Titanium dioxide (titanium dioxide, TiO₂) is a widely used white pigment, used in many fields such as coatings, plastics, paper, cosmetics and food. Its main function is to provide high hiding power and whiteness. However, the effect of titanium dioxide on skin barrier is a topic of great concern.
Basic properties of titanium dioxide
Titanium dioxide has the following basic properties:
- Chemical stability: Titanium dioxide is chemically stable and does not easily react with other substances.
- Physical properties: Its particle size and morphology affect its dispersibility and hiding power in different media.
Function of skin barrier
The skin barrier is mainly composed of the stratum corneum, and its main functions are:
- Preventing the invasion of external substances: The skin barrier can prevent most harmful substances (such as bacteria, viruses, chemicals, etc.) from penetrating the skin.
- Keeping skin hydrated: The skin barrier can prevent excessive evaporation of moisture inside the skin, thereby keeping the skin moist and soft.
Effect of titanium dioxide on skin barrier
Effect of particle size
1. Large-particle titanium dioxide: Generally, titanium dioxide particles are large and difficult to pass through the skin barrier layer. Therefore, large-particle titanium dioxide is unlikely to have a significant effect on the skin barrier.
2. Nano-grade titanium dioxide: When the particle size of titanium dioxide is reduced to the nanoscale (usually less than 100 nanometers), its surface area increases significantly, which may increase the possibility of its interaction with the skin barrier. However, the specific impact of nano-grade titanium dioxide still needs further study.
The role of surface treatment and dispersion medium
1. Surface treatment: In order to improve the dispersibility and stability of titanium dioxide in different media, the particles are usually surface treated. These treatments may affect its interaction with the skin barrier.
2. Dispersion medium: Titanium dioxide is usually mixed with other ingredients, which (such as emulsifiers, thickeners, etc.) will also affect its behavior on the skin and its effect on the skin barrier.
The impact of skin condition
1. Intact skin: Under normal circumstances, a healthy skin barrier can effectively block most foreign substances, including titanium dioxide.
2. Damaged skin: When the skin is damaged or inflamed, its barrier function may be weakened, increasing the likelihood of foreign substances (including nano-sized titanium dioxide) interacting with the skin barrier.
Health effects and safety assessment
Although titanium dioxide is considered safe in many applications, its potential effects on the skin barrier still need to be carefully evaluated. In particular, nano-sized titanium dioxide, due to its smaller particles, may have different biological activity and toxicity characteristics.
1. Acute toxicity: Current studies have shown that titanium dioxide has low acute toxicity under normal conditions of use.
2. Chronic effects: Long-term exposure to titanium dioxide, especially nano-sized particles, may have chronic effects on the skin barrier and internal organs. Research in this area is still ongoing and no clear conclusions have been reached.
Conclusion
In summary, the effect of titanium dioxide on the skin barrier depends on multiple factors, including particle size, surface treatment, dispersion medium, and skin condition. Although large-particle titanium dioxide is unlikely to have a significant impact on the skin barrier, the potential effects of nano-sized titanium dioxide still need further research and evaluation to ensure its safety in various applications.
