New 2016 — Public Proof About Zinc
Physical sunscreens, also known as "mineral" or "barrier sunscreens" work literally like perforated metal on the skin, reflecting some light before it has the potential to enter the skin and initiate rosacea symptoms of redness, irritation and capillary damage.
The main physical sunscreens are zinc oxide and titanium dioxide, although a few brands indicated for extreme sun exposure also utilize magnesium and iron oxide.
The stellar reputation of zinc, and to a less extent titanium, in blocking UV rests on old versions of these ingredients which are rarely used today.
Original zinc and titanium products are thick, enirely white and opaque, melt in the sun, stain clothing and have a tendency to cause acne.
Today, these older products are usually reserved for use on the nose and lips alone and often come in bright neon colours.
Newer formulas made of extremely fine (in some cases nano) particles, while cosmetically acceptable, do not block UV nearly as well as original opaque zinc and titanium, particularly in the UVA solar wavelength.
Patients often find this out the hard way, in the short-term as sunburn, or the long-term as disappointing management of their rosacea, and poor results in the prevention of visible aging.
I believe most cosmetically-oriented, experienced dermatologists are well-versed in this "secret," but recently consumers on social media are helping get the word out, with voices as loud or louder than that of PR.
You can read about the Jessica Alba "Honest Company" zinc sunscreen fiasco at Forbes Magazine Online, which provides a lengthy analysis of the hubris (and skin damage) linked to many sunscreen manufacturers, and the lawsuit facing the company (including sunburn photos) at Refinery29. There are similar articles at Time Magazine and The Washington Post.
You can also see my 2016 summary about zinc in sunscreens and the FDA.
If you're able, please post a link to this page on Facebook and/or Twitter and help get the word out about the inadequacy of modern physical blocks.
Manufacturers sometimes use high concentrations of zinc and titanium dioxide (10-25%) to raise the protection offered by their products, but these higher concentration products typically drag on the skin and are difficult to remove properly, leading to problems.
Skin irritation from cleansing which attempts to remove water-resistant sunscreen and reduced efficacy of topically applied rosacea medications and other skin care due to a physical barrier against their absorption formed by tenacious residual sunscreen (zinc, titanium, and the oilier bases, frequently including mineral oil or beeswax, in which they are formulated) are common.
Taking into account the entire experience of patients with sunscreens, they are less likely to experience irritation from physical than chemical blocks because they are not absorbed into the skin.
Nevertheless, I believe that chemical sunscreens, if carefully chosen, are superior.
I make this claim primarily on the basis of clinical experience, but also for the following purely technical reasons:
Used as directed, they are also much more protective against UVA than any modern physical sunscreen.
Author: Jeremy Cleckley