Ingredients in Sunscreens That Block UVA Radiation

You may have heard that some sunscreens won't adequately protect you from damaging effects of the sun and that you need to understand more than the number on the label. These comments are true, and it is important to educate yourself on the ingredients you need in a sunscreen. Here's what you need to know before you shop for sunscreen.

Sun Protection and UV Rays

Sunscreens are important skin-care products used to prevent photoaging and skin cancer. In the past 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.

We know that UVA radiation also damages the skin. Although the FDA has proposed a rating system that lets you know how well a sunscreen blocks UVA, that proposal has not yet been approved. Unfortunately, the only way to know about the UVA-blocking ability of a sunscreen is to look for at least one of these ingredients.

Sunscreens Which Block UVA Radiation

When you look for a sunscreen, it's necessary to read the label and make sure that one of the ingredients mentioned here is on the list. Don't trust packaging information that claims the sunscreen is "best" or "complete." Make your own educated choice based on your own research. You may also wish to look at the different options for ingredients which protect against UVA rays to decide which one best fits your own personal needs.

Avobenzone

Avobenzone (Parsol 1789) is the only chemical that absorbs the whole UVA spectrum from 310-400 nm. It does not provide any UVB absorption. The problem with avobenzone is that it breaks down in sunlight. As a matter of fact, 50 to 90% of this sunscreen is lost one hour after exposure to sunlight. Some of the UVB absorbers like OMC and octocrylene make avobenzone much more stable.

• Advantages: Blocks full UVA spectrum and does not cause skin irritation
• Disadvantages: Breaks down quickly in sunlight unless combined with certain UVB blockers

Benzophenones

The benzophenones, oxybenzone, and dioxybenzone are a mixed bag of good and bad properties. They are a common ingredient not only in sunscreens but also in UV-protective fabrics. They are good UVA absorbers but they also absorb in the UVB range. Oxybenzone is the most irritating of all the sunscreen ingredients on the market now.

• Advantages: Blocks a broad spectrum of UV radiation including UVA
• Disadvantages: Potentially irritating and not water resistant

Helioplex

Helioplex is a proprietary formula by Johnson & Johnson Neutrogena. This new formulation is a combination of several different UVA and UVB blockers plus stabilizers that keep the more sun-sensitive ingredients from breaking down. It is a broad-spectrum sunscreen that is not irritating. It comes in SPFs of 55, 70, and 85. The active ingredients in Helioplex with their concentrations are:

• Avobenzone (3%)
• Oxybenzone (6%)
• Octocrylene (2.8%)
• Homosalate (10% in SPF 55 and 15% in SPF 70)
• Octisalate (5%)

Mexoryl SX (Ecamsole)

The other names for this compound include terephthalylidene dicamphor sulfoic acid (TDSA), ecamsule, and Anthelios SX. L'Oreal Paris developed mexoryl and it has been used in Europe since 1982. In 2006 the FDA approved its use in the United States. It is combined with avobenzone and octocrylene and marketed in the US by La Roche Posay as Anthelios SX. This sunscreen is a broad-spectrum blocker that is water resistant, very stable in the sun, and not irritating to the skin. The active ingredients in Anthelios SX with their concentrations are:

• Ecamsule (2%)
• Avobenzone (2%)
• Octocrylene (10%)

Meradimate

Meradimate contains the ingredient menthyl anthranilate which provides coverage against UVA rays though the coverage is not as extensive as Mexoryl or the benzophenones.

Titanium Dioxide and Zinc Oxide

Titanium dioxide and zinc oxide are considered sun blockers rather than sunscreens. They offer protection against UVA rays but are limited by their opaque appearance. Sunblocks work as physical blockers, reflecting UV rays back off the skin.