Rainytigermouth says…I’ve read your previous blog posts on our exposure to cosmetic chemicals, but was wondering what your view is on the information flying around the internet that it takes 26 seconds to absorb chemicals from cosmetics into your bloodstream. All of these posters claim this statistic is based on ‘studies’, but I have yet [...]
Rainytigermouth says…I’ve read your previous blog posts on our exposure to cosmetic chemicals, but was wondering what your view is on the information flying around the internet that it takes 26 seconds to absorb chemicals from cosmetics into your bloodstream. All of these posters claim this statistic is based on ‘studies’, but I have yet to see a study which demonstrates this. As many of the chemicals in our cosmetics cannot be absorbed at all, I can’t help but wonder if this is a myth. What do you think?
The Beauty Brains respond:
This question really bugs us because it implies that science works in the opposite way that it should.
How science works
The websites that you mention all make the same claim: that cosmetic ingredients are absorbed into the blood in “26 seconds.” They put forth this statement without any supporting evidence, thereby leaving it up to others to refute their claims. Unfortunately, that’s not how science works. In science you put forth your hypothesis with your supporting data (or at least a suggestion for a test that could generate data). In this way the burden of proof is on the person(s) making the claim. It’s very difficult (sometimes impossible) to prove a negative. (For example, I can’t prove that there is NOT a giant pink elephant on Mars right now.) So, let’s look at a few sources of this claim to see if they provide any evidence.
Is there evidence that cosmetic ingredients absorb in 26 seconds?
Pure Home and Body claims that “some studies have shown that it can take only 26 seconds for something to be absorbed into the bloodstream after being applied to the skin.” Yet, there is NO reference to even a single such study. This is heresay, not data.
Lexi Yoga says “It only takes 26 seconds for whatever you put on your body to be absorbed into your bloodstream.” Again, this is presented as fact without any suggestion of data.
Botanical Tans reports that “Anything you put on your skin is absorbed in 26 seconds.” Interestingly they DO provide a reference but that reference is to an ABC news report which was about potential safety issues of a specific ingredient, the self-tanner DHA. Evidence showing that one ingredient may penetrate skin does NOT support that claim that “anything you put on your skin” penetrates into the blood.
We could go on but you get the idea – these sites make a unsupported claims that science now has to “undo.” It’s not supposed to work that way!
What does the data show about skin penetration?
Now, having said all that, what does science say about ingredients that penetrate skin? It’s well known that certain drugs can be delivered through skin patches, right? So some data must exist about how quickly these chemicals penetrate skin.
Case in point, here’s an article which gives the dynamics of transepidermal drug diffusion along with equations that factor in all the variables. The penetration of drug actives is complicated and it depends on how the ingredient is delivered, but the article says that for nitroglycerine (one of the chemicals most ideally suited for penetration) the maximum absorption you can get through skin is about .5mg/sq.cm/day. Let’s look at a couple of specific examples to see what this penetration rate means in terms of how long drugs take to reach the blood stream.
- Instructions for the Scopalamine patch (for sea sickness) tell you to apply the 4 hours before you need it. So it take quite a while for the drug to penetrate skin and take effect.
- The same thing is true for the Nitroglycerine patch (for heart attack prevention). The patch is left on for 10 to 12 hours. The instructions say “Nitro-Dur is a skin patch, it does not start working fast enough to actually treat an angina attack that has already started.” Hmm. The timing is not definitive but it certainly doesn’t sound like it delivers much in 26 seconds.
- Here’s another: Fentadyl (a pain medication patch): “When you first start the patch, it takes about 17 to 20 hours to feel its effects.”
- And finally for Nicotine patches, after applying the patch ”nicotine levels in the blood rise and level off within 2 to 4 hours.”
While this quick survey doesn’t provide definitive proof, it appears that drug penetration into blood is typically measured in hours not minutes and CERTAINLY not seconds. And remember, these are ingredients are SPECIFICALLY DESIGNED TO PENETRATE THE SKIN. Average chemicals won’t penetrate at all or will penetrate to a much lesser degree.
The Beauty Brains bottom line
Considering that ingredients that have been optimized to penetrate into the blood stream appear to take hours to work it seems unreasonable to assume that cosmetic ingredients (which either don’t penetrate at all or penetrate poorly) would be absorbed in a matter of seconds. Of course, if anyone has reliable scientific data to the contrary we’d be more than happy to share that with our readers.
All this doesn’t mean we never need to worry about what we put on our bodies. We should understand what really penetrates and what doesn’t. But the way to do that is to look for the most current science research for that information. Paying attention to unreferenced, scaremongering sites that make broad, unsupported claims is not helpful.
Image credit: http://fc02.deviantart.net/
Source: thebeautybrains.com
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