I have been reading scientific papers on the skin for many many years now, but I am afraid that people are publishing them quicker than I read them so I am sure that there is still a lot of interesting stuff out there that I haven’t seen yet. I am always grateful for a good review paper, where someone summarises work in a particular area.
A good review paper is worth its weight in gold and I particularly love one in the most recent issue of the International Journal of Cosmetic Scientists by H.Tagami from the Department of Dermatology in Sendai, Japan. I am afraid I know nothing about the author other than what I can glean from the paper itself, which is that he is very conscientious and well read and is interested in some of the things that matter if you take skin seriously.
Tagami considers what we know about the differences between the skin on different parts of the body. He also talks about the differences between skin of different ages and on different genders. I think I am going to be coming back to this paper a lot in the future now I have been through it – it really is a treasure trove of information.
Why is skin on the hands less sensitive than on the face?
One of the things I do at work is go through all the complaints received for the products we sell. There aren’t very many as a percentage of sales but they do build up over the year. One of the things I have noticed is that most of the complaints about skin reacting to products refer to the face. Sometimes people send photos in. Normally what you see is a reddening of patches of the skin, typically the forehead, cheeks and nose, much more rarely the chin and neck areas. I don’t know how many of these complaints have come across my desk, probably a few hundred. Not once have I had someone complaining that the hand that they used to apply the product was as badly affected.
Pores – Key to Sensitive Skin
Now it is certainly possible to irritate the skin of the hands. There are whole journals devoted to contact dermatitis which is most common on the hands. But there does seem to be something about facial skin that makes it especially liable to react to products. It is a bit of a puzzle because the skin is generally a pretty good barrier – and why should the most exposed part of the skin be the worst at keeping nasties out? Thanks to Tagami, I now know why. It turns out that the skin on the face is particularly rich in pores, and it seems to be these that are letting the allergens through. So the face is the most sensitive to irritation because it has a lots of pores.
Can patch tests get skin sensitivity wrong?
What this means is that trying a product on your arm to see if it irritates you might not be very helpful. It also means that the patch tests that dermatologists carry out on people’s backs to see what they are sensitive to might not always give the right answer either. It also explains the reports I get from customers from time to time saying that they have used a product for years and now it has suddenly started bringing out their face in blotches. They usually ask if we have changed the formulation, and we usually haven’t. It is more likely that their pores have changed.
(Another post about why the face is so sensitive is http://colinsbeautypages.co.uk/why-your-face-is-the-most-sensitive-part-of-your-skin/)
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I wouldn’t be surprised if I refer to this paper again soon- its full reference is Location-related differences in structure and function of the stratum corneum with special emphasis on those of the facial skin by H.Tagami International Journal of Cosmetic Science Volume 30 Issue 6, Pages 413 – 434