How Mineral and Chemical Sunscreens Differ in Absorption and Safety

So Yvonne says, “Hi, Rhonda. In your August 2023 Q&A, you mentioned that titanium dioxide was toxic and that we should avoid oral consumption. I recently purchased a cream for my face that contains titanium dioxide for sunscreen. Is this harmful when applied to the skin?” Okay, so there are really two ingredients that are considered safe and effective, based on current data, for preventing sunburns and protecting against UVA and UVB radiation. Those are zinc oxide and titanium dioxide. At concentrations up to 25%, they do not permeate the skin significantly. There are also chemical sunscreens for which there are insufficient data to show effectiveness and even safety. There are 12 of them. They include avobenzone, octinoxate, octocrylene, and oxybenzone, among others. Those are the main ones you will find in some sunscreens. A lack of data showing that these chemicals are safe or effective does not mean they are unsafe. It means the FDA has not yet recognized them as safe and effective and is seeking more information on those components. There are absorption concerns with oxybenzone, octinoxate, and avobenzone because they are systemically absorbed into the body after one use. They can remain on the skin and in the blood for weeks after the last application. I find that concerning. There is also a growing body of evidence, although much of it is animal evidence.

One of the dose-related concerns is that some of these chemicals can be endocrine disruptors. These would include homosalate, avobenzone, octocrylene, and oxybenzone. Those are the ones that, again, linger in systemic circulation for weeks after one application. That is concerning in and of itself, particularly if a compound is being investigated as a potential endocrine disruptor. The European Commission’s findings in 2021 proposed limiting oxybenzone to 2.2% and homosalate to 1.4% after evaluating their safety. I would say probably the safest bet is to avoid those compounds in sunscreens, face creams, or makeup. Just try to avoid them in general because, again, they potentially linger in systemic circulation. The fact that they can linger in systemic circulation is enough to make you think, “Okay, we do not really know what these are doing.” So let’s talk about titanium dioxide. I wanted to get those other compounds out there because there are many sunscreen chemicals, and we will talk about some products in a minute. Just know that the chemical ones are the main ones being found in circulation, and that is the concern. Titanium dioxide serves as the white pigment that you find in creams and cosmetics. It is an inorganic ultraviolet filter used mainly in sunscreens, and it filters out UVB radiation. There are different particle sizes of titanium dioxide. Nano-sized titanium dioxide is used because larger particles leave a white residue. The smaller particles can scatter and absorb light more effectively than the larger, whiter particles. The safety concern with nano titanium dioxide is that it might produce a little more reactive oxygen species when exposed to UV radiation.

However, this effect is reduced if the particles are coated with substances such as silica or alumina. Those coatings prevent titanium dioxide nanoparticles from forming reactive oxygen species when exposed to UV radiation. Despite its smaller, nanoscale size, titanium dioxide does not significantly penetrate the skin’s outermost layer. At least one study showed very trace amounts in plasma and urine after sunscreen application. The FDA has proposed that titanium dioxide is generally recognized as safe and effective at concentrations up to 25% in sunscreens, which is consistent with what the European Commission found. Both the FDA and the European Commission agree with respect to consumer safety. The International Agency for Research on Cancer classified bulk titanium dioxide, such as a powder, as a possible inhalation carcinogen. That inhalation risk applies to people handling the powder in manufacturing, not to consumers applying a cream.

Let’s talk about zinc oxide because it is also commonly found in sunscreens. It is another inorganic type of sunscreen. Zinc oxide, even in its nano form, does not penetrate the skin significantly. Any minor penetration that occurs is not thought to lead to adverse health effects because zinc is something the body uses. Zinc is an important component of many of our enzymes. Most penetration of zinc oxide occurs in skin folds and hair follicles, not in deeper skin layers. A vast database shows that zinc oxide is safe in many products, including diaper-rash products for infants. Zinc oxide is thought to be one of the safe forms of sunscreen. Combining titanium dioxide with zinc oxide provides a broader range of protection against UVA and UVB radiation. Titanium dioxide is most effective against UVB rays, while zinc oxide is most effective against UVA rays. Some studies suggest that zinc oxide can degrade other organic ingredients in sunscreens, potentially reducing their efficacy.

We have already discussed some of those other organic ingredients that we do not want to use. A general note on sunscreen composition is the photoactivity of titanium dioxide. Titanium dioxide exhibits what are called photocatalytic properties, so it might cause other sunscreen ingredients to break down. That is the issue I was just discussing. When we talk about organic versus inorganic sunscreens, our brains tend to think organic is best, but that is not the case here. Organic sunscreens contain chemical ingredients that absorb UV rays. Those are the ingredients we were discussing, such as oxybenzone, that we want to avoid. I think they should really be called chemical sunscreens, but they are called organic. Inorganic sunscreens are the mineral type, such as zinc oxide and titanium dioxide. Those are the safer ones. They reflect and scatter UV rays rather than absorbing them. Zinc oxide and titanium dioxide also stay on the skin longer after water exposure, such as swimming, and studies have examined that. The Environmental Working Group has rated sunscreens for health concerns and UVA and UVB protection. It uses a color system in which dark green indicates no health concerns and excellent UVA and UVB protection. Light green is similar. Orange and red indicate higher health concerns and poorer UVA and UVB protection.

For example, you can look up its list. It includes Babo Botanicals Baby Skin Mineral Sunscreen Lotion, along with a variety of other Babo Botanicals sunscreens. True Botanicals is on there. These are all among the good ones in dark green. The list also includes Rejuva Minerals Sheer Daily Sunscreen, Attitude mineral sunscreens, Beautycounter sunscreen, AO Skincare, and Solara Suncare Clean Freak Nutrient Boosted Daily Sunscreen. There is a whole list you can find from the Environmental Working Group. Some of the sunscreens that I like and use include CeraVe, which I think I have discussed before. I use it a lot. Another one I use is Drunk Elephant. That one has a high concentration of zinc oxide. I also use COOLA, but I have been using less of it. In fact, I did not use it at all this past summer. This past summer, I used CeraVe, Drunk Elephant, and Colorescience. Colorescience is mostly a little sunscreen powder that I put on after I apply something like CeraVe. Those have been my go-to sunscreens this past summer. Okay, so just to summarize: titanium dioxide and zinc oxide are generally, I think, safe to use in sunscreens. They are the best options for broad-spectrum UVA and UVB protection, protecting against both skin aging and sunburns. The chemical, or quote-unquote “organic,” sunscreens contain ingredients that are not actually organic; they are chemicals. Those are the ones to avoid. We do not have good evidence that they are safe, and they remain in circulation for a very long time, even after one application. My son Joe is asking in the chat what I use for my son. I use CeraVe for him. I really like the CeraVe brand, so that is my go-to for my family. At the end of the day, the take-home is to choose titanium dioxide and zinc oxide and avoid the chemical sunscreens as well.