Screen Test: Reading the Micro-Fine Print

by Maureen Ryan
The Green Guide
May 22, 2007

With Memorial Day right around the corner, we have a lot to look forward to: long, hot days, pool parties, barbecues, baseball games and picnics in the park. But with these outdoor activities comes the very real threat of the sun's dangerous—and deadly—rays: Ultraviolet-B (UVB) rays, known to cause sunburn and associated with an increased risk for basal and squamous cell cancers and melanoma skin cancer, and ultraviolet-A rays which penetrate deeper into the skin, enhancing UVB’s carcinogenic effects.

In fact, approximately 90 percent of all skin cancers are caused by sun exposure, and this year alone, the American Cancer Society estimates that over 1 million Americans will be diagnosed with skin cancer and more than 10,000 will die from it. And atmospheric scientists are concerned that massive Asian sales of air conditioners, which rely on ozone-depleting chemicals, bode ill for the hole in the ozone layer.

That information, coupled with research demonstrating that sunscreen poses its own risks, is reason enough to scrutinize product labels.

Chemical sunscreens that absorb the sun's rays commonly contain compounds that have been shown by numerous studies to interfere with the body's hormonal systems. The most prevalent include benzophenone, homosalate and octyl methoxycinnamate (also called octinoxate). Other chemicals like padimate-0 and parsol 1789 (AKA avobenzone) have the potential to damage DNA once activated by UV rays.

Mineral sunblocks that contain titanium dioxide (TiO2) or zinc oxide (ZO) 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. The choice of most lifeguards, these sunblocks are famous for giving off that unattractive "white" mask.

But this is where problems with minerals arise. In order to reduce the visibility of sunscreen, many manufacturers use nanometer-sized particles of TiO2 and ZO. A nanometer (nm) is about a billionth of a meter—a unit so small that a single human hair is about 80,000 nm in diameter. The U.S. government has defined nanomaterials as particles smaller than 100 nm, and according to the Australian government, most nano-sized sunscreens use particles that size or smaller because the sunscreens become transparent on skin.

Nanoparticles are unpredictable because their small size and high ratio of surface area to volume can produce chemical or physical properties that are very different from their larger counterparts. For instance, once TiO2 nanoparticles enter the bloodstream, they are at risk of infiltrating the brain where they can damage cells, whereas larger micron-sized (millionths of a meter) particles of TiO2 are blocked by the blood-brain barrier, which protects the brain from harmful substances in the bloodstream. Fortunately, the consensus in the scientific community, as demonstrated by a 2006 Australian government literature review on the topic, is that neither TiO2 nor ZO penetrate the skin deep enough to actually enter the bloodstream.

That's not to say that the Food and Drug Administration, which hasn't assessed the safety of nanoparticles, can rest easy on Australia's research. Last May, a coalition of advocacy groups, led by the International Center for Technology Assessment (CTA), petitioned the FDA for nanoparticle toxicity testing and stricter labeling on products that contain nanoparticles. "They have not acted on our petition yet except to form, for the first time, a new committee of FDA staff to look at how they should regulate nanoparticles," says Jay Dee Hanson, CTA program director and member of their nanotechnology team.

Further confusing the issue, some companies use the term "micronized" to describe micron-sized particles, while other companies use it to describe particles that undergo what some dictionaries define as "breaking into very fine particles." Since the FDA has no set definition for the term, some companies misleadingly advertise nano-sized particles as "micronized," which is why it's important to verify particle sizes when you're purchasing a product that contains "micronized" or "nanoparticle" ingredients.

Nano-Free Suggestions

Because the studies present greater evidence against chemical sunscreens, and because it's riskier to spend time outdoors with no sun protection whatsoever, The Green Guide feels that mineral sunscreens are the better alternative, in addition to common-sense measures such as limiting time spent outdoors during peak sun hours and covering up with hats and long-sleeved clothing.

To avoid confusion, we have only included products containing TiO2 and ZO in micron-sized particles (1 micron or larger) or nano-sized particles larger than 100 nm, which are too large to penetrate the deepest skin layers. These are also free of The Green Guide's Dirty Dozen chemicals:

New for '07

Burt's Bees new Chemical Free Sunscreen SPF 15 with TiO2 ($15/3.5 oz.; www.burtsbees.com, 800-849-7112)

Alba Botanica Sun Fragrance-Free Mineral Sunscreen SPF 18 with TiO2 ($9.95/4 oz. bottle, www.albabotanica.com, 877-263-9456).

Old Favorites

Avalon Organics Baby Avalon Natural Mineral Sunscreen SPF 18, good for babies and adults with sensitive skin; the American Academy of Pediatrics recommends keeping babies younger than six months out of direct sunlight and only applying sunscreen when shade is unavailable ($9.95/3.5 oz. bottle, www.avalonorganics.com, 877-263-9456)

California Baby No Fragrance and Everyday/Year-Round SPF 18/30 Moisturizing Sunscreen lotions ($17.99) and sticks ($12.99) with TiO2 (www.californiababy.com, 877-576-2825)

EcoLani SPF 15 sunscreen with TiO2 also contains micronized Green Coffee Extract, which reflects ultraviolet light ($15/4 oz. bottle, www.lanisimpson.com/ecolani).

JASON Natural Sunbrella Chemical-free Sun Block SPF 30+ ($19/6 oz) and Earth's Best Chemical-Free Sunblock SPF 30 for kids ($12.48) with TiO2 and ZO (www.jason-natural.com, 877-527-6601).

Juice Beauty SPF 30 Tinted Moisturizer includes organic white grape and pomegrante juices ($29/2 oz.) and the Green Apple SPF 15 Moisturizer contains a brightening hydroxy-acid complex of organic apple and lemon juices ($38/1.7 oz; www.juicebeauty.com, 415-457-4600).

A Final Note: In January 2007, the FDA approved a new sunscreen called Mexoryl SX, or ecamsule, for use in the U.S. Hailed by dermatologists as a highly effective UV-A barrier, the only product in which it is currently used is L'Oreal's Anthelios SX. However, to make the sunscreen a broad-spectrum UV-A and UV-B protector, avobenzone was added, which, as previously stated, may damage DNA.

Resources

Sunscreens and Sunblocks Product Report www.thegreenguide.com/reports/product.mhtml?id=27

"Nanoparticles: Small Ingredients, Big Risks," Friends of the Earth, www.foe.org/camps/comm/nanotech/

International Center for Technology Assessment, www.icta.org

For practical tips on sun protection, see www.greenerpenny.com.

© 2007 National Geographic Society