by Dr. Hannah Sivak | February 9, 2015
Let’s talk about preservatives
How do we make a product that is microbiologically safe for the user? First, we start with very clean ingredients and work in a very clean environment: the objective is to limit bacterial and fungal presence to a minimum. But bacteria and mold are part of our environment and, sooner or later, spores will make their way into your skin care products. A minute percentage of those spores belong to microorganisms capable of causing dangerous infections, and a larger proportion of spores belong to organisms capable of producing spoilage. Infection or spoilage will happen unless the product contains chemicals that will kill and/or stop growth of microorganisms whenever and wherever they come in contact with the product.
Every company in the skin care industry uses preservatives. Without preservatives a product would spoil a few days after manufacture, without even making it to the store shelves. Very few formulations are self-preserving, i.e. they don’t need added preservatives. Absence of water, high salt, high sugar, or extreme pH will stop growth of most microorganisms.
New products are put through a ‘challenge test’. What is a challenge test? A variety of microorganisms are added to the product being tested. After incubation for some time in conditions favorable for the bacteria/mold, the product is analyzed to see how many (if any) of the microorganisms survived.
Combinations of several chemicals (synergistic combinations) are preferred to single chemicals because different chemicals will stop a wider variety of microorganisms. This way, the concentrations required for effectiveness are lower, decreasing the potential for irritation and toxicity.
Choosing a preservative or, more often, a combination of preservatives is a craft based on scientific information. Used at the right concentrations, preservatives in skin care products are effective, safe, and non-allergenic. Time is the best tool in the testing of a preservative, so it is better to use a combination tested for decades because new combinations may be ineffective in some circumstances, or have undesirable side effects.
Manufactroversy is a term coined by Harriet Hall, MD (see skeptic.com) to designate a manufactured controversy “created by junk science, dishonest researchers, professional misconduct, outright fraud, lies, misrepresentations, irresponsible reporting, unfortunate media publicity, poor judgment, celebrities who think they are wiser than the whole of medical science, and a few maverick doctors who ought to know better.”
I would like to apply this lovely new word to the issue of preservatives. I am not very keen in revisiting this subject, because in a manufactroversy, no matter how often you demonstrate that X is safe, whatever you say will be taken by the converted as further proof that there is a conspiracy to hide the dangers of X. In the years since the paraben wars started, many people have made lots of money thanks to this manufactroversy. This campaign has pushed the industry to use new preservatives without enough testing before they were brought to the market. Manufacturers are selling powerful synthetic preservatives as “natural extracts”, skin care companies are selling “paraben-free products”, and shady “non-profits” have invented false toxicity indexes. I would not be surprised if several of the new preservatives were found to not be very good or have some undesirable side effects. Time will tell.
What are parabens? They are synthetic chemicals used in skin care and food that imitate natural antimicrobials like methylparaben (present in blueberries). Parabens are esters of 4-hydroxybenzoic acid widely used as antimicrobial agents in a large variety of food, pharmaceutical, and cosmetic products because of their excellent antimicrobial activities and low toxicity. They are stable, effective at very low concentrations and over a wide pH range, and active against a broad spectrum of microorganisms, including bacteria and fungi. Parabens have a long record of safety. Also, parabens don’t contribute a smell to the finished product. One of the problems of natural preservatives containing a mixture of extracts from oregano, rosemary, and more is that the smell can be overpowering, and several of the natural extracts used as preservatives are allergenic.
It is not easy to find antimicrobials suitable for use in skin care, because the main requirement is that they will be active on bacteria and mold but harmless to humans. The anti-parabens campaign (just google the word ‘parabens’ and you will see what I mean), which was started with a weak scientific paper and was spread via mass emails, has resulted in the industry scrambling to find alternatives to parabens. Although reasonable substitutes were devised for use in creams (see our European base cream), we at SAS stuck to parabens in water-based serums because we could not find a safe, effective alternative.
Parabens have a very slight “estrogenic activity”, meaning that they bind to estrogen receptors with very low affinity (1,000 to 1,000,000 times below the potency of 17β-estradiol). This is important for women who have breast cancer that responds to estrogen. For these women, it may be useful to avoid plant chemicals with relatively high affinity for estrogen receptors; including diosgenin, daidzein, resveratrol, kaempferol, naringenin, phloretin, and many others (before worrying about parabens), but talk to your MD if you are worried.
Although parabens are not particularly allergenic, a very small section of the population may become allergic to parabens. This is not very common, and is one of the reasons why parabens are such desirable preservatives. Another is that they are absorbed into the body but are quickly broken down, with the breakdown products eliminated through the urine.
The European Union Directorate for Consumers Affairs in the meeting of 12/14/10 issued yet another report to the effect that parabens are safe for use in skin care products. (SCCS Scientific Committee on Consumer Safety, Opinion on parabens, 14 December 2010). In short (the opinion is 35 pages long), the committee examined very carefully all the evidence available, including new research that had been solicited in previous opinions.
The issues considered included:
1) The relationship between the use of parabens in deodorants and the development of breast cancer.
2) The potential in vitro and in vivo endocrine modifying effects of parabens, in particular estrogenic/anti-androgenic activities.
3) The toxicokinetics (dermal absorption and biotransformation) of the different paraben esters.
The committee “considers the use of parabens as preservatives in finished cosmetic products safe to the consumer, as long as the sum of their individual concentrations does not exceed recommended concentrations”. Find the complete opinion at:
Parabens are still part of my preferred combination of preservatives, but our new European Cream contains a different combination of chemicals: potassium sorbate, phenoxyethanol and caprylyl glycol.
Phenoxyethanol has very low toxicity and is non allergenic. Sometimes referred to as ‘rose ether’, it is a good general bactericide that is most active against gram negative bacteria. Because it is not very effective against fungi, it must be used in combination with other preservatives. It has been in use since the 1980s.
Potassium sorbate is a poor bactericide, has some activity against yeast, but it is very active against mold. It has been used for a very long time to preserve foods.
Caprylyl glycol is a good emollient base for the other two chemicals and improves their performance.
A preservative by any other name (or no name)
“What’s in a name? That which we call a rose
By any other name would smell as sweet.”
Romeo and Juliet (II, ii, 1-2)
True for roses, but what applies to roses does not necessarily apply to skin care. In a battle that involves pressure groups, environmental politics, fear and marketing, the first casualty is science.
A prospective client wrote to me demanding to know why we at SAS continue to use preservatives in our products when she has been doing so well with products that contain no preservatives whatsoever. My answer: those products DO contain preservatives. How come she does not know this but I do?
There are at least three ways to hide preservatives from consumers
* Hide: The preservatives in the formulation are presented as emollients, or essential oils, or anything else but what they are: preservatives. This is possible for ingredients that are not well known.
* Confuse: The preservatives are not explicitly included in the list, but are included (and unmentioned) in the “natural” extracts. For example, if licorice root is extracted with a solution made of water, propylene glycol, and preservatives such as parabens, all that needs to appear in the ingredient list for the final product is “licorice extract”. Moreover, if the plant was grown without synthetic fertilizers, herbicides, or pesticides, the extract (which is mostly water, propylene glycol, and preservatives) can appear on the label as “organic licorice extract”. If plant extracts are a good part of the product, no further preservatives will be needed, because the concentration of preservatives contributed by the “extracts” to the final product will be enough for safe preservation.
* Lie: A company adds preservatives and simply lies about the formula (yes, it happens). Unless somebody sends the product to an analytical laboratory to be tested (at a cost of several hundred dollars) nobody will be any wiser.
In short, preservatives, i.e. chemicals added to the formula with the purpose of killing or delaying growth of bacteria and mold, are always present in any formula, whatever the label may say. Notable exception: products completely free of water, because microorganisms need water to grow and divide.
The trouble with non-existent preservatives
No matter how many references, appendices, and pages there may be in the carefully considered SCCS opinion regarding parabens, I am sure that some people will still be buying products with non-existent “Japanese honeysuckle extract” or “grapefruit extract” as preservative.
What’s wrong with a non-existent preservative? The skin care product still has to be on the shelf for a few months, and somebody will open it and take a bit with a never-clean-enough finger, so the manufacturers had to add something to the product to prevent bacteria and mold from growing on it. If they say their product is paraben-free, how did they manage it? Would an extract made from Japanese honeysuckle prevent growth of microorganisms?
The chemistry of Japanese honeysuckle flowers is not a mystery. A thorough chemical analysis will not reveal any potent chemicals with the power to keep your skin care products safe from bacteria and mold. The same is true for grapefruit seeds, meaning that any such chemicals were introduced by the manufacturers with the aim to fool the consumer.
This is what happens when you force the formulators to stop using safe preservatives, you end up with unknown chemicals in your skin care products, and with unknown chemicals come unknown dangers. This is not to excuse the formulators, or the companies selling the mystery preservatives, or the marketing people pushing for unsafe alternatives to avoid alienating the “unknowing populace”.
Preservatives you may find in our products
Diazolidinyl urea, phenoxyethanol, methylparaben, propylparaben, potassium sorbate, and caprylyl glycol are used in groups to cover the wide range of microbes (bacteria, mold) that surround us and will grow and divide in our nutrient-rich products unless stopped. The preservatives we use in our products have been used for many decades without trouble, and they were found to be non-mutagenic and unlikely to lead to allergies. It helps that the preservatives we use are required at very low concentrations to be effective. Our first priority is product safety.