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Why do manufacturers of natural actives still disperse them in petrochemical humectants?

September 8, 2017
How many times have you heard about a wonderful new ingredient only to find that it is dispersed in propylene or butylene glycol making it unsuitable for use in a natural or organically certified product?   I’ve certainly had that happen quite a lot!   As tempting as it can be to say ‘why, oh why’ and then lament the stupidity of the ingredient manufacturer I thought it best to put the emotion aside and look at this situation with a more critical eye.
Ok so Propylene glycol, butylene glycol and pentylene glycol are all petroleum derived ingredients often found in combination with natural or synthetic actives. As I’m sure we are all aware by now petroleum is a non-renewable resource in as much as it takes thousands of years to ‘make’ and we are quite literally burning it up faster than we can grow it.  This ‘use faster than you can replace’ mentality is not exclusive to petrochemicals by the way, Indian Sandalwood is a natural victim of our insatiable appetite as indeed is natural vanilla so you could say that if we were less greedy, petroleum would be a renewable resource – renewable and natural given that it’s all just dead little fish and plants anyway……
But before we go any further on that let’s look into WHY these glycols might be used. 
 The reasons for using these ingredients are many and varied including:
  • The glycols prevent the crystalisation of the active. Crystalised actives may not work at all.
  • As a fixative – improving adhesion of the active to the skin or longevity of a fragrance or aromatic active.
  • Humectant – to prevent the active from drying out or to ensure the biologically ‘active’ water components remain viable.
  • As a preservative – glycols are anti-microbial and can be used INSTEAD of a preservative and as a SAFER way to preserve an active with less irritation (and often at a lower cost).
Glycols such as those above have a long history of safe use in cosmetics and propylene glycol is generally regarded as safe by the FDA and can even be ingested in reasonable doses over a long-term without any detrimental effects (although you wouldn’t down a bottle of it). That said, there are some down sides such as the potential for skin irritation if used in large doses – something that most formulators would be aware of and seek to avoid to be honest.
So it is fair to say that glycols do help us to make the most out of the ‘active’ that we are buying and it is probably also fair to go on and say that they increase the efficacy of it too, thus making the whole thing of having the active in the first place worth while – and what could be more sustainable than that?
I’m going to mostly be talking about Propylene Glycol here even though other glycols are used.  This is because PG is the cheapest of the lot, the most widely used and ironically the most likely to irritate to be honest. So if we look at the worst case scenario first, we can only get better from there.
But the petroleum industry is so polluting!
While there is no doubt that there is an environmental cost of digging up this stuff and burning it, it is also an important thing to remember that burning anything has a cost – even if you are burning pine on a bonfire!  The petroleum industry has become synonymous with belching trucks, smoke stacks, massive chemical plants, oil spills, toxic wastes and all things cancerous but I don’t think that’s completely fair.  There are two layers to this situation – the first layer is that the oil which starts it all is a feedstock and the second layer is the down-stream use of that feedstock.   While it is true that ingredients like propylene and butylene glycol are, pretty much entirely petroleum derived at present, they need not always be. The main reason for their petroleum derived status is because that is the cheapest and most abundant feedstock at the moment.  As the world changes and resources run out it may be that the best feedstock changes and becomes palm, coconut or some other vegetable.  With that in mind it is important for us to weigh up the environmental impacts that we might experience by replacing all that petroleum feedstock  with plant-based.  How much space would that take up?  How much pollution would that result in? How would that look and feel?  I’m not insinuating it would be better or worse but I do think that we have become so used to coupling petroleum with pollution that we are in danger of downplaying the environmental impacts of other choices, potentially to the point of ignoring them altogether and that worries me. Not least because it takes away the need for us to start really focusing on how to do things better and to value ALL of our resources more.  Remembering that ‘reduce’ comes before ‘reuse’ and ‘recycle’…..
But are these chemicals ‘bad’ and if they are bad, is it because of the petroleum or because their chemistry is toxic?
Based on toxicity data you’d be hard pushed to call glycols particularly toxic and while it is true that everything can cause problems at some point, these glycols are pretty tame. Non carcinogenic, non sensitising and ingestible in small (but not tiny) doses these glycols are not even a major hazard to those working in a glycol factory unless you happen to fall in a vat of it – it is a skin penetration enhancer which is another reason it is used to solubilise actives but in big doses that can mean skin damage by softening – or get some in your eyes (that is irritating).  So the idea that these are the devils sporn maybe does need re-thinking.
What about when they go down the drain or get dumped in a forest?
The environmental fate of propylene glycol is also more love story than horror story.  Glycols in general degrade readily in soil and/or water releasing carbon dioxide (which isn’t great but many things ‘exhale’ Co2 so to speak) and nothing much else really given their simple C + H + O chemistry.  The only thing worth noting really is that propylene glycol does require a lot of oxygen to degrade it in water ways and that may lead to a lack of oxygen for fish and plants but as long as the dose is reasonable it will  degrade relatively quickly to carbon dioxide and water.  In general, these glycols have not been found to bioaccumulate and are quickly broken down in the environment giving them a low-impact end-of-life really.
And degradation in the body.
In the body propylene glycol is quickly metabolised into pyruvic acid, acetic acid, lactic acid and propionaldehyde. While the propionaldehyde is toxic to humans it is a minor bi-product and mainly gets excreted rather than building up.
Ok but surely manufacturing these things is a blight on society – dirty, polluting chemical factories….
In terms of their manufacture, it is another fairly positive story. The manufacture of propylene glycol and others is an industrial process but it is fairly clean and very efficient.  The intermediate chemicals needed to make this are also, for the most part safe and non-polluting and the resulting material clean and very pure. 99.5% ad 99.9% propylene glycol is possible.   Again, I think what’s happened here is that we have all equated these glycols with the whole kit-and-caboodle that can come out of a factory capable of this chemistry.  The companies that make propylene and butylene glycol on an industrial scale are the big chemical players such as BASF and Dow Chemicals.  Now I know of a few horror stories relating to Dow Chemicals and their chemical mis-haps that have no doubt made even the least skeptical person doubt everything that comes out of their mouthes but again, taking a step back from that emotion it is likely to be just a hang-over prejudice.   The reason these big chemical giants make propylene glycol is because it is then used as a feedstock for other things, namely plastics, coatings, paints, solvents and more.  Some of THESE chemicals ARE pretty nasty and don’t break down so well in the environment so I can see how it is easy to throw all the chemistry that comes out of these plants into the ‘nasty’ bucket but that doesn’t make it right or helpful.   In terms of the nasty polluting chemical factories I do think it is worthwhile knowing that while it is true that some of the up-stream chemicals they produce can be quite nasty, the factories themselves are increasingly run to be clean and to meet the toughest environmental and OH&S standards.  That doesn’t mean to say that they always achieve that but having worked on a chemical plant for a couple of years I do know that they are not in the business of slopping crap around everywhere and just hoping nobody sues.  Those days are gone (at least in Europe where I experienced it first hand they were).
So are we making a fuss out of nothing with all this then?
Well yes and no if my opinion on that.
While is true to say that these ingredients are petroleum derived now, they don’t always have to be petroleum derived. Their ‘nasty polluting chemical’ name that cosmetic glycols have got is not really warranted based on the evidence that I’ve found  and indeed, there are many benefits to including them in an active, including making sure the active works and the preservative load of the formula is lower (thus potentially saving resources).  While it would be great for brand owners looking to say ‘petroleum free’ if  actives came dispersed only in  naturally derived humectants such as glycerin and propane diol there are many reasons why that’s not currently the case AT THE MOMENT.   I am sure that as time goes by petroleum derived propylene glycol and friends will be placed under review and made even more sustainable than they are now but I’d hesistate to say that means we will see no propylene glycol in future. It is important to remember that propylene glycol CAN be manufactured from glycerin and glycerin can come from coconuts so we (brand owners and industry insiders) should be careful what we say when we say we are ‘free from’ as we might just lock ourselves out of a very useful, cost-effective and sustainable solution.
So that’s why manufacturers do what they do at the moment and I’m kind of OK with that, especially as there are so many different actives out there at the moment that if you really do want to avoid the glycols there will be something else you can use instead.
Amanda x
One Comment leave one →
  1. Peter permalink
    September 17, 2017 10:12 am

    “it is a skin penetration enhancer which is another reason it is used to solubilise actives but in big doses that can mean skin damage by softening”

    A while ago you mentioned Propylene Glycol can be irritating in higher percentages. The Ordinary released some products with 94%, 95% and 99.9% Propanediol. While Propanediol is considered less irritating than Propylene Glycol, could Propanediol be irritating to skin in these very high percentages? The products feel very warm when applying them on skin.

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