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Sunscreen Information - UVB Sunscreen Ingredients

Ingredients in Sunscreens that Block UVB Radiation

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Updated August 04, 2008

Sunscreens are important skin-care products used to prevent photoaging and skin cancer. Until recently, it was believed that blocking UVB radiation and sunburn were the only measures needed to prevent sun damage. The SPF rating was developed to measure the ability of a sunscreen to block UVB radiation. Now we know that UVA radiation also contributes significantly to damaging the skin. These chemicals are used in sunscreens to absorb UVB radiation only.

PABA

PABA, or para-aminobenzoic acid, came on the market in the United States in the early 1970s and was the first true sunscreen to be generally available. It is not used much in sunscreen formulations now because it frequently caused allergic reactions.
  • Advantages - Sticks tightly cells in the epidermis keeping it from getting washed off in water or even rubbed off with a towel
  • Disadvantages - Causes allergic reactions in 4% of the population and stains clothing

PABA Esters

The only PABA ester approved by the FDA for use in the United States is Padimate O or octyl dimethyl PABA. This compound is chemically similar to PABA but isn't as irritating. Once PABA-free sunscreens were developed, the popularity of Padimate O declined quickly. Now Padimate O is used with other chemicals to increase the SPF of a product.
  • Advantages - Water resistant and doesn't stain clothing
  • Disadvantage - Can cause allergic reactions

Cinnamates

The cinnamates, Octyl methoxycinnamate and cinoxate, are the most frequently used UVB absorbers in the United States. They are often found in color cosmetics that have an SPF factor.
  • Advantages - A potent UVB absorber and when combined with other more "delicate" chemicals, helps make those chemicals more water resistant and stable
  • Disadvantages - People with sensitivities to balsam of Peru, tolu balsam, coca leaves, cinnamic aldehyde, and cinnamic oil can also be sensitive to the cinnamates

Salicylates

The salicylates are homomenthyl salicylate, octyl salicylate, and triethanolamine salicylate. Salicylates have been used for a long time, even before PABA. Trolamine salicylate is water soluble so it is frequently used in hair products that protect against UV radiation. Homosalate is the chemical the FDA uses as the standard for measuring SPF.
  • Advantages - Stable in the presence of sunlight and water resistant
  • Disadvantages - Protects only against a small part of the UVB spectrum so have to be used in high concentrations

Octocrylene

Octocrylene is often used to stabilize avobenzone, a UVA absorber, especially in products that are non-comedogenic. It's one of the few UV absorbers that can be used in gel sunscreens.
  • Advantages - Rarely irritates the skin
  • Disadvantages - Has to be combined with other UV filters to make it more stable and is costly to make

Ensulizole

Ensulizole or PBSA is water soluble so it's used in many moisturizers. It does a good job of blocking UVB rays but it does not block any UVA rays. The other UVB filters above block a small amount of UVA radiation.
  • Advantages: Rarely causes skin irritation
  • Disadvantages: Blocks a narrow band of UV radiation

Sources:

Lautenschlager, S, HC Wulf, and MR Pittelkow. “Photoprotection,” Lancet. 370(2007): 528-37.

Nguyen, Nathalie, and Darrell Rigel. "Photoprotection and the Prevention of Photocarcinogenesis." Cosmetic Formulation of Skin Care Products. Ed. Zoe Draelos & Lauren Thamon. New York: Taylor & Francis, 2006. 156-9.

Palm, MD, and MN O'Donoghue. “Update on photoprotection.” Dermatol Ther. 20(2007): 360-76.

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