Outdoor testing of the photoprotection provided by a new water-based broad-spectrum SPF50+ sunscreen product: two double-blind, split-face, randomized controlled studies in healthy adults

Outdoor sunscreen testing with high-intensity solar exposure in a Chinese and Caucasian population

BACKGROUND

Currently, sunscreens' sun protection factor (SPF) and ultraviolet (UV) A protection are tested separately under indoor conditions, without considering external conditions that may affect performance. Studies are often conducted in Caucasian individuals; other racial groups may respond differently.

METHODS

An outdoor, double-blind, intra-individual study was performed in 63 healthy Chinese and Caucasian volunteers in Singapore. Subjects underwent one outdoor sun exposure lasting 2-3 hours. ISO reference products P3 (SPF 15), P5 (SPF 30), and P8 (SPF 50+) applied at 2 mg/cm² were compared against each other and against an untreated exposed area (positive control) and an unexposed area (negative control). Endpoints were investigator global assessment (IGA) of erythema at 24 hours, IGA of pigmentation at 1 week, and colorimetry (a*, L*, and ITA) at 24 hours and 1 week.

RESULTS

Clinical erythema and pigmentation scores were statistically significantly different among the three sunscreens, with the highest SPF product providing the highest protection, confirming the discriminatory capacity of the model used. Colorimetric assessment correlated well with clinical evaluation.

CONCLUSION

This study confirmed the feasibility of ranking sunscreens (at 2 mg/cm² ) based on clinical effects of high-intensity outdoor solar radiation. Larger studies are needed to look at differences in erythema and pigmentation reactions between Chinese and Caucasian individuals, which could be relevant for photoprotection.

Synthesis-property-performance relationships of multifunctional bacterial cellulose composites fermented in situ alkali lignin medium

This work demonstrates a unique approach of utilizing alkali lignin (AL), as smart additive to in situ BC fermentation in which it concurrently acts as promoter to microbial growth as well as reinforcing filler for fabrication of multifunctional composites. Traditionally, BC fermentation is accompanied by inhibitor formation with sudden drop in pH leading to low yield and biomass growth. AL due to its antioxidant nature prevents formation of gluconic acid as byproduct, at ∼0.25 wt.% AL based on inhibitory byproduct kinetics. Interestingly, AL self-assembles to form primary and secondary structures in BC pores, resulting in simultaneous improvement in thermal stability as well as toughness. The BC/AL films show strong UV-blocking capacity with prolonged radical scavenging activity and preventing browning of freshly cut apples making it suitable as food packaging. Therefore, present work opens up new avenues for fabrication of high-performance BC-based composites through selection of smart materials which can simultaneously improve BC bioprocessing.

New Methodology to Evaluate Sunscreens Under Outdoor Conditions: A Double-Blind, Randomized Intra-Individual Clinical Study of a Water-Based Broad-Spectrum SPF50+ Versus SPF15 (P3) and SPF50

Introduction

This study explored a new method to test sunscreens in outdoor conditions (very high to extreme ultraviolet [UV] radiation) approximating real-life solar exposure while maintaining scientific standards and acceptable conditions, and assessed the efficacy of a water-based sun-protection factor (SPF) 50+ versus a reference SPF15 and two comparator SPF50+ products.

Methods

Thirty-five subjects underwent testing in summertime Mauritius. In each subject, five test areas were marked on the back. One area was left unprotected, and four sunscreens were applied to the others: investigational product (IP), SPF15 (ISO 24444:2010 reference standard P3), and two marketed SPF50+ controls. Subjects spent 1–2 h (depending on skin type) in the sun. After 24 h, erythema was assessed by clinical scoring (0–5) and colorimetry (a*, L*, and ITA). Secondary endpoints were correlation between clinical and colorimetry assessment, product tolerability, and total UV radiation received.

Results

All subjects were exposed to a very high UV index (≥ 8) and 30/35 were exposed to an extreme UV index (≥ 11). The IP showed statistically significant differences in clinical erythema scoring compared with unprotected skin and SPF15, but not with SPF50+ controls. On colorimetry, differences in a* (redness) and L* (lightness) reached statistical significance for the IP vs SPF15 but not vs SPF50+ controls. Clinical and instrumental erythema assessment correlated strongly (Spearman’s rho 0.663). No tolerability issues were reported.

Conclusion

This exploratory study confirmed the ability of this outdoor model to discriminate sunscreens with different SPF using clinical evaluation as an objective measure. The water-based sunscreen maintained its efficacy in outdoor conditions of very high to extreme UV radiation: it was superior to SPF15 and comparable to SPF50+ controls in preventing erythema. The method used represents an option for sunscreen efficacy comparison outside of the laboratory.

Funding

Isdin.

Electronic supplementary material

The online version of this article (10.1007/s13555-019-00315-4) contains supplementary material, which is available to authorized users.