DMDM Hydantoin
Should cosmetics be as safe as what you eat?

I have seen people commenting online that they want cosmetics safe enough to eat.  Well they have pretty much got their wish.  Not many cosmetics would suit the palates of ladies or gentleman of fine and delicate taste, but with the possible exception of underarm deodorants tucking into your personal care products is going to do you no actual harm in either the long term or the short term.

But the idea that what is safe to put on your skin can be inferred from what it is safe to eat isn’t a very good guide to action.  I can think of things I would not want on my skin that I am sure would be harmless to eat. There is one very good example that is quite memorable.  A lot of snake venoms will kill you if they get directly into your blood stream but can be swallowed without any harm at all.  I am pretty sure that I was taught at school that Queen Eleanor sucked the poison from the wound when a snake bit Edward I, saving his life.  Sadly, when I researched it for this post it turned out not to be true.  But the biology is still correct even if the history isn’t.

Snake bites are mercifully rare, but here is something that you will definitely to come into contact with.  Formaldehyde is a naturally occurring material that we are all exposed to on a daily basis.  One source is the breakdown of carbohydrates to sugars by enzymes such as the ones in saliva.  It doesn’t matter if the source of the carbohydrate is a Big Mac or an organic apple straight off the tree.  Formaldehyde can usually be found in fresh fruit and vegetables from similar sources.  So up to a certain level the body is perfectly able to cope with formaldehyde.  On the other hand, a large dose would kill you instantly.  Prolonged exposure to levels higher than you normally experience can cause cancer – it is probably one of the main carcinogens in tobacco smoke.  It really is the perfect example of the dose making the poison.

So it is safe to eat low levels of formaldehyde and we all do so every day.    I have put a link to some published figures below. Pears have one of the higher values at 60 ppm.  A pear weighs about 100g and so when you eat it  you  are swallowing about 0.006g of formaldehyde in a few minutes.   The EU legislation on formaldehyde in cosmetics seems pretty reasonable on the face of it.  It is permitted at 2000 ppm as a preservative, with the proviso that you have to put a ‘contains formaldehyde’ warning on the pack.  Unlike the pear, most of the formaldehyde won’t end up in the body.  Even the most determined beauty product lover will not get anywhere near as much formaldehyde into their body from a cosmetic than they will from eating a pear.

So if you subscribe to the if its good enough to eat it is good enough to go on my skin philosophy you should be very happy to use products with the EU’s maximum formaldehyde level in them.  Formaldehyde is one of the few chemicals that can easily penetrate the skin, but even so compared to the formaldehyde you are generating yourself and the formaldehyde that you are eating as part of your normal diet the liver is hardly going to even register the extra contribution getting in via your skin.

I am afraid you won’t be able to try this out though.  Formaldehyde is now almost unknown as a cosmetic raw material. This hasn’t always been the case. When I first started in the business in the early eighties it was still being used in some lines, but it was rapidly being dropped.  Formaldehyde as a cosmetic ingredient is basically a thing of the past, though it does crop up in a few formulations from time to time.

If you can somehow manage to find a cosmetic containing it I still would not worry unduly, formaldehyde is very volatile and any exposure you get is going to be of a very short duration.  I wouldn’t chose to put it on my skin but I doubt very much it would do you any harm.  But I think we were wise to stop using it.  Although it never posed a significant risk to end users, certainly less risk than spending time in the company of a smoker or being in a room with an open fire, I don’t think it is a sensible preservative.  For a start people who work in the factories who make cosmetics would be at risk of higher levels of exposure.  And the formaldehyde itself has to be made and transported.  So we have moved on to better alternatives.  Or have we?

One of the preservatives that has replaced formaldehyde is DMDM Hydantoin.   This is one of a number of preservatives that work by acting as formaldehyde donors.  So instead of adding formaldehyde itself you add a chemical that breaks down slowly over time to release a tiny amount of formaldehyde.  This solves the handling problem.  And if you follow the ‘safe enough to eat principle’ it is fine as well.  If you like lots of data you’ll be fine with this material too.  There is plenty of toxicity data on it and the CIR have given it a clean bill of health at the low level it is generally used at.   So on paper it should be fine. And there have been no issues with its use.

Nonetheless I don’t use it myself, and I avoid using products that contain it.  I wouldn’t be troubled using a product preserved with formaldehyde itself.  But I am not happy with formaldehyde donors.  It seems to me that there is a risk that hasn’t been considered. If you have a molecule that can absorb into the skin which releases formaldehyde slowly, there is going to be formaldehyde around for quite a lot longer than using the stuff neat.  And this is not something that the skin is likely to have evolved any mechanism for dealing with.  Formaldehyde is quite likely to be toxic to the Langerhans Cells that are a key part of the skin’s defences.  In some ways Langerhans Cells themselves are a bit like bacteria.  DMDM hydantoin is definitely harmful to bacteria – that is why we use it – so I don’t find that too hard to believe.

An effect like this would be very hard to pick up in lab work or in subsequent screening.  The risk is that if the DMDM hydantoin compromised the skin’s defences it might well leave you more prone to developing skin cancer from exposure to light.  I freely confess that this is pure speculation on my part and I don’t have any actual evidence that this happens.  Indeed I am not sure how I would go about proving it if I had the time and resources.  But if I had to place a bet on which preservatives might turn out to be harmful in the long run I’d pick the formaldehyde donors ahead of the parabens and ahead of formaldehyde itself.

Incidentally when you see scare stories about formaldehyde in products nowadays, they are usually referring to products containing formaldehyde donors.  They always seem to be baby products as well, which is always a good way of getting more publicity.  What they have done is performed a test where the full amount of formaldehyde in the molecule is released in one go.   You can have any opinion you like about the safety of formaldehyde itself but the high figures that get quoted are irrelevant to anything since those figures only ever occur under the condition of the test.

The release of formaldehyde is the chief issue with this material but when it is breaking down other less well known materials are also released.  There are other preservatives that break down to release formaldehyde which also release other sensitising materials.  The quantities are low but even so I am not at all keen on the idea of biologically active breakdown products spontaneously forming on the skin.  DMDM Hydantoin hasn’t been shown to have this problem, but the molecule itself turns out to sensitise a reasonable number of people.  There is no such thing as a perfect preservative but this one seems to fall rather further short of perfection than most of them.

But there it is, a preservative I would happily eat but which I wouldn’t personally put on my skin.  It is probably safe enough, but I’d rather not take the chance.


WHO data on levels of formaldehyde found in food

Contact Dermatitis. 2010 Oct;63(4):192-202. doi: 10.1111/j.1600-0536.2010.01770.x. Epub 2010 Aug 20. Preservatives in cosmetics: reactivity of allergenic formaldehyde-releasers towards amino acids through breakdown products other than formaldehyde. Kireche M, Gimenez-Arnau E, Lepoittevin JP.

Scary story about formaldehyde in bath products (4/2/17 this story has been taken down, but it wasn’t very convincing while it was up as is always the case with EWG stuff)

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