Ingredients in Sunscreen: Chemical vs. Physical Sunscreen
One of the most effective ways to keep skin looking its best is using daily sun protection. UV (ultra violet) rays from the sun cause premature aging by creating free radicals, which are unstable molecules that break down collagen in the skin. Over time, UV exposure and free radicals lead to premature aging.
There are two types of UV rays that breach the ozone layer and cause damage to the skin: UVA rays and UVB rays. UVA rays penetrate the layers of the skin, causing most premature aging. UVB rays cause tanning and burning on the upper layers of the skin.
Both UVA and UVB rays are linked with skin cancer and long-term harm for your health. Adding sunscreen to your daily skincare ritual, as well as being mindful of sun exposure, helps defend skin against from both types of UV rays. It’s never too late to begin protecting your sun and researching information about the active ingredients to determine which sunscreen is best for your skin and lifestyle.
Physical and Chemical Sunscreens – What’s the Difference?
There are two types of sunscreen actives available: physical (often also referred to as “mineral”) and chemical. In this article, we will use the term “sunscreen.”
Physical sunscreens use UV filters that reflect, scatter and block the sun’s rays. Chemical sunscreens use active ingredients that absorb UV radiation, preventing them from penetrating the skin. Over time, some chemical filters slowly break down and release heat. While all physical UV filters block from both UVA and UVB rays, most chemical UV filters protect one or the other, not both. Some widely available sunscreens contain both physical and chemical ingredients to provide broad spectrum protection.
Ingredients in Sunscreen
To help you better understand UV filters, we’ve created two lists below of the most commonly found UV filters:
- Para-aminobenzic acid (PABA): One of the first chemical UV filters used in early formulas, this chemical filter protects skin from UVB rays. This UV filter is less common in newer sunscreen formulations because it may be an irritant for those with sensitive skin.
- Avobenzone: For a chemical UV filter, Avobenzone has the best UVA protection. The EWG (Environmental Working Group) notes it has limited skin penetration and no evidence of hormone disruption.
- Homosalate: Homosalate has been found in mother’s milk and disrupts estrogen, androgen and progesterone. There is also concern that it releases harmful by-products as it breaks down.
- Octisalate: Usually added to help stabilize Avobenzone, Octisalate is unlikely to cause allergic reactions according to the EWG.
- Octinoxate (also known as Octylmethoxycinnamate): Octinoxate has been found in mother’s milk and mimics hormonal activity, which may cause disruptions.
- Oxybenzone: Oxybenzone has one of the highest penetration percentages in lab studies (1-9%) and acts like estrogen. It has been associated with endometriosis in women and has high rates of allergic reactions.
Based on the information provided by the EWG, we recommend avoiding Oxybenzone, Homosalate and Octinoxate because they have higher rates of allergic reactions and penetrate the skin. However, it’s important to always check with your doctor on the best sunscreen for your health and lifestyle.
Common Ingredients in Physical Sunscreen
Titanium Dioxide and Zinc Oxide are the only physical UV filters approved by the FDA for sun protection. They are also the least likely to cause a reaction on the skin, so sunscreens that use these UV filters as active ingredients are a good choice for young children and those with sensitive skin.
- Titanium Dioxide is a naturally occurring mineral with a distinct, white pigment. In skincare and cosmetics, Titanium Dioxide is used for its UV-reflective properties and for its ability to remain stable when exposed to UV rays. Unlike many chemical UV filters, Titanium Dioxide does not degrade in the sun.
- Zinc Oxide is another mineral that can be found in nature, but most Zinc Oxide is manufactured synthetically. Like Titanium Dioxide, it scatters and reflects UV rays, preventing them from reaching the surface of the skin. It is the only ingredient approved by the FDA that effectively protects against both UVA and UVB rays.
In some formulations, these ingredients can leave a white cast on the skin, which causes many to avoid products that use them. However, there are sophisticated, well-formulated sunscreens that include both chemical and physical actives without leaving traces of white pigment or sensitizing skin.
A Note on Nanoparticles
For use in skincare and cosmetics, both Titanium Dioxide and Zinc Oxide must be micronized (a method of milling solids into extremely fine particles) in order to have an effective, high-performance SPF and PA rating.
In recent years, some have expressed concern about whether nanoparticles are absorbed into the skin. European countries require that sunscreen labels indicate whether nanoparticles are present. Research in this area is ongoing on the potential health impacts of nanoparticles in personal care products.
It’s important to remember that sunscreen is an excellent addition to your everyday skincare ritual—even on overcast and cold days because the sun’s rays are still present. Don’t forget to apply enough sunscreen to cover all exposed areas, especially those often overlooked such as the back of the neck, ears, neck and décolleté, which are particularly susceptible to sun damage. Keeping track of your sun exposure, and reapplying sunscreen as often as needed depending on how long you are outdoors, is your first line of defense against UV radiation.
Additionally, simple lifestyle changes such as wearing a hat, opting enjoying the shade and wearing long sleeves also help your skin stay healthy.