The use of nanomaterials (NMs) has been rapidly increasing in recent years, and this is reflected in their large-scale use for cosmetic applications. For example, it is expected that silica nanoparticles will reach a global market size of 5 trillion USD by 2025. Amorphous silica nanoparticles (aSiNPs) are widely used to enhance the effectiveness, texture and shelf-life of various commercial cosmetics and act as an anti-caking agent and an absorbent to release active compounds over time in a range of cosmetic formulations (e.g. foundation, lipsticks, and blushes). However, widespread use of cosmetics with aSiNPs increases exposure and may induce effects on human health and the environment that are not yet known.