Who doesn't want to look good and be fair?! And when the demand being more than half the population of the world, who will not take the advantage of it?
Today, I attended a dermatology class as a part of my pg entrance preparation and the dermatologist told a few things about UV rays and sunscreens. I came home and searched in wiki and a few other websites and below are few things about the sunscreens.
Ultra-violet rays:
There are 3 types of UV rays: UVA, UVB and UVC. Of these, UVA is concerned with photoaging (wrinkling, sagging, leathering etc) and UVB is implicated in causing sunburns.
Natural defence against UV rays:
Melanin - UVA increase the amount of the melanin pigment in the melanocytes and increases the release of melanin from the cell. UVB increases the synthesis of melanocytes.
Melanin absorbs the harmful UV rays and dissipates it as heat.
Difference between sunblock and sunscreen:
Sunblock is opaque and is stronger than sunscreen since it is able to block a majority of the UVA/UVB rays and radiation from the sun, thus not having to be reapplied several times a day. Titanium dioxide and zinc oxide are two of the important ingredients in sunblock.
Sunscreens are more transparent and protect mainly against UVB and not against UVA. The newer, broad spectrum sunscreen have at least three active ingredients: They are PABA derivatives, salicylates, and/or cinnamates (octylmethoxycinnamate and cinoxate) for UVB absorption; benzophenones (such as oxybenzone and sulisobenzone) for shorter-wavelength UVA protection; and avobenzone, ecamsule, titanium dioxide, or zinc oxide for the remaining UVA spectrum.
What is SPF?
SPF — or Sun Protection Factor — is a measure of a sunscreen's ability to prevent UVB from damaging the skin. Here's how it works: If it takes 20 minutes for your unprotected skin to start turning red, using an SPF 15 sunscreen theoretically prevents reddening 15 times longer — about five hours. So it's mainly concerned only with the duration of the block, not the actual strength of the block.
The strength of block also increases as the SPF number increases but no sunscreen is 100% effective and more importantly, the brands availabe in the market might not actually contain in them, the ingredients printed on the pack.
Now coming to the actual practical utilization:
1. Sunscreens are effective only after they are organised into a thin coat on the surface of the skin that binds to the skin and hence need to be applied half an hour before going out in sun; those applied before 2 hours are also ineffective.
2. Reapplication every 2 hours is required irrespective of the SPF used as the sunscreens are broken down quickly after exposure to sunlight. There is also no use if the sunscreen is applied just before going out in the sun because the sunscreen breaks down before binding to the skin, releasing reactive oxygen species.
3. The amount that needs to be applied is 4 times more than the amount one generally applies for other fairness creams etc. Generally, nobody applies enough of the sunscreen to be enough.
4. Only UVB is blocked by most of the sunscreens and only sunburn can be prevented in sunburn prone individuals. The incidence of Squamous cell carcinoma and basal cell carcinoma might decrease if applied in the right quantity and duration, but the UVA associated malignant melanoma and photoaging go unrestrained.
5. Most importantly, sunscreens release ‘reactive oxygen species’ which are being implicated in all the diseases in the body, including cancers (Free radical injury). The sunscreens penetrate into the skin in 30 minutes to an hour and start releasing the free radicals, which increase in concentration after an hour. Hence, the sunscreens applied just before going out in the sun and those which are not reapplied do more harm than good.
6. Whether it is summer, winter or cloudy, UV rays penetrate the atmosphere all the time and reach the earth’s surface. So it doesn’t mean that you don’t need sunscreen if there’s no hot sun.
7. There are concerns about vitamin D deficiency in countries where people don’t spend much time in the sun and those who spend, use sunscreen all the time (sunlight is essential for the skin to synthesise the precursors of active vitamin D). Of course, this doesn’t hold good for our country.
Coming to the most important question: Who needs a sunscreen?
When Indians have such a good natural protection of melanin, why bother about sunscreen?! Well, to keep oneself fair, you've to apply the sunscreen as mentioned above and then only it'll be a 'little' useful; because all persons don't react equally to the sunscreen. For one person's skin, it might be very effective (the sunscreen might bind well to that particular skin) and for another, it might be useless. Also, too much sweating and washing face with plain water will wash away the sunscreen. Water resistant ones have also been developed but it's not in the market much and can't rely upon whatever is written on the label.
I think the people who actually need sunscreen are the very fair skinned people who have less of the natural sunprotector -melanin, people living at high altitudes, people living in cold countries where snow reflects the sun's light and more UV rays hits the face and for people who are inherently more prone for sunburn. For these people, I think sunblock is more essential than just applying a sunscreen; but for Indians, sunscreens are either not effective because of improper application or are not necessary at all. And if used improperly, it might do more harm than being useful. Beware!
https://secure.wikimedia.org/wikipedia/en/wiki/Sunscreen
http://www.skincancer.org/Sunscreen/
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