[article]
| Titre : |
Importance of substrate roughness for in-vitro sun protection assessment |
| Type de document : |
texte imprimé |
| Auteurs : |
Louis Ferrero, Auteur ; Marc Pissavini, Auteur ; Adeline Dehais, Auteur ; Stephanie Marguerie, Auteur ; Leonhard Zastrow, Auteur |
| Année de publication : |
2006 |
| Article en page(s) : |
p. 97-108 |
| Note générale : |
Bibliogr. |
| Langues : |
Anglais (eng) |
| Tags : |
'Sunscreen testing' 'In vitro SPF' 'UVA protection' 'Surface roughness' microtopography' 'Irregularfilm geometry' 'UV filters' |
| Index. décimale : |
668.5 Parfums et cosmétiques |
| Résumé : |
The purpose of this study is to demonstrate the influence of plate roughness on well-known absolute or relative UV
spectroscopic indices such as the in vitro SPF, in vitro UVA PF (PPD), UVA/UVB ratio, critical wavelength and SPF/UVA
PF (PPD) ratio. First a roughness index was measured by non-contact surface topography analysis on different
PMMA plates which are available today on the European market. A large difference between maximum and minimum
plate roughness values could be measured ranging from 1.88 μm to 6.76 μm. Then the PMMA plates were grouped
into five different roughness classes. To measure the different spectroscopic indices, the same sunscreen preparation
was applied at the same amount rate (1 mg cm-2) to each of the selected plates. Large differences were noted for
the absolute in vitro indices SPF and UVA PF (PPD), with the SPF varying in one instance from 13.5 to 40.7. On the other
hand, the relative absorbance indices UVA/UVB ratio and critical wavelength showed a small but significant variation
in relation to roughness. The SPF/UVA PF (PPD) ratio index based on direct in vitro values was found to be very
sensitive to roughness variation. However, adjusting the UV absorbance curve to reach equality between the in vitro
SPF and in vivo SPF is a recognized and efficient mathematical process to limit the variation.
All these results can be interpreted using the irregular sunscreen film theory. Mathematical developments can be
achieved by modeling the height distribution with a gamma function. |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10847 |
in IFSCC MAGAZINE > Vol. 9, N° 2 (04-05-06/2006) . - p. 97-108
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