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Cropwatch Three b
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 eugenolmethyl 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 fragrancecompound.
In effect this means that there is an obligation on ingredient suppliers, under the
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requirements of due diligence, to supply information to customers, to make sure that theyreceive the necessary information in order for them to comply with the above requirementsof the IFRA Standards. To spell this out in more detail, reporting the methyl eugenol contentof the specific batch of the ingredient will then allow the customer to further calculate finallevels of methyl eugenol appearing in the finished product. It is difficult to see how manysmall essential oil suppliers, without resort to internal analytical expertise, will be able toperform this function. Additionally, it is relatively easy to find plants for sale on the Internet,whos essential oils contain high levels of methyl eugnol e.g. Black tea tree plants can beordered at http://www.hotkey.net.au/~macs_oils/plant01.htm. No warning about the potentialtoxicity of methyl eugenol is presented.
It has long been established that methyl eugenol occurs in essential oils such as CanadianSnake 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 tothe 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 eugenolcontent of a number of analysed commercial oils. Oils were classified by botanicalname (no chemotypes were distinguished) and by origin. There are no particularsurprises, although methyl eugenol contents on rose otto seemed low-ish comparedwith other published data, and the range of methyl eugenol contents of the 23 basiloils (all apparently from Egypt) was relatively large. No data on fennel oil (identified bythe EU Scientific Committee on Food as a dietary source of methyl eugenol) wasincluded. The BEOA data document makes comment that expert analysis of genuineessential oils shows how widely essential oils vary in composition, and makescomment that the BACIS commercial data-base of essential oils shows methyleugenol contents of 258 oils, that some of this data is misleading, and notrepresentative of genuine high volume essential oils used in commerce.
3. IFRA data on methyl eugenol contents of essential oils, as presented on the IFRAwebsite www.ifraorg.org in May 2004 does not define the plant source species, thegeographical origins of oils or any chemotype information. A document circulated byIFRA (to members only not in the public domain but most of the information thesame as on the IFRA website) on April 6th 2004 lists 21 essential oils, again giving nobotanical identification, only giving geographic origins for two types of oils (citronellaand rose), and giving chemotype information for basil only. As has been observedpreviously by this author, the standard of botanical reporting in IFRA documents, andin EU legislation leaves a great deal to be desired.
4. A list of plants containing methyl eugenol, duplicating the species names of many ofthe entries below, can be found on the Agricultural Research Services data-base athttp://www.ars-grin.gov:8080/npgspub/xsql/duke/chemdisp.xsql?chemical=METHYL-EUGENOL
Table I - Various References re: Methyl Eugenol content of EOs.
Essential oil Remarks Methyl eugenolcontent
Reference key(see below)
Acorus calamus Calamus Indian 1.0% Shiva et al.
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Acorus calamus CalamusMediterranean
0.9% max BEOA
Acorus calamus (?) Calamus oil
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winterianus (Java type)
Cymbopogon sp. Citronella oil
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Myrstica
fragrans
East Indian Nutmeg oil tr 1.2% EOS
Myrstica
fragrans
West Indian Nutmeg oil 0.1- 0.2% EOS
Myrstica fragrans
(?)
Nutmeg oil < 1.0% IFRA website
IFRA 06.04.04Myrstica fragrans
(?)
Mace oil < 0.5% IFRA website
IFRA 06.04.04Myrtus communis Myrtle oil 1.21% TQ
Myrtus communis Myrtle berry oil 2.3% Mazza
Ocimum basilicum Sweet basil oil Often below
0.2%, Comores
(exotic type) to
1.6%
Ocimum basilicum Oil of Egyptian origin 5.6% max BEOA
Ocimum spp. Basil oil < 6.0% IFRA website
IFRA 06.04.04Ocimum basilicum Basil Oil 2.6% FEMA
Ocimum basilicum var.
basilicum
Described by F & P as
Exotic type Basil oil
1.6% F & P.
Ocimum basilicum var.
feuilles de laitre
Described by F & P. as
European type Basil oil
2.5 to 7% F & P.
Ocimum basilicum var.
grand vert
Oil 55-65% F & P.
Ocimum basilicum var.
minimum
Described by F & P. as
Small Basil
55-65% F & P.
Ocimum gratissimum
var. thymoliferum
Described by F & P. as
Basil oil thymol type
1.7% F & P.
Ocotea pretiosa (Brazilian Sassafras
oil- methyl eugenol
type)
> 50.0% TB
Pelargonium
graveolens
Geranium oil China
Geranium oil Bourbon
Not detected in
either oil
BEOA
Pelargonium
odoratissum
Geranium oil Egypt Not detected BEOA
Peumus boldus Leaf 100-125 ppm Duke
Pimenta dioica Pimento leaf oil to 2% TB
Pimenta dioica Pimento leaf oil 2% FEMA
Pimenta dioica Pimento leaf oil 15.4% TQ
Pimenta dioica Pimento leaf oil 3.9% BEOA
Pimenta dioica Pimento berry oil to 8% TB
Pimenta dioica Pimento berry oil 15.0% BEOA
Pimenta dioica (?) Pimento berry oil < 15.0% IFRA website
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Pimento leaf oil
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aromaticum Syzygium-aromaticum
Clove leaf oil Indonesia 0.5% TB
Syzygium-aromaticum
Clove oil
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26.09.01, which can be viewed at http://europa.eu.int/comm/food/fs/sc/scf/out102_en.pdf
The committee remarked that methyl eugenol is a multi-site, multi-species carcinogen, being
both genotoxic and carcinogenic. Average human intake from diet of methyl eugenol
amounted to 13 mg/person/day and the 97.5th percentile was 36 mg/person/day (on a body
weight basis these values correspond to 0.19 and 0.53 mg/kg bw/day, respectively). The
committee was unable to establish a safe exposure limit.
Subsequently IFRA decided to severely restrict the limits of methyl eugenol in finished
fragranced products in 2001 (36th Amendment to the Code of Practice).
Low methyl eugenol rose oil has been commercially offered by a small number of aroma
houses. Removal of the methyl eugenol content by high vacuum fractional distillation seems
to adversely affect the typical rose character in products offered. Removal of the methyl
eugenol content by spinning band or spinning cone distillation may be more satisfactory, but
production time is at a premium on this expensive technology. Rose oils naturally very low in
methyl eugenol are known in Eastern Europe and further East, but the quality is very poor to
actually unacceptable for most purposes, even before methyl eugenol removal.
As a closing comment, it is hard to see why the aromatherapy and cosmetic industries are
led by the nose on the choice of available commercial rose qualities utilised, which merely
reflect historical perfumery trade uses. It has previously been established that rose absolutes
from varieties of garden roses can demonstrate beneficial cosmetic properties (tienne et al.
2000) whereas a conventional commercial rose absolute showed none of these effects.
Further, it is likely that certain of these other varieties will only present a fraction of the
methyl eugenol levels encountered in conventionally sourced rose ottos and absolutes.
Methyl Eugenol in Aromatherapy.
The author is unable to find any detailed advice given by professional aromatherapyorganisations to members on this issue, on a par with that put by IFRA for its membership in
the perfumery profession. Harris (2002) has reviewed the position of methyl eugenol in
aromatherapy practice in the light of IFRA restrictions in the fragrance industry. It is worth
exploring a number of points.
Firstly, Harris notes that the IFRA have published a list of essential oils (e.o.s) with methyl
eugenol contents, commenting that these figures only pertain to oils used in the fragrance
industry. Harris instead quotes e.o. data from Lawrence (1998-2002). However IFEAT have
previously criticised the use of Lawrences data (specifically over the separate 26 allergens
issue), as they maintain it is relates only to experimental data and does not relate to the
composition of commercial oils. In any case, in the real world, the e.o.s distributed by many
(but certainly not all) aromatherapy oil suppliers are identical to those distributed by the
fragrance industry.
Harris further maintains that the average aromatherapy treatment regime consists of 5-10
sessions, given at most once per week, generally with the essential oils employed being
changed during this regime according to the improvement of the client, and goes on to
state, those most at risk from methyl eugenol are the aromatherapists themselves, but
does not investigate exposure of this most at risk group in any satisfactory detail. Harris
further mentions avoidance of high methyl eugenol containing oils by therapists, and talks of
using 3 drops in a blend which, as several professional therapists have privately
commented, is not Aromatherapy.
Since aromatherapy is a poorly paid profession, many professional aromatherapists are
obliged to work extended hours, and may have to perform 6-8 massages per day, 5-6 (or
more) days per week. Further, a whole body massage may well be carried out with 20-50
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mls of massage oil containing 2-2.5% e.o., although some practitioners apparently havebeen known to use even higher concentrations (Guba 1998). Unknown amounts of methyleugenol are therefore absorbed by the therapist throughout the week, via skin absorptionthrough the hands, and by inhalation of vapour. Harris doesnt mention the fact that diet isadditionally adding to the therapists body burden of methyl eugenol.
The above factors may eventually allow a more realistic calculation of daily human bodyloading from methyl eugenol for aromatherapists, but interpretation of the data revolvesaround interpretations of the NOEL (no-effects) level in the longer-term and appropriatesafety factors (IFRA used a factor of 1000 X). Since aromatherapeutic treatments such aswhole body massage are vastly different from animal dosing studies, drawing directconclusions about possible toxicological effects is distinctly risky. Further, it is already knownfrom human liver microsomal preparations that metabolism rates by human cytochromeP450 isozymes for methyl eugenol varies more than 37-fold (Gardner et al. 1997) suggestinga wide range of serum concentrations will occur in the general population following methyleugenol exposure.
Meanwhile Schecter et al. (2004) have produced a study on human consumption of methyleugenol and its elimination from serum under a mandate from the National ToxicologyProgram of the US Department of Health and Human Services. In particular the teaminvestigated the consumption of methyl eugenol from a brand of gingersnaps, found tocontain a relatively high concentration of methyl eugenol at 3.3mg/g (a number of otherfoodstuffs containing lower concentrations of methyl eugenol are also listed in the article &cigarette tobaccos were identified as another possible source of methyl eugenol exposure!).Serum peak levels of methyl eugenol were found to be within range of a concurrent study of213 non-fasting subjects in the third Nutrition Examination Survey (NHANES III, 1988-1994).However in this latter study, the authors found that methyl eugenol levels in the blood of thegeneral US population were higher than expected (but the highest concentration found,390pg/g, was still 2000 X lower than the lowest dose used in the NTP rodent studies referredto above). Nevertheless, as Schecter et al. remark, the significance of the elevated levelswith respect to any toxicological consequences, still remains to be determined.
It may well eventually turn out that a working aromatherapist, constantly using basil and roseoils, and with a fondness for pesta and flavoured cigarettes is more likely to be hit by ameteorite than to contract a toxicological problem due to daily methyl eugenol exposure fromall these routes. Its just that it would be nice to think that those entrusted with a duty of caretowards working people in our society were actively investigating this topic. The situationbeing as it is, assessments on this topic are more likely to be made by self-educated laymen,than by formerly qualified toxicologists and to this end, Cropwatch has written to sometoxicologists for some learned opinions on this matter. Any replies will be published in furthereditions of this organ.
STOP PRESS!
Professor Arnold Schecter (see reference above) kindly read my piece on methyl eugenolabove and hinted from the tone of the article above that I might have understated the risk
slightly, commenting further as follows:
What my work followed during a year I worked at NIH was that methyl eugenol is extremelycarcinogenic to rodents and causes cancers in rats and mice, two species, and in multipletissues. The human levels may or may not be of concern, both those we reported and thehigher levels we alluded to in the general US population, so high for unknown reasons. MEdoes not occur by itself in humans but in combination with many other toxic chemicals sopotential human health effects might be from ME alone or in combination with others.
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And further: In combination with other carcinogens (methyl eugenol) might be harmful atlower levels than those derived dosing animals with one chemical only. Many chemicals in
our bodies.
I take these points on board, and suggest even louder now, that the aromatherapyprofession needs to take this issue seriously, perhaps appealing for outside help to more
properly evaluate the risk.
Glossary
BFA: British Fragrance Association
IFEAT: International Federation of Essential Oils and Aroma Trades
IFRA: International Fragrance Research Association
Table Data References:
Aurore, G. S. Abaul, J. Bourgeois, P. Luc, J. (1998) Antibacterial and Antifungal Activities of the Essential Oils of Pimenta racemosa var. racemosaP. Miller (J.W. Moore) (Myrtaceae). J. Essential Oil Res. 10(2), 161-164.
BEOA: British Essential Oils Association 9th Nov 2001 data reproduced by kind permission.
Brophy JJ: Brophy JJ (1999) Potentially Commercial Melaleucas in Tea Tree the Genus Melaleuca eds. Ian Southwell & Robert Lowe. HarwoodAcademic Publishers.
Brophy et al: Brophy et al. (1999) J Essen Oil Rec 11, 327-332.
Duke: Duke J (?) from Chemicals and their Biological Activities in: Peumus boldus MOLINA (Monimiaceae) Boldo see http://www.rain-tree.com/db/Peumus-boldus-phytochem.htm
Duke 2 : see http://www.ars-grin.gov:8080/npgspub/xsql/duke/chemdisp.xsql?chemical=METHYL-EUGENO
EOS: Essential Oil Safety Robert Tisserand & Tony Balacs Churchill-Livingstone 1996.
F & P: Franchomme P. & Peneol D (1995) lAromatherapie
Exactement pub. Jollois. R.
Guba R (1998) Toxicity Myths the Actual Risks of Essential Oil Use. Centre for Aromatic Medicine 1998.
IFRA website: www.ifraorg.org information as at 01.05.2004
IFRA: Annex 1 IFRA Standards.doc April 6, 2004.
IS: Ian Southwell (1999) Tea Tree constituents in Tea Tree the Genus Melaleuca eds. Ian Southwell & Robert Lowe. Harwood AcademicPublishers
Kam: Kameoka H. (1993) The Essential Oil Constituents of Some Useful Plants from China in Recent Developments in Flavour & FragranceChemistry Proceedings of the 3rd Int. Haarman & Reimer Symposium Pub. VCH NY 1993.
Lawr.: Lawrence BW (1989) EOs 1981-7 Allured Publ.
Lawr. a: Lawrence BM et al. (1985) Perf & Flav 10(6), 56-58 Dec 1985-Jan 1986
Mazza G. (1983) GCMS Investigation of Volatile Components of Myrtle Berries J. Chromatog. 264, 304-311.
SCIB: Zhu Lianfeng et al. (1993) Aromatic Plants & Essential Constituents South China Inst of Botany, Hai Feng Publishing Co.
Shiva et al: Shiva MP, Lehri A, Shiva A. (2000) Aromatic & Medicinal Plants pub IBD 2000.
TB: Tony Burfield (2000) Natural Aromatic Materials: Odours and Origins pub. AIA Tampa.
TB see: http://www.users.globalnet.co.uk/~nodice/new/magazine/odprofile.htm
TBb: Tony Burfield (unpublished data)
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TBc: Tony Burfield & Sylla Sheppard-Hanger (2002) Basil Oils Monograph AIA UK 2002.
TQ: trade suppliers questionnaire (IFF 2003)
Poucher (1991) Pouchers Perfumes, Cosmetics and Soaps - Vol 1 The Raw Materials of Perfumery 9th edn. Blackie Academic & Professional.
Zhu Liangfu et al. (1993) Aromatic Plants & Essential Constituents South China Inst of Botany.
Text References.
tienne et al. (2000) New and unexpected cosmetic properties of perfumes. Effects upon free radicals and enzymes induced by essential oils,absolutes and fragrant compounds. International Journal of Cosmetic Science 22, 317-328.
Gardner et al. (1997) Cytochrome P450 mediated bioactivation of methyleugenol in Fisher 344 rar and human liver microsomes. Carcinogenesis18, 1775-1783.
Harris B. (2002) Methyl eugenol the current bete noir of aromatherapy. Int. J. of Aromatherapy 12(4), 193-201.
Lawrence B.W. Progress in Essential Oils (1998-2002).
NHANES III 1988-94 National Centre for Health Statistics (1994). Plan and Operation of the Third National Health & Nutrition Examination Survey,1988-94. Series 1: Program & Collection Procedure No 32.
Schecter A et al. (2004) Human Consumption of Methyleugenol and Its Elimination from Serum Environmental Health Perspectives 112(6), 678-680.