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Sun protection factors: world wide confusion
1Ciba Inc., Basel, Switzerland. uli.osterwalder@ciba.com
The British Journal of Dermatology
|September 25, 2009
Summary
Understanding sunscreen's Sun Protection Factor (SPF) is crucial for effective sun safety. This study clarifies SPF limitations, how sunscreens work, and promotes better consumer compliance for optimal sun protection.
Area of Science:
- Dermatology
- Photobiology
- Cosmetic Science
Background:
- The Sun Protection Factor (SPF) is widely used but often misunderstood by consumers.
- Consumer confusion regarding SPF, application amounts, and Vitamin D synthesis impacts sun protection compliance.
- Limitations in current SPF determination methods hinder accurate consumer guidance.
Purpose of the Study:
- To explain the mechanism of sunscreen action and the determination of SPF.
- To address the limitations of current SPF assessment methods.
- To discuss UVA protection, other protection factors, and Vitamin D synthesis inhibition.
Main Methods:
- Explains sunscreen function and SPF determination.
- Introduces dynamic 'UV radiation applied' and 'UV dose transmitted' concepts for in vitro assessment.
- Utilizes in silico calculations based on UV filter absorption spectra and sunscreen film assumptions.
- Employs a sunscreen simulator program to assess SPF variations with different application amounts.
Main Results:
- Highlights the importance of understanding SPF limitations for consumer compliance.
- Demonstrates how in vitro and in silico methods can improve sunscreen assessment.
- Discusses the distinct roles of SPF (quantity) and UVA protection (quality) in overall UV defense.
- Examines other protection factors (IPF, iSPF, RSF, p53) and Vitamin D3 synthesis inhibition.
Conclusions:
- Accurate and robust SPF and other protection factors improve with true broad-spectrum sunscreens.
- Uniform protection profiles enhance protection efficacy, independent of specific endpoints or UV sources.
- Broad-spectrum sunscreens offer more reliable and consistent photoprotection compared to UVB-biased formulations.
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