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Sun Protection
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76 Results
Type: Article
Section: Testing > Sun Protection
Sun Protection
In vitro/vivo SPF Correlation and Repeatability According to Substrate
This work evaluates the impact of three different substrates on in vitro SPF measurements, and defines experimental conditions to improve their correlation with in vivo values. Evaluations of 32 products, shown here, led the authors to conclude that molded substrates improved repeatability and correlation with in vivo SPF values.
Sun Protection
Testing SPF 15–100, Indoor vs. Outdoor
Lab tests on sunscreens show it takes more energy to produce mild erythema on protected skin than unprotected skin. Yet the FDA questions the need for SPFs higher than 50. In response, two outdoor studies were conducted using commercial products to challenge standing premises and determine if there is a measurable difference in an SPF 100 and SPFs of 50 or less.
Sun Protection
Testing Sun Protection Factor on Skin
There are various test methods set by global governing bodies for SPF protection, but this article will discuss the five time-point internationally approved ISO 24444 method.
Actives
Research Pathways to Photostable Sunscreens
This article provides a visual depiction of pathways that UV filters undergo when exposed to solar radiation; such pathways often lead to photo-instability. A fluorescence technique is described that has led the author to identify compounds that preserve photostability in a novel manner— by quenching the UV filter’s singlet excited state.
Sun Protection
Characterizing Roughness: A New Substrate to Measure SPF
Here, the authors describe a variable that affects the results of SPF testing in vitro—the roughness parameter—and investigate this variable using standard and molded poly(methyl methacrylate) (PMMA) substrates. They conclude that use of a molded substrate, along with the described control chart, improves the reproducibility of in vitro SPF test results.
Sensory
UV Transmission Assessment: Influence of Temperature on Substrate Surface
This work evaluates the impact of temperature on test substrate surfaces during the application, spreading and drying steps of the in vitro method to measure ultraviolet (UV) transmission. The authors work in a range between 20°C and 35°C, and demonstrate that controlling temperature is a key test parameter that should be strictly controlled to ensure reliability.
Sun Protection
Interpretation of SPF In vivo Results: Analysis and Statistical Explanation
Methods for determining SPF in vivo are based on a biological response by human skin. To overcome intrinsic variation in these methods, large numbers of volunteers and statistics are required; however, these concepts are often poorly understood or worse, misinterpreted. This article discusses how these values should be interpreted and explains what they mean to formulators.
Sun Protection
Adapting SPF Testing Methods for Mineral Sunscreen Density
A sunscreen layer’s thickness is critical to its SPF. However, current regulations specify a mass application rate for testing, rather than a volumetric application rate. This significantly underrates the SPF values of mineral sunscreens due to their higher densities since, compared with their relative organic counterparts, thinner films are being tested, as will be shown here.
Sun Protection
UV Transmission Assessment: Influence of Temperature on Substrate Surface
This work evaluates the impact of temperature on test substrate surfaces during the application, spreading and drying steps of the in vitro method to measure ultraviolet (UV) transmission. The authors work in a range of temperatures, between 20°C to 35°C, and demonstrate that controlling temperature is a key parameter and should be strictly controlled to ensure reliability.
Sun Protection
Adjusting Substrate/Product Interfacial Properties to Improve In vivo/In vitro SPF Correlation
This work evaluates the impact of a plasma treatment on test substrates to modify their surface energy, to more closely correlate in vitro SPF measurements with in vivo measurements—without chemically altering the test products. The authors chose the level of plasma modification to use on a substrate based on in vivo values; they explain how to choose it regarding specific formulas in a further paper.
Sun Protection
Adjusting Substrate/Product Interfacial Properties to Improve In vivo/In vitro SPF Correlation
This work evaluates the impact of a plasma treatment on test substrates to modify their surface energy, to more closely correlate in vitro SPF measurements with in vivo measurements—without chemically altering the test products. The authors chose the level of plasma modification to use on a substrate based on in vivo values; they explain how to choose it regarding specific formulas in a further paper.
Sun Protection
Wise Words From the Bench with Gavin Greenoak
After 25 years in the industry, Gavin Greenoak, managing and scientific director of the Australian Photobiology Testing Facility Pty., Ltd. (APTF), continues to strive for a better understanding of the interaction of light and the human body. Greenoak’s career began in cancer research, which has afforded him unique insight of skin biology and the effects of sun exposure.
Sun Protection
New method to Reproduce In vitro Cosmetic Product Photostability Findings
The present article describes a reproducible method for determining the photostability of sunscreen products. This method is based in part on the in vitro determination of the UVA protection factor as proposed by Colipa for the irradiation aspect, and on the spectroscopy of a sunscreen in dilute solution for the absorbance measurement aspect.
SPF/Sun
Science Exposed—What Should the Minimum Recommended SPF Be to Avoid Sunburn?
“Science Exposed” is a new column aimed at digging into industry controversies to strip them down to the scientific facts. Here, sun protection expert Brian Diffey, PhD DSc, critiques the current SPF test method.
Sun Protection
Comparatively Speaking: SPF and Calculated SPF
In order to prepare the industry for the upcoming Sunscreen Symposium, organized by the Florida chapter of the Society of Cosmetic Chemists, industry expert Tony O’Lenick asks Dennis Lott to explain the difference between SPF and calculated SPF. This is the first of two columns on sun protection.
Sun Protection
Interpretation of SPF In vivo Results: Analysis and Statistical Explanation
Methods for determining SPF in vivo are based on a biological response by human skin. To overcome intrinsic variation in these methods, large numbers of volunteers and statistics are required; however, these concepts are often poorly understood or worse, misinterpreted. This article discusses how these values should be interpreted and explains what they mean to formulators.
Sun Protection
Adapting SPF Testing Methods for Mineral Sunscreen Density
A sunscreen layer’s thickness is critical to its SPF. However, current regulations specify a mass application rate for testing, rather than a volumetric application rate. This significantly underrates the SPF values of mineral sunscreens due to their higher densities since, compared with their relative organic counterparts, thinner films are being tested, as will be shown here.
Sun Protection
Characterizing Roughness: A New Substrate to Measure SPF
Here, the authors describe a variable that affects the results of SPF testing in vitro—the roughness parameter—and investigate this variable using standard and molded poly(methyl methacrylate) (PMMA) substrates. They conclude that use of a molded substrate, along with the described control chart, improves the reproducibility of in vitro SPF test results.
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