Sunscreens are important skin-care products used to prevent both aging skin 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.

However, it is now known that UVA radiation also damages the skin. the only way to know about the UVA-blocking ability of a sunscreen is to look for at least one of these ingredients.

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

Benzophenones
The benzophenones, oxybenzone, and dioxybenzone are common ingredients 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.

Helioplex
Helioplex is a proprietary formula by Johnson & Johnson Neutrogena. This 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.2 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.

Source: msn.com