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By: Rachel Grabenhofer, Cosmetics & Toiletries magazine
Posted: August 28, 2009, from the September 2009 issue of Cosmetics & Toiletries.
In a recent discussion with an industry colleague I unearthed a new fact about myself: I am a lazy gardener. I like plants that grow themselves once they are in the ground. However, most plants need some sort of attention otherwise they die, like many of my flowers.
Considering all the variables in my “gardening failure” equation, I could blame the deaths of my flowers on the weather or unfavorable soil conditions, but had I followed through on weeding and watering them—factors more easily controlled—they likely would have bloomed. While this failed lesson in gardening is more about common sense than science (i.e., plants - water = dead plants), it does translate into something more complex: controlling variables.
Controlling variables and understanding how any change in them affects an outcome is an important part of conducting valid scientific research—and as the industry knows, it can make or break any claims substantiation work. While this is true across all fields, it is especially crucial in industries that touch consumer health.
In recent years, one of the most scrutinized categories impacting consumer health is sun protection and debate continues regarding how to best measure it. While recent focus has been on product stability, UVA and UVB radiation, and evenness/thickness of test sample application, a new approach presented here by Pissavini et al. instead considers the roughness of the test substrate to which the sample is applied.
The authors examined different batches of standard test substrates made from PMMA and found that their physical variances impacted SPF test results. Thus, to improve upon the validity and consistency of SPF measurements, the authors propose a molded substrate to better control variations between substrates and ultimately to provide more consistent SPF readings.