What You Need To Know About Sunscreen Nanoparticles

By Jasmine Hanner
May 08, 2018

As seen on www.runnerclick.com

Surprisingly, nanotechnology is nothing new under the sun. The earliest use of nanotechnology can be said to reach as far back as 600 A.D. when the smiths of Damascus (modern day Syria) forged their sabers with a type of metal called wootz. When researchers dissolved part of a Damascan sword in hydrochloric acid, nanotubes (a type of nanoparticle) of the mineral cementite were revealed. In the modern world, when researching the topic of nanoparticles in cosmetic products to determine whether or not they are harmful, there are many studies that contain phrases such as “it’s unlikely that…”, “generally…” or “the study could not determine…”.

What is a nanoparticle?

At a size smaller than 100 nanometers, nanoparticles are invisible to the human eye. They come in various different forms, such as nanocrystals or nanotubes; can occur naturally or be produced by nanotechnology; and are used in many different applications and industries such as medicine, physics, optics, and electronics. Nanoparticles are of great interest to science because they are a link between bulk materials (the world visible to your eyes) and atomic or molecular structures (the world that is invisible to your eyes).

Sunscreens vs sunblocks

The definitions are easy to remember, as the names reflect their meaning. Sunscreens ‘screen’ the sun through their finer particles by absorbing the harmful UVA (Ultraviolet Aging) sun rays. Sunblocks literally ‘block’ the sun with their larger particles, and reflect or scatter the UVB (Ultraviolet Burning) sun rays. In order to protect against both UVA and UVB rays, many sunscreen products today are a broad spectrum combination of sunscreen and sunblock.

Are nanoparticles bad for you?

The current public debate about the safety of nanotechnology and nanoparticles in sunscreen, in particular, started about ten years ago. In 2009, Friends of the Earth (FOE), an Australian environmental activist association, began a campaign to bring attention to the fact that nanoparticles in sunscreens could have adverse effects on the human body. FOE is now well-known for publicizing the potential issues of nanoparticles in cosmetic products. Their view is that micronizing metal particles, like zinc oxide and titanium dioxide, may be harmful if the nanoparticles can penetrate the skin barrier and enter the bloodstream. In May of 2011, The Australian Education Union formally recommended that “all education workspaces refrain from using sunscreens that contain nanoparticles”, and furthermore that sunscreens used by members on children should be selected from those “highlighted in the Safe Sunshine Guide produced by Friends of the Earth”.

FOE succeeded in eliciting change in product labeling through the campaign, and some Australian manufacturers were required to correct their sunscreen labels by removing a “non-nano” label where it was not applicable. Marketing a sunscreen as “non-nano” can be a misleading claim in some cases as many sunscreens today do contain nanoparticles. For example, when you purchase a “clear zinc” sunscreen or any other sunscreen that is invisible after being applied, the particles have often been micronized to nano size to achieve the transparent appearance.

Particle sizes can vary from manufacturer to product to country, but much of this information is not provided to the public in the United States. This can make it difficult for a U.S. consumer to determine the extent of any potential harm when choosing which sunscreen to apply before heading out for a run.

Most sunscreens and sunblocks are made with the active ingredients of titanium dioxide and zinc oxide. These inorganic metal compounds have photocatalytic properties at the nanoparticle level (this does not apply to ‘visible’ mineral sunblocks, like the zinc sunblock that shows white on your skin). This is because nanoparticles have a larger surface-to-mass ratio than larger particles, and this causes them to be more affected by UV rays. When this occurs, the nanoparticles react with UV radiation and water to generate free radicals.

Free radicals? What are they?

The best description is a simple one. Free radicals are molecules that are each missing an electron. They basically go on a rampage through your body looking for their “missing piece”, and cause a range of damage along the way known as oxidative stress. Free radicals destroy cells and can cause diseases, lowered immune system and signs of aging such as wrinkling or sagging skin. The reason that antioxidants are so important is because they help fight oxidative stress by ‘lending’ that missing electron to the free radical, essentially putting it out of order.

Sunscreen manufacturers over time have developed methods of coating the zinc oxide and titanium dioxide nanoparticles to reduce their photocatalytic properties. This, in turn, reduces the potential of cytotoxicity by preventing their bond to human cells. However, these coatings are not always stable and their use is not always regulated, so the result is not guaranteed.

So what should I do?

The general consensus of the public health community until recent years has been:

  1. Excessive exposure to sunlight can cause skin cancer.

  2. Sunscreens and sunblocks can reduce the incidence of squamous cell carcinoma and help prevent skin cancers like melanoma.

  3. Therefore, applying any sunscreen or sunblock before heading outside for any extended period of time is preferable to none.

A 2016 study by the Royal Australian Commission of General Practitioners summed it up as, “Current evidence suggests that the likelihood of harm from the use of sunscreens containing nanoparticles is low; however, further research into this area is required.”

But without a definite answer, it seems reasonable that if there’s any chance of harm with long-term use, cosmetic labeling should at least reflect that. Until that happens, you can refer to many online resources such as Friends of the Earth to see a list of sunscreens and sunblocks that do not contain nanoparticles. Other websites like Sustainable Living 808, a Hawaiian based sustainable science website, note other benefits to carefully choosing your sunscreen – like saving the coral reefs in our oceans (some sunscreen ingredients cause coral bleaching and other harm to sea life). There are many sunscreens available that are organic, nanoparticle free, and cause no harm, in addition to sun protective clothing options, so don’t let anything deter you from protecting your skin from the sun.

Your skin is a very effective barrier, and it has to be. It’s constantly exposed to all of the elements. However, it’s also your body’s largest organ with the most exposed surface area, and this can make it a vulnerable front line. If you are consistently applying any topical solution to your skin over a long period of time, it’s worth asking questions.


  1. Alicia Wood, New Sunscreen Bill for Hawaii, Website, May 01, 2018

  2. Oncosec Immunotherapies, Sunscreen vs Sunblock, What's the Difference?, Website, Aug 03, 2018

  3. Friends of the Earth, Nanosunscreens Not Worth the Risk, Blog,

  4. Nature International Weekly Journal of Science, Sharpest Cut from Nanotube Sword, Science Journal, Nov 15, 2006

  5. Environmental Working Group (EWG), Nanoparticles in Sunscreens, Website,

  6. Penelope C. McSweeney, The safety of nanoparticles in sunscreens: An update for general practice, Study, Jun 01, 2016

Aloha, my name is Jasmine.

I'm a freelance writer, editor, and content creator based out of Maui, Hawai'i, USA.

I travel the world, write, take photos, surf, and hike!