everything you want to know about zinc oxide
What is zinc oxide?
The chemical formula for Zinc Oxide is ZnO, which stands for one zinc atom and one oxygen atom that is held in place by an ionic bond. ZnO is an inorganic compound with a white, powdery consistency; it is also insoluble in H2O.
When was it first used?
History suggests that early humans likely used zinc compounds as a topical, healing ointment and as a paint. However, the composition they used is unknown. The Indian medical text Charaka Samhita mentions a salve for the eyes and open wounds that is probably zinc oxide, and the passage is thought to date from 500 BC.
Where does it come from?
Zinc oxide occurs naturally as the mineral zincite, which is a rare element and commercially unavailable. Zinc oxide is mostly produced synthetically today. There are numerous specialized methods for synthesizing and producing ZnO. For industrial use, it is produced en masse by three main processes: Indirect process, direct process and wet chemical process.
How does ZnO end up in our products?
Since the compound zinc oxide is not water-soluble, it can’t be applied by itself topically; it usually needs to be combined with a carrier agent. For example, zinc oxide is usually blended with active mineral ingredients, along with inactive ingredients such as beeswax, to make products such as sunscreen.
Also, nanoparticles are used in the making of sunscreens with titanium dioxide and zinc oxide. The process makes it easier to absorb into your skins vs.the the gloopy, white sunblocks of the past.
What are the primary uses and benefits of zinc oxide?
ZnO is quite ubiquitous, and it is used in a wide array of consumer products. Products made from it protects the skin from the elements and enhances properties. The technique also makes the ingredients it’s blended with less harsh, which makes the product gentler on the epidermis.
Sunscreen products composed of it are particularly handy because ZnO sits on top of the skin. There it does its job of reflecting, scattering and blocking harmful ultraviolet rays.
The following consumer products listed include zinc oxide in their composition:
- Cosmetics Sunscreen & sunblock
- Personal care products
- Nail products
- Baby lotion
- Foot powder
- Diaper rash ointment
How well does sunscreen protect your skin from the sun?
Shielding your skin from ultraviolet radiation (UVR) the sun emits is important to your health and well-being. When it comes to protection from the sun’s harmful rays, zinc oxide does such an excellent job because its properties effectively block ultraviolet (UV) light waves that make it to the earth.
Another valuable property that ZnO has that helps with sun protection is that it is photostable, meaning that it resists change in the presence of light. When zinc oxide is used as an ingredient in sunscreen, it blocks a certain amount of radiant energy in UV light waves.
Although there are three types of UVR, photoprotection from both UVA and UVB radiation is of the most importance.
UVB, also known as burn rays, is usually what comes to mind when people think of applying sunscreen coverage. The third UVR the sun emits is UVC, which is of nominal concern because the ozone layer blocks it before it reaches earth. However, the depletion of the ozone layer is of great concern because of the protection it provides.
According to researchers at the National Institute of Health, the sun emits 280–320 nm of UVBR and 320–400nm of UVAR. Those facts are telling when it comes to protecting skin, the largest organ in the human body. Let’s learn more.
As you can tell, UVA has a longer wavelength than UVB. This property means that its harmful rays penetrate deeper and damage the epidermis and dermis of the skin.
UVA rays contribute to skin cancer, wrinkles, problems in immune regulation and more. These health threats are always present, even when it’s cloudy and regardless of the season. That is why dermatologists recommend wearing sunscreen at all times.
Since UVA rays are potent enough to penetrate window glass, photosensitive people may even need sunscreen protection indoors.
How did we discover zinc oxide’s sun-protecting abilities?
The history of zinc oxide being used in this manner is somewhat murky. We do know that its effectiveness as a protective skin barrier against the sun gained traction in the 1980s. At that time, extensive clinical research officially brought ZnO’s potential for better skin health and fighting sun damage to the forefront.
Which skin types benefit most from this ingredient?
Sunscreens containing ZnO are beneficial for all skin types. Even if you don’t sunburn easily, wearing it is still important. Getting a sunburn is an immediate reaction, but damage from the sun damage occurs over the years and cumulates throughout a lifetime.
Although skin cancer is more commonly found in light-skinned people, the sun’s damaging UV rays don’t discriminate, affecting dark-skinned people too.
Zinc oxide is also an exceptionally effective shield against the sun for babies and youngsters whose skin may not be as mature and developed as adults.
Because zinc oxide is both antimicrobial and non-comedogenic (non-pore clogging), sunscreens that contain it are a good choice for people with redness and rosacea due to extremely sensitive skin. The antimicrobial properties of ZnO can aid in healing burns and other skin damage that results from sunburn.
How does ZnO stack up against those with chemical SPF ingredients?
For starters, sunscreen that doesn’t contain zinc oxide as an ingredient won’t block those longer UVA rays. Also, skin that has a weak barrier due to dryness and eczema often allows greater skin penetration. Also, skin that has a weak barrier due to dryness and eczema often allows greater skin penetration.
As a result, more chemicals in the products applied to the skin can be absorbed. Because zinc oxide-containing sunscreens sit on the skin’s surface like a barrier, they are not absorbed the same way chemical sunscreens are.
Besides penetration and absorption, zinc oxide is also better tolerated overall by those with more sensitive skin.
Are there any drawbacks to consider? Maybe, a potential for clogging pores or white tinting on dark skin?
Chemical sunscreens often contain ingredients that clog pores and cause acne flare-ups. Sunscreen ingredients to look out for if you are prone to acne include quaternium-15 (a preservative), Balsam of Peru fragrance, benzophenones such as oxybenzone, octocrylene and cinnamates, to name a few.
One of the benefits of zinc oxide that is important to acne-prone is that it is non-comedogenic. In a nutshell, that means it's oil-free and won't clog your pores.
Zinc oxide and titanium dioxide, another popular sunscreen type, also have the benefits of being non-irritating and non-allergenic.
With darker skin types, it can be challenging to find a zinc oxide-containing product that rubs in without leaving the skin with a greyish hue, but formulas are getting better and better every day. Otherwise, there is no reason not to use zinc oxide for sun protection!
Credit to Ashley Magovern, MD, Board-Certified Dermatologist. Co-Founder, Project Sunscreen (www.projectsunscreen.com); Owner, Manhattan Dermatology, Manhattan Beach, CA.