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Sunscreens for Today’s Clients
By: Rachel Ametsitsi, Ada S. Polla and Anne Pouillot
Posted: January 2, 2014, from the January 2014 issue of Skin Inc. magazine.
Teaching clients about sun protection, the damage caused to the skin by UV rays and how to choose the right sun care products are some of the most essential tasks faced by the professional skin care industry. Although it may feel light years away, summer will arrive before you know it, and given all of the recent U.S. Food and Drug Administration (FDA) changes to sunscreen legislation, a review of sunscreens is in order.
UVA and UVB
It is well-known that UV exposure involves free radicals and leads to various types of damage at the level of the skin. Indeed, in the skin, free radicals induced by UV radiation cause damage to DNA and proteins, leading to the premature aging of the skin cells. When exposed to UV radiation, the skin undergoes alterations resulting in inflammation, photoaging and various skin disorders. Typical signs of photoaging include wrinkling, loss of elasticity, increased skin fragility and slower wound-healing.1
Specifically, UVB rays are absorbed by epidermal chromophores, such as melanin, and lead to direct molecular damage while also generating free radicals, including the very nefarious hydroxyl radical, which causes DNA damage.2 UVA rays penetrate more deeply in the dermis, increasing the production of free radicals and contributing to long-term cellular damage. Both UVA and UVB rays induce the activation of enzymes that degrade collagen and elastin.3 As such, sun protection is key. Before delving into the various types of sunscreens and molecules involved in these products, three essential concepts should be emphasized.
- A sunscreen product is meant to remain on the surface of the stratum corneum to ensure optimal efficacy against UV radiation.
- Numbers can be misleading. While an SPF 30 blocks about 97% of the sun’s damaging rays, SPF 50 will only block one additional percentage point—98%. As the numbers increase above 30, the additional protection increase is negligible.
- Most consumers do not apply sunscreen at the concentration tested by the U.S. Food and Drug Administration (FDA), meaning that emphasizing how to apply this product to your clients is key. The correct amount of product to use is a teaspoon for the face and a shot glass for the body.4 Repeated application is also key, no matter how high the SPF—think every two hours when indirect sunlight or after swimming.
Sunscreens: An overview
Sunscreen compounds can be classified into three main categories:
- Physical blocks that reflect UV light—for example, by using titanium dioxide molecules of a size of 200–400 µm;
- Physical (mineral) filters that absorb UV light—for example, by using titanium dioxide in nanoparticle size; and
- Chemical filters that absorb UV light—for example, octyl methoxycinnamate.
See Table 1, which outlines these types of sunscreens and their properties.