Pseudevernia furfuracea

Pseudevernia furfuracea

Pseudevernia furfuracea - the source of 'tree moss' extract. Credit: Wikimedia Commons/Stemonitis

In various news outlets over the past few days, a lot of noise has been made about the EU calling for a ban on some of the signature ingredients of Chanel No 5 and other high-end perfumes.

These stories stem from an opinion report by the European commission’s scientific committee on consumer safety. The opinion report expands on a list of fragrance ingredients that are demonstrated to cause allergies, and suggests that some should be banned. Perfume makers are currently required to list 26 ingredients on the packaging of products that contain them.

The new list comprises 82 ‘established allergens’ and many more ingredients identified as ‘likely’ or ‘potential’ allergens. That list includes 54 individual chemical ingredients and 28 natural extracts, and it is the inclusion of one specific extract that is causing the majority of the fuss.

An ingredient listed only as ‘tree moss’ in many places is the steam-distilled essential oil extract from the lichen-like moss Pseudevernia furfuracea. It has a characteristic woody, earthy scent and is a crucial part of several top-end fragrances, including the famed Chanel No 5. Many large perfumery companies cultivate this moss on the bark of trees, particularly around the French town of Grasse.

But with the wonders of modern chemistry, can’t we just synthesise a replacement with the same scent but without the allergy potential?

atranal

Atranal

Chloroatranal

Chloroatranal

Unfortunately, it’s not that simple. Tree moss extract, and the related oak moss extract, are mixtures of around 100 different compounds: various aromatic acids, esters, steroids and other terpenoids. While the European commission committee report seems to provide some clarification on which of these constituents are the predominant allergens, it is much less clear which ingredients are most important for scent and other functions within perfumes.

The offending allergens are atranol and chloroatranol, which the committee concluded in 2004 should not be present in consumer products. But is it possible to extract those two elements and retain the rest of the performance of the extract? Or to make a single compound that replicates the scent?

Orcinyl 3 (3-Methoxy-5-methylphenol)

Orcinyl 3

Evernyl (methyl 2,4-dihydroxy-3,6-dimethylbenzoate)

Evernyl

The big perfumers have tried, with different extracts and mixtures, or single molecule products like Givaudan’s Evernyl (methyl 2,4-dihydroxy-3,6-dimethylbenzoate) and Orcinyl 3 (3-methoxy-5-methylphenol). But none of these reliably reproduce the complexity of the true moss extract – unsurprising, given the exquisite sensitivity of our olfactory receptors to myriad different molecular odours.

So what to do? The outcome of this opinion report is not law and the commission has expressly stated that it has no intention of banning Chanel No 5 or other perfumes using these ingredients. However, it is likely that the perfume industry will come under increasing pressure to reduce or at least label products including some or all of the ingredients on this expanded list.

As for us chemists, perhaps we should see it as a challenge to come up with new replacements, or new techniques to separate the allergens from the extract. The challenge is on to keep chemistry smelling of roses (or at least woody, earthy moss…)

Phillip Broadwith

PS. For those who don’t get the headline of this post, here’s a clue

For more information on the compounds in tree moss and oak moss extracts, see:
D Joulain and R Tabacchi, Flavour Fragrance J., 2009, 24, 105 (DOI: 10.1002/ffj.1923)
D Joulain and R Tabacchi, Flavour Fragrance J., 2009, 24, 49 (DOI: 10.1002/ffj.1916)

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No disassemble number five!, 10.0 out of 10 based on 1 rating
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