of the test product to decrease when a
constant mass application rate is specified, causing an error in the value of SPF
measured. For high mineral loadings,
the SPF measured can be significantly
less than if it were measured using the
same volume application rate as an
organic sunscreen.
In conclusion, the product application rate used in current test procedures
should be changed from 2 mg/cm2 to
2 μL/cm2 as a matter of high priority
to ensure that all sunscreens are tested
using the same average film thickness.
Acknowledgements: The author would like
to thank Malcolm Nearn, PhD, Innovative
Suncare Pty., Ltd.; Takuya Tsuzuki, PhD, Deakin
University; and M. Muroi and Jun Chai, Antaria
Ltd., for their helpful discussions and comments
on this paper.
Reproduction of all or part of this article without
expressed written consent is prohibited.
To get a copy of this article or others
from a searchable database, visit www.
CosmeticsandToiletries.com/magazine/
pastissues.
References
Send e-mail to paulm@mech.uwa.edu.au.
1. Preventing skin cancer, Cancer Council
Australia,
www.cancer.org.au/cancersmart-lifestyle/SunSmart/ Preventingskincancer.htm
(Accessed Jan 14, 2011)
2. Sunscreen products–Evaluation and classification, Australian/New Zealand Standard, AS/
NZS 2604 (1998)
3. Sunscreen drug products for over-the-counter
human use; proposed amendments to the
Final Monograph, Federal Register 72 165
49070-49122 (Aug 27, 2007)
4. European Commission recommendation of the
efficacy of sunscreen products and the claims
relating thereto, Official J of the European
Community, L265, 7647/EC 39–43 (2006)
5. In vitro method for the determination of the UVA
protection factor and critical wavelength values
of sunscreen products, Colipa, In vitro Protection Method Task Force Guideline (2009)
6. S Brown and BL Diffey, The effect of applied
thickness on sunscreen protection: In vivo and
in vitro studies, Photochem and Photobiol 44
509–513 (1986)
7. R Bimczok et al, Influence of applied quantity
of sunscreen products on the sun protection
factor–A multicenter study organized by the
DGK task force sun protection, Skin Pharmacol
Physiol 20 57–64 (2007)
8. B Herzog, S Mongiat, K Quass and
C Deshayes, Prediction of sun protection factors and UVA parameters of sunscreens by
using a calibrated step film model, J Pharm
Sciences 93 1780–1795 (2004)
9. B Diffey, Sunscreen isn’t enough, J Photochem
and Photobiol B: Biology 64 105–108 (2001)
10. Sunscreen Products for over-the-counter
human drugs; Proposed safety, efficacy
effective and labeling conditions, Department of Health, Education and Welfare,
FDA, USA, Federal Register 43/166 (1978)
pp 38206–38269
11. A Faurschou and HC Wulf, The relation
between sun protection factor and amount
of sunscreen applied in vivo, Photobiol 156
716–719 (2007)
12. L Ferrero, M Pissavini and O Doucet, How a
calculated model of sunscreen geometry can
explain in vitro and in vivo SPF variation,
Photochem and Photobiol Sci 9 540–551 (2010)
13. B Herzog, Prediction of sun protection factors
by calculation of transmissions with a calibrated step film model, J Cosmet Sci 53 11–26
(2002)
14. JJ O’Neil, Effect of film irregularities on
sunscreen efficacy, J Pharm Sci 73 888–891
(1984)
15. S Thompson, D Jolley and R Marks, Reduction
of solar keratoses by regular sunscreen use,
N Engl J Med 329 1147–1151 (1993)
16. RM Sayre and PP Agin, Comparison of human
sun protection factors to predicted factors
using different lamp spectra, J Soc Cosmet
Chem 35 439–445 (1984)
17. RM Sayre, PP Agin, GJ LeVee and E Marlowe,
A comparison of in vivo and in vitro testing of
sunscreening formulas, Photochemistry and
Photobiology 29 559–566 (1979)
18. G Groves, PP Agin and RM Sayre, In vitro and
in vivo methods to define sunscreen protection, Austr J Derm 20 112 (1979)
19. DF Robertson and GA Groves, Classification of
sunscreen preparations, Aust J Derm 18 109
(1977)
20. BL Diffey and J Robson, A new substrate to
measure sunscreen protection factors throughout the ultraviolet spectrum J Soc Cosmet
Chem 40 127–133 (1989)
170 | Cosmetics & Toiletries® magazine www.CosmeticsandToiletries.com
Vol. 126, No. 3/March 2011
