The Cropwatch Series

Cropwatch 11



Initial Cropwatch Objection to SCCP Opinion on Opoponax

(Sensitisation Only) SCCP/0871/05.








Copyright Ó Cropwatch Sept. 2005




Preamble: Available Safety Data for Opoponax – Paucity & Confusion.

Opoponax qualities from several Commiphora spp. (see below) are widely used in perfumery, especially in oriental fragrances, to impart sweet balsamic notes. 


The SCCP Opinion on Opoponax oil (Sensitisation only) SCCP/0871/05 adopted 15th March 2005 can be found at:


It concludes that “The provided data do indicate that Commiphora Erythraea Glabrescens has an allergenic potential [This botanical naming can be more correctly expressed as Commiphora erythraea Engl. var. glabrescens Engl. - according to the rules of the International Code for Botanical nomenclature]


Previously, essential oil safety authors Tisserand & Balac (1995) had cited a 1977 RIFM photo-toxicity testing report (Forbes et al. 1977) indicating photo-toxic properties for opoponax oil, but also noted that “RIFM have not published a monograph on opoponax oil nor have IFRA issued a guide-line…”. This latter statement appears incorrect since a guideline was first issued on 1st March 1978, and amended on 1st July 1994, to presently read:


IFRA recommends:  Opoponax preparations, obtained from opoponax gums (the exudation from the bark of Commiphora erythraea var. glabrescens Engler) by solvent extraction or steam distillation, should not be used such that the level in consumer products exceeds 0.6%. This is equivalent to 3% in a fragrance compound used at 20% in the consumer product. This recommendation is based on test results of RIFM with samples of resinoids, concretes, absolutes and oil of opoponax. Earlier samples showed limited sensitisation reactions when tested at 8% whereas tests on a larger number of more recent samples showed no sensitisation at 8% (private communication to IFRA)”.


Watt (undated) maintains that IFRA recommended to members that only preparations obtained by alcoholic extraction of opoponax gums or resinoids should be used, as alcoholic extracts do not show sensitizing potential, but Cropwatch has been unable to independently verify this, although Moyler & Clery (1997) confirm that (earlier) IFRA advice stated that the crude gums should not be used in fragrances.


The Botanical Dermatology Data-base has no entries for named opoponax spp., but warns that “In common with other volatile oil containing materials of natural origin, the oleo-gum-resins obtained from members of this family (Bursuraceae) may have mild rubefacient properties and may be weakly allergenic. Some of the resin acids also present in the oleo-gum-resins are similar to abietic acid, a known contact allergen. Thus, cross-sensitivity to certain Pinus spp… and their products is theoretically possible.” Saeed & Sabir (2004) presented a study on the irritant potential of some constituents from the gum of the related Commiphora myrrha (myrrh) by open mouse vear assyay, concluding that the essential oil, curzerenone, furanodiene-6-one and furanoeudesma-1,3-diene showed potent and persistent irritant effects while others possess least irritant potentials.


These 3 components have been found to occur in opoponax oil from C. holtiziana at least (see below).


Botanical identification: Confusion Reigns.

The first thing to note is that the economic botany of commercial opoponax commodities is not actually as the EU Inventory of Cosmetic Materials (1st Update 2000) or the SCCP Opinion present it, being at variance with the literature.


Originally thought to derive from Opoponax chironium, Burfield (2001), FAO (1995) Gachathi (1997), Guenther (1950), Mabberley (1998), Langenham (2003), and others, describe opoponax qualities deriving not only from Commiphora erythraea Engl. var. glabrescrens Engl. growing in Somalia, Kenya, E. Ethiopia, and S. Arabia., but also from other species such as:



C. kataf (Forssk.) Engl. N. Kenya to S. Arabia (Mabberley 1998), including Yemen (Wood 1997). Wood notes the close morphological similarity of Yemeni shrubs to Commiphora erythraea Engl. var. glabrescens Engl. (however main use of C. kataf in Yemen is as firewood).


C. guidottii (Chiov) – S. Somalia, Ethiopia, and which Mabberley (1998) maintains is the principle source of opoponax with other Commiphora spp; as does the ANLAP data-base (ANLAP undated); Neuwinger (2001) however describes C. guidotti as the principle source of scented myrrh as defined by Thulin & Claeson (1991).


C. holtiziana Engl. spp. holtziana Kenya


C. pseudopaoli JB Gillet Kenya.


The SCCP refer to the previously unpublished work of RIFM, which gives no published audit trail from identifying botanist to dermatology researcher for these ingredients. Since there is a derth of botanical information in these studies, an appendix is attached to this document setting out some of the medicinal resin-producing Commiphora spp.


Brief Chemistry Notes on the different Opoponax oils.

There is an industry standard for Opoponax oil (EOA No. 67). A review of the chemistry of the Burseaceae has been published by Khalid (1983), and of the composition of opoponax oil itself by Lawrence (1983; 2004). Early work using IR & NMR analysis by Nigam & Neville (1967) established a-santalene, a-bisabolene and b-bisabolene as components of opoponax oil although slightly later Wenninger & Yates (1969) through Khalid (1983), described eighteen sesquiiterpenoid components of C. erythraea, including b-bisabolene, ar-curcumene, b-santalene & humulene. Moyler & Clery (1997) report 228 components in the oil of C. erythraea var. glabrescens of which they identify 13, with tr-b-ocimene (26.2%), a-santalene (14.2%) cis- & tr-a-bisabolene (14.2%) being stated as the major components. 


Baser (2003) analysed the oils of several Boswellia & Commiphora spp. including C. guidottii,  finding the major components of the latter oil to be E-b-ocimene (33.0%), a-santalene 15.8% and cis-a-bisabolene 22.2%. Neuwinger refers to the analysis of Creveiro et al. (1983) who describes C. guidotti as containing a- and b-santalenes, epi-b-santalene, b-bergapten, b-farnescene a- & b- bisabolene and furanodiene. Cleason et al. (1991) further identified T-cadinol in the oil of C. guidottii. The ANLAP data-base reports the following compoents from an Ehiopian steam distilled C. guidotti oil: ocimene (27.8%), santalol – isomer not stated - (24.4%); bergamotene (4.1%), germacrene D (5.7%),  cis-a-bisabolene (8.1%).


The main constituents of the oil of C. holtiziana are 1 (10),2-methoxy-8,12-epoxygermacra-1(10, 7, 11-trien-6-one, 5-acetoxy-2-methoxy-8,12-epoxygermacra-1(10),7,11-trien-6-one, 3-methoxy-8,12-epoxygermacra-1,7,10(15),11-tetraen-6-one, elemol, furanodiene, furanodienone, isofuranogermacrene, curzerenone, lindestrene, furanoeudesma-1,3-diene, furanoeudesma-1,4-diene-6-one, 1(10)Z, 4Z-furanodiene-6-one, 2-methoxy-furanodiene, 2-acetoxyfuranodiene, 4,5-dihydrofuranodiene-6-one (Provan et al., 1987). Baser (2003) notes germacrene-D and furanosesquiterpene are found to be the major constituents of C. holtziana. The ANLAP data-base reports the following components (confirmed by GC-MS and NMR) for essential oil from Kenyan C. holtiziana a-copaene (1.3%), methyl cinnamate (1.5%), b-elemene (5.2%), a-humulene (2.6%),  germacrene D (22.5%), germacrene B (7.4%), curzerenone (10.7%), furanosesquiterpene (6.2%), dihydropyrocurzerenone (2.1%), furano germacra 1,10(15)-diene-6-one (13.4%).


Baser (2003) indicates the presence of the following components in C. kataf oil: germacrene D, germacrene B, furanosesquiterpene and (1E)-8,12-epoxygermacra-1,7,10,11-tetraen-6-one. The ANLAP data-base reports the following components confirmed by GC-MS and NMR in a Kenyan steam distillled essential oil of C. kataf: camphene (0.8%), g-elemene (2.4%), b-elemene (14.4%), germacrene-D (15.5%), elmol (4.6%), furanogermacra-1, 10(15)-diene-6-one (16.7%).


The evidence for sensitisation.

The SCCP Opinion virtually rules out the 1972-1980 RIFM maximisation test studies on the grounds of ill-defined materials, and confused record-keeping with respect to clear botanical identification (plus the fact that no chemical analytical data is indicated). This leaves five cited studies in Section 3.3. Study 3 (Itoh et al. 1986) can also be ruled out since there are insufficient details on which to make a judgement, and in Study 4 (Spott 1970) no adverse reactions to opoponax were seen. Study 5 (Ishihara 1977; 1978) gave 2 reactions out of 65 subjects with 5% opoponax in petroleum – a concentration 30 times over the 1995 IFRA limit. In Study 2 (Hjorth, 1961), the SCCP Opinion omitted to clearly indicate that 11 patients who were contact sensitive to Balsam of Peru were in fact tested, six proving positive to opoponax. Balsam of Peru is no longer an allowed fragrance ingredient (only molecular distilled oil of Balsam Peru is allowed, and this is subject to an IFRA limit). Patients pre-sensitised to Peru Balsam via fragrances employed in this 1961 test therefore should not now exist, so the study is of questionable validity. This leaves Study 1 [Takenaka (1986) – “taken from an unknown source”!] where we are told that 3 patients out of 118 reacted, 2 with only slight erythema, to 0.05 to 0.5% opoponax in base cream or ethanol in a 24-48 hour patch test. This series of studies with no audit trail from identifying botanist to dermatologist and no composition data for materials employed, fails to clearly distinguish sensitisation to opoponax from cross-reaction. Cropwatch therefore recommends that the IFRA voluntary guideline for opoponax qualities continues to apply therefore, whereby as a precautionary measure, a concentration limit of 0.6% maximum concentration is imposed, until such a time as proper rigorous scientific studies for opoponax sensitisation can be organised. 




  1. Cropwatch has been astonished at the apparent lack of scholarship in the SCCP Opinion – for example, it’s hard to see that a literature search had been carried out - if it had, relevant key articles would surely have been found [like that of Saeed M.A. & Sabir A.W. (2004)].
  2. Carrying on from above, the entry for opononax in EU Inventory of Cosmetic Materials (1st Update 2000) needs revision by a competent economic botanist to accurately reflect the realities of the five or more botanical origins of commercial opononax qualities. Statements such as “The names Opoponax Oil, Bisabol-myrrh Oil and Sweet Myrrh Oil are known as generic synonyms C. Erythraea Glabrescens Gum Oils” do not reflect the present state of knowledge gained over the last sixty years. The EU Inventory of Cosmetic Materials and the SCCP itself also needs to follow the International Code of Botanical Nomenclature more closely, so we can all understand common terms of botanical reference. It seems incredible that the poor, archaic and outdated defining standards of the EU Inventory of Cosmetic Materials, which has been widely criticized elsewhere, should continue be used as a reference tool for professional judgments from ‘expert’ committees which can so profoundly affect the use of fragrance ingredients.
  3. The SCCP Opinion gives a sketchy account of RIFM data not previously available in the public domain, which fails to accurately identify the botanical & geographic origins of opoponax qualities used in the sensitivity protocol testing, nor establishes the absence of adulteration.  The usefulness of the RIFM data presented is almost zero, and can be completely ruled out.
  4. The main evidence for the SCCP Opinion seems to hinge on five studies, several of which can be severely criticised. Overall, the evidence from these studies is too flimsy to conclude anything, and Cropwatch recommends that the SCCP committee adopts the IFRA voluntary limit of 0.6% concentration maximum of opoponax qualities in fragrances, until such a time as proper rigorous scientific studies can be carried out. 
  5. The SCCP Opinion fails to link alleged dermal sensitivity to specific opoponax components, although prospective candidates for this are mentioned in the literature. The brief BoDD statement (above) on gum oleoresins from the Burseraceae which might be weakly allergenic would seem to give a better overview of the subject, than  musings from the SCCP, so far.




Appendix I – Some Resin-producing Commiphora spp (complied from a number of sources, including Gachathi 1997).


Commiphora sp.

Common name




C. africana (A. Rich) Engl. syn C. pilosa

Source of “myrrh-like resin” (Gachathi 1997)

Ethiopia, Sudan, Nigeria

Fragrance ingredient, termite repellent

C. confusa Vollesen

Source of “myrrh-like resin” (Gachathi 1997)

N. Kenya


C. erythraea Engl.

Source of opoponax

Somalia, Kenya, E. Ethiopia, and S. Arabia.

Fragrance ingredient

C. gileadensis (Forssk.) Engl.

Source of Balm of Gilead/Mecca balsam

SW Arabia, also Djibouti, Ethiopia, Kenya, Somalia, Sudan.

“more valuable than frankincense” Chaudhary & Al Jowaid (1999)

C. guidotti Chiov. ex Guidottii

Source of opoponax/scented myrrh

S. Ethiopia, Somalia.

Fragrance ingredient; extract is anti-diarrhoeal.

C. habessinica (Berg) Engl. syn. C. madagascariensis Jacq.

Source of “myrrh-like resin” (Gachathi 1997)

N. Kenya


C. holtiziana ssp. holtziana syn. C. caerulea Burtt.

Source of opoponax


Fragrance ingredient; tick repellent. Popular use on animals in USA (Gachathi 1997)

C. incisa Chiov. syn. C. candidula Sprague

Source of “myrrh-like resin” (Gachathi 1997)



C. kataf (Forssk.) Engl.

Source of opoponax

N. Kenya to S. Arabia incl. Yemen.

Fragrance ingredient

C. merkeri Engl.


S. & E. Africa

Gum-resin is used as anti-inflamm, anti-septic etc.

C. molmol Engl. ex Tschirch

Source of “myrrh-like resin” (Gachathi 1997)


Gum-resin is used as anti-inflamm, anti-septic etc.

C. mukul Engl. (syn . C. wightii)

Source of guggul or Indian bdellium

India, Pakistan, Bangladesh, Iran.

Used as incense ingredient, astrigent & antiseptic. Common adulterant of C. myrrha.

C. myrrha (Nees) Engl. or C. myrrha Engl. var. molmol

Not source of myrrh! (Wood 1997); is the source of myrrh! (Chaudhary & Al Jowaid 1999)

Yemem, S. Arabia; also Somalia, Ethiopia & N .E. Kenya.

Resin used for treatment of colds & fevers, to treat haemorrhoids & toothache.

C. pseudopaoli JB Gillet syn. C. paolii Chiov.

Source of opoponax (Gachathi 1997)


Tick repellent. Popular use on animals in USA (Gachathi 1997)

C. schimperi (Berg.) Engl. syn. C. buraensis

Source of “myrrh-like resin” (Gachathi 1997)

N. Kenya


C. tenuis K. Vollesen



Vetinary: wound healing uses


Notes: Dekebo (2002) has indicated that gum myrrh is frequently adulterated with gums of C. sphaerocarpa and other Commiphora spp., adding to the picture of widespread Commiphora commodity adulteration.







Baser K.H.C., Demirci B., Dekebo A. & Dagne E. (2003) “Essential oils of some Boswellia spp, Myrrh and Opoponax” Fl. & Frag. J. 18, 153-6.


Burfield T. (2001) Natural Aromatic Materials – Odours and Origins pub. AIA Tampa 2001.


Chaudhary & Al Jowaid (1999) Vegetation of the Kingdom of Saudi Arabia pub. Ministry of Agric. & Water, Kingdom of Saudi Arabia 1999.


Creveiro A., Corsano S., Proietti G., Strappaghetti (1983) “Constituents of the Essential Oil of Commiphora guidotti” Planta Medica 48, 97-98.


Claeson P., Anderson G. & Samuleson G. (1991) “T-Cadinol a pharmacologically active constituent of scented myrrh. Introductory pharmacological characterisation of h-field H- and C12-NMR data. Planta Medica 57, 352-6.


Dekebo A., Dagne E. & Sterner O. (2002) “Furanosesquiterpenes from Commiphora sphaerocarpa and related adulterants of true myrrh.” Fitoterapia – Milano 73(1), 48-55.


FAO (1995) Flavours & Fragrances of Plant Origin: Non Wood Products –1. publ. FAO Ch. 9.


Forbes P.D. et al. (1977) “Phototoxicity testing of fragrance raw materials” Food & Cosmetics Toxicology 15(1), 55-60.


Gachathi F. N. (1997) “Recent Advances on Classification and Status of Main Gum-Producing Species in the Family Burseraceae” available at

Guenther (1950) The Essential Oils Vol 4.


Hjorth N. (1961) Eczematous Allergy to Balsams Ch 16, pp 141-143. Munksgaard, Copenhagen.


Ishihara, Μ., 1977. Problems of closed patch tests with ingredients of cosmetic products. Journal of Japanese Cosmetic Science Society, 1, 87-102.


Ishihara, Μ., 1978. The enνironment and the skin. Journal of the Medical Society of Toho Uniνersity, 25 (5-6), 750-766.


Itoh, Μ., Ishihara, Μ., Hosono, Κ, Kantoh, Η., Κinoshita, Μ., Υamada, Κ, Nishimura, Μ., 1986. Results of patch tests conducted between 1978 and 1985 using cosmetic ingredients. Skin Research 28 (suppl. 2), 110-119.


Khalid (1983) “Chemistry of the Burseraceae” Ann. Proceed. Phytochem. Soc. Europe 22, 281-299.


Langenham J. (2003) Plant Resins: Chemistry, Evolution, Ecology, Ethnobotany Timber Press, Portland, Oregon.


Lawrence B.M. (1983). “Opoponax oil Commiphora erythraea var. glabrescens” Perfum. & Flav. 8, 27-28.


Lawrence B.M. (2004) Progress in Essential Oils: Opoponax & Other Commiphora spp. Perf. & Flav. 29(7), 88-101.


Mabberley D.J. (1998) The Plant Book 2nd rev edn. Cambridge Univ. Press. 

Moyler, D.A. and Clery, R.A. (1997). “The aromatic resins: their chemistry and uses.” Paper presented at Royal Society of Chemistry Symposium on Flavours and Fragrances, 1 May 1997, University of Warwick, UK.

Neuwinger H.D. (2001) Afrikanische Arzneipflanzen und Jagdifte: Chemie, Pharmakologie, Toxikologie. Wissenschafliche Verlagsgesellschaft mbH Stuttgart.


Nigam I.C. & Neville J. (1968) “Essential Oils and Their Constituents Part XLI. Identification of sesquiterpene hydrocarbons in Oil of Opoponax.” J.  Chromatog 34, 85-88.


Provan, G. J., Gray, A. I. and Waterman, P. G. (1987) “Monoterpene-rich Resins from some Kenyan Burseraceae” Flav. Frag. J. , 2, 115-118.


Saeed M.A. & Sabir A.W. (2004) “Irritant potential of some constituents from oleo-gum-resin of Commiphora myrrhaFitoterapia 75(1), 81-4.


Spott, D.A., Shelley, W.B., 1970. Exanthem due to contact allergen (benzoin) absorbed through skin. Journal of the American Medical Association, 214(10), 1881-1882.


Takenaka, Τ., Hasegawa, Ε., Takenaka, U., Saito, Ρ., Odaka, Τ., 1986. “Fundamental studies of safe compound perfumes for cosmetics. Part 1. Τhe primary irritation of compound materials to the skin.” Unknown-Source, pp. 313-329.


Thulin, M. and Claeson, P. (1991). “The Botanical Origin of Scented Myrrh (Bissabol or Habak Hadi)” Economic Botany, 45, 487-494.


Tisserand R. & Balacs T. (1995) Essential Oil Safety: a Guide for Health Professionals pub. Churchill-Livingstone,


Watt M. (undated previous edn.) Plant Aromatics Vol 4: Adverse Effects on the Skin of Aromatic Plant Extracts p89.


Wenninger J.A. & Yates R.L. (1969) J. Assocn. of Anal. Chem. 52, 1155 through Khalid S.A. (1983) “Chemistry of the Burseraceae” Ann. Proc. Phytochem. Soc. Europe 22, 281-299.


Wood J.R.I. (1997) Handbook of Yemen Flora publ. Royal Botanic Gardens Kew.


Further reading:

Brieskorn, C. H. and Noble, P. (1980) “Drei Neue Furanogermacrene aus Myrrhe” Tetrahedron Letters , 21 : 1511-1514.


Brieskorn, C. H. and Noble, P. (1983) “Furanosesquiterpenes from the Essential Oil of Myrrh Phytochemistry” 22, 1207-1211.

Ghazanfar Shanina A. (1994) Handbook of Arabian Medicinal Plants CRC Press, Boca Raton 1994.


Gillett, J.B. 1973. “Commiphora Jacq. (Burseraceae) - Englerian species which disappear.” Kew Bull. 28(1), 25-28.


J. Gillett (1991) Flora of Tropical East Africa - Burseraceae. Pub A.A. Balkema, Rotterdam, Brookfield.


Hedberg I. (1989) Flora of Ethiopia Vol III.  Addis Abbaba, Upsala.

The information supplied in this bulletin is believed to be accurate, but views, comments, criticisms, corrections or additional material can be forwarded to for consideration in future communiqués in the Cropwatch series.