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Sunscreens for Today's Consumers

By Rachel Ametsitsi, Ada Polla and Anne Pouillot
Posted: March 24, 2014, from the April 2014 issue of GCI Magazine.

Editor’s note: This is an edited version of the article “Sunscreens for Today’s Clients” that originally ran in the January 2014 issue of Skin Inc. magazine. Reprinted with permission. All rights reserved.

  • With recently increased regulation and the nature of the formulas themselves, sunscreens can require complicated product development parameters.
  • Having a strong base knowledge of how sunscreens provide UV protection, what ingredients are available to use and how those ingredients work, and how the FDA is regulating those ingredients is important for product developers, as well as brand owners and marketers.
  • Legislation continues to change for sunscreen, as do new ingredient innovations and product breakthroughs, so continue to keep an eye out for sun care-related updates.

Teaching consumers about sun protection, the damage caused to the skin by UV rays and what to look for in quality right sun care products are some of the most essential tasks faced by the beauty industry. And given the recent U.S. Food and Drug Administration (FDA) changes to sunscreen regulation, a review of sunscreens is in order.

UV

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

As such, sun protection is key. Before delving into the various types of sunscreens and their ingredients, three essential concepts should be emphasized.

  1. A sunscreen product is meant to remain on the surface of the stratum corneum to ensure efficacy.
  2. Numbers can be misleading. For example, while an SPF 30 blocks about 97% of the sun’s damaging rays, SPF 50 will only block one additional percentage point.
  3. Most consumers do not apply sunscreen at the concentration tested by the FDA, meaning emphasizing how to apply sun care is key. The correct amount of product to use is a teaspoon for the face and a shot glass for the body.2 Repeated application also is a must.

Sunscreens: An Overview

Sunscreen compounds can be classified into three main categories:

  • Physical blocks that reflect UV—for example, using titanium dioxide molecules of a size of 200–400 µm;
  • Physical (mineral) filters that absorb UV—by, for example, using titanium dioxide in nanoparticle size; and
  • Chemical filters that absorb UV—for example, octyl methoxycinnamate.

See Table 1, which outlines these types of sunscreens and their properties.

Physical blocks. Physical blocks are substances with a particle size of about 200–400 µm that act by reflecting solar radiation. The most commonly used are titanium oxide, zinc oxide, iron oxide, mica and silica. The last three mentioned are not sunscreens, but soft-focus effect powders. When incorporated into a cream at such size, titanium and zinc oxides often leave a white deposit on the skin, which consumers dislike. These compounds, however, are well tolerated by most skin types because they do not penetrate the skin.

Iron oxide, mica and silica also are not sunscreen ingredients. From a regulatory perspective, they are considered cosmetic ingredients or excipients that provide skin-coloration or assist in formulation. However, given their particle size, these compounds act as particulate matter that may reflect and scatter UV, although they are not regularly accepted as active sunscreen ingredients.3 Table 2 lists the properties of titanium dioxide and zinc oxide.

Physical filters. The most common example of a physical (mineral) filter is titanium oxide in particle sizes between 15–80 nm. These particles absorb UVA and UVB radiation. Due to their small size, they do not leave a white deposit on skin, an advantage appealing to consumers. However, some have reported this ingredient leaves a sensation of dryness on skin.

Chemical filters. Chemical filters are characterized by the wavelength at the absorption maximum and by their absorption coefficient, which is a unit measure of a chemical filter layer’s ability to absorb light radiant energy.

Chemical filters have the advantage of being very elegant in cream formulations—the product does not feel heavy, oily or leave a white film. However, chemical filters are known to cause contact dermatitis, irritative dermatitis and photosensitivity.4 The filters that most commonly cause such reactions include benzophenones (benzophenone-3 or oxybenzone), butyl methoxydibenzoylmethane, methoxycinnamate, methylbenzylidene-camphor and aminobenzoic acid. Table 3 lists the advantages and limitations of chemical filters.5,6,7

Sunscreen Buzzwords

Now that you know the different classifications of sunscreens, it is important to understand how they work. Several popular buzzwords used in sunscreen marketing are starting to be regulated by the FDA, including “broad spectrum,” “waterproof,” and “water-resistant.” Nanoparticles and the term “environmental protection factor (EPF)” also are under the microscope.

Broad spectrum. The FDA requires a sunscreen that carries the label “broad spectrum” provide protection against both UVA and UVB radiation. For a sunscreen to be effective against erythema (redness and sunburn), it must contain filters that absorb UVB radiation. UVA protection also is key because UVA is responsible for photoaging and the skin appearance of actinic keratosis, as well as some forms of skin cancer.