Choosing which preservative to use is one of the hardest ingredient selections a cosmetic formulator needs to make. Why?
Not only is correct preservative one of the essential components of creating a product with a good shelf life, they are the subject of much scrutiny by consumers questioning their safety and necessity. So, here are some preservative myths – busted! And some great facts that will help guide your selection in the future.
Why are preservatives needed in personal care anyway?
Preservatives are needed in just about every personal care formulation containing water. Bacteria, yeast and mould are incredibly opportunistic organisms that given just enough favourable conditions, will grow and multiply rapidly. The ideal growth conditions for most bacteria, yeast and mould are temperate climate, source of water, nutrients and a pH anywhere from 3 to 10. Personal care commonly contains water, nutrients, stored at room temperature with a pH around 5 – 6. This means, most personal care products are an ideal food source for these micro-organisms to grow. The only thing that stops them: suitable preservative selection! So let’s take a look at some of those myths…
Myth #1: Some essential oils/extracts act as preservatives
While it is true that some essential oils and extracts can control or prevent some micro-organisms from growing, their mode of action is very selective – which means even when they are effective against some micro-organisms, their action is not broad enough to provide effective coverage of the huge array of micro-organisms that a personal care product may be exposed to over its shelf life, and consumer (ab)use. So, if we relied on the few essential oils/extracts that do have some anti-microbial activity, we’d be leaving a formula unprotected from many hundreds, possibly thousands, of micro-organisms that would still readily contaminate it. This means, a broad-spectrum preservative is still needed to ensure adequate protection.
The same applies to anti-microbial drug agents: they may be effective against very specific bacteria or fungi, but are not sufficiently broad spectrum to provide effective coverage of a cosmetic product to ensure safe use by a consumer.
Myth #2: My product has a pH of 3.5 so it’s mostly protected, and it’s too low for bacteria to grow anyway.
Mostly protected is not totally protected. You need to remember that micro-organisms are extremely opportunistic, so they’ll try to survive in even very adverse conditions. While ‘ideal’ growth conditions for most bacteria is a pH around 6 – 8; and for fungi (yeast and mould) pH 5 – 6, bacteria can still grow in more acid conditions just as fungi can grow in more alkaline conditions. That hair conditioner with a pH of 4-4.5 still needs broad spectrum preservation. That non-oxidative hair dyes have a pH of 9 – 9.5, still needs broad spectrum preservation. In other words, EVERY personal care product containing sufficient water to sustain growth needs a preservative where it has a pH greater than 3 or less than 10.
Myth #3: One broad spectrum preservative is all we need.
Just why are there so many preservatives anyway? The truth is, there is no ‘1’ preservative that is perfect in every formula, especially when you add in consumer selection criteria!
- Some preservatives are only effective where the pH is less than 5.5.
- Others may only be suitable up to a pH of 7. If these conditions don’t suit the final pH of my formula, then they may as well not be present!
- Some INCI names contain the words ‘acid’ or ‘alcohol’ – and that can be off putting to some consumer groups.
- Some preservatives are based on parabens – proven to be safe when used within limits but if a consumer is concerned about, you’ll have little chance of convincing them otherwise!
- Others contain propylene glycol as a solvent that some consumers want to avoid.
- Some aren’t compatible in anionic environments; some aren’t compatible with high contents of non-ionic surfactants.
- Some contain formaldehyde releasers, also the subject of bad publicity.
- Some have aromas that may not be compatible with the target market or other fragrances you want to use.
- Some preservatives have a ‘static’ action to stop growth but can’t kill micro-organisms already present.
- Some cause products to lose viscosity, or cause a pH to drop too much for the formulation created.
- Under EU Cosmetic Regulation, only preservatives listed in Annex V can be used in cosmetic products, within the limits stated. Some companies marketing preservatives have taken liberties to extend this ruling to infer that substances that control or kill micro-organisms that are not on this list then aren’t preservatives, but that is misleading. You may see these marketed as ‘preservative free options’ or ‘preservative alternatives’, but that too is misleading. Technically, any substance that controls or kills micro-organism growth in a cosmetic product is acting as a preservative; and the defining question is this: if you removed the so-called preservative alternative from the formula, would micro-organisms be able to grow? If the answer is yes, then the substance/s is acting as a preservative and it is misleading to market it as not being a preservative. Sure, it may serve other purposes in the formula, but it is acting as a preservative if its removal would lead to microbial growth.
- Myth #4: This preservative is not a preservative.
- The point is, there is no ‘1’ perfect preservative that suits every formulation type – they need to be selected to suit the formulation, its charge, all ingredients it contains, pH range including drift over shelf life and the increasingly strict ‘free from’ list of different consumer groups. This is why there are so many preservatives available – because without them, most formulas would be rendered unsafe.
Myth #5: Some preservatives are harmful.
You’ve probably heard that parabens will give you cancer. You’ve probably heard about formaldehyde releasing preservatives. What you probably haven’t heard is that there has been, and continues to be, ongoing and extensive investigation to ensure safe input levels of these, and all, preservatives in personal care products. There are strict input limits on the use of parabens, formaldehyde releasers and just about every preservative used in personal care actually! The EU database has the most extensive list of permissible preservatives along with limits to ensure safe use. They also have several Scientific Opinions that have considered cumulative daily exposures of various preservatives to ensure consumer safety. If its considered safe in the EU, you can be sure of its safety within the specified limits in your personal care products, even on cumulative daily exposures.
Myth #6: There are preservative in my functional/active materials, so that’s enough.
No, it’s not. Some functional and active materials come with preservatives present to protect them from microbial contamination during storage – but they are used in small amounts in the raw materials; so, when they get added to a larger formula, they are no longer in amounts that are sufficient to protect the finished product. Every formula containing sufficient water needs broad spectrum preservation, regardless of the preservatives present in other materials.
Why are preservatives so controversial?
Preservatives interfere with one or more of the following: cell membranes, enzyme function, protein structure or cellular metabolic systems. But let’s face it, that’s exactly why we use them… on micro-organisms. Perhaps it is lack of understanding by consumers and misleading fear campaigns by organisations that highlight their activity for bacteria and fungi as if it will have the same impact on us! But, we are talking about tiny microscopic organisms here compared to 70kg adults (or even 5kg babies!!!) Again, using these materials within the limits set, especially by the EU, helps ensure confidence and safe use in a finished formula.
Perhaps its pressure from consumers or marketing departments to avoid certain preservatives that makes formulators take risks in these otherwise very hospital environments? One thing is certain, an inadequately preserved formula is a greater risk to a company’s reputation than an unpopular preservative choice!
Now, if we can just get back to focusing on the needs of the formula and ensuring compatibility, we’d have a lot more choices for every formula…
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