Toxicity assessment of nanocosmetics: techniques and necessity for safety evaluation

BACKGROUND: The application of nanotechnology to cosmetic formulations has gained recognition due to enhanced stability, efficacy, and aesthetic appeal of products. These engineered nanomaterials are purposefully produced to possess nano-specific properties, whereas traditional microsized particles are manufactured primarily to improve formulation texture. However, their increasing use for beautification and medicinal purposes has raised serious concerns regarding nanocosmetic toxicity. This review highlights the distinct physical and chemical characteristics of nanocosmetics that influence skin penetration, cellular interactions, and potential systemic uptake following dermal application, emphasizing the need for comprehensive toxicity evaluation. METHODS: This review compiles appropriate peer-reviewed literature from various scientific databases along with regulatory documents from authoritative sources. The review focuses on toxicity assessment approaches for nanocosmetics, including in vitro, in vivo, and alternative methods. Special emphasis is placed on skin irritation and sensitization models, cytotoxicity assays, genotoxicity assessments, and embryonic toxicity tests for evaluating nanocosmetic-associated toxicity. RESULTS: The review summarizes current approaches for evaluating the skin and ocular safety of nanocosmetic ingredients and discusses the influence of nano-specific physicochemical properties on dermal penetration and biological interactions. It also identifies existing data gaps in current regulatory frameworks, particularly concerning nano-specific safety assessment, physicochemical characterization, and dermal exposure evaluation. These findings highlight the importance of adopting comprehensive and standardized toxicity testing strategies for nanocosmetics. CONCLUSIONS: The increasing application of nanotechnology in cosmetic formulations necessitates robust toxicity evaluation to ensure consumer safety. Strengthening regulatory frameworks by incorporating nano-specific safety assessment and exposure evaluation is essential to promote the safe use of nanomaterials in cosmetic products while supporting their continued development and commercialization.