The Cropwatch Series

Cropwatch                                                No: 3b

OPINION: Methyl eugenol-containing essential oils.

© Tony Burfield May 2004

Worries about possible risks due to the methyl eugenol content of natural materials – herbs, essential oils - have surfaced in the recent past but there is a dearth of information on the subject directly available in the public domain to aromatherapists or complementary health practitioners. The following feature is an attempt to add some background information to this subject.

The warm, musty-mild-spicy odoured aromatic compound Methyl Eugenol (aka eugenol methyl ether, or 4-allyl-1,2-diomethoxybenzene)  is prohibited from being directly added as an ingredient to fragrances intended for retailed cosmetic products, due to worries about its’ potential carcinogenicity. 

As it occurs naturally in many essential oils and extracts, the addition of these ingredients is not restricted outright, but on provision that the methyl eugenol content does not exceed the following concentration in the following finished products according to the IFRA standards (see www.ifraorg.org/):

Fine Fragrances             0.020%*

Eau de Toilette              0.008%

Fragrance Cream           0.004%

Rinse off products          0.001%

Leave-on products/

Oral hygiene products 0.0004%

Non skin (as defined on IFRA website) 0.010%*. 

*The limit of 0.02% for the starred items applies to the concentration in the fragrance compound.

In effect this means that there is an obligation on ingredient suppliers, under the requirements of due diligence, to supply information to   customers, to make sure that they receive the necessary information in order for them to comply with the above requirements of the IFRA Standards. To spell this out in more detail, reporting the methyl eugenol content of the specific batch of the ingredient will then allow the customer to further calculate final levels of methyl eugenol appearing in the finished product. It is difficult to see how many small essential oil suppliers, without resort to internal analytical expertise, will be able to perform this function. Additionally, it is relatively easy to find plants for sale on the Internet, who’s essential oils contain high levels of methyl eugnol e.g. Black tea tree plants can be ordered at http://www.hotkey.net.au/~macs_oils/plant01.htm. No warning about the potential toxicity of methyl eugenol is presented.

It has long been established that methyl eugenol occurs in essential oils such as Canadian Snake root, Bay, Citronella, Laurel, Emodia, Fennel, Betel, “Brisbane Sassafras”, Pimento, Hyacinth etc., and its occurrence often coincides with the additional presence of eugenol (Poucher 1991). And so, purely as a guide, here below is presented a “snapshot” guide to the reported methyl eugenol content of several further essential oils. 

Published data on Methyl Eugenol Contents of Essential Oils.

1.    FEMA have published data to members on methyl eugenol contents of essential oils (no geographic origins specified).

2.    The BFA on 12.02.02 circulated BEOA data from 09.11.01 on the methyl eugenol content of a number of analysed commercial oils. Oils were classified by botanical name (no chemotypes were distinguished) and by origin.  There are no particular surprises, although methyl eugenol contents on rose otto seemed low-ish compared with other published data, and the range of methyl eugenol contents of the 23 basil oils (all apparently from Egypt) was relatively large. No data on fennel oil (identified by the EU Scientific Committee on Food as a dietary source of methyl eugenol) was included. The BEOA data document makes comment that expert analysis of genuine essential oils shows how widely essential oils vary in composition, and makes comment that the BACIS commercial data-base of essential oils shows methyl eugenol contents of 258 oils, that some of this data is misleading, and not representative of genuine high volume essential oils used in commerce.

3.    IFRA data on methyl eugenol contents of essential oils, as presented on the IFRA website http://www.ifra.org/ in May 2004 does not define the plant source species, the geographical origins of oils or any chemotype information. A document circulated by IFRA (to members only – not in the public domain – but most of the information the same as on the IFRA website) on April 6^th 2004 lists 21 essential oils, again giving no botanical identification, only giving geographic origins for two types of oils (citronella and rose), and giving chemotype information for basil only. As has been observed previously by this author, the standard of botanical reporting in IFRA documents, and in EU legislation leaves a great deal to be desired.

4.     A list of plants containing methyl eugenol, duplicating the species names of many of the entries below, can be found on the Agricultural Research Services data-base at http://www.ars-grin.gov:8080/npgspub/xsql/duke/chemdisp.xsql?chemical=METHYL-EUGENOL

Table I - Various References re: Methyl Eugenol content of EO’s.