Misunderstanding  SPF sunscreens / Sunscreen, Sun Cream, Sunblock

SPF only measures protection against UVB, and does not measure UVA protection. Also, an SPF 30 sunscreen is not twice as effective as SPF 15. An SPF 15 sunscreen blocks around 93% of UVB; whereas an SPF 30 sunscreen blocks about 97%. In addition, people generally apply sunscreen more thinly than recommended, which lowers the SPF. SPF measures the time it takes to produce a sunburn reaction on protected skin compared to unprotected skin. However, avoid believing you can stay in the sun 10 times longer with SPF 10 sunscreen, because there are misconceptions about SPF and sunscreen.

Misunderstanding high SPF sunscreens

High SPF sunscreens do provide more protection but can also lead to misunderstanding. Sunscreens with SPF 70 + do not provide all-day protection especially when you are exposed to intensive sunlight. You still need to reapply within two hours.

When it comes to avoiding sunburn and sun damage, the form of sunlight we’re most concerned with are invisible waves of ultraviolet light classified as UVA and UVB. UVA and UVB pass through air to the Earth’s surface, and they can even pass through clouds, which is why you can sunburn on a cloudy day. UVB accounts for about 5% of the UV light that strikes your skin. Although UVB doesn’t penetrate as deeply as UVA, it has more energy and is the primary cause of sunburn. Most sunscreens protect against UVB, and fewer protect against both UVA and UVB.   Approximately 95% of the ultraviolet light that penetrates your skin is UVA. This form is responsible for tanning, penetrates more deeply than UVB, and is an important factor in causing sun damage and skin cancers.  The sun protection factor (SPF) rating is a general measure of how well a sunscreen protects against developing a sunburn from UVB.  Research shows 90 percent of wrinkles are caused by the sun’s UVA light and sun damage is the #1 cause of premature aging in women and men.  The best UVA protection is provided by products that contain zinc oxide, avobenzone, and ecamsule. Titanium dioxide probably gives good protection, but does not completely cover the entire UV-A spectrum, as recent research suggests that zinc oxide is superior to titanium dioxide at wavelengths between 340 and 380 nm.

Sunscreens contain one or more UV filters of which there are three main types:

* Organic chemical compounds that absorb ultraviolet light (such as oxybenzone, a suspected photocarcinogen)

* Inorganic particulates that reflect, scatter, and absorb UV light (such as titanium dioxide, zinc oxide, or a combination of both).

* Organic particulates that mostly absorb light like organic chemical compounds, but contain multiple chromophores, may reflect and scatter a fraction of light like inorganic particulates, and behave differently in formulations than organic chemical compounds.[clarification needed] An example is Tinosorb M.

Medical Benefit

Organizations such as the American Cancer Society recommend the use of sunscreen because it prevents the squamous cell carcinoma and the basal cell carcinoma.  However, the use of sunscreens is controversial for various reasons. Many do not block UVA radiation, which does not cause sunburn but can increase the rate of melanoma, another kind of skin cancer, so people using sunscreens may be getting too much UVA without realizing it. Additionally, sunscreens block UVB, and if used consistently this may cause a deficiency of vitamin D.

UV radiation suppresses the body’s immune responses that protect against and fight disease and infection. UV light interferes with the body’s immunity, giving cancer cells the opportunity to grow. The development of a sunscreen that could prevent UV-inducted immune suppression, often referred to as the immune protection factor (IPF) of sunscreen, is currently under development. However, there is research available now that shows that sunscreens are already providing protection against pre-cancers. One such study from the New England Journal of Medicine shows that sunscreens prevent actinic keratosis, the earliest stage in the development of skin cancer.

The SPF is the amount of UV radiation required to cause sunburn on skin with the sunscreen on, relative to the amount required without the sunscreen.^[9] So, wearing a sunscreen with SPF 50, your skin will not burn until it has been exposed to 50 times the amount of solar energy that would normally cause it to burn. The amount of solar energy you are exposed to depends not only on the amount of time you spend in the sun, but also the time of day.

Sunblock

Although some believe that sunblock and sunscreen are both the same, they are not. Although they have similar properties and are both important in caring of the skin, 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 also.

Use Regularly During The Day

Recent research at the University of California, Riverside, indicates that sunscreen needs to be reapplied within 2 hours in order to remain effective. Not reapplying could even cause more cell damage than not using sunscreen at all, due to the release of extra free radicals from those sunscreen chemicals which were absorbed into the skin!

VITAMIN D DEFICIENCY & SUNSCREEN – A POLARIZED DEBATE

The high risk group would include nursing home residents, patients with skin type I, transplant, other immunosuppressed patients and other individuals live indoors mostly as well as women who wear the veil as it being the ultimate sunblock. The later is evidence itself of a high sunblock causing vitamin D deficiency which is commone in many middle-eastern countries.  In fact a study of 316 young adults aged 30-50 from the Middle East showed that 72.8% had 25(OH)D values of less than 15 ng/dL (that is, severely deficient). This was significantly more common in women than in men (83.9% vs 48.5%) .   There is plenty of clinical evidence to suggest that complete sunblock is possible and may cause vitamin D deficiency. However, does this amount of complete sunblock practically impossible in a normal individual not too obsessed with re-applying sunscreen every few hours or everytime they sweat, wipe some off?

REFERENCES

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