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Distribution of sunscreens on skin
J Schulz1, H Hohenberg, F Pflücker
1R&D Cosmed, Beiersdorf AG, Function 4243, Unnastrasse 48, D-20245, Hamburg, Germany. jens.schulz@beiersdorf.com
Advanced Drug Delivery Reviews
|December 4, 2002
Summary
Sunscreens use organic UV absorbers or mineral pigments like titanium dioxide for protection. Micronized titanium dioxide sits on the skin
Area of Science:
- Cosmetic Science
- Dermatology
- Materials Science
Background:
- Sunscreens historically relied on organic UV absorbers.
- Efficacy of organic UV filters depends on their absorption properties.
- Micronized pigments like titanium dioxide and zinc oxide are now used for UV protection.
Purpose of the Study:
- To evaluate the dermal absorption of micronized pigments in sunscreens.
- To understand the safety and deposition of titanium dioxide and zinc oxide on the skin.
Main Methods:
- Optical microscopy
- Electron microscopy
- Analysis of sunscreen formulations with UV absorbers and micronized pigments.
Main Results:
- Micronized titanium dioxide and zinc oxide do not penetrate the skin.
- Pigment deposition is limited to the outermost skin layer (stratum corneum).
- Particle characteristics (size, shape, surface) do not influence dermal absorption.
Conclusions:
- Micronized titanium dioxide is safe for topical use as it does not absorb into the dermis.
- Mineral UV filters offer a safe alternative or addition to organic UV absorbers.
- Further research into pigment-skin interactions can optimize sunscreen formulations.
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