Zinc Oxide and titanium dioxide: Friend or Foe?

Jun 16, 2024

How safe are zinc oxide and titanium dioxide?

Are Zinc Oxide and Titanium Dioxide your friends or foe?

If you search the internet for information about good, safe sun filters, then some experts will always advise zinc oxide and titanium dioxide, in particular those based in the US. However, when it comes to zinc oxide and titanium dioxide, I have slightly mixed views about this.

Why do I have mixed views?

It is worrying to see how everyone accepts information they find on the internet - trusting a trade magazine or a person that says something or simply who shouts the loudest. Did you know what the FDA (Food and Drug Administration) in America has only approved two sun filters as safe to be used in American-made sun products? Yes, you heard correctly. Only two. And this hasn't changed since 1999! When it comes to sun protection, America is far behind other countries. But it is funny to see how everyone accepts information they find on the internet without checking the source. And American dermatologists advise zinc oxide and titanium dioxide, because they don't have access to the UV-filters we use in Europe as they haven't been approved by the FDA to be used.

If you are not living in America, why would you diminish your options?

In America there are only 16 UV-Filters that have been approved. In Europe it is now 30 UV-Filters that we can use in sun protection. In Europe, we have come along way but still we look over to the 'Big Brother' and believe that Zinc Oxide and Titanium Dioxide are our only options when it comes to UV-Filters.

But why has the FDA not approved more UV Filters since 1999?

In America, sun cream products come under the medicines Act. This means that the registering of new filters is an expensive and endless process carried out through the FDA, leaving the country trailing behind with regard to the filters which are used and advised for use. We should know better and not simply believe what we read.

How do Zinc Oxide and titanium Dioxide work?

Zinc oxide and titanium dioxide are mineral filters. At present they are the most commonly used filters and very rarely cause an allergic reaction. They are so called broad spectrum filters. That is to say they protect against UVB as well as UVA rays. Zinc oxide is superior to titanium dioxide in this; the latter is missing a small part of the UVA spectrum in its protection.

Are Zinc Oxide and titanium Dioxide natural filters?

No, these two filters are not natural and are being produced synthetically. I know many say they are natural but this is simply not accurate. And in most cases, they are also coated with a synthetic filter, a polymer.

Are they still good filters?

They are good filters, however both zinc oxide and titanium dioxide do make your skin white. They are therefore not good to use in their original state, unless you prefer to look like a geisha. Manufacturers have found a solution for this. By breaking down the active substances into microscopic particles the cream becomes more transparent. This process is called nanotechnology, and is controversial.

What is Nanotechnology?

Simply put, one nanoparticle is not the same as another. The effectiveness and safety of nanoparticles directly relate to properties such as the ability to mix, the reaction in sunlight such as the generating of free radicals, the nature of the material, the exact size, weight and shape, the effect on the cell and the ability of the body to break it down. All of these properties determine the ultimate action and the effect in the body. You can compare it with a raindrop or a small stone on your car windscreen; the same size but with a very different impact.

Another point you should realise about titanium oxide and zinc oxide is that when exposed to sunlight they form free radicals. I am going to tell you more about these and other (negative) effects of zinc oxide and titanium dioxide (also described in their chemical abbreviation form ZnO and TiO2) below so that you can decide for yourself if you want to apply this substance onto your skin.

Why do these two filters form free radicals?

Zinc oxide and titanium dioxide are known photocatalysts, meaning that the substances can form free radicals as soon as they come into contact with sunlight. And those free radicals can damage your cells and DNA, most definitely if you have an insufficient amount of antioxidants in your skin to eliminate them. This applies to both the ordinary particles and the nano version, and titanium dioxide appears to be slightly worse than zinc oxide. The problem is partly solved by the use of coated zinc oxide and titanium particles. A clever manufacturer who keeps their products up to date and doesn’t mind paying a little more for ingredients will use this. In case someone is wondering why sometimes sunscreen is more expensive than others. YES! There is a HUGE difference which ingredient from which manufacturer one is using. And there is a difference in raw material prices. Quality is more expensive! I appreciate that this is not always clear to the consumer. You can always check with the supplier if coating has been used or nano-particles have been used if it isn't clearly stated on the packaging.

The question of the day: do nanoparticles of zinc oxide and titanium dioxide penetrate the skin?

Several studies have shown that both sun filters in nano form penetrate into the skin no further than the stratum corneum (the outermost layer of the skin) – that is on a healthy, undamaged skin (i.e. these studies 1, 2, 3, 4, 5). However, in 2016 a study found that, in nano form, titanium dioxide can penetrate into the dermis. I appreciate this study is a little older. Nano-zinc oxide penetrates no further than the epidermis (i.e. these studies 1, 2, 3, 4). That was recently confirmed again in a study whereby subjects applied a cream, containing zinc oxide, onto the skin twice a day for five consecutive days.

However, the penetration is not the greatest risk. As toxicologists see the greatest risk by the inhalation of the nano particles titanium dioxide and zinc oxide. According to the International Agency for Research into Carcinogenic Substances, titanium dioxide can be carcinogenic when inhaled in high doses and it is therefore better to avoid using sunscreens with these particles in spray and powder forms. I am shocked in how many sprays and powders titanium dioxide is being used. Unknowingly for the consumer that it is carcinogenic.

Are these two filters reef-friendly?

I could write a whole blog on this subject; the mass use of sunscreen products is an environmental disaster. Oxybenzone for example is notorious, this sun filter has already turned many corals into powder! But there is also something to say about zinc oxide and titanium dioxide, and again titanium dioxide comes out worse than zinc oxide. (for example in these studies 1, 2) The negative effect on the environment is mainly due to the fact that these substances can form free radicals. The uncoated version especially causes problems. It is reckless for any brand to use titanium dioxide in powder form or spray.

Which Mineral filter is banned in Europe?

Only recently, as little as two years ago in 2022, titanium dioxide has been banned in Europe to be used in foods as a food colourant. Titanium dioxide is a white colourant and hence it provides an even more white cast when applied onto the skin. It will only be a matter of time, till titanium dioxide will be banned from skincare products as well.

Do Zinc oxide and titanium dioxide leave a white cast?

Don’t be fooled, a cream which is translucent or quite translucent, always uses nano particles, even if the manufacturer doesn’t mention this. Organic brands also make use of it; and this is also acceptable in American products. It doesn’t have to be a problem at all, certainly not with coated nano particles zinc oxide, but if you would rather not, then check with the supplier. With regard to the environment, if you are swimming in a coral area, think about wearing sun protective clothing instead. Every little bit helps.

My advice

As you can read, I am not a big fan of these two filters. In particular titanium dioxide is scoring in my books low to the point that is makes me angry when I see brands using it in their products and stating in the same sentence "high quality" "safe" and "good for your skin health and environment". But I can see that there is a need and requirement for mineral-based sunscreen. But zinc oxide only.

My conclusion: If, for instance, you are allergic to most sunscreen products (first check that you don’t have a sun allergy) then a mineral filter based sunscreen is the option for you. My suggestion, then, is to use a cream with a zinc oxide base and steer away from titanium dioxide.

One last tip! Make sure that you have a good supply of antioxidants in your skin. Always eat plenty of fruit and vegetables and apply a cream with antioxidants and ideally also prior to your sunscreen. Then you will reduce the risk of free radicals damaging your skin.

I hope you found this helpful. And if you have any questions, please feel free to reach out.