach children sun protection early.
- Use a good-quality skin care product, such as a moisturizer containing sunscreen ingredients with an SPF factor of at least 15, and active against UVA and UVB. Use it regularly, everyday.
Chemical vs. Physical Sunscreens
Chemical Sunscreens are synthetic chemical substances with the following properties:
These sun filters are formulated with other compounds in order to obtain highly effective products with protection factors varying from 4 to 30. Importantly, they often have to be reapplied quite frequently.
For many people, however, the advantages of chemical sunscreens outweigh the disadvantages. With all products it is advisable to read the label, to check that the product blocks both UVB and UVA radiation.
Physical sunscreens contain inert mineral particles that reflect UV rays like a mirror. The most common type used is ultrafine titanium dioxide (TiO²), made up of minute particles only 20-30 mm³ in size.
These products have advantages over chemical sunscreens in that they are inert substances that do not break down over time. They are far less liable to cause skin irritation, since they are in the form of insoluble particles that are not absorbed through the skin. Because of the small size of the particles, modern physical sunscreens reflect radiation in the UVB and short UVA regions better than earlier products did. Also, whereas their predecessors left a slight residue on the skin that looked like a trace of make-up base, which some people found unattractive, today's products have better transparency and avoid this problem.
There are formulations for use on the face and lips, and special preparations that can be used by small children. All should be reapplied after sweating or swimming, even if the product claims to be waterproof and rub-proof, or to offer 'all-day protection'. Ideally, whichever sunscreen you choose, make sure that it blocks both UVB and UVA and has a sun protection factor (SPF) rating of at least 15.
Slip, Slap, Slop
In Australia the Government and doctors led a public information program to reduce the effects of sun damage. They used the slogan 'Slip, slap, slop':
Slip on a tee-shirt, slap on a hat and slop on some sun cream.
