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A noninvasive objective measure of sunscreen use and reapplication
David L O'Riordan1, Kevin B Lunde, Johann Urschitz
1Cancer Research Center of Hawaii, University of Hawaii, Honolulu, HI 96822, USA. doriordan@crch.hawaii.edu
Objectives:
To study whether a noninvasive swabbing technique can detect sunscreen use for up to 6 hours, and whether the technique can detect reapplication of sunscreen.
Methods:
Thirty volunteer office workers were randomly assigned to have one of a variety of sunscreens applied using recommended application techniques, and half were randomly assigned to have sunscreen reapplied after 3 hours. Alcohol-based swabs were used to obtain a sample from participants' arm at 20 minutes, and hourly from 1 to 6 hours post-application. Absorption readings were analyzed using an UV-visible spectrophotometer.
Results:
The swabbing technique was consistently able to distinguish the sunscreen from control swabs for up to 6 hours. The absorption readings between 20 minutes and 6 hours were significantly higher than control swabs. There were no differences between the group that had sunscreen reapplied and the group that did not.
Conclusion:
The sunscreen swabbing technique is an effective noninvasive method for detecting a variety of sunscreen products in adults over a 6-hour period. No differences in absorption readings were found with sunscreen reapplication. This procedure will be a useful adjunct to other objective measures of sun protection and UV radiation exposure, resulting in a more accurate picture of the sun protection habits of individuals.