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 our bodies. In cosmetics, it has become a key ingredient thanks to its versatility. However, it is never used on its own in its metallic form: it is systematically combined with other molecules to create specific compounds. Depending on the substance with which it is associated, its properties change radically. Zinc can thus shift from acting as a shield against the sun to functioning as a sebum regulator or a soothing agent for irritated skin.

The zinc oxide is an inorganic compound whose safe use is linked to its particle size distribution.

On the one hand, there are zinc oxide microparticles, often referred to as “non-nano”. With a size on the order of a micrometre, they are too large to pass through 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 limits their cosmetic acceptability.

On the other hand, zinc oxide nanoparticles, with a size of less than 100 nanometres, have revolutionised mineral sun care. Their small size makes it possible to create transparent and much more fluid formulations. However, this also raises toxicological questions, as some fear that particles this fine could cross the skin barrier and enter the bloodstream.

According to a report by ANSES, the French 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 outermost skin layers, making the assessment of this penetration complex. Some studies highlight that numerous 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 strengthens the need for vigilance.

To assess the potential hazardousness of ZnO nanoparticles, researchers carried out in-depth experiments, notably 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 exhibit a substantial capacity for cellular uptake. Using flow cytometry, the scientists observed that the entry of the particles into glial cells is “dose-dependent”: the higher the concentration and the longer the exposure time, assessed up to 48 hours in the study, the more the particles accumulate inside the cells. In contrast, zinc sulphate, a non-nanoscale form, showed no such internalisation, 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 a cause for concern. From a concentration of 10 to 25 µg/mL, a sharp drop in cell survival is observed. Furthermore, the zinc nanoparticles damaged DNA, highlighting their genotoxicity. The researchers suggest that this toxicity arises from the release of zinc ions Zn2+ once the particle has been taken up. These ions disrupt cellular homeostasis and generate oxidative stress, which “breaks” DNA strands.

Finally, the in vivo experiment on zebrafish embryos adds another dimension of hazard to zinc oxide. Although no visible physical malformation was detected, exposure to ZnO led to a drastic and progressive reduction in overall locomotion. The 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 findings must of course be interpreted with caution, as they have not been obtained in humans, but they remain nonetheless a cause for concern.

In response to these suspicions regarding 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 formulations that can be inhaled, such as sprays, aerosols or airborne powders. Indeed, while healthy skin still acts as a relative barrier, the pulmonary mucous membranes are extremely vulnerable: inhalation of zinc can cause severe pulmonary inflammation and immediate systemic toxicity.

Moreover, its use as a UV filter is capped at 25% of the total formulation. When it is used as a colourant (under the code CI 77947), its concentration 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, in order to avoid any unwanted absorption.

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

Unlike zinc oxide, the 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 applications, these forms of zinc do not lead to irritation. They can therefore be used by a very broad range of individuals. Products formulated with zinc PCA or zinc gluconate can thus be incorporated without concern into the skincare routine of pregnant or breastfeeding women, as well as that 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).