Sun Protection Basics
By Joel Fuhrman, M.D. www.drfuhrman.com
Get The Safest And Best Sun Protection Products!
Twenty years ago, consumers picked sunscreens based on which brand smelled the best or had the prettiest bottle. Ten years ago, the amount of sun protection factor (SPF) offered by the product began to play a role in purchasing decisions. Today, we’re learning that there is even more to consider when choosing a sunblock or sunscreen.
UVB And UVA Rays
Ultraviolet light from the sun comes in several wavelengths: UVA, UVB, and the rarely discussed UVC (which is blocked out by the Earth’s ozone layer). UVB, with shorter waves, are the rays we are all familiar with; they damage the outer layer of the skin, cause tanning and sunburn, and contribute to skin cancer and aging. UVB rays vary with the season; they are more intense in the summer than in the winter. They are more intense at midday than in the morning or late afternoon. They vary with weather conditions. UVB rays cannot pass through window glass and do not penetrate clouds, fog, or smog. They help the body with normal vitamin D production.
Recently, however, research has shown that UVA, with longer waves, while not causing sunburn, affects long-term skin damage. UVA rays penetrate deeper into the skin and play a role in wrinkling, spotting, lost elasticity, and skin cancer. They are not affected by a change in altitude or weather, can pass through window glass, and are equally potent year round and at all times of the day.
Most of the sunscreen formulations on the market protect mainly against UVB radiation. The SPF number refers only to the UVB burning protection a product offers. A product with an SPF of 20 for example, would let a user remain in the sun 20 times longer without burning. The FDA has no standards for measuring how well a sunscreen blocks UVA rays. Ironically, a product with a high SPF factor, and no UVA protection, could allow you to stay in the sun longer, overexposing yourself unprotected to UVA rays.
Sunscreens And Sunblocks
There are two types of sun protection: sunscreens and sunblocks. Sunscreens absorb and deflect the sun’s rays through a chemical reaction. They vary in their ability to protect against UVB and UVA rays depending on the ingredients used in the formulation. Sunblocks create a physical barrier against the sun’s rays. They physically block or scatter both UVA and UVB rays.1
Ingredients In Chemical Sunscreens
For UVB protection:
- padimate O
For UVA protection:
- avobenzone (Parsol 1789)
For both UVB and UVA protection:
Ingredients In Physical Sunblocks
For both UVB and UVA protection:
- zinc oxide
Physical sunblocks like titanium dioxide and zinc oxide are the least irritating sun protection ingredients and are less likely to cause allergic reactions. These factors are especially important for young children and those with sensitive skin. They also do not burn your eyes and are better for use on your face if you are playing sports and sweating. Chemical sunscreen can dilute with sweat and burn your eyes, ruining your day.
A number of studies have linked allergic reactions to chemical sunscreens, particularly oxybenzone.2,3 Mineral sunblocks that contain titanium dioxide or zinc oxide are preferable to chemical sunscreens because rather than being absorbed into the skin, the minerals lie on top of the skin, reflecting UV rays before they cause damage.
Questions have been raised about the safety of some chemical sunscreens. Studies have indicated that they have the potential to interfere with the body’s hormonal systems by mimicking the hormone estrogen. Some sunscreen ingredients, including oxybenzone, have been shown to behave like estrogen in lab tests, making cancer cells grow more rapidly.4
It is often assumed that little or none of a topically applied sunscreen is absorbed into the systemic circulation, but it has been shown that substantial amounts of an applied chemical sunscreen are absorbed and subsequently excreted in human urine. Little is known about the potential harm of chronic sunscreen use and the systemically absorbed chemicals deposited after topical application.5,6 This is a special issue for young children who may not be able to metabolize high concentrations of these chemicals.
The fact that red flags keep showing up regarding oxybenzone is of particular concern since it is a benzophenone commonly used to make sunscreens with especially high SPF factors and belongs to a small group of UVA blocking agents.
Overall, the physical sunblocks, titanium dioxide and zinc oxide, are the safest choices for sun protection. They are the least irritating, and they safely provide protection against both UVA and UVB rays. Keep in mind, however, that titanium dioxide and zinc oxide products that contain nanoparticles should be avoided until more is know about the effects of this technology. The Lavera line of sun-care products sold at DrFuhrman.com uses titanium dioxide, a physical sunblock. They are nanoparticle-free.
Remember, sun protection products must be applied liberally to insure you receive the SPF protection claimed on the label. To get the labeled protection, an adult in a swimsuit needs to use 2-3 tablespoons of product. Most people apply 25-75% less sunscreen than the amount used when the manufacturers test their products.7
1. Levy S. “Sunscreens and Photoprotection.” www.emedicine.com (accessed June 20, 2007).
2. Szczurko C, Dompmartin, Michel M, et al. “Photocontact Allergy to Oxybenzone: 10 years of Experience.” Photodermatol Photoimmunol Photomed 1994;10(4):144-7.
3. 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.
4. Schlumpf M, Cotton B, Conscience M, et al. “In vitro and in vivo estrogenicity of UV screens.” Environ Health Perspect 2001;109(3):239-44.
5. Hayben H, Cameron, M. Roberts H, et al. “Systemic Absorption of Sunscreen after Topical Application.” The Lancet 1997;350:9081.
6. Gustavsson G, Farbrot A, Larko O. “Percutaneous Absorption of Benzophenone-3, a Common Component of Topical Sunscreens.” Clin Exp Dermatol 2002;27(8):691-4.
7. “Sunscreens: Some are short on protection.” Consumer Reports July 2007.