What is the correct information about zinc oxide in sunscreens?

Regarding what you said about percentages of zinc in sunscreen... I was wondering how you would respond to what I just now read: "When looking for a quality sunscreen, I often hear people ask what the percentage of Zinc Oxide is in a particular formula. Even when the product already states having a high SPF rating. Why? There is a misconception that more Zinc Oxide in a product will deliver higher level of UV protection and it just isn’t true. It’s not that simple. Percentage of Zinc Oxide in a product does not equate to higher or lower SPF or more or less UVA protection. SPF measures UVB rays only - the damaging rays that burn and age skin. UVA rays are responsible for skin damage but they do not cause sun burn. UVA rays are the ones that make their way through the clouds in the sky and your windows and cause skin damage. UVA protection is not given a number or a rating to measure it’s ability to protect against UVA rays. A products ability to guard against UVA rays is either approved as meeting the minimum requirement for blocking a high percentage of the UVA rays, which concludes it Broad Spectrum, or not. I’ve witnessed a few brands capitalize on and perpetuate the miseducation by marketing their higher percentage of ZO as a USP (Unique Selling Point), saying, “we have 20% zinc oxide for the most protection.” I’m not sure if they actually know this isn’t true or if they are miseducated as well." Thank you for your time. Jennifer F.

I’m thinking the easiest way to explain this is to use the table below.

Please remember that the SPF number – like 30 or 50 – only refers to the UVB component. The sunscreen industry fought the dermatologists’ (AAD.org) attempts to require 2 SPFs. There should be an SPF for both UVB and UVA, in my opinion. There is NO SPF that refers to UVA. The industry is allowed to say “broad spectrum” no matter how poor the UVA block in the product is. The industry definition of “minimum” requirements are lacking in the opinion of most dermatologists.

An SPF of 30 blocks 95-98% of the UVB rays. This is assuming that the correct amount is put on and then reapplied every 2-3 hours. We all know that many people don’t put enough sunscreen on and then forget to reapply it.

Why does zinc oxide matter?

When you look at the table below, a great sunscreen would have a blue bar all the way across the table. Yellow just means a partial (attenuation) block only. The only sunscreen ingredient that does that is ZINC!! Iron oxides are good too, but are only in powder sunscreens currently in the U.S. that I’ve been able to find.

The problem with what you said above, is the statement that a product meets the minimum requirement for blocking a high percentage of UVA. Zinc oxide is the only ingredient which does that. See below. If out in high risk sun situations, try to find zinc 15-20%.


Why you should be using Zinc sunscreen | By Dr. Brandith Irwin on SkinTour

Dr. Brandith Irwin, MD

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