As I've said before, I don't want to pick a fight with parabens. Despite internet rumors to the contrary, they are relatively safe (the breast cancer claims have been rubbished by the National Cancer Institute, which is good enough for me). However, they get into the eco system and are harmful to marine life. So I'm inclined - but not obsessively so - to avoid them. Phenoxyethanol, on the other hand, is one mean SOB. So what are the alternatives and do they work?
Just because something is 'natural' doesn't mean it's benign. The efficacy of a preservatives relies, by definition, on its ability to kill live cells. This means they are intrinsically toxic. A number of natural extracts, plants and essential oils contain substances that have the power to effectively kill bacteria, yeast and fungi. However, some of them could be be toxic for humans. Good examples are citrus or grapefruit seed extracts.
Although lemon and grapefruit seeds do contain antimicrobial properties, some of their constituents are thought to be responsible for wreaking havoc on hormonal balance. Citrus seed extracts are not approved for cosmetic use in Europe and in Japan.
Fermented radish root
is a natural preservative that several companies have started to use (update: it is in Truth In Aging's Hair Vitality Complex
launched in 2012). It does a good job at 05%-2% concentrations against a whole range of tiny nasties from e.coli to a.niger and it is recommended that it can be used as the sole preservative in a cosmetic.
A new antibacterial, Dermosoft 688 ECO, recently became available and is claimed to be safe. It has been around as a cosmetic fragrance ingredient for some time. The insight that the manufacturer of Dermosoft, a German company called Dr Straetmans, had is that it decided to look at essential oils and then isolate one or two of the components that coincidentally have antimicrobial activity. One of these was anisic acid. In fact, it is a paraben (parabens occur all the time in plants) and, in this case, is found in aniseed (pimpinella anisum).
There are a few other botanicals that are worth looking at. For example, rosemary oleoresin extract, or ROE, is a proven antioxidant. This means that it stops oxidation, but is not antibacterial (it doesn't stop formation of yeast, fungi, bacteria). Nevertheless, it may work well enough for extending the shelf-life of essential oils.
A company called Vitiva claims that its ROE derivative called Inolens 4 "outperformed widely-used tocopherols as well as synthetic ingredients, such as BHA and BHT while extending the shelflife of oils up to six times depending on the oil type".