Shielding your skin from the sun may not be as easy as once thought.
At the current Maui Derm for Dermatologists 2020, Curtis Cole, Ph.D., president of Sun & Skin Consulting, presented on controversies in photoprotection, namely, that it’s not always best to trust the number on the bottle.
Dr. Cole showed a study published by Consumer Reports depicting major differences in the SPF number on the product and their testing results, with some having less than half the value listed on the label.
“Some of the numbers can be found for SPF 50 showed up as an SPF 8,” says Dr. Cole. “This report indicated that as much as 50% of the sunscreens did not meet their label claims and
over 74% of sunscreens with only inorganic (ZnO and TiO2) were overrated in terms of their SPF results.”
With sunscreen research beginning in the 40s, Dr. Cole says it wasn’t until 2010 that the International Organization for Standardization (ISO) created a unified global protocol for SPF testing.
More recently, he has been working with ISO for the last 5 years as their project leader to revise and improve the method for sunscreen SPF testing to give lower variability and higher accuracy.
To do this, Dr. Cole says ISO has taken steps to objectively determine a test subjects skin phototype. Instead of using questions like, “do you burn in the spring?”, he says “we replace that with an objective, instrumental colorimetric and measurement for selection of subjects for the SPF test and prediction of their sunburning dose (Minimal Erythema Dose - MED).”