The weather is warm, school is out, and summer is upon us. Because of depletion of the ozone layer that protected against harmful radiation in earlier times, today’s sun exposure is not truly natural, and is more damaging. As we plan to spend more time outdoors, we must also avoid excessive sun exposure to protect ourselves from the free radical damage and wrinkling that can ensue and to minimize the risk of skin cancer. First we should be sure to seek shade often, wear protective clothing, and avoid noon time sun. When choosing a sunscreen or sunblock is important to use the safest and most effective methods of sun protection – the SPF number does not tell the whole story.
Exposure to sunlight triggers vitamin D production. However, according to the American Academy of Dermatology there is no safe amount of unprotected UV exposure that can allow for sufficient vitamin D production without increasing the risk of skin cancer. Supplementation is the safest method of maintaining sufficient vitamin D levels.1
Melanoma, the deadliest form of skin cancer, has been steadily on the rise since, its prevalence increasing approximately 2.9% per year since 1981.2 It is essential to protect your skin from the sun’s rays.
UVA and UVB rays
UVB rays are the rays that cause sunburn. They bind DNA and can cause mutations that lead to skin cancer. UVA rays penetrate more deeply into the skin, causing oxidative damage that can lead to skin aging and skin cancer.3
Both types of radiation are believed to contribute to melanoma, but many sunscreens block only UVB.
Types of sun protection
- Sunscreen absorbs and deflects the sun’s rays away from the skin through a chemical reaction. Sunscreens vary in their ability to protect against UVB and UVA rays depending on the ingredients used. Common sunscreen ingredients include oxybenzone, octisalate, and avobenzone.
- Sunblock creates a physical barrier between the UVA and UVB rays and the skin.4 Titanium dioxide and zinc oxide are the most common sunblocks. Physically blocking sunlight from penetrating the skin is the most effective way to block UVA radiation.
Which type of sun protection is safer? Which is more effective?
Many sunscreens do not protect against UVA rays. The SPF listed on these products refers only to UVB protection. The FDA has no standards for measuring how well a sunscreen blocks UVA rays. Ironically, a product with a high SPF, and no UVA protection, could promote unsafe sun exposure behaviors – you may falsely believe that you can safely stay in the sun longer, overexposing yourself to UVA rays even though you avoid sunburn from the UVB rays.5
The Environmental Working Group reported troubling news about sunscreens: Vitamin A is often listed on sunscreen labels as an antioxidant that can fight skin aging. Vitamin A is an antioxidant, but in isolation it could be dangerous, both in supplements and for the skin. Sunscreens may actually promote the progression skin cancer if they contain vitamin A – vitamin A applied to the skin has been shown by FDA studies to accelerate the growth of skin tumors in animals.6
Sunscreens may also damage your skin. Common sunscreen ingredients can generate free radicals, causing oxidative damage. The sunscreen itself and how often it is applied determines whether it releases or absorbs more free radicals.7
Chemical sunscreen ingredients, including oxybenzone, can potentially disrupt hormonal systems in the body, which could have long-term health implications.8
In addition, a number of studies have linked allergic reactions to chemical sunscreens, particularly oxybenzone.9 Little is known about the potential harm of chronic sunscreen use and the systemically absorbed chemicals deposited after topical application.10
These sunscreen ingredients are potentially harmful and should be avoided:11
- Oxybenzone (found in 60% of sunscreen products)
- Octisalate (found in 58% of sunscreen products)
- Octyl methoxycinnamate (OMC; found in 40% of sunscreen products)
- Padimate O
Mineral sunblocks contain either titanium dioxide or zinc oxide, and these are preferable to chemical sunscreens. These minerals do not penetrate as deeply into the skin as chemical sunscreens. They lie on top of the skin and penetrate only into superficial layers, reflecting UV rays before they cause damage. Mineral sunblocks are the only method of sun protection that blocks UVA rays.
Nanoparticles in sunscreens
There are concerns about certain sunblock products that use small particles of titanium dioxide and zinc oxide produced via nanotechnology. The purpose is to make the sunblock more easily absorbed by the skin and therefore more transparent. These tiny nanoparticles, however, can penetrate biological membranes and easily reach cells. Nanoparticles are smaller than anything humans have put into commercial products before. Preliminary investigations have found only a limited ability of mineral nanoparticles to penetrate the skin12, but oxidative stress and DNA damage to skin cells have been observed. Also, upon inhalation these particles reach the bloodstream and several organs.11,13 Additional studies are needed in order to definitively determine whether these products are safe.
Mineral sunblock is the safest choice.
Overall, the physical sunblocks, with titanium dioxide and zinc oxide, are the safest choices for sun protection. They are the least irritating, and they safely provide protection against both UV-A and UV-B rays. According to the Environmental Working Group, mineral sunblocks containing nanoparticles are still a safer option than chemical sunscreens. Unfortunately, sunblock labels most often do not disclose whether the product contains nanoparticles. We've done our research and found a product-line which uses nonmicronized zinc oxide that is safe and effective. Our GreenScreen line protects against both UV-A and UV-B without the use of nanoparticles or harmful chemicals.
Remember, sun protection products must be applied liberally to insure you receive the SPF protection claimed on the label. Most people apply 25-75% less sunscreen than the amount used when the manufacturers test their products.14
Make the summer sunshine a safe, fun, and healthy experience for you and your family!
4. Levy S. "Sunscreens and Photoprotection." www.emedicine.com (accessed June 20, 2007).
5. Autier P. Sunscreen abuse for intentional sun exposure. Br J Dermatol. 2009 Nov;161 Suppl 3:40-5.
8. Schlumpf M, Schmid P, Durrer S, et al. Endocrine activity and developmental toxicity of cosmetic UV filters--an update. Toxicology. 2004 Dec 1;205(1-2):113-22.
Schlumpf M, Cotton B, Conscience M, et al. In vitro and in vivo estrogenicity of UV screens. Environ Health Perspect. 2001 Mar;109(3):239-44.
9. Szczurko C, Dompmartin, Michel M, et al. "Photocontact Allergy to Oxybenzone: 10 years of Experience." Photodermatol PhotoimmunolPhotomed 1994;10(4):144-7.
Schauder S, Ippen H. "Contact and Photocontact Sensitivity to Sunscreens: Review of a 15-year Experience and of the Literature." Contact Dermatitis 1997;37(5):221-32.
10. Hayben H, Cameron, M. Roberts H, et al. "Systemic Absorption of Sunscreen after Topical Application." The Lancet 1997;350:9081.
Gustavsson G, Farbrot A, Larko O. "Percutaneous Absorption of Benzophenone-3, a Common Component of Topical Sunscreens." ClinExp Dermatol 2002;27(8):691-4.
12. Filipe P, Silva JN, Silva R, et al. Stratum corneum is an effective barrier to TiO2 and ZnO nanoparticle percutaneous absorption. Skin Pharmacol Physiol. 2009;22(5):266-75.
13. Consumer Reports - July 2007 " Nanotechnolody Untold promise, unknown risk."
14. "Sunscreens: Some are short on protection." Consumer Reports July 2007.