Nanotechnology in Your Sunscreen: Doing More Harm than Good?

While soaking in the sunshine may feel good, and you may have heard about solar ultraviolet (UV) radiation harm, you may not be aware of what’s in your sunscreen. Lee Hong explored the benefits of sunscreen in his post on The Pipettepen, and today, we dive deeper into a smaller world – the nanotechnology in our sunscreen.

The two minerals available to sunscreen in form of nanosized particles (NPs) are zinc oxide (ZnO) and titanium dioxide (TiO2). They are less than 1/1000th the size of a human hair. Bulkier minerals in traditional sunscreen reflect visible light, making it opaque and cakey on your skin. NPs on the other side, scatter light instead of reflecting it, resulting in a disappearing and lighter feeling sunscreen.

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Traditional sunscreens block out UV rays but many with ghostly white color. Nanotechnology make them disappear on your face!

While the resulting nanoproduct can be a big help, people have raised concerns over the safety of NPs-based cosmetic sunscreens. With their smaller size, NPs could in theory be absorbed into the skin at a higher level than their bulkier counterparts. The real question to ask is if these tiny particles are more harmful if absorbed, than good in protecting us from UV rays.

Studies are divided about whether NPs can pass through the skin. A few reassuring words from Paul Wright, a toxicology researcher at RMIT University, “There’s a negligible penetration of sunscreen particles,” as he told The Guardian, “They don’t get past the outermost dead layer of human skin cells.” In 2017, the Australian Therapeutic Goods Administration (TGA) published its review that NPs absorption is unlikely, based on both via in-vitro (i.e. studies using isolated skin cells) and in-vivo (i.e. studies on live skin tissue) studies. It appears that we are in a safe zone!

Other scientists have tested on the toxicity of these tiny metal oxides when exposed to UV light, simulating the real-life scenario for use of sunscreens. Their results indicated that the metal oxides may generate reactive free-radical species, leading to cancer due to DNA damage. However, this alarming impact on human health depends on whether NPs in sunscreen are absorbed into our skin. Providing some comfort, research associate Simon James at the Australian Synchrotron told to The Guardian that “Our study demonstrates that the human immune system has the right equipment to remove any nanoparticles that somehow make it through the skin, assuming some do at all.” Their work showed that human natural defenses can gather and destroy ZnO nanoparticles. Moreover, sunscreen manufacturers utilize surface coatings to improve transparent effect and as a result, the coated components can essentially reduce toxicity from lessen reactivity to UV lights.

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It’s not a bad idea shielding your skin from burning sun with an umbrella’s shade whenever you are up for outdoor activities.

With the increased popularity of the nanotech-based products, another concern is noxious effects caused by inhalation of NPs. The Environmental Working Group (EWG), based out of Washington, D. C., announced a warning to refrain from spray sunscreen and loose powder cosmetics containing ZnO or TiO2 particles. The lungs have difficulty removing small particles and thus end up with organ damage possibly in the same way that air pollution is linked to lung cancer.

Evidence suggests there is more harm from skipping the sunscreen than exposing your skin to nanoparticles, but, if you’re not comfortable with these tiny oxides, UV protection umbrellas are another option!

Peer edited by Bailey DeBarmore.

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