Safest Skincare Preservatives
Which preservatives are safest in your skincare, and why are preservatives even necessary in your skincare products?
Let's start with a definition of preservatives.
What is a preservative?
Preservatives are ingredients added to a product to increase its shelf life. Preservatives fall into one of two categories:
- stabilize ingredients in the product
- prevent microbial growth in the product
Antioxidants (stabilizing preservatives)
Ingredients like vitamin E (commonly listed by its INCI name: tocopherol or mixed tocopherols) and rosemary leaf extract are both powerful antioxidants that extend the shelf-life of oils and oil soluble ingredients. They're commonly used in formulas containing fragile botanical oils (think evening primrose oil, rosehip seed oil, and other oils with a really short shelf-life).
These ingredients are also oil soluble and scavenge free radicals and reactive oxygen species, and this scavenging action protects the fragile botanical oils, specifically the polyunsaturated fatty acid chains.
When these strong antioxidants are paired with fragile botanical oils and shelf stable oils (like meadowfoam seed and jojoba), it's possible to extend the shelf-life of really fragile oils from 6 months to a couple of years.
Antimicrobial preservatives in skincare
For any water based product, preservatives are necessary to protect from microbial growth, including bacteria and mold growth.
These types of preservatives are antimicrobial and keep pathogenic bacteria (and yeasts and molds) from growing in your skincare products.
Antimicrobial preservatives are necessary because your skincare products aren't aseptically manufactured in a sterile manufacturing suite or terminally sterilized.
In case you're wondering, sterile manufacture also isn't a requirement for many drugs.
Tablets and capsules, which are dry in nature, don't pose a risk to microbial growth, so no preservatives are needed. These drugs, while made in sanitary conditions aren't made in sterile conditions.
What's the difference between sanitary and sterile?
At first glance, those might sound like synonyms for each other, however, there's an ocean of difference between these two.
- Sanitary means clean.
- Sterile means free from bacteria or other living micro-organisms, in other words totally clean.
A sanitary suite requires specific cleaning procedures and typically must also meet guidance for air flow turnovers.
A sterile suite requires specific cleaning procedures, regimented air flow turnovers, routine testing to ensure sterility, and a particle free environment (per ISO standards, there are 9 classifications of particles in air within a manufacturing suite, ISO 9 is regarded as room air and ISO 3 is a sterile suite).
Check out cleanroom classification levels in this table.
Sterility is not a requirement of the finished packaged formula (either for cosmetics or topically applied drugs), however, both skincare and topical prescription drugs have to demonstrate that they don't grow microbes on storage, and they have to be made in sanitary conditions.
Despite the widespread myth stating the contrary, FDA regulates cosmetics, and microbial growth is one of the fastest ways for a company to get flagged by the FDA.
Per FDA guidance, cosmetics (both makeup and skincare products) have to be manufactured in a sanitary environment.
For drugs, USP testing is required to demonstrate that products are sufficiently preserved (from a microbial standpoint), and for skincare, ISO testing's required.
USP and ISO are acronyms for two standards organizations. Skincare should meet ISO standard microbial growth limits when the formula is tested as described in a standardized test called antimicrobial preservative efficacy testing (typically referred to as APET)).
Legit skincare companies subject their formulas to APET prior to release to market. APET tests (yes, it's redundant, and that's still how it's referred to in the field), are conducted by inoculating a formula with a minimum concentration of 5 different strains of pathogenic bacteria and yeast/mold and then looking at how much the growth of each of these strains is inhibited at specified durations and when incubated within a given temperature range.
As someone who's challenged the limits of possible to preserve formulations for years, it's not easy to pass ISO testing with just any alternative preservatives.
How to find the 1% level in skincare ingredients label
The ingredients list on a skincare label has to be written in a certain way. Specifically, ingredients have to be listed in descending order based on their concentration... until you hit 1%, and then the ingredients can be listed in any order. This is to help keep formulas trade secret for the brand.
So, as a consumer, how do you know where the 1% level is?
It's a guess, however, it's possible to make an educated guess...
here are a few examples:
Formula 2: Aloe Barbadensis (Aloe Vera) Leaf Juice*, Caprylic/Capric Triglyceride, Glycerin, Helianthus Annuus (Sunflower) Seed Oil, Rosa Damascena Distillate (Rose Hydrosol)*, Aqua (Water), Rosa Damascena (Rose) Flower Oil, Squalane, Sodium Dehydroacetate (preservative), Sodium Bicarbonate (Baking Soda) (we hit baking soda! commonly used as a pH adjuster... because you need teeny, tiny amounts to move that pH, sodium bicarbonate, sodium hydroxide, and citric acid are a telltale that you're below 1%), Xanthan Gum, Sodium Hyaluronate, Sodium PCA, Lauryl Glucoside, Myristyl Glucoside, Polyglyceryl-6 Laurate, Beta-Glucan, Dehydroacetic Acid, Benzyl Alcohol (preservatives), Citronellol**, Eugenol**, Geraniol** *Organic Ingredient **Component of Natural Essential Oil
with this one, I'm on the fence. While sodium dehydroacetate is likely in the product at less than 1%, EU limits for dehydroacetic acid AND sodium dehydroacetate is 0.6% in acid form. This is one where I'd reach out to the company to ask whether they follow EU guidelines for preservative limits.
Formula 3:
water/eau/aqua, dimethicone, neopentyl glycol diethylhexanoate, tetrahexyldecyl ascorbate, polyglycerin-6, propanediol, phenyl trimethicone, glycerin, hydroxyethyl acrylate/ sodium acryloyldimethyl taurate copolymer, sodium hyaluronate crosspolymer, ergothioneine, xanthophyll, allantoin, citrus aurantium amara (bitter orange) flower oil (this is the INCI name for neroli essential oil, and this almost assuredly is in the product at less than 1% (since this is a face cream)), sodium acryloyldimethyltaurate/vp crosspolymer, mannitol, pentylene glycol, isododecane, dimethicone crosspolymer, sodium phytate, pentaerythrityl tetra-di-t-butyl hydroxyhydrocinnamate, benzotriazolyl dodecyl p-cresol, polymethylsilsesquioxane, ammonium acryloyldimethyltaurate/beheneth-25 methacrylate crosspolymer, carthamus tinctorius (safflower) seed oil, citrus aurantium dulcis (orange) peel oil, phenoxyethanol(preservative), caprylyl glycol, chlorphenesin (preservative), ethylhexylglycerin, citric acid, Polysorbate 60, sorbitan isostearate
from a preservatives standpoint, this formula's fine. From a "would I put this on my skin standpoint?" No way. Do you notice all of the crosspolymers, copolymers (look for ingredients with numbers at the end, like a dash and then a number along with poly- in the ingredient name), and ingredients containing "acryl" and ending in "-eth"?
Here's the ingredients list again with those ingredients in bold:
Formula 3:
water/eau/aqua, dimethicone, neopentyl glycol diethylhexanoate, tetrahexyldecyl ascorbate, polyglycerin-6, propanediol, phenyl trimethicone, glycerin, hydroxyethyl acrylate/ sodium acryloyldimethyl taurate copolymer, sodium hyaluronate crosspolymer, ergothioneine, xanthophyll, allantoin, citrus aurantium amara (bitter orange) flower oil, sodium acryloyldimethyltaurate/vp crosspolymer, mannitol, pentylene glycol, isododecane, dimethicone crosspolymer, sodium phytate, pentaerythrityl tetra-di-t-butyl hydroxyhydrocinnamate, benzotriazolyl dodecyl p-cresol, polymethylsilsesquioxane, ammonium acryloyldimethyltaurate/beheneth-25 methacrylate crosspolymer, carthamus tinctorius (safflower) seed oil, citrus aurantium dulcis (orange) peel oil, phenoxyethanol(preservative), caprylyl glycol, chlorphenesin (preservative), ethylhexylglycerin, citric acid, Polysorbate 60, sorbitan isostearate
This particular formula is very... ungreen (and far from clean). Those acrylates and crosspolymers are pretty chemical-y as are:
- the UV filters (used as antioxidants in this formula instead of a plant based or at least "natural" antioxidant like vitamin E, coenzyme Q10, rosemary extract, vitamin C (which is in this formula in a stabilized form), green tea extract
- the silicones (ingredients ending in -cone)
Hopefully, these examples give you an idea of what to look for:
- peptides
- essential oils
- pH adjusters
when you're trying to figure out where that 1% cutoff is in a product. This is only a very general guide and a topic we'll likely revisit in future episodes.
Stay tuned for the additional episodes in this series on preservatives in your skincare.
About the Author
Brandy's a formulation scientist and self-proclaimed health geek who loves hiking, gardening, bird-watching, and body boarding.
Her struggle with acne during her teens and 20s led to a holistic and healthy approach to skincare, embracing skin as an organ to be loved and cared for rather than a canvas to wage war on.
Since 2008, she's been developing all-in-one products for a simple routine at home, & Rain Organica started when her backpacking friends asked for a portable skincare routine to keep their skin healthy & happy on and off the trails.
You can try Rain Organica for yourself with The Essentials Kit, a complete skincare routine in just 3 steps.
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