Wednesday, February 13, 2008

Smelly Facts: Wrongfully Accused - Does Coumarin Deserve its Bad Rep?

Are our favorite fragrances getting reformulated for no good reason? Ingredients like coumarin and oakmoss are increasingly getting a lot of bad publicity and gaining in notoriety. But are the claims against them substantiated? Some researchers tend to think that it might not all be as black and white as so far presented. Perhaps judgment has been passed too quickly - at least in the case of coumarin.

The main problem with coumarin is that it is suspected to cause skin allergies, namely contact dermatitis. The most commonly accepted way to test for contact dermatitis, is by doing a patch test. But can we actually accept a positive patch test as clear indication of contact allergy to the tested chemical itself? According to some researchers, some confounding variables might be at play. Specifically, as Vocanson M, Goujon C, Chabeau G, et al, state in a 2006 article, "contaminants and derivatives rather than the suspected chemical itself could be responsible for the allergic skin reactions”. They chose coumarin for their experiments, since it had already produced conflicting results in previous research exploring its allergenic potential (for example Frosch et al. observed positive patch tests to coumarin in less than 0.3% of the 1,855 Allergic Contact Dermatitis patients tested). After testing both mice and humans with three different coumarin preparations, Vocanson et al found that Pure coumarin did not exhibit irritant or sensitizing properties in the local lymph node assay. In contrast, two other commercially available coumarins and three contaminants that were detected in these coumarin preparations were identified as weak and moderate sensitizers, respectively. In humans, pure coumarin was extremely well tolerated since only 1 out of 512 patients exhibited a positive patch test to the chemical.” The researchers concluded “that the coumarin chemical is extremely well tolerated. In contrast, derivatives contaminating some coumarin preparations are responsible for both the irritant and sensitizing properties previously attributed to coumarin.” and further emphasized that “purity of chemicals is mandatory for the assessment of their allergenicity.”

Reference: “The skin allergenic properties of chemicals may depend on contaminants - Evidence from studies on coumarin”, source: International archives of allergy and immunology [1018-2438] Vocanson yr:2006 vol:140 iss:3 pg:231 -238

Image: Chemical Structure of Coumarin,


PinstripedZebra said...

Interesting data Divina! Enough to warrant some more research. I did find some more information on the subject: the problem with coumarin seems to be related to oral exposure and has potential hepatoxic (i.e. liver) effects. According to the German industry association representing the cosmetics industry, IKW, these effects are not to be expexted from intake of coumarin through the skin.

The German Federal Institute for Risk Assessment (BfR) though however has decided that to be cautious and to assume that the effects will be comparable to oral ingestion...

The fragrance industry, via its Research Institute for Fragrance Materials (RIFM), considers this a conservative approach and will be in communication with the BfR about this issue.

Just thought this would be interesting information for the parfumistas to have..


* Press release from the German industry association representing the cosmetics industry (IKW)
* Fragrance Industry Position Statement regarding Coumarin in cosmetic products (IFRA)

Anya said...

Dear Divina
Thanks for taking on the often-confusing world of fragrance allergens. Supposed allergens, I should say. The Natural Perfumers Guild and our partner association, Cropwatch are ever vigilant and trying to correct a lot of the misinformation out there. Tony Burfield of Cropwatch just wrote a brilliant bit on the fallacies behind the coumarin restriction. Scroll down this page (the current newsletter) to download his PDF on the subject:

Don't miss the other two articles in the newsletter - real gist for the blog there, also!

tmp00 said...

I'll never understand the constant whingeing on about these "contaminants", especially in light of the garbage that we put into our bodies legally. I think I'd rather bathe in coumarin that drink a gallon of Nutrasweet, but we do the latter practically every day without even thinking about it...

Divina said...

Thank you so much for the extra information, Z. Indeed as you point out, not only is coumarin wrongfully accused for contact dermatitis, there is also the issue of its hepatoxic effects on the liver. As your research shows, this bears absolutely NO relevance to perfume: coumarin is only hepatoxic when eaten..not when it is sprayed on the skin! Thank you for helping reinforce this.

Divina said...

Dearest Anya, I was hoping you would chime in on this issue - thank you for doing so! Keep up the good work!


Divina said...

Oh Tom, I practically live on sweeteners! I close my ears and go 'lalalalala' when I hear something bad about them :P I am not ready to give them up just yet!