The One Sunscreen We Recommend
If you thought all sunscreens are pretty much alike, our board-certified dermatologists at Genesis Dermatology in Jupiter would like to take this opportunity to describe the two main types of sunscreens, and tell you why we recommend one particular kind over the other.
You already know that exposure to the ultraviolet (UV) rays of the sun is the leading cause of both skin cancer and premature wrinkling of the skin. And even though we’ve reached the end of meteorological summer, you need to protect your skin from UV rays year-round. In addition, those of us who live here in the southern part of Florida need extra protection, because the sun’s rays are stronger here so near the equator.
There are two main types of sunscreens.
The first, chemical sunscreens, have been used for decades, with varying results.
When they were first manufactured, most had a sun-protection factor (SPF) of 15. That means that if you’d normally burn with ten minutes’ exposure to the sun, an SPF of 15 would allow you to safely stay in the sun for 15 times longer than that, or 150 minutes. As more research was done on sun exposure’s effect on the skin, researchers recognized the need for greater protection, so SPF factors were boosted to 30 and higher.
Chemicals cause problems
There are several problems with chemical sunscreens.
First, because they break down when exposed to the sun, they lose their protective ability after less than two hours, and must be reapplied frequently. They can also be affected by excessive heat exposure, which means if you store them in hot places like a car or beach bag, they can lose effectiveness well before their expiration dates. But there’s no way to tell this just by looking at the product.
Another problem with chemical sunscreens is that, when applied, they are absorbed into the skin.
This issue is the most concerning, because the active ingredients in many sunscreens, especially oxybenzone, may cause endocrine disruption in the body. That is, once absorbed into the bloodstream they may disrupt normal functioning of the hormones, including thyroid, estrogen, progesterone, and testosterone.
In addition, some people are allergic to one or more of the compounds contained in chemical-based sunscreens.
A better alternative
The other main type of sunscreen is mineral-based, containing either zinc oxide or titanium dioxide or a combination of both. Comprising these crushed minerals, the sunscreen remains on top of the skin, forming a barrier against the sun’s rays. And unlike chemical sunscreens, these do not break down in the sun.
In the past, these types of sunscreens left a telltale white coating on the skin.
But a newer generation of mineral sunscreen has addressed this problem by crushing the minerals into even smaller particles, which makes the whitening effect negligible. Mineral sunscreens also are better tolerated by far more users, including those with sensitive skin.
Solving the absorption problem
One issue with these types of sunscreens is that many are crushed into fine nanoparticles to achieve the invisibility effect. (A nanoparticle is a particle smaller than 100 billionths of a meter.) Many people are concerned about nanoparticles’ effect on the lungs when inhaled. They are also concerned that if nanoparticles are absorbed into the bloodstream, they could cause harm to various organs in the body.
But when zinc oxide is incorporated into lotions or creams, it is not inhaled, simply applied to the skin, where it remains until it is removed in the shower.
If nanoparticles still concern you, you can look for zinc oxide or titanium dioxide sunscreens whose particles are “micronized”; that is, the minerals are crushed into larger sizes than those containing nanoparticles, but which are still transparent (or nearly so) on skin. Products containing “non-nanotized” zinc oxide—meaning particles are 100 nanometers or more in diameter—are generally considered safe. Sometimes people complain about the white color of these sunblock’s but we suggest a tinted version or adding tinted skin drops to create a more cosmetically elegant product.
A final concern about mineral sunscreens is that they can react with the sun’s UV light, producing the free radicals that have been implicated in the development of various cancers. Many manufacturers have solved this problem by coating (or “microencapsulating”) the minerals’ surface with inert ingredients, thus mitigating this effect.
Given all these factors, our board-certified dermatologists recommend you consider mineral-based vs. chemical-based sunscreen for optimal sun protection.