Ah, summer! It’s a great time to be outdoors, enjoying the warm, sunny weather. Before you go outside, be sure to grab your sunscreen, that essential product that protects against skin cancer and sun damage. But which kind of sunscreen is best? There is a mesmerizing array of sunscreen options, but for our purposes let’s limit the question to one: Nano or not nano?
We all recall the white noses of the beach lifeguards. The zinc oxide or titanium dioxide in these nose-protecting potions form a thick, white barrier that blocks damaging ultraviolet (UV) radiation by reflecting and scattering light. These days, nanoscale titanium dioxide and zinc oxide are increasingly popular sunscreen ingredients, as they provide a UV barrier but are nearly transparent.
One of the concerns raised by using nanoscale titanium dioxide and zinc oxide in sunscreens is the dearth of safety data on potential health that could arise from applying nanoscale minerals to the skin on a daily basis – including to skin that may be damaged (e.g., already sunburned). The sunscreens are then released into lakes or oceans, or washed down the drain with the bathwater with unknown environmental effects.
First, it must be pointed out that the same concern – lack of adequate safety data — applies to many of the traditional chemical sunscreen ingredients. Nanoscale materials may require additional scrutiny, however, because their properties can differ from their bulk-scale counterparts.
Some environmental advocacy groups, such as Friends of the Earth, citing the lack of safety data and unclear product labeling, have called on the Food and Drug Administration to require more testing and exercise better regulatory oversight. Meanwhile, because of these problems, Friends of the Earth ranks nanomaterial-containing sunscreens among the worst.
In contrast, Environmental Working Group, while recognizing the critical data gaps, generally ranks sunscreens with nanoscale zinc and titanium oxides as having a lower hazard than those containing the most common active ingredients, such as oxybenzone and octyl methoxycinnamate. As summarized by EWG, these non-nano ingredients are linked to a number of health hazards, including cancer and developmental and reproductive toxicity. EWG argues that, in addition to being more effective, sunscreens made with nanoscale zinc and titanium oxides generally contain fewer hazardous ingredients overall.
A range of opinions regarding nanoscale zinc and titanium oxides are available on popular websites, including Treehugger, Huffington Post, and the Green Guide. The one thing everyone seems to agree on is that the lack of adequate safety data makes it hard to draw definitive conclusions regarding the safety of nanomaterials in sunscreens.
The US Food and Drug Administration will soon be updating its “Sunscreen Monograph” – the regulatory document that specifies what chemicals can be used in sunscreen formulations, and in what concentrations. This is a clear opportunity for FDA to be more proactive, by requiring that more data be developed to demonstrate sunscreen ingredient safety, and that more data be made publicly available so that consumers can make better-informed choices.
In the meantime, if we are to avoid the real harm that over-exposure to the sun can cause, we have little choice but to select among sunscreen formulations — all of which contain insufficiently tested ingredients — hoping that whatever we do is better than the burn.