Sun exposure is the most preventable risk factor for skin cancer. Sun protection should really begin on day one. So while babies under the age of 6 months should not have sunscreens applied to their skin, protective measures such as seeking shade and dressing the infants in appropriate clothing are a must. Above 6 months, everyone should apply a sunscreen every single day, regardless of season, to sun-exposed areas, whether more time is being spent indoors or out.
Beginning next month, new labeling guidelines from the Food and Drug Administration (FDA) for sunscreens will go into effect that may make benefits and protection levels clearer to consumers. But these new requirements fall short in some areas, such as defining the effectiveness and safety of spray sunscreens and indicating the use of nanoparticles in these products.
In June 2011, the FDA issued a final ruling on sunscreens, specifically focusing on labeling and on standardizing the testing requirements a manufacturer needs to meet to use specific language, such as “broad spectrum” or “prevents skin cancer,” on sunscreen package labels.
Furthermore, terms such as “sweatproof” or “waterproof” were abolished, replaced by “water resistant,” which indicates that a sunscreen is effective after being in water up to 40 minutes.
One critical issue still needs to be addressed: the safety of nanotechnology in sunscreens. Nanotechnology is the purposeful development, investigation, manipulation, exploration and translation of materials existing at the nanometer (nm) level (one billionth of a meter). One nm is 100,000 times smaller than the width of a human hair.
Nanotechnology is a rapidly growing field with enormous implications for consumers, patients and society. Matter made at the nano level possesses unique properties, allowing for the creation of substances with advantages over their macroscopic precursors. These advantages include specificity, adaptability and targeted delivery of active ingredients.
Nanoparticles are now used in commonly available sunscreens, making these formulations more effective at blocking rays and more aesthetically pleasing. Zinc oxide and titanium dioxide, long-standing and highly effective mineral sun-blocking agents, are thick and bright white at the micro and macro levels. Nano-sized titanium and zinc can be made so small as to all but vanish when applied to the skin.
So what’s the concern? Both zinc oxide and titanium dioxide are known photocatalysts, which means that they generate free radicals, or reactive oxygen species (ROS), when exposed to ultraviolet radiation. ROS are chemically reactive molecules that have the potential to do significant damage to proteins, DNA, RNA and fats within cells. However, these sunscreen ingredients have been used for decades in their bulk size, and are considered perfectly safe. Therefore, concern arises only if these particles penetrate the skin and are taken up by cells. The studies that have received the most negative reactions regarding nano-level particles have been based on bench research demonstrating ROS generation by raw, unmodified materials, which are not commonly used in consumer products; also, these studies were performed on cells, not in animals or humans.
All evidence to date suggests that these tiny particles do not penetrate any deeper than the top layers of the skin, and should not pose any risk. Furthermore, many if not most commercial nanosunscreens are modified to prevent deep penetration and limit reactivity to enhance their safety, unlike those materials tested in the lab. However, the FDA has provided little guidance on how to separate safe use from potentially harmful use, as these ingredients come in various forms (liquid, stick or packed or loose powder) and various concentrations.
At the “suggestion” of several nonprofit environmental groups such as Friends of the Earth, the FDA has issued a draft guidance noting its initial efforts to investigate this matter and welcoming public suggestions regarding how to do so.
Clearly, more-definitive guidance is needed.
One big issue is the need for clear labeling so consumers can make informed choices. Foods may be labeled “GMO” to denote genetically modified ingredients, or say “contains trans fats” to alert consumers to the presence of hydrogenated oils, but sunscreens are not required by law to state that they contain nanoparticles. Even savvy consumers reading ingredient lists won’t be able to tell for certain because particle sizes are not required to be listed on labels. A label may say “titanium dioxide” or “zinc oxide,” but the product’s manufacturer is not required to specify that these ingredients are “nano-sized.” The FDA reports in its draft guidance that it agrees with the scientific consensus that nano-sized materials have the capacity to be fundamentally different, and therefore might result not only in new products and devices, but also in new risks, necessitating innovative testing. For now, however, the FDA has taken only a voluntary, not a mandatory, approach to regulation.
There is no question that sunscreen is part of the best defense against skin cancer. Nanotechnology is currently being employed to improve the feel, and thus encourage the use, of well-established and effective sun-blocking agents. All available data, in clinical study settings as well as in some real-world settings such as after multiple applications and application to sunburned skin, suggest that nanosunscreen agents do not penetrate the skin. However, it is important for the FDA to provide guidelines to define the safe use of these ingredients by manufacturers and consumers alike. Not all nanoparticles are created equal, and standards must be set. And full transparency in labeling is important to allow consumers to make informed decisions when choosing sunscreens.