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Should you keep your nuts off your face?

May 20, 2019

It was hard not to be affected by the keyboard warrior backlash Kylie Jenner got last week after announcing that her new skincare line would include a walnut facial scrub. Being a 90s teen I didn’t really think too much of it at first. I came of age in an era before political correctness, when nobody questioned where you put your nuts but hey, times have changed and so have I!

So what’s going on?


Picture from here. 

Walnuts, that’s what.

If you read even a handful of the comments online it leaves you with the impression that there is nothing worse for your skin than a dollop of walnut face scrub.  As a cosmetic chemist that is often asked to incorporate natural scrub particles into cosmetic products I wanted to dissect this backlash a little, flesh it out, play with these ideas a little, work out where the truth lies.  I did this first from my perspective as a cosmetic chemist and then by chatting to the lovely Amy Erbacher, facialist-to-the-stars and someone with heaps of up-close-and-personal insights into what people do to their skin and how the skin takes it.  Chemists don’t really have that sort of insight you see.

The backlash – a semi-scientific appraisal.

So what people seem to be upset most about are these things called ‘micro tears’ that allegedly form on the skin after you scrub it with walnut particles.

After thinking on this for a moment, I found myself wanting to form a mental picture of how ‘this’ rates against ‘that’. What that means is, if I assume that the people are right, that Walnut does form micro tears on the skin and that they are bad, how does that compare with other exfoliating particles, with harsh towelling of the skin,  with environmental factors (sand, wind, dust etc) and with other things we might do to our skin (needling, microdermabrasion, lasers etc).

Walnut particles are abrasive. They are abrasive because they are hard and un-yielding (they aren’t squishy like a sponge) and they also have some jagged rather than smooth edges. It is likely that these jagged edges could cause tiny skin tears.

Here are two microscope images of some Walnut scrub particles that came out of St Ives Apricot Scrub. The left side is at 4 x magnification and the right side is 10x. You can see some big particles and some small, some clumps and some individual particles. You can see the rough edges but generally these are just bulky and woody with little spiked bits.

A while a go, I looked at a whole bunch of other exfoliant particles. They are shown below. Looking at this you can see a range of natural and an un-natural particle. The Jojoba beads are round and soft-edged. These also melt at around 45-50C which is face-wash temperature.  The micro-plastic is somewhat round but with little jagged bits in the background.  The other materials, sugar excepted, are quite jagged and un-even.

Exfoliant particle line up

How can looking at this help with understanding micro tears?

If it is true that walnut particles cause micro tears to the skin, looking at the above range of exfoliant particles it would seem reasonable that at least some of the above could also cause the same.  This to me is interesting as the response online to Kylie Jenner’s launch was very emotional and ultra specific about Walnut shell.  Some early responders also cited a law suit brought against St Ives that got into the USA court system late last year.   As fairly typical of people trying to drive home a fast point, they neglected to inform their readers that the law suit application failed. Maybe looking at the above gives us some idea of why…

desk scrub

So what does using scrubs like this do to the skin?

This is where I couldn’t really answer and is why I got Amy Erbacher involved.

About Amy

Amy came to me a few years ago when she wanted to develop her own range of skin cleansers based on what she had learned from years in the beauty trade.  Amy explained that she often picks up visual signs that a clients skin has been treated too harshly during her practice as a facialist. Typical signs of past trauma include hyper pigmentation, irritation, adult acne and/or hypersensitivity.  Of course, being a facials Amy doesn’t give any medical diagnoses but it is her job to attempt to bring the skin back to looking and feeling good.

So they are the symptoms but what about the causes?  

Amy thought it entirely possible (even probable) that the habitual use of harsh abrasives, especially when applied vigorously and often to the skin,  could be contributing  to the symptoms she sees.  However, she felt it unlikely that physical exfoliant of the type purchased over-the-counter are the only cause of clients woes with  UV exposure, lifestyle habits such as smoking and a poor diet,  over-use of AHA’s and Enzymes and our addiction to instant results also playing a part.  On that front, as a facialist, Amy has observed clients growing appetite for cosmeceuticals as a potential double-edged sword.  Demands for stronger AHA products, faster-acting serums and deeper dermal delivery have (potentially) pushed the skin barrier to its limits for some clients resulting in various symptoms of premature ageing. When talking to Amy there was a clear vibe coming from her that the best approach to skin care was to take it gently and…care for it.

Stopping there for a moment there are clearly some subtleties to the case of ‘nut gate’ that we must address. Maybe it’s time for a little self-analysis and therapy?

Going back to my teenage years I just could not get enough facial scrub into my life. I had acne and part of that was blocked pores and blackheads. I was convinced that a good old scrub was the best way to get that dirt out.  Coming into modern times I’ve had more than one client send back the scrub samples I sent them for a bit of ‘toughening up’ when I went a bit too easy (gentle) on the physical exfoliation.  So while Amy is clearly telling me to calm it down in one ear, my other ear is hearing ‘give it to me hard baby’.  Who do I listen to!

Balance, perspective and application.

Amy clearly has a point.  The skin (and remember, we are talking facial skin here) is delicate but it is not pathetic.  This report looks at how skin resists tearing  and by looking at that we can clearly see that a little exfoliation isn’t likely to cause long-term damage when used sparingly and with care.  As we have eluded to above, there are many cosmetic procedures and practices that leave our skin slightly traumatised, indeed, that’s often how we get fast results.  Acids, needles and microdermabrasion treatments all stimulate the skin, instructing them to repair, re-build and restore the skin hopefully to its brighter, smoother and more youthful self.  In that way we could say that our trauma led to personal growth  – what doesn’t kill us makes us stronger.  So maybe the only trouble when it comes to exfoliating our skin is knowing when enough is enough…

When exfoliation has to stop. 


In Amy’s professional practice she recommends only the gentlest of scrubbing in all cases  and never for skin with live acne pustules – see that’s where I used to go wrong. I had the mindset that the scrub would set the pimple free and leave my skin clean and un-clogged. Looks like all I was doing back then is spreading the germs around!  So that’s one down-side of physical exfoliants – spreading microbes around the skin.  Are there any more?

Sensitive types. 

Amy points out that another down-side of harsh scrubbing is the disturbance of the micro biome. We are only just starting to learn how our few Kg’s of microbes that live in and on us keep us safe and well.  While exfoliants won’t damage the microbiome per se, they do ‘clean’ a bit more thoroughly than a product without them and for some people this can leave their micro biome a little scattered and when that happens, the skin can become more sensitive.   Again, it is a case of ‘less is more’.

Damaged Skin.

Amy points out that it is really tempting for those with sun-damaged thickened skin to go crazy with exfoliants but again this isn’t recommended.  The skin is thickened due to sun damage and so scrubbing that off won’t really help long-term as you are just layering more stress onto already stressed skin.   From my perspective these probably are the clients that ask for harsher scrubs.  From now on I’ll be talking to them more about cosmetic retinol products and gentle chemical exfoliants as safer alternatives.

When you have an addiction to harshness.

I have had several conversations with Amy over the years and there definitely does seem to be a section of the population that just can’t get enough when it comes to beauty treatments.  I think I was semi-addicted to the ‘freshly scrubbed’ feeling I used to get from my walnut exfoliant even though it was probably not doing me any good.  This behaviour is definitely going to result in long-term skin complications if it is kept up but it pays to remember that this is NOT, I repeat NOT the nuts fault.

The bottom line in nut-gate.

Amy is clearly in the ‘treat it ultra gentle’ camp whereas I like it a little rough (probably based on my earlier facial abuse) so who is right?

Amy is coming from a strong evidence-based mindset that over-exfoliating is one of the contributing factors leading to skin issues down the track. Because of that she strongly warns her clientele against harsh scrubs.  This advise is backed up by many other facialists, dermatologists and skin professionals.

When I look at the St Ives Apricot Scrub I see that it suggests using it 3-4 times a week, the Kylie Jenner product is apparently gentle enough to use every day or, as the pack suggests, 2-3 times a week.  I don’t know if the exfoliation rate is equivalent for these two products but having worked with Walnut exfoliant as an ingredient for many years it is unlikely to deviate much from the general shape, size and hardness typical of this ingredient.  What could vary is the dose,  the cushioning effect of the base and potentially the formula pH, perfume and preservative, all of which can contribute to the overall harshness or gentleness of a formulation.

Do we do what the packet says?

Looking back to my most addicted period I think I used the St Ives scrub 1-2 times a day in my bid to ‘clean my pores’.   Clearly it would be reasonable to expect a difference in results between people that over-use a product and those that follow the  normal/ recommended use pattern. That said, Amy was strongly of the opinion that 2-3 times a week would be too much, in general for skin to handle and I feel inclined to agree.  Maybe the days of exfoliating the shit out of our faces should be resigned to history, like the Spice Girls, Shell Suits and Cherry Coke…

So where does that leave nut-gate?

Ummmm, I think it is all a bit more nuanced than the good folks of the inter webs would like us to believe.  There is a clear ‘OMG NO, are you trying to kill us Kylie’ vibe going on online at the moment but maybe that’s all a smart publicity ploy, one never knows.

Traumatising the skin is a strategy that some cosmetic products and procedures use to their advantage so to single out walnut scrub as the worst thing to have ever happened to the skin is a bit silly really and does nothing to progress the conversation.  Micro tears are a type of trauma that a scrub could produce, but physical exfoliants won’t tear up your skin to any noticeable degree unless you scrub like a daemon, have skin that is already damaged or use the product in excess (and excess is going to differ for everyone) – all things being equal. If you are an abusive scrubber then you should not just be wary of walnut scrubs, you should be wary of any hard-particulate scrub agent that can generate sufficient friction.  There is nothing inherently worrying about walnut when compared to other natural exfoliants unless you are allergic to nuts and nut products.

I think the last word has to be to plead to our sense of balance.

If, like me, you like exfoliating scrubs then use them carefully, sparingly, gently and in a way that doesn’t damage your skin or spread infection.  I can see why the skin professionals hate them and I do agree that a gentle approach to skin care is most likely the best plan.

Most of us don’t know how to ‘do’ moderation but that’s not Kylie or the professionals fault, that’s ours.  That said, in telling us that she uses this product (which I haven’t tested) 2-3 times a week but that you COULD use it daily to achieve a skin like hers (which is kind of perfect) is somewhat irresponsible especially given that her audience is quite young, potentially acne prone and highly susceptible to celebrity marketing messages.

So should you keep your nuts off your face?


Amanda x









Titanium Dioxide in food, cosmetics and your gut AKA ‘E171 gut gate’.

May 14, 2019

So this morning I logged onto Facebook and almost immediately fell down a science-ing worm hole (I have no idea how that should be spelled).  It was catalysed by on line discussions about the safety of Titanium Dioxide as used in cosmetics (and foods) as a colourant. It turns out that this interest was sparked by a scientific report published by the University of Sydney last week and discussed on popular TV show ‘The Project’ which I didn’t see. I have since read the article, the scientific report abstract (which is all there is so far, and, (nerd alert) I spoke to the lead author, Professor Wojtek Chrzanowski PhD. So let’s see what all the fuss is about shall we…

Titanium Dioxide.

So, it turns out that while this was the molecule of study, the E171 food additive that has grabbed the headlines. It is the size of this molecule that is more interesting than its chemistry. That said, we should investigate its chemistry.

Titanium Dioxide is an inorganic chemical (it contains no carbon) that exists in nature. It forms in nature  in blocks or lattice structures where several Ti’s and O’s get together and don’t let go. These are the primary particles.  Titanium Dioxide can also be manufactured to make purer, more even grades with more marketable features and so it is important to note that the way you manufacture Titanium Dioxide will determine how big (or small) these primary particles will be.   Different manufacturing methods create materials that are better suited to certain jobs – sunscreen particles are different to food particles for example.

In addition to the particle size, there are also the 8 ways that titanium dioxide likes to get its self together – think of there being 8 different ways you can combine the same few lego bricks.  The most common of these are Anatase and Rutile.

Titanium Dioxide as a chemical is pretty un-reactive in the body and most bodies will poop it out. However, with any particle you get a particle size distribution which means that you buy a bag of titanium dioxide with an average particle size of 200 nm it will have some particles that are bigger and some that are larger. Their distribution will usually look like a camel hump on a graph.  Better quality products generally have a steeper hump as the particle distribution is smaller.

Any particles that are 100nm or smaller are in the nanoparticle range and in this study the average primary particle size was definitely less than 100nm.  There is another part to the cosmetic definition of ‘nano particle’ which talks about ‘intentionally made’ so as to differentiate manufactured nanoparticles from  naturally occurring ones but I’m not sure that will be relevant in this case.

The Study.

The study here found that nano titanium dioxide was affecting the gut microbiota.

I found that immediately interesting and used my Deep Dyvve subscription to look for other papers in this area. I found a few including this one that confirmed an affect on the intestinal brush border.


I’ll just stop here and show you a bit of a mind-map of how I start interacting with new information that comes across my desk.  This very brief diagram shows you that I consider the original paper, play around with it in my mind, evaluating it against my prior knowledge to see how well it addresses or confirms what I know about Titanium Dioxide and/ or nanoparticles – at this stage I also have to check and note any bias I have. I then look to the wider context and for more papers, develop my own questions and finally call the author!


My Big Question.

So one thing that confused me after reading this paper and comparing it to other papers was whether it was the titanium dioxide chemistry or the particle size that was causing changes. I put that question to Professor Chrzanowski and he set me straight.  I won’t quote him verbatim as it wasn’t that kind of chat but this is the crux of it in laymen terms.

Answer: It’s the size. The Titanium Dioxide is likely not an issue per se.

Before we go into that I was reminded that titanium (and zinc) particles are usually in agglomerates when they are purchased.  This basically means that the product contains loosely bonded clumps of particles that are lots bigger than their specified primary particle size.  The first step of the scientific process is to de-agglomerate them and then to identify the particle size distribution. Apparently this is typical of what would happen in our digestion anyway and is how our gut will eventually see the particles. The situation in sunscreens is somewhat different which again reminds me that what we put in the body isn’t dealt with in the same way as what we put on the body.

The nanoparticles enter the body naked but don’t stay naked for long. The body dresses them up with a protein coating as part of the digestion process.  I got the feeling that the body dresses up all of its food that way if it gets a chance so this is just standard procedure.

Once this protein wrapped nano particle gets into the gut, the gut tries to eat it but it finds it can’t because it doesn’t like eating titanium dioxide.   The down side in this case is that in attempting to eat the wrapper, the gut unleashes a nanoparticle and that’s when the trouble starts with the nanoparticle then causing some disruption to the micro biome and brush border.

The exact dynamics of this process is actually quite hard to study as Professor Chrzanowiski mentioned that this is a good example of where there is almost no correlation between animal studies and humans.  I did notice that many of the other studies I read through used in-vitro methodology – cell culture and models.  There is quite a bit more work to do to correctly map cause-and-effect from this understanding in terms of how much, for how long and how damaging this type of upset to the gut turns out to be.

The last step is excretion and titanium dioxide has been found to pass through the body happily via either toilet route depending on its size, dose and solubility I presume.

We know from lots of work in the pharmaceutical area that titanium dioxide in large form does pass out via the poo and this work helps to pinpoint particle size as the real issue to focus on.

So why mention Titanium Dioxide when it’s Nano that is at fault?

Basically in this study, the titanium was just the nano particle that demonstrated the concept, it wasn’t the problem, it was just the gimp…

The reason that Titanium Dioxide is grabbing the headlines is:

Titanium Dioxide is a potentially unnecessary source of unhelpful nanoparticles in our diet.  

Titanium Dioxide is used to make food whiter or more opaque. It may be mixed with other colourants to produce pastel colours or used on its own.  It has a similar function in cosmetics plus it can be used as a sunscreen. It does appear in lipstick formulations which, I feel, is important to note and why I, as a cosmetic chemist, am particularly interested.

More Details about this study.

I don’t know, at this point, whether any damage seen or suspected from the nanoparticle ‘hit’ is permanent or recoverable, how long damage might last or even how the dose used in this study compares to what we would be exposed to in ‘real life’.

In ‘real-life’ applications food grade titanium dioxide has been found to have somewhere in the region of 15-35% particles in the nano range. In the USA Titanium Dioxide is permitted as a whitening agent at levels up to 1% in food. France is looking to implement a ban in using this as a food colourant from 2020.  France has banned things before that other countries have not. Whether this is good governance or something else is up for debate.

The answers to these, my supplementary questions, will come out when the full data is published, when more work is done and when further funding for more detailed investigations become possible.  As Professor Chrzanowski said to me, this is fundamental research and as such it acts as a scaffold upon which more applied research can be built but we are not done yet, we haven’t finished with the fundamentals yet. We don’t yet understand everything.

So what does this mean for cosmetics?

I must say that this research has resonated with me as being a) interesting b) representing a new level of understanding. c) potentially game-changing when it comes to how we think about and handle man-made nano materials.

I wish to iterate that this is NOT about titanium dioxide as a chemical molecule and that banning or being ‘free from’ that will NOT guarantee you a formula that is ‘free from’ nanoparticles, especially if you just swap this with any old alternative that may also be particulate and contain some nanoparticles.

We don’t eat our cosmetics but there are times when we incidentally ingest them, especially lipsticks and sometimes sunscreen. Maybe we should be looking into ways to make our cosmetic nanoparticles easier to pass through the body (and, while we are at it, easy to digest by the right microbes once they get into the environment).

What I was heartened by is the fact that the team behind this research do seem excited about the potentials that understanding this brings.  We now have more insight on one thing that causes gut damage (ingested nanoparticles that reach this part of the gut), now we can start forming ideas about how we might engineer a solution. Whether we need,  want or can afford to or not is another matter.

In terms of what to do as a cosmetic manufacturer/ formulator, I feel I want to  keep my eyes peeled and doing some more reading into the fate of nanoparticles  in our water treatment plants and in the soil/ on soil microbes. I would be focusing not only on our own health and safety but also of the product life-cycle as a whole.

I  feel it is important to reflect on what this, and other studies have found and work  to limit the potential for cosmetic nanoparticles to be ingested so claims like ‘food grade’ on cosmetic products are probably a bit reckless and maybe use directions could be tightened.

So my take on this is that we should keep our eyes on the science, our minds open wide and keep those nanoparticles on the outside!

See you another day

Amanda x



When Sunscreen is found in your blood…

May 12, 2019

So earlier this week the US Food and Drug Administration released this summary of some fascinating research they had recently concluded.  The full study report can be found here. 

If, after reading that report you feel like your only option is to say ‘fcuk it, I’m going out like this from now on’ I understand.

Fat Lady

Sun Hongbin ‘Fat Lady’ 2012 as seen at the White Rabbit Gallery.

However, hold tight, and we’ll see if there is any light at the end of this tunnel.

The FDA study focused on how four sunscreen actives were adsorbed through the skin when four different sunscreen products were applied using a ‘maximum use’ protocol.   The shorthand for this type of trial is  MUsT (Maximum Usage Trial) and in the USA, this type of test is essential for topical medicines.  Up to now sunscreens have not been required to   produce information with regards to this because the Sunscreen industry has indicated that these products are designed not to absorb. It looks like the FDA finally called ‘bullshit’ on that.  Good.

So what I’m going to do now is give my thoughts on what I’ve read.  My thoughts are formed on a) personal bias in using and choosing sunscreens – this constitutes my opinion b) my volunteer practical hands-on experience of testing sunscreens (Via APTF in Australia with Gavin Greenoak (R.I.P)  c) My experience in buying, selling and marketing of a range of sunscreen actives into the Australian market between 2004-2007 and d) my own sunscreen development work  and consulting research on behalf of my  clients (2007-present day).



When it comes to global sunscreen regulations I like the FDA the best (opinion).  I like the way they are slow and steady and I love how they don’t bend to the whims of individual manufacturers.  I am not convinced that this is the case in Europe (opinion based on my interpretation of what I’ve seen professionally).

So what happened?

This small, scene-setting study ran by the FDA (which in its self is quite unusual as they usually just report on things) showed that we (the cosmetic industry) may have been suffering from denial or misplaced optimism when it comes to sunscreen active absorption.  Now I know that some of you readers like to jump to the ‘OMG I’m going to die’ conclusion but I don’t, instead I’m going to focus first on the fact that sunscreen doesn’t work if it is in your blood…

The study basics.

24 people (men and women) were split into 4 groups and tested 4 different sunscreens (spray, spray, lotion, cream) over 4 days, applying it to 75% of body surface area at the recommended 2mg per Cm2 as per industry guidelines.  As sunscreens are tested this way, you are unlikely to reach the pack SPF if you apply the product any lighter.

Now if we use this method to work out the skin surface area of the average person (70Kg, 165cm) we get 1.73 m2.

If we take 75% of that we have 1.3 m2 which is 13000 cm2

If we want to apply 2mg per CM2 we would need 26000mg of product per application.

This is the same as 26g per application.

In this study the product was applied 4 times during the day.  This was following pack instructions.

So each participant wore 104g of sunscreen per day.

**** Before you judge the rest of this study it is worth reflecting on the above.  Have you ever used sunscreen like that? does that amount surprise you? Is it representative of reality that SPF is calculated based on that application?  ****

Next time you go for your weeks holiday remember to take 2 litres of sunscreen per family of 4. 

This protocol looked at the following target actives:





Systemic concentrations greater than 0.5 ng/mL were reached for all 4 products after 4 applications on day 1 (direct quote from here).  0.5ng/ml is equivalent to 0.00000005%

I wanted to be able to visualise or relate to that number better as it seems very small. Maybe worrying is unnecessary after all…

To put the findings into percentage terms, which I relate to better, the ingredient found at the highest concentration after the four days was oxybenzone and it was found at concentrations of 209.6ng/ml which is the same as 0.000021% of the blood.

I’m not a pharmacologist so I may have interpreted this incorrectly but a standard dose of paracetamol gives a blood ‘active’ level of around 30mg/l or 0.003%

Looking at the contraceptive pill which interacts with our hormones we see that a typical regimen results in a blood concentration of 0.0000006%. This is based on the report I found here. 

Now I decided to look into the typical blood concentrations of other chemicals to help me build up a reference framework for how big or small a change in our blood this represented. I claim no equivalence between these drugs but I chose paracetamol because that’s a drug that most people have a relationship with (having taken it before) and the contraceptive pill because again, most people understand that and also because this drug affects our hormones and one common fear about sunscreens, especially the chemical ones, is that they are hormone disruptors.  All I can conclude from my exercise is that the sunscreen actives were present at a level significantly higher than that expected when taking the contraceptive pill.  This doesn’t mean that these chemicals will work like the contraceptive pill.  Each drug has its own pharmacology, but I feel this comparison does add something to the debate. It seems more urgent to me that we address this, at least so we can fully understand it better.

So sunscreen actives get into the blood to some degree. Why?

Another potential failing I see highlighted in this study is that of efficacy.  If a proportion of your sunscreen slips into your blood steam it can’t reduce the burning effect of the suns energy as it is nowhere near the UV at that point.  What I want to know is this.  Is this a failure of the formulator or a failure of the ingredients manufacturers to fully understand the solubility of their actives?

A formulator can only formulate within the scope of their ‘view’ so they review data from manufacturers, create a chassis (or base) which should hold or deliver those actives and then work on the softer features (price, look, feel, smell) to improve consumer appeal. If there was no data available to formulators about potential skin penetration then the only measure the formulator has with regards to efficacy is standard SPF testing and consumer aesthetic trials.  If neither of those required a MUsT study and if the product reached the expected SPF within usage guidelines then there would be no need (or money probably) to investigate further.

So why wasn’t skin penetration of actives tested before?

I don’t know how much data exists but if the FDA are correct, they weren’t presented with enough data outlining how likely these particular actives are to penetrate to ascertain their safety.  It could be that data did exist but wasn’t shared or that data just did not exist. In either case, it’s time for that to change.

What the article and study I’ve linked to above do point out is that test methods and tracking protocols have progressed over the years so it is possible that it has only been recently that the tracking of the chemicals found in sunscreen can be traced in this way.  Further, even if this type of tracking has been available for a long time, unless it is part of an actual SPF approval process (which it is not), there would be no obligation for independent sunscreen manufacturers to carry out this testing.  It is easy, as a consumer to sit there and think ‘well shouldn’t they do everything in their power to prove their products safety’ but let’s face it, we’ve all gone to the supermarket and bought a litre of the cheapest stuff with the highest SPF as we’ve either run out of money or can’t see the point in spending double on the same thing.  Testing is expensive and testing like the FDA just did may make it impossible for smaller, boutique brands to participate so unless the playing field is level. So, in short, this requirement may have to be legislated for in or

Is there anything else worth noting at this point in time?

As far as I am concerned I believe that the FDA have taken a great step towards making sunscreens better and safer for all of us.  Even if it turns out that the levels of sunscreen active absorbed make zero difference to our or our planets health,  as a cosmetic chemist I’d still want to improve products to stop the dermal penetration of actives.  If nothing else, it is a complete waste of resources and energy to have these chemicals end up in the blood. It’s like swallowing a raincoat and expecting it to keep you dry.

The article is right to note that dermal absorption does not automatically mean death (or even slight inconvenience to ones health).  Chemicals can be absorbed and just excreted with minimal fuss, absorbed and cause minor issues, absorbed and improve our life or absorbed and bioaccumulate, causing longer-term problems.  As humans our instinct is to fear the worst but that’s not necessarily helpful.  We know that too much sun will give us skin cancers and for many of us, sunscreen is a necessity if we wish to enjoy the great outdoors.  My advice is to continue to watch this space avidly, to continue with ‘safe sun’ behaviour, however you choose to interpret that, and to encourage your sunscreen providers to be part of this advancement of science.

As an industry I feel we should welcome any scientific investigation into our ingredients and/or products, especially when they are lead by a team like the FDA who has safety as their key objective.  It is all too easy for us to brush off things like this saying ‘just keep slapping on the sunscreen folks, nothing to see here’ but that’s part of the reason why nobody trusts us.

I don’t know how the dice will fall when this study is expanded and/or when all of the sunscreen manufacturers come forth with their data but I do know that necessity is the mother of invention and maybe, now, because of the FDA all of us sunscreen industry participants will NEED to get our thinking caps on as we aim for zero dermal penetration and more reflective (of how products are actually used) SPF testing.

The campaign for Zero penetration….

Doesn’t sound like it will catch on, must think up another slogan 🙂


PS: I’m putting this report by MDPI here as this is also interesting and I want to digest this further.  This report looks at how studies into dermal penetration of sunscreens have been carried out in the past.  This raises a number of interesting questions too, especially in light of the FDA report above.

PPS: I didn’t talk much about the fact that in the FDA study the test subjects were inside and the group was small because I felt that it was clear that this was a first-step study so these conditions could be looked into during further studies. Staying inside is unlikely to make a sunscreen more likely to penetrate in my opinion.

When Your Science Doesn’t Overcome Your Bias

May 5, 2019

I read a fair few science papers and not all of them contain what would be thought of as ‘good science’, mostly because there is something lacking in the methodology or the way conclusions are drawn. In some cases what is lacking is an understanding of how ones personal bias can cloud your judgement.

I’ve talked about biases before but here is an example of a bias that is common in our industry:

Natural is best for the skin so I am going to run an experiment to find out how much better my natural product is than a synthetic one. 

By highlighting that as a common bias I am not saying that I think there is no way this can be true or that I also want it to be true and think it likely to be so.  I’m just saying that we all have an emotional attachment to these words, the words are loaded and when we see the ‘natural vs synthetic’ question posed, our brains flood with ideas (or conceptions) that we will inevitably bring to whatever we do next.

As a science trained individual I have to be careful not to fall into the ‘don’t be stupid, everything is chemical’ mindset and thus refuse to give any discussions along these lines the attention and academic rigour they deserve.  Further, I have to avoid projecting what I think the words ‘natural’ and ‘synthetic’ mean onto the general public without explicitly explaining them.  I want to stop there for a moment to point that out more clearly,  we throw words like ‘natural’ and ‘synthetic’ around in this space as if it is universally known what we mean by them but actually, most people don’t have a clue and neither should they given that neither word has a really good and clear boundary around it. There simply is no logical and definitive way of defining these things when you really think about it. Both are human constructs and as such, have meanings that can shift depending on where humanity is sitting on the issues relating to how these words are used at the time.

I’ll leave you to ponder that  and carry on in the direction that I originally intended, that is about bias science.

So this morning I read this.

I found the above to be, in my mind, a good example of where personal bias had clouded the interpretation of the results and even prevented the development of a robust set of experimental conditions.  Now before I go on I must state that just because I found this paper to display bias that doesn’t mean that any of the products under the test conditions are bad or otherwise deficient. I’m just critiquing the method and interpretation rather than the subject or aims.

I debated in my head about what would be the most appropriate way to critique a paper like this without pulling it to shreds and then looking like I was attacking it (not my aim) so I decided that, in the name of promoting good science, I’d just stick to an outline of where I felt the experiment fell short. The aim of this is to inform you, my reader, of how you might avoid falling into these traps and how you might actually progress your understanding of your product rather than potentially just wasting time and money.

The experiment in brief.

  1. The big question was whether modern-day synthetic cosmetics are a main cause of long-term damage to the skin microbiome.
  2. The premise put forward was that there is a thought that synthetic chemicals are one factor that disrupt the skin micro   biome.
  3. The investigation undertaken pitched a truly natural, a ‘claims-to-be-natural-but-isn’t’ and a synthetic product against each other in a body wash challenge.
  4. The conclusion drawn was that this work indicates that synthetic ingredients have an effect on skin microbiome biodiversity.

The main points that made me go ‘huh?’ were:

  • On point 1. The experimental protocol was to wash twice a day for 4 weeks. That is not a long-term study so can’t answer the question. A way around this would have been for the microbial analysis to continue post the 4 week time frame, maybe for a further 2 months with results of the micro biome mapped against the pre-experiment levels to see how the skin had responded once the product phase was over. As there are no results post the 4 week time frame we are unable to gauge whether the changes experienced persisted or constituted long-term damage. I would expect that long-term damage be demonstrated by a longer-term change in microbiome towards one that more closely resembled a dysfunctional skin sample.  That then brings up another question, what specifically does a dysfunctional skin sample look like for that skin area (given that the micro biome changes all over the body).
  • On point 2 I felt there needed to be a much deeper analysis of what constituted a synthetic chemical for the purpose of this study given the importance of that definition in drawing up a roadmap for future work.  I’ve looked at the brands webpage and they point out their philosophy there.  For the record they include soap (as in bars of soap), alcohol, alkalis,  fermented products (as separate from alcohol),  xanthan gum or antiseptics.  This list presents a number of other challenges in its self-given that the brands own product doesn’t meet it – the current cleaner formulations contain several essential oils which have antiseptic activity.   With such an unformed and scattered concept of what constitutes natural and synthetic I would find it hard to draw any meaningful conclusions from this study that relate to the ingredient profile of the products.  This again means the purpose of the study can’t be addressed.
  • On point 3 see point 2. The truly natural product does not meet the brands definition of a natural product as it contains antiseptics.
  • The conclusions (point 4) reached are misleading in my opinion.  It is true that the testing did show a micro biome response to the test protocol but that is all we can conclude.  This article from 2007, which has been cited 568 times so far tested the microbial diversity on the forearm of 6 healthy subjects and found there to be great diversity between subjects and diversity on the same subject over time.  They found that some microbes appear to be more transient than others, responding to varying external and internal factors while other microbes are more settled.  If this is true it would be unwise to read too much into small microbiota changes over a short time frame in a small sample size.

The bottom line.

It is true that us humans don’t have all the answers to how our micro biome is affected by cosmetic products, ingredients or even treatment protocols (habits).  It absolutely is likely that everything we do to our skin has an effect but we must not forget that what we do to our skin includes the types of clothing we wear, where we live (weather/ how suited the climate is to our skin),  our home environment, our general health and our other habits (food, drink, sleep, stress etc).   There seems to me to be a thought-trap that many brand owners fall into that centres around cosmetic products being the be-all-and-end-all of skin health.  Mainly because that’s what they are selling, that is what is within their control and making better products (or having a point of difference) is what helps them to sell. However, this is a trap and micro biome science absolutely will be the undoing of these brands as microbes respond both to what happens on the skin and under it in a homeostatic feedback loop that informs our immune system according to this paper. 

I think it is great that cosmetic brands of all shapes and sizes are looking towards a scientific approach to back up their claims and progress their thinking and I really hope we see more of that in future.  However, if your biases shape your science your science won’t be very robust and that’s not going to help anyone long-term.


Gynaecologically tested.

May 4, 2019

Have you seen this on a product recently?

Well I was reading ‘Cosmetic Business‘ and saw this word on the new Femfresh vegan friendly wash and just had to comment.

Do you know what it means?

It means that the product was tested on fannies.

Yes, that’s right, the product was tested on the area of the body that it was designed to be used on.


Ok so I’m being a bit harsh but that my friends is the long and the short of what that means.  It doesn’t mean it was tested and found to be good/ bad/ different/ better/ worse than other products, just that it was tested on that area.

It may well be that the company involved has carried out more testing and that the results of that are available somewhere but on its own, the word doesn’t really make the ground shake for me.

Have a great evening.

Amanda x

This week I’ve mostly been reading about armpits…

May 4, 2019

I wrote a post the other week debunking the myth (well, attempting to) that our armpits ‘detox’ when we change deodorants and since then I’ve been itching to know more about what turns out to be a truly fascinating part of our anatomy.  I thought you guys might like to join in the fun too so I’m going to write about it all here.

Firstly I was introduced to a chap called ‘Dr Armpit‘ by one of my readers (thank you) and I was immediately drawn to his wall of agar plates article, so fascinating.   Now if anyone out there in reader land wants to buy me a present, I’d love a ticket to go see this chap in his lab as there is just so much to talk about and learn.  Seriously, please fund me :). Anyway, what I like about what Dr Armpit has done is that he is clearly a great scientist but his work is instantly understandable, relatable and engaging. I don’t always have that response to the researchers that I read.   So, what does he say?

What makes us smelly?

Dr Armpit has done a fair bit of research into what makes us smelly and it turns out that a few other people have done this too.  Now it has been known for a longish time (I know, not very specific but this is a blog rather than an academic journal) that bacteria play a part in producing body odour – sweat doesn’t smell until it is broken down by something.  However, it is only relatively recently that we have started to welcome and nurture our microbiomes and see what joy they can bring us.  Turns out this joy applies to the armpit area too.  So not only does Dr Armpit give us a good look at the microbes that grow on different people’s armpits thanks to his wall of agar plates, he also goes a long way into explaining which microbes cause the stink and how our own personal hygiene habits impact on them.  As a product developer this is absolutely fascinating to me as I have been pondering on how I can make an antibacterial deodorant without risking wiping out the ‘good’ bacteria or referencing the bad.  It turns out that my fears seem to have been valid as there is truth in the idea that some deodorants can alter our micro biome and allow an opportunity for less pleasant microbes to flourish – our habits change our micro biome.

Formulating for our micro biome.

Understanding that our microbiome is affected by our choice is deodorants isn’t the same as knowing how to fix it and I have to say that I’m not 100% there yet with a solution in my mind and I’m not alone.  The truth of the matter is that scientific understanding of the complexity of our micro biome is still under-developed and while we can measure what is there now and what is there later (when later comes around) we (scientists) are not yet able to accurately predict what results our actions may have and why.  This is partly to do with the fact that armpit micro biomes are not just affected by deodorant use, they are affected by our genetics, diet, environment, clothing choices, health and emotional states.   Now you might be thinking ‘well, of course you know that something is working because the smell goes away’ and to a point that is true. However, the why, how’s and what (are the longer-term implications) are still to be answered as we strive for better products which give better results.

What we do know is that gram positive bacteria of the Corynebacterium species are the type most likely to cause a stink, that armpit bacteria populations have a fairly low diversity compared to other areas of the body and that men tend to have more of these present than women (who are dominated by Staphylococci).  Now that’s interesting too isn’t it?

Why would men and women have different armpit microbes?

This is a question that popped up into my head.  Dr Armpit suggests it is because of a difference in skin thickness with mens skin being thicker than women.  That may well be a contributing factor but I also feel it could have something to do with armpit hair maybe.  This study does mention that the test panel they used had to refrain from shaving their armpits for a couple of weeks before the test and during the test period. That would mean that most participants would have some armpit hair. However, I can’t see that hair has been discussed as a factor in these experiments really so I’m still curious about that. The question in my head is whether the surface area / air entrapment area under the armpit increase that you would get with a bush of hair may act as a nutrient source for microbes that could either a) feed the good bacteria and help them thrive or b) feed the bad bacteria and encourage their growth or c) feed all bacteria and lead to more bacteria being present of which some is the smell-inducing type or d) the lack of hair removal helps maintain a more natural barrier functioning that helps keep the armpit microbiota in check or e) hair is irrelevant.   I’d like to know more about that, especially as hair removal in women literally became fashionable in modern western times thanks to deodorants and that it is now becoming OK for western women to choose if they want to maintain or remove their armpit hair – woohoo for us!  I just don’t want people to feed any misconceptions about hair under there really…

Anyway, there is so much more to learn including this bit on chemistry:

Chemically speaking sweat from our eccrine glands (of which we have around 200 per square CM of skin) is around 99% water!  The other 1% contains bicarb, potassium, chloride, sodium, amino acids, urea, magnesium and a few other bits.  These trace minerals can be quite good for the skin, in fact, as a cosmetic chemist I’m often putting this type of thing back into a water phase to make the water better.  It makes sense that something we generate ourselves as part of our homeostasis would be ‘good’ for us don’t you think?  That rather than see our sweat as dirty, it is actually our bodies pumping out some freshly squeezed made-with-love spritzer for us.  Aaahhh bless.

But eccrine gland are not the only ones. We also have apocrine and apocrine glands (which people are still a bit confused about) under there.  Apocrine glands are attached to hair follicles whereas eccrine glands are not.

Apocrine glands are responsible for our emotional sweating and while the sweat is still quite watery it also contains some fatty bits.  This may be because it gets mixed with sebum on its way out of the hair follicle or may not. I don’t know at this point in time.  While we have eccrine glands all over us, our apocrine glands are concentrated in our genital, armpit and breast areas. Grossed out by that?  Well we also have these little suckers on our eyelids, up our nose and in our ears – weird!

Some say that our apocrine glands secrete pheromones and it is our pheromones that make us fall in love.  Now I tend to believe that as I do like to remember that we are all animals after all but it can sometimes be hard to find any robust science on this type of thing.   But then I found this.  That link is to PUBMED by the way so you may not be able to view the full study but if you go to Deep Dyvve you can find it there to download for a small fee.  Ok so the paper I just put a link to talks about this:

Body Odours affect our emotions.

Sure, we’ve all sat next to some smelly bar-stuard that forgot to wear deodorant and that’s brought up some emotions in us but I’m not talking about that.  I’m talking about something more subtle.

The paper above found that we respond emotionally to other people’s emotional sweat.  So when your best friend Sally is having a bit of a meltdown because she’s got an exam in the morning you may start to feel anxious too, not because of her behaviour but because of her smell.

Apparently our emotional sweat odour was able to induce changes in heart rate, sweating rate and how test subjects felt which is probably not surprising as it is definitely the case that most animals pick up on our non-verbal cues very quickly. However, it is totally worth thinking through, especially if we are working in trauma settings.  We want our body odours to be calm and calming so that the unspoken environment is one that spreads joy rather than fear.  Now there’s an opportunity.

And another thing. Alcohol and Caffeine.

So probably one chemical you don’t want to put into your deodorant or antiperspirants is caffeine.  Caffeine increases the body temperature, sweating volume, number of active sweat glands and sweating sensitivity.   None of that is a good thing when you have a body odour issue.  I hadn’t really thought of that before but it is very useful for deodorant brand marketers to consider.  In the days of insta-goodness make sure you aren’t promoting sweating with your deodorant.

Then there is alcohol.  Now it turns out that this is a double-edged sword (good and bad).  Alcohol changes blood pressure, flushes the skin and increases sweating because of that and that can make the old deodorant work harder.  However, pop a bit of alcohol into your deodorant and you have a faster drying, anti-microbial solution.  Maybe the key is keeping the alcohol on the skin rather than under it.

So there you go.  There’s a whole lot more interesting things that I’m discovering about armpits as I go off on this tangent in order to make better products but that will do you for now.  The only other thing I want to tell you about is why I do this.  As a cosmetic chemist it would be all too easy to just copy someone else work and create deodorants for people who are exactly like someone else already has.  Now you might say ‘and yes, that would be smart too as it saves time and if the deodorant works, why wouldn’t you’.  That is a good point but as you can see from the above,  there are many angles that we are uncovering and investigating with the armpit area and I want to be sure to make the best products that I can make, not just a cheap knock-off of something else.  As a formulating chemist I do quite often see products that work but I don’t know how or for how long they will work – brand longevity is an issue and you don’t want customers to only stick around while it is a novelty. Or I see products that are popular/ trendy but that don’t really work.  I feel it is my duty to add value to brand owners by working out the why, how’s and what’s of a product. After all, if I don’t do that, all I am is just a glorified lab technician who puts your wish list into a generic base and then rides off into the sunset not giving a shit about what I’ve done to your micro biome over the long-term – not my problem.  Now that’s just not me, that’s not what I signed up for when I became a chemist and I hope that’s not what you want either.

The bottom line is that our armpits are actually quite fascinating and deserve a heck of a lot more attention than I’ve previously given them.

I hope that has been interesting for you and I look forward to sharing some more news from the nerd factory with you later.

Amanda x



What cream do you turn to when you scratch off your own skin with a knife?

April 26, 2019

Has this ever happened to you?

What about the desire to scald your skin to take away the itch? Ever had that?

I know what that feels like and I know I’m not alone.

Eczema and other chronic skin conditions are no joke and while I appreciate the well-meaning efforts of those caring for their eczema prone loved ones, I mostly find them lacking in understanding of what it’s really like to prefer the pain of no skin to your own itchy stuff.  It’s dysfunctional.

Most people I meet want to ‘cure’ their loved ones eczema with a natural cream as nature is best. That’s the logic.  I truly get that but I grew up with steroid cream, petroleum and parabens and in the professional eczema space, nothing much has changed because that shit works.

I’m not a dermatologist so I won’t pretend to sum up the pro’s and con’s of steroids in a cosmetic chemist blog post but suffice to say that when your itching has rendered you sleepless and in danger of sepsis, the relief that steroids bring is heavenly albeit in a fingers-crossed kind of way as you hope that you rid yourself of the itch before your skin thins.  Steroids aren’t a long-term fix.

Barrier and aqueous creams are more of a long-term essential for those prone to any of the above and if you are bad enough to need long-term dermatological support they will most likely suggest petroleum-based, nothing-fancy products. These simple, old-fashioned formulations are not prescribed because god hates you,  all dermatologists are sponsored by big petroleum/big oil/ big daddy or because the dermatology world forgot to check ‘what’s hot’ in cosmetics.  No, these things are prescribed or recommended because they are, themselves, pretty inert.

Pretty inert doesn’t mean nothing by the way…

A month or so ago I was explaining petroleum oils vs vegetable oils to a client and I said that ‘the reason petroleum derived oils have a long shelf life is because they are already dead whereas vegetable oils are not’.  I feel like the customer took that quite literally as in ‘OMG, who would want dead things on their skin, that’s another reason why petroleum derivatives are bad, they are dead and dead is bad’.   Noting this was not quite the response I wanted I attempted to re-frame my analogy:  ‘I meant ‘dead’ as in less likely to chemically change in ways that could be detrimental. I probably should have used the term ‘chemically stable”.  I went on to say that ‘vegetable oils are still in a dynamic chemistry state and will inevitably oxidise as their triglycerides break down. One break-down product being free oleic acid, a dermal penetration enhancer and potential skin irritant.  That’s not all but that’s fairly significant in terms of their potential to precipitate a negative skin reaction or flair-up in skin that’s already damaged’.   However, as is with life,  once a person has had a light bulb turn on, albeit prematurely and in the wrong room, it is very difficult to pursued them to reconsider.

So what I was trying to say was..

Petroleum derivatives are intentionally chosen for products aiming at atopic skin because they are predictable, un-reactive and very slow to change. Vegetable oils are the opposite of that.


How I attempt to handle my own skin. 

My own experience shows me that there are three distinct phases in coping with an eczema type skin situation and in each phase, different ‘treatment’ products may be of use.  I’m giving my own experience, observations and preferences here as something to ponder on, not as a prescriptive view of how everyone with eczema is and prefers to manage it.  Also note that if I was a wiz at managing my eczema it wouldn’t still be plaguing me today, 44 years after it first started (boohoo).

Stage 1 = the stinger

This is trauma central and is the phase that I opened with, where you quite literally want to scratch, boil or chew off your own skin.  In this stage everything, even water stings and irritates and the thought of soothing skin like this in coconut oil, soap or anything else is quite repugnant to me.  When I’m like this I reach for the antihistamine (to reduce the itch),  relaxation (to reduce the subconscious impulse to scratch), cooling (clothes, foods and environments (to reduce a scratch trigger = sweating, over-heating) and then after that I’ll go for a product.  If my itching is very bad still or I’m worried about infection I’d go for a cortisone cream. If not I’ll go for a basic barrier cream.  I choose a cream rather than an ointment or balm because I have a real problem with the skin feeling over-heated or occluded so a water-and-oil product suits me best unless I’m in a very dry and cold environment in which case I might use a balm.  Remember that at this point in time the above will sting me and I’ll need to use mind-over-matter to stick with the program and get my barrier back in one piece.

Stage 2= The wounded soldier.

This is where we have recovered from rock-bottom but it’s still a long way from happiness. Here I’ll be mostly reaching for loads of aqueous cream to just provide the skin with hydration and a little barrier protection while it rebuilds.  I’ll probably apply this once or twice an hour in the beginning as my skin is ripped to shreds and dehydrates quickly when in this phase. Also I find the pulling sensation of dry skin gets confused in my brain with itching so I can subconsciously scratch again and end up back at stage 1.  At this stage I’d be concerned about using creams that are too ‘active’ as the skin is still a long way from normal.  That’s why I’d advocate against vegetable oils, too much too soon.

Stage 3= Almost normal.

I say ‘almost’ because skin like mine is never completely normal, it’s quite fragile and can easily be tripped into disfunction again. However, in this stage the barrier is repaired, it’s no longer itchy and I am no longer stinging at the touch of water.   This is where I am more able to tolerate ‘active’ creams if that’s what I want. However, for me, I still have to be careful not to use products that make my skin feel sweaty and occluded as that can kick-start a new round of scratching for me.  I have often wondered if natural ‘essential fatty acid’ rich oil creams are best for my skin during this time but to be honest, I’ve not noticed any particular benefits, on my hands at least (and it’s my hands that are most affected these days).  Maybe it’s because my hands are so often exposed to surfactants (washing up, washing hands etc) that they are already primed for irritation, I don’t know.  I can’t see any reason why a lovely, natural fatty acid enriched cream wouldn’t be good for my skin in this stage as long as it didn’t itch whether I’d notice the benefit would really depend on what else was going on in my life at the time.  I feel that for my skin it’s not what I put on it as much as what I take out of it (put it through) that matters if you know what I mean.


The bottom line for me as an eczema sufferer is that I want people selling into this space to be aware of the phases that us itchy folk go through. I think it would be really useful if wanna-be brand owners think about their ‘solutions’ be they cosmetic (maintaining your good skin) to therapeutic (stopping the dysfunction) in a holistic way and not just as a one-size-fits-all.  It would be awesome is brand owners could demonstrate an understanding of the huge emotional, physical and economic impact itchy skin has and to be sensible and measured in their response (rather than jumping on each and every cure-all band wagon).  Finally, I’d like brand owners in this space to understand that for some of us, sometimes (or even all the time) petroleum-based, simple creams are lifesavers mostly because dead things are more predictable.

Hand Model