Properties and Usage of Micronized/Nano vs. Non-Nano Zinc Oxide and Titanium Dioxide in Sunscreen
คำถาม
Regarding the use of Zinc Oxide and Titanium Dioxide in sunscreen formulations:
1. Is it true that sunscreens should not use micronized Zinc Oxide or micronized Titanium Dioxide because some research suggests they can penetrate the skin?
2. Why is Zinc Oxide Micronized described as "not suitable for use in sunscreens requiring high dispersion for good sun protection efficiency," implying its dispersion is lower than Non Nano Zinc Oxide?
3. Is the water resistance efficiency of Zinc Oxide Micronized and micronized Titanium Dioxide less than that of Non Nano Zinc Oxide and Non Nano Titanium Dioxide?
4. Is the main reason why sunscreens in Thailand do not solely use Non Nano forms because they would cause a white cast, necessitating the inclusion of Micronized forms?
คำตอบ
Hello,
Thank you for your questions regarding the use of micronized Zinc Oxide and Titanium Dioxide in sunscreens. Based on the information provided:
- Regarding skin penetration of micronized/nano particles: There are conflicting research findings on whether nano-sized particles can penetrate the skin. While some studies suggest this, others confirm their safety. Regulatory bodies worldwide, such as the FDA, approve the use of nano sunscreens, and they have been used for a long time without confirmed adverse effects. The staff cannot definitively state which research is correct but highlights the long history of safe use and regulatory approval.
- Regarding the dispersion of Zinc Oxide Micronized: The description states that Zinc Oxide Micronized is not suitable for sunscreens requiring high dispersion because its dispersion is lower than Non Nano Zinc Oxide. This difference in dispersion is due to the particle size. Larger (micronized) particles may not disperse as effectively as smaller (nano) particles, which is important for creating a uniform protective layer for optimal sun protection.
- Regarding water resistance: According to the staff, particle size is not related to the water resistance of Zinc Oxide or Titanium Dioxide.
- Regarding the use of Non Nano sunscreens in Thailand: The white cast is not the main reason why sunscreens in Thailand are not exclusively Non Nano. Other important factors, such as the efficiency of UV protection, which is affected by particle size, also play a role.
We hope this clarifies your questions.
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Zinc Oxide (Micronized)
