Zinc Oxide Sunscreen, Nanoparticles & Clear Zinc

In Brief

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

All Badger sunscreens are made with either Non-Nano Zinc Oxide or Clear Zinc Oxide as their only active ingredient.

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.

Badger non nanoparticle zinc oxide sunscreen

Badger sunscreens with this logo contain uncoated non-nano zinc oxide, the same kind of zinc oxide used in calamine lotions and diaper rash creams.

Clear Zinc Oxide Sunscreen Logo

Badger sunscreens with this logo contain clear zinc oxide which has the non-whitening characteristics of nano zinc oxide and the large particle assurance of non-nano zinc oxide.

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 into pharmaceutical grade zinc oxide.

Badger Non Nano Zinc Oxide Sunscreen

What is clear zinc oxide in sunscreen?

Badger's clear zinc oxide is a specialized zinc oxide powder with high transparency and low whiteness and the safety and efficacy profile of a non-nano zinc oxide. It is made of nanoparticles that are strongly bonded together to form non-nano porous aggregate clusters. Importantly, no detectable nanoparticles exist in the final product and this clear zinc oxide meets the Haereticus Environmental Laboratory’s standard for non-nano. Although there are no US regulations prohibiting the use of a “non-nano” claim on clear zinc oxide products, and some other companies make this claim on their clear zinc oxide sunscreens, Badger believes this would be misleading to customers and we are not claiming our clear zinc oxide products are “non-nano”. This decision is in line with Australian definition of the term, which is more stringent than both the US and EU policies. You can read more about the research that Badger has conducted with Scanning Electron Microscope Imaging and Light Scatter Analysis to confirm this claim below.

Badger has been aware of this type of clear zinc oxide since 2008, but we had to be absolutely sure it was safe before we started using it. We conducted independent analyses on the ingredient and followed all the published research. After almost a decade, we now feel confident that this type of clear zinc oxide is safe for use in our sunscreen creams. It is listed as a safe and acceptable UV filter in the US and all major international markets, it meets Badger’s stringent standards for ingredient safety and efficacy, and is acceptable for use in our sunscreen products. Additionally this ingredient is compliant with the natural cosmetic standards of the Natural Products Association (USA) and ECOCERT (EU).

See below for images and particle size analysis of clear zinc oxide. Shop Clear Zinc Sunscreens

What is a nanoparticle and what is non-nano zinc oxide?

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 zinc oxide 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 do we measure zinc oxide particle size to determine nano or non-nano?

In addition to obtaining written statements from our zinc oxide manufacturers outlining the particle size ranges, we've done some independent research into our zinc oxide particle sizes using the following methods:

Scanning Electron Microcope Images of Sunscreen Zinc Oxides

We took scanning electron microscope (SEM) photographs of Badger's clear zinc oxide, Badger's non-nano zinc oxide, and a nano zinc oxide (for comparison). We thought these were pretty cool and wanted to share them with you. Notice that the first image is at lower magnification (with a 10,000 nanometer scale bar) and the other 3 images are more zoomed in (with 500 nanometer scale bars). Note, these photos were taken of the raw zinc oxide powders, not of sunscreen products.

clear zinc oxide SEM image sunscreen
clear zinc oxide SEM image sunscreen
non nano zinc oxide SEM image sunscreen
nanoparticle zinc oxide SEM image sunscreen

Visual analysis of these SEM images reveals the following:

Clear Zinc Oxide: At low magnification you can see that the product is composed of large aggregates of between about 500 and 9000 nanometers in diameter. The high magnification closeup of one of the aggregates shows smaller nanoparticles fused together into a larger particle. There do not appear to be any loose nanoparticles.

Non-Nano Zinc Oxide: This image shows that the non-nano zinc oxide contains few, if any, particles smaller than 100nm and that most particles appear to be in the 100 to 500nm range. You can also see that some of the particles appear to be stuck together into loosely formed agglomerates.

Nano Zinc Oxide: You can see that this zinc oxide powder is made of a variety of smaller particle sizes, most of which have at least one dimension that smaller than 100nm, classifying it as 'nano'. These particles are clumped together into loose agglomerates which easily break apart.


Light Scattering Analysis of Sunscreen Zinc Oxide

We hired a third party independent lab to analyze our clear and non-nano zinc oxide particles sizes via light scatter analysis using an instrument called a 'Saturn DigiSizer II'. The results do not differentiate between agglomerates/aggregates and free particles, however, they do accurately determine if there are free nano particles in the samples. Looking at the charts below, we expect that the bumps in the larger (right hand) end indicate agglomerates, or the natural sticking together of particles. Because of this we expect that the true particle sizes are somewhat lower than the averages (which include these agglomerates). Note, these data were from our actual sunscreen products, not the raw zinc oxide.

Clear Zinc Oxide results show a particle size range of 565nm to 19,000nm with an average particle size of 3400nm and no detectable nanoparticles. clear zinc oxide size distribution badger sunscreen

Non-Nano Zinc Oxide results show a particle size range of 200nm to 26,000nm with an average of 1500nm and no detectable nanoparticles. non nano zinc oxide size distribution badger sunscreen

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.

Additionally there are studies showing that very small nanoparticles (smaller than 35nm) of uncoated zinc oxide and uncoated titanium dioxide can be harmful to the environment by being toxic to marine life. The extremely small size of these particles generates oxidative stress under UV light potentially causing cellular damage to sensitive organisms such as coral or juvenile fish and invertebrates.


Why doesn't Badger use nano zinc oxide?

Many mineral sunscreens use nano sized zinc oxide because it is less whitening and therefore more aesthetically appealing than larger particle zinc oxide. Even though we believe that nanoparticle zinc oxide is safe and effective (all research has shown that particles in the size range used in sunscreens (>30nm) do not penetrate the skin and are completely safe to use in sunscreen creams and lotions), we've chosen to not use nano zinc oxide for a few reasons. Our customers have insisted that they don't want nanoparticles in our sunscreens. We've figured out a method of working with larger particle zinc oxide that allows us to use a minimal amount of zinc oxide making it less whitening than ever. We would rather not use nanoparticles if we don't need to because of their shorter record of safe use and their potential environmental concerns.


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, but this is not a concern with cream and lotion-based sunscreens. Additionally, zinc oxide can 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 Sunflower Oil, Vitamin E, Seabuckthorn Fruit Extract 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 generally 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 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.


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.

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 to 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

References:

(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

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