Pros & Cons of UVB Sunscreen Ingredients

The Ingredients That Block UVB Radiation

Sun Protection on a Beach. Credit: Getty Images / wragg

Sunscreens are important skincare products used to prevent sunburns, 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 a sunscreen's ability to block UVB radiation. Now we know that UVA radiation also significantly contributes to skin damage.

Because SPF is a measure of UVB protection, the ingredients vary between a sunscreen that absorbs UVB radiation and one that offers broad spectrum - or UVA and UVB - protection.

These common chemical ingredients 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 that was widely available. However, it's a known allergen and has since been phased out of many formulations. It's not often used in today's sunscreens.

  • Advantages: PABA sticks tightly to cells in the epidermis, keeping it from getting washed off in water or even rubbed off with a towel.
  • Disadvantages: It causes allergic reactions in 4 percent of the population and it also stains clothing.

PABA Esters

The only PABA ester approved by the FDA for use in the United States is Padimate O, also known as octyl dimethyl PABA. This compound is chemically similar to PABA, but it isn't as irritating. Once PABA-free sunscreens were developed, the popularity of Padimate O declined quickly. Padimate O is still present in some sunscreens because it's used with other chemicals to increase the SPF of a product.

  • Advantages: It's water resistant and doesn't stain clothing.
  • Disadvantages: It's known to 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 cosmetics that have an SPF factor.

  • Advantages: They are potent UVB absorbers. When combined with more "delicate" chemicals, they help make those chemicals more water resistant and stable.
  • Disadvantages: They can be irritating. People with sensitivities to balsam of Peru, tolu balsam, coca leaves, cinnamic aldehyde and cinnamic oil can also be sensitive to 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: They are water resistant and stable in the presence of sunlight.
  • Disadvantages: They protect against a small portion of the UVB spectrum, so they have to be used in high concentrations.

Octocrylene

Octocrylene is often used to stabilize avobenzone, a UVA absorber, and is especially present in products that are non-comedogenic.

It's one of the few UV absorbers that can be used in gel sunscreens.

  • Advantages: It rarely irritates the skin.
  • Disadvantages: It must be combined with other UV filters to make it more stable and it's also expensive to produce.

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 UVB filters listed above block a small amount of UVA radiation.

  • Advantages: It rarely causes skin irritation.
  • Disadvantages: It 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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