Optimizing Sunscreen Safety: The Impact of TiO₂ Particle Size on Toxicity and Biocompatibility

Area of Science:

• Materials Science
• Toxicology
• Dermatology

Background:

• Titanium dioxide (TiO2) is a common inorganic UV filter in sunscreens, offering broad-spectrum UVA/UVB protection.
• Nanoscale TiO2 enhances cosmetic transparency, increasing consumer acceptance, but its safety is debated due to potential toxicity and membrane permeability.
• Concerns exist regarding TiO2 nanoparticle reactivity, DNA damage potential, and interactions with biological systems.

Purpose of the Study:

• To compare the toxicological profiles of microscale and nanoscale titanium (IV) oxide sunscreens.
• To assess the safety of commercially available TiO2 sunscreens with different particle sizes.
• To evaluate potential interactions of TiO2 nanoparticles with cytotoxicity assessment methods.

Main Methods:

• Characterization of TiO2 nanoparticle morphology and hydrodynamic diameter.
• Investigation of potential interferences between TiO2 nanoparticles and cytotoxicity assays.
• Evaluation of hemocompatibility, cytotoxicity, phototoxicity, and genotoxicity using human keratinocytes.

Main Results:

• Characterization confirmed differences in particle size and morphology between microscale and nanoscale TiO2.
• No significant cytotoxic, phototoxic, or genotoxic effects were observed for either micro- or nano-sized TiO2 in human keratinocytes.
• Hemocompatibility assays indicated good compatibility for both particle sizes.

Conclusions:

• Commercially available microscale and nanoscale TiO2 sunscreens demonstrate a favorable safety profile.
• The evaluated TiO2 nanoparticles did not induce significant toxicity in human keratinocytes under the tested conditions.
• Findings support the continued use of TiO2 nanoparticles in cosmetic formulations, addressing consumer demand for transparent sunscreens.