Deb asks whether natural preservatives are safer than synthetic ones.
Hi Colin, stumbled across your site somehow and so now have a question – I personally prefer to use “natural” preservatives (well actually prefer to make natural products with essential oils etc) over synthetic preservatives – the thought being that the synthetic preservatives may be more likely to cause skin irritation due to their synthetic make up – so what is your view in the whole dilemma? Is my thought process correct or is it flawed? Would love to know your professional cosmetic scientist view and the chief instigators of skin sensitivity synthetic or natural.
I don’t think there is any particular reason other than prejudice to believe that one is safer than the other. There isn’t even a particularly hard and fast dermarcation between what is synthetic and what is natural. In my personal experience the preservatives that generate the most skin reactions are the organic acids like benzoic acid and sorbic acid. These are often described as natural, and they are in the sense that they can be found in nature. But the material used in cosmetics, including most natural cosmetics, is actually made from petrochemical sources. The parabens are about the safest when it comes to skin reactions, and almost nobody describes them as natural.
The enzyme approach to preservation is the one that can best be described as natural and also gives rise to very few skin reactions. But it is both expensive and requires quite a lot of skill in formulating and handling so wouldn’t be suitable for people making their own cosmetics.
Talking a bit more widely, natural products in theory ought to give rise to more skin reactions. There are more different chemical entities in natural products than synthetic ones, so there are more triggers for an allergic reaction. But I can’t say that I have ever noticed this in real life. Products that contain a high natural content don’t seem to generate more reports of skin reactions.
The only thing I think we can be confident about is that prejudice is the enemy of good judgment.