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Simplified method to substantiate SPF labeling for sunscreen products.

Robert M Sayre¹, Joseph Stanfield, Dennis L Lott

¹Rapid Precision Testing Laboratories, Cordova, TN 38016, USA. rptl@aol.com

Photodermatology, Photoimmunology & Photomedicine

|October 11, 2003

Summary

A new sunscreen testing method improves accuracy for high sun protection factor (SPF) products by addressing uniform application and subjective grading. This rigorous approach offers a more reliable SPF determination than current standards.

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Area of Science:

Dermatology
Photobiology
Cosmetic Science

Background:

Current sunscreen sun protection factor (SPF) testing relies on outdated technology, established when maximum SPFs were significantly lower.
Existing SPF tests exhibit reduced reliability for SPFs above 15 due to challenges in uniform product application and subjective response evaluation.

Purpose of the Study:

To introduce and validate a novel SPF substantiation method designed to overcome the limitations of current sunscreen testing protocols.
To enhance the accuracy and reliability of SPF measurements, particularly for higher SPF values.

Main Methods:

The proposed method utilizes uniformly spaced sub-sites receiving identical UV doses, with a pass/fail grading based on the absence or presence of skin response (tanning or erythema).
Two commercial sunscreens (SPF 30 and SPF 45) and a P2 sunscreen standard were tested across two laboratories using the new protocol.

Main Results:

The SPF 30 product and SPF 15 standard were accurately labeled according to the new testing method.
The reliability of the SPF 45 product's claimed protection level was found to be questionable under the proposed rigorous testing conditions.

Conclusions:

The novel SPF substantiation method offers objective, reproducible, and conservative SPF estimations, overcoming issues of non-uniform application and subjective grading.
This systematic and rigorous testing approach is proposed to supersede the current method for final SPF label determination, while acknowledging the existing test's value for dose ranging.