Little is known about how nanoparticles — ultra-small particles that are so teeny that they can have different physical properties than “macro” sized particles. For example, says Consumer Reports, carbon becomes 100 times stronger than steel, aluminum turns highly explosive, and gold melts at room temperature. What do titanium dioxide or zinc oxide do? Well, whatever it is — it may be in your sunscreen without your knowledge.
Consumer Reports tested 5 sunscreens that claimed not to contain nanoparticles — and only one was actually nanoparticle-free.
Four of them, all labeled natural or organic, actually did contain nanoparticles: Aubrey Organics Natural Sun SPF 25 Green Tea Protective Sunscreen, Badger SPF 30 Sunscreen, Kiss My Face SPF 30+ Sun Screen with oat protein complex and Mexitan SPF 30 Sunscreen. Only one product—Zinka Colored Nosecoat—turned out to be actually free of the
Companies put nanoparticles in sunscreens because it makes them clear, rather than opaque, which consumers tend to prefer. Consumers Union, the organization that publishes CR, is asking the FDA to require a full safety assessment on the use of engineered nanoparticles particularly in cosmetics, sunscreens and sunblocks, and to investigate possible enforcement action to ensure accurate labeling as to the presence or absence of nanoparticles.
They also cite animal studies that suggest that titanium dioxide nanoparticles can damage the lungs. The effect of absorbing these particles through the skin is unknown.