Zinc Oxide Sunscreen & Nanoparticles

In Brief

Zinc oxide is a powdered mineral that sits on top of the skin, scattering, reflecting, and absorbing UVA & UVB rays.

Although zinc oxide is the safest and most effective active sunscreen ingredient, the best protection from the sun is to seek shade and cover up with clothes and a hat.

All Badger sunscreens use pharmaceutical grade uncoated Non-Nano Zinc Oxide as their only active ingredient.

Badger non nanoparticle zinc oxide sunscreen

Badger uses uncoated non-nano zinc oxide as the only active ingredient in all our sunscreens. This is the same kind of zinc oxide used in calamine lotions and diaper rash creams.

What is zinc oxide and where does Badger's come from?

Zinc oxide is the metal zinc that has been oxidized. The chemical formula is ZnO, 1 zinc atom and 1 oxygen atom held together by an ionic bond. Zinc oxide does occur in nature as the mineral zincite, but it is quite rare and commercially unavailable. Badger's zinc oxide is manufactured using mined zinc which is then purified via distillation into pharmaceutical grade zinc oxide. Our zinc oxide powder is a 'nature identical mineral', in other words, it is the exact same thing that you would find in nature but it is made in a laboratory.

Badger sunscreens are often called 'chemical free sunscreens'. Isn't zinc oxide just another chemical?

The term 'chemical-free sunscreens' is commonly used to describe 'physical' or 'mineral' sunscreens, those that use the minerals zinc oxide and/or titanium dioxide as their only active ingredients. Conversely 'chemical sunscreens' use only non-mineral, or chemical, active ingredients such as oxybenzone, oxtinoxate, and octisalate.

Some people argue that every substance under the sun is either a chemical or composed of chemicals, therefore nothing can accurately be called 'chemical-free'. This is technically true, and we've stopped using the term 'chemical free' to eliminate confusion. Zinc oxide is a mineral that does not dissolve into our sunscreens and does not absorb into your skin and we consider it to be significantly different than the synthetic sunscreen chemicals that only work by absorbing into your skin. 'Chemical-free sunscreens' is a commonly used term to describe mineral sunscreens and you will probably still see others using this term to describe our sunscreens.

Badger Non Nano Zinc Oxide Sunscreen

What is a nanoparticle and what is non-nano?

A nanoparticle is a particle smaller than 100 nanometers, or 100 billionths of a meter. Defining whether a powder is non-nano or not is actually rather difficult as it is virtually impossible to ensure that a product is 100% nanoparticle free. Furthermore, many particles are not spherical in shape and thus are difficult to measure.

  • The US FDA has declined to weigh in on this controversial issue and does not currently define 'nano' or 'non-nano.’
  • In the EU, a nanomaterial is defined as “a natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1nm – 100nm." 
    • The definition is further explained in that “materials where for 50% or more of the particles in the number size distribution, one or more external dimensions are in the size range 1nm – 100nm are classified as nanomaterials.”
    • This means that if < 50% of the total particles in the distribution, including aggregates and agglomerates, are within the 1-100nm range in any dimension the particles would be considered non-nano.
  • Australia defines a nanomaterial as an “industrial material intentionally produced, manufactured, or engineered to have unique properties or specific composition at the nanoscale, that is a size range typically between 1nm and 100nm, and is either a nano-object (i.e., that is confined in one, two, or three dimensions at the nanoscale) or is nanostructured (i.e., having an internal or surface structure at the nanoscale).”
    • The definition continues to state that these nanomaterials must exhibit unique unknown properties. Furthermore, if “a material includes 10% or more number of particles that meet the above definition (size, unique properties, intentionally produced),” then this would be considered a nanomaterial.
    • This means that if either of the following are true, the zinc oxide material is considered to be non-nano: a) < 10% of primary particle size is within the 1- 100nm range in any dimension; OR b) < 10% the particles exhibit unique properties

The key element of the Australian definition of nanomaterials is that these particles should display novel characteristics when compared to larger “bulk” particles of the same material. To date, we have not observed any new behavior in the zinc oxide when manufacturing our sunscreens. Badger’s zinc oxide has exhibited the same characteristics as bulk zinc oxide, and so b) is true. According to our SEM micrographs, sedimentation analysis, surface area calculations, and dynamic light scattering studies, our primary particle size is greater than 100nm, so Badger zinc oxide also fulfills the requirement in a) above.

Since the Australian definition of nanomaterials is more stringent than the EU definition (with which we comply), we have decided to adopt Australia’s policies when choosing minerals for our sunscreens. By following these regulations, we can ensure that people around the world can use our sunscreen safely and effectively, and that Badger’s claims are backed up by scientific data collected from independent labs..

How does Badger substantiate our non-nano claim?

We used four methods of testing in order to verify our non-nano claim (see below). Additionally, we have a written statement from the zinc oxide manufacturer outlining how the process used to create our zinc oxide differs from that needed to make nanoparticle zinc oxide. Our zinc oxide manufacturer produces three cosmetic grades of zinc oxide; USP1 (the pharmaceutical non nano grade that Badger uses), a micronized (slightly smaller) grade, and a nanoparticle grade. They use the USP1 grade as the starting feed material for the other two grades, which are created through additional processing.

1. Scanning Electron Micrographs (see images below)

We took scanning electron microscope (SEM) images of our zinc oxide, and of three other types of zinc oxide commonly used in other sunscreens. We found the images fascinating and thought you might like to see what zinc oxide particles look like under such powerful magnification. The manufacturer of Badger's zinc oxide claims it is: 'solid particle non-nano zinc oxide' and visual analysis of the SEM results show <10% free particles are below 100nm (and all particles appear greater than 70nm.) The manufacturer's claims of the other zinc oxides are printed above the images, they are 'non-nano clear zinc oxide', 'micronized zinc oxide', and 'nanoparticle zinc oxide'. All 4 of the SEM images are presented at the same s cale (see 500nm scale bar on each) for comparison.

Scanning Electron Microscope Images of Four Sunscreen Zinc Oxides
Badger non-nano zinc oxide sunscreens photo
non-nano clear zinc oxide sunscreens photo
micronized zinc oxide sunscreens photo
nanoparticle zinc oxide sunscreens photo

2. Sedimentation Analysis

The particle size of our zinc oxide was also determined in a lab using a Sedigraph, or a device that measures particle settling rate and calculates particle size using Stokes Law. These results showed a median particle size of 293nm.

3. Surface Area Calculations

The manufacturer of our zinc oxide also used surface area calculations to estimate the particle size of our zinc oxide. They found that the mean surface particle diameter was 120nm. This number is not fully accurate as it is based on the assumption of a solid sphere, whereas the actual particles are irregular in shape. Many sunscreen manufacturers will use this single number to validate their non-nano claim, however, we feel that particle size should be measured in a distribution graph with a minimum, maximum, and mean for the greatest accuracy. See Light Scattering Analysis (below).

4. Light Scattering Analysis (see image below)

Light Scatter Analysis to determine our zinc oxide particle size was conducted by a third party independent lab. The results do not differentiate between agglomerated particles and free particles, however, they do accurately determine whether there are nano particles in the sample.

Light Scatter Analysis Results: <1% free particles found below 100nm – all particles found to be greater than 70nm We expect that the bump in the larger (right hand) end of this logarithmic graph indicates clumping, or the natural sticking together of particles. So, even though the test results tell us that the mean particle size is 6879nm, when we exclude these 'clumped' particles a visual analysis indicates that the mean particle size may be closer to 600nm.

Badger sunscreen Zinc Oxide size distribution

What is the zinc oxide nanoparticle controversy about anyway?

The nanoparticle controversy stems from the potential health risks caused by nanoparticles if they were to enter the human body. When a substance is so small that it is measured in nanometers (1 to 100 billionths of a meter), the surface area to volume ratio is so great that the actual properties of the substance may change. One comprehensive review of the scientific literature(1) shows that nano-particles of zinc oxide greater than 30nm do not exhibit properties any different than those of larger non-nano sized particles. Science overwhelmingly shows that particles of zinc oxide greater than 30nm, when applied to the skin in a lotion or cream based product, do not get absorbed into the body, do not enter the bloodstream, and are not a threat to human health.(1)(2)(3)(4)(5) There are no studies showing that nanoparticles of zinc oxide can penetrate healthy human skin, whereas chemical sunscreen ingredients, which are molecular in size and thus significantly smaller than nanoparticles, are designed to be absorbed into the skin, and thereby they can get into the blood. The biggest concern with nanoparticles in cosmetics is the threat of inhalation when they are used in powders and sprays. This is not a concern when the zinc oxide is dispersed in a cream or lotion base. Even the Environmental Working Group recommends the use of nano-sized mineral sunscreens over chemical sunscreens.

Why does Badger use non-nano zinc oxide?

Prior to 2011 we used ‘micronized’ zinc oxide (see photo above) which had a particle size ranging from 70nm to 300nm, in which about 20% of the particles were smaller than 100nm. We felt this zinc oxide offered excellent UVA and UVB protection, was relatively non-whitening, and was totally safe (all scientific literature concluded that particles in this size range do not penetrate the skin and are completely safe to use in sunscreen creams and lotions).We switched over to totally non-nano zinc oxide for two reasons. First, many of our customers asked us to stop using nanoparticles in our sunscreens. Second, we discovered a new way of working with larger particle zinc oxide that makes our sunscreens just as effective while using less zinc oxide. Our sunscreens are now even less whitening than when we used the smaller particles.

What does uncoated zinc oxide mean?

Many sunscreens use zinc oxide particles that have been coated with an inert substance. The reasons for coating zinc oxide particles are usually to make them less reactive (see below), and to make them easier to mix with the other ingredients. Badger used coated zinc oxide for years, until we found a better way to mix uncoated zinc oxide into our base then we switched to using larger particles (which are less reactive than smaller particles). The zinc oxide we now use in all our sunscreens is uncoated pharmaceutical grade zinc oxide, the same kind used in calamine lotion and diaper rash cream. We know that uncoated zinc oxide is somewhat more photo-reactive than coated zinc oxide, but we believe that this is not a health risk. Read details in the next section.

Are there any health risks with zinc oxide?

Zinc oxide, like most powders, can be a health risk if inhaled. This is not a concern with zinc oxide in cream and lotion-based sunscreens. Zinc oxide can also be photo-reactive, meaning that UV exposure can generate reactive oxygen species, or free radicals, which can damage living cells. This too is not a concern with the zinc oxide in our sunscreens because:

  1. The rate of reactivity is still very low compared to that of titanium dioxide, nanoparticle zinc oxide, and many other chemical sunscreen actives.(6)
  2. Zinc oxide sits on the outer, dead, layer of skin, and any free radicals generated will not affect living cells below.(4)
  3. Our inactive ingredients such as Organic Olive Oil, Sunflower Oil, Vitamin E, and more provide powerful antioxidants which help scavenge, or absorb, free radicals.

How does zinc oxide work as a sunscreen?

Zinc oxide is one of only 17 active ingredients currently approved by the FDA for use in sunscreens. Upon application, zinc oxide particles sit on the outermost layer of your skin, the stratum corneum, where they scatter, absorb, and reflect ultraviolet radiation, protecting your living skin below. Zinc oxide is unique among sunscreen ingredients in that it is truly a broad-spectrum blocker, protecting from UVA, UVB, and even UVC. Titanium dioxide is another mineral active ingredient you may see in other brands' sunscreens. While it protects from UVB rays very well it does not protect from UVA as well as zinc oxide does.

Why does Badger use zinc oxide as the only active ingredient?

We've determined that zinc oxide is the safest, most effective active sunscreen ingredient available. It also stands alone in that it is a truly effective, single-ingredient, broad spectrum blocker, meaning that it protects from UVA, UVB, and even UVC rays. It also has a time tested safety record having been used in other topical drugs such as calamine lotion and diaper cream for a long time.

Why doesn't every sunscreen just use minerals such as zinc oxide and titanium dioxide instead of chemicals?

You have to use a lot of zinc oxide and/or titanium dioxide to get an SPF 30. This makes these mineral sunscreens expensive and whitening, so not everyone likes it. Have you noticed how much less expensive chemical based sunscreens are compared to mineral sunscreens? We feel that peace of mind is worth the additional cost and a little whitening on the skin.

What does Badger think about titanium dioxide?

We think that titanium dioxide is safe and effective for protection against UVB (and some UVA) rays, however, titanium dioxide should always be used in combination with zinc oxide to attain true broad spectrum protection. Truthfully, we think titanium dioxide received an unfair reputation when a 2011 Swiss study(7) likened titanium dioxide to asbestos. The study was referring to toxicity when inhaled, which is not a threat with sunscreen creams. The media did not seem to understand this and wrote several alarmist stories about the dangers of sunscreens containing titanium dioxide.

What does Badger think about chemical sunscreens?

We don't like them. We are concerned about the potential toxic effects of the chemicals when they enter the body. Oxybenzone, for example, is in about 60% of sunscreens sold in the US. The US Center for Disease Control found that 97% of Americans have oxybenzone in their blood(8). This ingredient has been shown to disrupt normal hormone functions and some health professionals are recommending that products containing this ingredient not be used on babies and kids. We are particularly concerned with the 'continuous spray' chemical sunscreens that are becoming so popular, mainly because of the risk of inhalation.

Wrap Up

Here at Badger we, and most natural health advocates, including Dr. Andrew Weil(9), believe that zinc oxide sunscreens are better for your body than either chemical based sunscreens or exposing your skin to the sun without sunscreen. We follow all of the latest sunscreen research closely, and we remain convinced that our sunscreens at Badger are the most effective and the safest for human health and for the environment (see our page about Sunscreens and Coral Reefs). The best protection from the sun is to stay in the shade or wear protective clothing and a hat. But if you're going expose your skin to the sun you should protect it, and a zinc oxide sunscreen is the safest and most effective means to that end.

Badger Sunscreen Products


(1) Towards a Definition of Inorganic Nanoparticles from an Environmental, Health and Safety Perspective. Auffan et. al. Nature Nanotechnology Sept. 13, 2009.
(2) Environmental Working Group's Sunscreen Guide
(3) Germany's Federal Institute for Risk Assessment (English website)
(4) Australian Government, Review of Scientific Literature
(5) FDAs Nanotechnology Scientific Research Website
(6) Smijs T. & Pavel, S. Titanium Dioxide and Zinc Oxide Nanoparticles in Sunscreens: Focus on Their Safety and Effectiveness; Nanotechnology, Science and Applications 2011:4 95–112.
(7) Amir S., Yazdi, et al. Nanoparticles activate the NLR pyrin domain containing 3 (Nlrp3) inflammasome and cause pulmonary inflammation through release of IL-1 and IL-1β PNAS 2010 107: 19449-19454.
(8) Calafat AM, Wong L-Y, Ye X, Reidy JA, Needham LL 2008. Concentrations of the Sunscreen Agent Benzophenone-3 in Residents of the United States: National Health and Nutrition Examination Survey 2003–2004. Environ Health Perspect 116:893-897
(9) Dr. Andrew Weil M.D.'s Question and Answer Library

Links to some helpful websites about sun protection.

The Environmental Working Group's Sunscreen Guide
Sunscreen: The Burning Facts – Document by the Environmental Protection Agency
American Academy of Dermatology's Facts About Sunscreens