There's a good chance you've been intrigued by a product that promises its ingredients "penetrate deep into the skin" to treat your biggest skincare concerns, whether that's laugh lines around your mouth or the hyperpigmentation on your jawline from hormonal acne. After all, the deeper it gets into your skin, the more effective it must be, right?

Factor in the widespread rumor that 60% of said skincare ingredients also get into the bloodstream, and it's not shocking that product absorption has become a hot topic in the clean beauty community. While many clean brands have used this stat as a reason to switch to "clean" and "natural" formulations, does the skin really absorb products this way? And more importantly, is there any reason to be concerned about it?

Let's check in with Dr. Marisa Garshick, board-certified dermatologist, and Krupa Koestline, clean cosmetic chemist and founder of KKT Consultants to bust this skincare myth.

What Is the Function of the Skin?

As the body's largest organ, it's important to understand the purpose of the skin. Dr. Garshick says the skin has many important functions including "serving as a protective barrier for the body and preventing entry of different substances or microbes." It also helps regulate body temperature and enables sensations like touching.

Do Skincare Products Get Absorbed into the Skin?

Let's circle back to the skin's main role as a barrier for the body. Because it's designed to keep things out, not every skincare product is going to soak into it like a sponge. "It's not as easy to just put something on your skin in order for it to penetrate; it takes a lot of testing and research and development to create transdermal drugs and cosmetics," Koestline confirms.

The formulation and dose of the product determines how the skin absorbs it. "Skincare ingredients break down and interact differently with the skin based on what they are," explains Koestline. "Biologically, our skin's outermost part is a phospholipid bi-layer. So oil-soluble (lipophilic) products and emulsions have an easier time penetrating than water-based ingredients." The molecular size of the ingredient is also a factor in how it penetrates the skin. Larger molecules stay on top of the skin, while smaller molecules have the ability to penetrate deeper.

However, even if a formula isn't able to penetrate into the skin, that doesn't mean it doesn't have any benefits. "In general, the larger the molecule, the more difficult it is to penetrate the skin barrier and get absorbed," says Dr. Garshick. "That doesn't necessarily mean these products are not effective as it is also important to care for and nourish the skin barrier, even without penetrating the skin and getting absorbed."

One delivery system is liposomes, which are found in topical patches. "Topical patches are designed in a way to penetrate deeper layers of the skin in order to make sure the active molecule ends up in the bloodstream," Koestline explains. "Liposomes are usually used in order to facilitate this."

"[Absorption] can also be impacted if the product is also being occluded, or covered on top, which can increase the penetration, if it is formulated with penetration enhancers which help substances absorb better, or if there are any other tools or devices used to help boost penetration," adds Dr. Garshick.

Does Absorption Depend on Where The Product Is Applied?

The short answer? Yes. The skin on or around your eyes is thinner than the skin on your elbows. "In some cases, the products penetrating the skin can depend on the area of the body as the thickness of the skin layers can vary based on where it is being applied," says Dr. Garshick. "Additionally, it is not just the ease of getting the product through the skin, but it can also depend on the degree and depth of blood vessels at a certain location."

VIDEO: How to Treat Stubborn Cystic Acne

So, Do 60% of the Skincare Products We Use Really Make It into the Bloodstream?

In order for a product to make it into the bloodstream, Dr. Garshick says it would have to consist of small molecules or have delivery system that enables it to penetrate the skin barrier and have both water- and oil-soluble properties. "Since many of the products we use do not necessarily fit this criteria, it is unlikely that 60% of products are absorbed into the bloodstream," she explains.

Chemical UV filters are one example of an ingredient that can make its way into the bloodstream. While this is one reason why there's been a backlash against chemical sunscreens in recent years, Dr. Garshick stresses that the actual impact of ingredients that get into the bloodstream is still unknown.

From non-toxic makeup and skincare to sustainability practices, Clean Slate is an exploration of all things in the green beauty space.