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Factors that influence sunscreen application thickness and potential preservative exposure
Rachel Novick1, Grace Anderson1, Eric Miller1
1ChemRisk, LLC, San Francisco, CA, USA.
Photodermatology, Photoimmunology & Photomedicine
|March 17, 2015
Summary
Sunscreen application varies by type, with sprays providing more coverage than lotions or sticks. Typical use of these sunscreens is unlikely to cause methylisothiazolinone (MI) sensitization.
Area of Science:
- Dermatology
- Cosmetic Science
- Photoprotection
Background:
- Studies indicate insufficient application of lotion sunscreen for labeled SPF.
- Limited data exists on the application of spray and stick sunscreens.
- Concerns regarding methylisothiazolinone (MI) sensitization in sunscreens.
Purpose of the Study:
- Quantify sunscreen application amounts across different product types (lotion, spray, stick).
- Investigate demographic influences on sunscreen application thickness.
- Assess sensitization potential of methylisothiazolinone (MI) in lotion sunscreens.
Main Methods:
- Participant application of lotion, spray, and stick sunscreens.
- Questionnaire data collection on application habits.
- Analysis of MI content in tested lotion sunscreens and calculation of margin of safety.
Main Results:
- Mean application thicknesses: lotion (1.1 mg/cm²), spray (1.6 mg/cm²), stick (0.35 mg/cm²).
- Age and skin type influenced sunscreen application thickness.
- MI concentrations were generally low, with likely exposures below sensitization thresholds (Margin of Safety > 8.1).
Conclusions:
- Sunscreen application amounts differ significantly by method, impacting sun protection levels.
- Typical usage patterns of tested sunscreens are unlikely to induce MI sensitization.
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