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Published on: July 13, 2009
Sunscreen tests: correspondence between in vitro data and values reported by the manufacturers
Denis Garoli1, Maria Guglielmina Pelizzo, Bianca Bernardini
1CNR- INFM LUXOR, Padova, Italy.
Journal of Dermatological Science
|August 30, 2008
Summary
Teflon is a viable substrate for in vitro sunscreen testing, correlating well with manufacturer SPF values. This method also aids in photo-stability assessments, revealing a potential role for infrared light in sunscreen degradation.
Area of Science:
- Cosmetic Science
- Photoprotection Research
Background:
- In vitro methods are crucial for evaluating sunscreen efficacy, including Sun Protection Factor (SPF) and photostability.
- Spectrophotometry enables rapid assessment of ultraviolet (UV) radiation absorbance by sunscreens on various substrates.
Purpose of the Study:
- To validate Teflon as a substrate for both in vitro SPF determination and sunscreen photostability testing.
- To assess the correlation between in vitro SPF measurements and manufacturer-reported SPF values.
Main Methods:
- Teflon substrates were used for photostability tests, involving irradiation with different wavebands and analysis of UV and infrared (IR) light effects.
- Comparative analyses were conducted using Polymethyl Methacrylate (PMMA) plates, the standard substrate for in vitro UVA testing.
Main Results:
- A strong correlation was established between in vitro SPF measurements and manufacturer-reported SPF values.
- The in vitro/label SPF correlation is influenced by the amount of sunscreen applied, unlike Critical Wavelength and UVA ratio.
- Infrared (IR) irradiation was identified as a potential factor in sunscreen photodegradation.
Conclusions:
- Teflon is a suitable substrate for both SPF determination and photostability testing of sunscreens.
- The compatibility of results from Teflon and PMMA plates supports Teflon's utility in standardized sunscreen analysis.
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