You may have noticed that there’s been a growing debate on the safety of preservatives - particularly parabens. Concerns range from their supposed endocrine-disrupting ability to their presence in breast tissue. Do parabens deserve to be blackballed or are they undeserving of the bad reputation they’ve garnered?

Preservatives in Cosmetics 

Let’s face it, cosmetics have a lot of challenges when it comes to remaining stable. They’re stored in warehouses, shipped in extreme temperatures, and then they’re used by customers who live all over the world. If that isn’t challenging enough, you also have to consider other obstacles like people sticking their fingers into jars or using their products in a warm, humid bathroom. Skincare products need to be able to survive all of that and remain stable for long enough to be used.

Imagine making a big smoothie, and then storing it at room temperature in your bathroom for a year. Would you want to take a big swig? That’s why preservatives are so important in cosmetics: we expect more stability and a much longer shelf life compared to things like food.

All cosmetics need to have a preservative strategy and it extends beyond just preventing microbial growth. We need to prevent oxidation of oils and other ingredients, keep emulsions from separating, colors from changing, and much more. Spoilage is just one piece of the big picture that is product stability.

When deciding on the appropriate preservation system, brands have several considerations:

• Water. The more water there is in a product, the higher the potential for microbial growth. Reducing the water content or adding humectants can make a formulation easier to preserve.

• “Bug food”. Certain ingredients like plant extracts are tastier to microbes like bacteria, mold, and yeast. The more bug-friendly ingredients you have, the stronger your preservative system needs to be. On the other hand, ingredients that are antioxidants or have antimicrobial action can act as “helpers” to improve stability.

• Contamination. The best way to ensure we aren’t increasing the burden on a preservative system is to ensure there’s no microbial contamination during the manufacturing process. This includes the raw ingredients, the equipment, and also the mixing and bottling.

• Packaging. A product designed to be scooped out with bare hands or used in the bathroom will have very different preservation needs than a pump bottle. Cosmetics also use primary and secondary packaging, both of which can influence stability and aesthetics. 

• Target Audience. Products designed for children or use around mucous membranes have more stringent requirements.

• pH level. A highly acidic or highly alkaline environment can help control microbial growth but this isn’t an option for every product. For example, it’s almost impossible to create an emulsion (think lotion or cream) at a very low pH.

How Preservatives Work

While the word “preservative” usually brings antimicrobial ingredients like parabens or phenoxyethanol to mind, there are a number of ways to preserve a product. Food is a great example of this - refrigeration, freezing, curing, canning, pasteurization, fermentation, and drying are just a few examples of how we have stored food over time. There is much to consider when it comes to preventing microbial contamination, extending shelf life, and making sure ingredients remain effective in cosmetics.

Cosmetic preservatives can be organized into 3 main categories:

 

These are just a few of the many considerations that brands take into account when deciding what their preservation strategy will be.

With the recent shift away from traditional preservatives, there have been some interesting alternatives pop up. “Hurdle technology” is one such example, using a combination of bacteria-inhibiting methods like sterilization, pH level, reducing water content, airless packaging, and more. But this isn’t appropriate for every product and doesn’t have the reliability and testing yet of more traditional preservation methods.

We’ll be focusing on antimicrobial preservatives as they’re highly effective, widely used, and are also usually at the center of the debate on safety. And while we know that they work by stopping germs from growing and making more germs, antimicrobial preservatives can vary in how they achieve this:

• Parabens target the cell membrane of microorganisms, causing them to spill their contents.

• Phenol derivatives aren’t as common in cosmetics but appear to function similarly to paraben esters.

• Phenoxyethanol targets the cell membrane and also inhibits enzymes.

• Organic acids and salts vary in how they work but it’s believed that in acidic conditions, weak acids can penetrate the cell membrane and decrease intracellular pH. This causes the microorganism to slowly starve as it uses up all its energy trying to pump the protons out of its cell.

• Formaldehyde donors cause cell death by interacting with several cell sites. Additional research is underway to better understand these specific interactions. 

 

While antimicrobials can vary in how they target unwanted germs in our skincare, they have all been well studied in terms of their efficacy and safety. Generally, they’re paired together to ensure broad-spectrum action against gram-negative bacteria, gram-positive bacteria, and fungi - different types of preservatives have different strengths when it comes to the microbes they kill and in what type of formulation they work best.

And the cosmetic chemists helping brands formulate products aren’t just picking the most appropriate preservatives and leaving it at that, either. Cosmetics undergo extensive testing to ensure they’ll hold up during shipping and other temperature changes (something called challenge testing), plus other tests to determine their expiration date and other important stability considerations.

Why Parabens are Used

Parabens have been used for decades and have only recently seen a decrease in use due to trends centered on natural skincare and clean beauty. They’ve enjoyed worldwide popularity since being introduced in the 1930s and not just in cosmetics - they’ve been used in the pharmaceutical industry and for industrial applications as well. Their popularity is well deserved and is evidenced by their long history of use.

The Benefits of Parabens

• Efficacy. The most popular parabens used are broad spectrum and work well in a fairly broad pH range.

• Cost. They’re generally fairly cost-effective.

• Ease of Use. They usually don’t alter the color, taste, or odor of the formula.

• Tolerance. Parabens rarely cause allergic reactions, which is uncommon for most preservatives.

• Safety. As we will get into, they have significant safety data.

The American Contact Dermatitis Society (ACDS) named parabens the 2019 Non-Allergen of the Year. The ACDS also noted that “Paraben reactions are quite uncommon and generally relevant. Parabens remain one of the least allergenic preservatives available. The unsubstantiated public perception of paraben safety has led to its replacement in many products with preservatives having far greater allergenic potential.

The Debate on Safety

The concerns over parabens seem to have all started with a misinterpreted 2004 study that found parabens in breast cancer tissue. While this caused a stir in the skincare community at the time, this study did not suggest that parabens cause breast cancer. It simply found parabens in breast cancer tissue – but it also found parabens in blank slides, with no tissue at all. Our founder Alli thoroughly debunked this 2004 study in a TikTok video.

Later on, the endocrine-disrupting potential of parabens would become the focal point instead, though these claims are equally shaky. All studies showing endocrine activity from parabens have three things in common: 1) they’re on mice or rats; 2) they involve either injecting or force-feeding those rodents with massive quantities of pure parabens, and 3) they demonstrate that parabens’ estrogenic activity is thousands of times less powerful than our own hormones. All studies on the use of parabens applied topically on human skin at the levels used in cosmetics have found absolutely no endocrine disruption.

To help get to the bottom of this debate, I decided to chat with an expert Ava Perkins, a cosmetic chemist, PhD student, and science communicator on Instagram. “You may have heard the term 'toxicity is in the dose’ or ‘the dose makes the poison’,” says Ava. “This essentially means that anything can hurt you at the right amount - even water!”

There is so much that goes into determining safety and usage rates with cosmetics. Toxicologists consider everything from the route the product will be administered, dose, cumulative exposure, every exposure route, and so much more. There is a lot of testing that goes into establishing ingredient safety and parabens are no exception. Every concern about parabens has been carefully researched and ruled out.

When asked about parabens, Ava says “parabens have been heavily and frequently studied since the 80s, especially due to concerns about their endocrine disrupting potential. What fear-mongering marketing fails to convey is that parabens are frequently used at less than 1% in your products and major governing bodies (FDA, CDC, SCCS, and CIR) have repeatedly stated that parabens are not a concern.” In fact, parabens are by far the most-studied preservative on the cosmetic market. It’s not that alternative preservatives are inherently safer because there’s not negative research about them; it just means that research hasn’t been done. 

The bottom line? There is extensive testing behind the use of parabens in addition to their long history of use. The Expert Panel for Cosmetic Ingredient Safety has done multiple safety assessments on parabens and determined that they were too weak compared to our own hormones to be a concern in terms of endocrine disruption. They are allowed per the European Union’s cosmetic regulations and here in the U.S. the Food and Drug Administration (FDA) recognizes them as Generally Recognized as Safe (GRAS). 

Shouting about the dangers of parabens will get you clicks on your article or help you sell your “clean beauty” product, but it isn’t based on fact.

 

References

1. https://pubmed.ncbi.nlm.nih.gov/25256527/
2. https://cosmetics.specialchem.com/selection-guide/preservatives-for-cosmetic-formulations#
3. https://books.google.com/books?id=26rSwpklHZcC&pg=PA163&lpg=PA163&dq=cosmetic.preservatives+mechanism.of+action&source=bl&ots=wG0ICqbycc&sig=ACfU3U04R1H-eTWp-Hfk3YOg778VIxNgSw&hl=en&sa=X&ved=2ahUKEwimme_5kNKEAxVPOTQIHZ6KB2M4HhDoAXoECAIQAg
4. https://www.medscape.com/viewarticle/508430
5. https://journals.sagepub.com/doi/pdf/10.1177/1091581820925001
6. https://www.fda.gov/cosmetics/cosmetic-ingredients/parabens-cosmetics
7. https://www.fda.gov/food/food-ingredients-packaging/generally-recognized-safe-gras
8. https://pubmed.ncbi.nlm.nih.gov/30570578/

Mira is a skincare educator, blogger, and the content creator behind Skin Science by Mira and The Skincare Forum on Facebook. While skincare keeps her busy, she’s also pursuing her degree in Nursing and loves to spend her free time hiking.  As a content writer for Stratia Skin, Mira shares her evidence-based approach to skincare topics and a passion for making science accessible.