Are there any risks associated with the use of zinc in cosmetics?

Zinc is an essential trace element for life and is naturally present in the human body. In cosmetics, it has become a key ingredient thanks to its versatility. However, it is never used alone in its metallic form: it is systematically combined with other molecules to create specific compounds. Depending on the substance it is paired with, its properties change dramatically. Zinc can therefore shift from acting as a shield against the sun to serving as a sebum regulator or a soothing agent for irritated skin.

The zinc oxide is a mineral compound whose safe use depends on its particle size.

On one hand, there are zinc oxide microparticles, often called “non-nano.” With a size on the order of a micrometer, they are too large to cross the skin barrier. They remain on the surface of the epidermis, creating a physical shield that reflects UV rays. Their main drawback is aesthetic: they leave an opaque white film, which reduces their cosmetic acceptability.

On the other hand, zinc oxide nanoparticles, with a size below 100 nanometers, have revolutionized mineral sun care. Their small size makes it possible to create transparent and much more fluid formulas. However, this also raises toxicological questions, as some fear that such fine particles could pass through the skin barrier and enter the bloodstream.

According to a report by ANSES, the French National Agency for Food, Environmental and Occupational Health Safety, while the effectiveness of the skin barrier is real, it is not absolute. Various studies have shown that the passage of nanoparticles through the layers of the epidermis is possible, particularly when the skin is damaged (irritation, micro-cuts, sunburn), but sometimes also on intact skin.

The repeated use of these products increases the duration of direct contact with the outer skin layers, making the assessment of this penetration complex. Some studies emphasize that many parameters intrinsic to nanoparticles—such as their shape, their tendency to agglomerate, or their surface electric charge—influence their ability to infiltrate more or less deeply. This scientific uncertainty regarding the depth of penetration of nanoparticles reinforces the need for caution.

To assess the potential hazards of ZnO nanoparticles, researchers conducted extensive experiments, in particular on human glial cells—support cells of the nervous system—and on zebrafish embryos, a model frequently used in biology. The study first shows that ZnO nanoparticles have a significant cellular uptake capacity. Using flow cytometry, the scientists observed that the entry of particles into glial cells is “dose-dependent”: the higher the concentration and the longer the exposure time—evaluated up to 48 hours in the study—the more the particles accumulate inside the cells. By contrast, zinc sulfate, a non-nanoscale form, showed no such internalization, demonstrating that it is specifically the “nano” structure that facilitates cellular intrusion.

Once inside the cell, the effects on viability and genetics proved to be concerning. Starting at a concentration of 10 to 25 µg/mL, a sharp drop in cell survival is observed. In addition, the zinc nanoparticles damaged DNA, demonstrating their genotoxicity. The researchers suggest that this toxicity results from the release of zinc ions (Zn2+) once the particle has been internalized. These ions disrupt cellular homeostasis and generate oxidative stress that “breaks” DNA strands.

Finally, the in vivo experiment on zebrafish embryos adds another dimension of risk to zinc oxide. Although no visible physical malformations were detected, exposure to ZnO caused a drastic and progressive reduction in overall locomotion. Exposed embryos swam significantly less than the others. This suggests that zinc nanoparticles, or the ions they release, could disrupt the molecular machinery of the nervous system, thereby mimicking certain symptoms of neurodegenerative diseases. These results must of course be interpreted with caution, since they were not obtained in humans, but they remain nonetheless worrisome.

Faced with these concerns about the toxicity of zinc oxide, the European Union has put in place strict safeguards to protect consumers.

Since February 2018, European regulations have formally prohibited the use of zinc oxide, whether nano or not, in all formulas that can be inhaled, such as sprays, aerosols, or airborne powders. While healthy skin still acts as a partial barrier, the pulmonary mucous membranes are extremely vulnerable: inhalation of zinc can cause severe lung inflammation and immediate systemic toxicity.

Moreover, its use as a UV filter is capped at 25% of the total formula. When it is used as a colorant (under the code CI 77947), its level is even more restricted: it must not exceed 5% in body lotions in order to limit chronic exposure. Finally, its application is not recommended on areas where the skin barrier is compromised, such as mucous membranes or in the presence of a wound, to avoid any unintended absorption.

At Typology, as a precautionary principle, we exclude nanoparticles from our products.

Unlike zinc oxide, other forms of zinc used in cosmetics, such as zinc PCA or zinc gluconate, are not the subject of any major scientific controversy.

These forms of zinc are very well tolerated when applied topically, even on the most sensitive skin. Unlike retinoids or certain fruit acids, which can cause redness, peeling, or burning sensations during the first uses, these forms of zinc do not cause irritation. They can therefore be used by a very wide range of individuals. Products formulated with zinc PCA or zinc gluconate can thus be safely incorporated into the skincare routines of pregnant or breastfeeding women, as well as those of children.

• Règlement (CE) No 1223/2009 du Parlement Européen et du Conseil du 30 novembre 2009.

• VINCHES L. & HALLE S. La peau est‐elle vraiment imperméable aux nanoparticules ? Bulletin de veille scientifique de l'ANSES (2015).

• SALIM R. & al. Zinc oxide nanoparticles: The hidden danger. International Journal of Biochemistry, Biophysics & Molecular Biology (2017).

• SINGH S. & al. Zinc oxide nanoparticles impacts: Cytotoxicity, genotoxicity, developmental toxicity, and neurotoxicity. Toxicology Mechanisms and Methods (2019).

• Scientific Committee on Consumer Safety (SCCS). Scientific advice on the safety of nanomaterials in cosmetics (2021).

• VALDIGLESIAS V. & al. Toxicity of zinc oxide nanoparticles: Cellular and behavioural effects. Chemosphere (2024).

• JUNGNICKEL C. & al. Nanoparticle skin penetration: Depths and routes modeled in silico. Nano Micro Small (2025).