In August, the FDA proposed a rule that would amend the final monograph for over-the-counter sunscreen products and specifically solicits comment on “the safety and effectiveness of sunscreen ingredients formulated in particle sizes as small as a few nanometers.” The debate over sunscreens containing nanoparticles-mainly zinc or titanium oxides-has been contentious of late, with NGOs, trade organizations, consumer advocacy groups, and manufacturers weighing in. The discussions have focused on the potential hazards of using these products and have not considered their benefits-which in this case includes protection from the known risks of skin cancer. In other words, the debate has focused on only half the story.
Overexposure to solar ultraviolet (UV) radiation has significant public health implications. The World Health Organization (WHO) estimates that 60,000 deaths annually are caused by cancers resulting from UV exposure and a staggering 1.5 million disability-adjusted lifeyears (DALYs)-a measure of the loss of full functioning-are lost each year to sun-related disease. That is a tremendous hit to productivity, earning potential, and quality of life.
In Australia, whose latitude gives residents significant solar exposure and which has a population high in susceptible skin types, skin cancer is a concern. With more than 1,000 people treated every day for this disease, the expense to the Australian healthcare system is estimated at more than $300 million annually-the highest cost for all cancers treated in the country. In the U.S., the South has very high rates of skin cancer for similar geographical and demographical reasons as Australia.
Sunscreen is pervasive in literature as a key component of preventing overexposure and is recommended by the American Cancer Society, the American Academy of Pediatrics, and the Australian Department of Health and Aging. The question for consumers, then, is which sunscreen is the safest and most-effective? The July 2007 Consumer Reports examined this topic by looking at only 19 sunscreens and then unequivocally declaring that there is “no correlation between [the presence of nano-particles] and sun protection.” Its study did not investigate in depth or rank the health impact of nanoparticles in the products. By contrast, the Environmental Working Group (EWG) recently developed a more comprehensive database of sunscreens and compared their efficacy and safety. Research took 18 months and examined 800 products and nearly 400 peer-reviewed studies. It found that 84% of brand-name sunscreens over SPF 15 are ineffective, while all but one of the top-50 “Best,” ranked by safety to consumers and light-blocking efficacy, contained nanoscale particles. In other words, sunscreens containing nanoparticles were overwhelmingly correlated with the best combination of efficacy and consumer safety.
Remedies and risks
Against these findings consumers should weigh the potential risks of nanotechnology: whether nanoparticles from the sunscreen penetrate the skin and enter the body, and whether nano-particles that do enter the body cause harm. On the issue of penetration, the majority of research shows that nanoparticles from sunscreens most likely do not enter the body. Some of the field’s foremost researchers, including Tilman Butz and Joke Bouwstra of the University of Leiden (the Netherlands), and Michael Roberts from Queensland University (Australia), have concluded that nanoparticles applied topically in cosmetic formulations do not penetrate the living part of the skin. This is for good reason: Sunscreens are designed stay on top of the skin where they will provide protection from sunlight.
On the issue of toxicity, no data definitively indicates that the nanoscale components of sunscreens, as they are used by most consumers, cause harm. Much of the data collected about these components has been based on inhalation studies or injection into cells, and not applications to skin-so the data is not entirely valid in relation to sunscreens. Another issue is that to be truly toxic, a certain threshold amount of the nanoscale materials would have to get into our body. Since the active nano-ingredients in sunscreens have a hard time getting through the skin at all, chances are slim that an amount sufficient to cause trouble will do so.
Nanoparticles are a part of our environment, and we’ve been exposed to them forever. The risk they pose is largely undefined, and there is no evidence that this risk is acute. The sun’s UV rays are also a part of our environment, and the risk they pose is very real and deadly for thousands every year. What a pity it would be if consumers were unable to buy nano-enabled sunscreens or shied away from them because of alarmists who presented only half of the debate.
Aatish Salvi is vice president of the NanoBusiness Alliance. He can be reached at firstname.lastname@example.org.