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The Anatomy of Adulteration
The Adulteration of
Part 1. Oil Adulteration.
Essential oils - a definition.
Essential oils should be produced by purely physical means, and be 100% pure and wholly derived from the named botanical source - but how are these standards to be guaranteed? No quality standards for the authentication of essential oils exist in aromatherapy, in spite of the revelations of gross adulteration of aromatherapy oils for retail sale (Health Which 2000). Professional aromatherapy organizations have failed to issue standards, in spite of individual schemes being put forward (Jones 1998) but, in contrast, other essential oil-using industries are served by the following standards:
The Pharmaceutical Trade: British Pharmacopoeia
(BP) 2004 is published on recommendation of the Medicines Commission UK. Oils
specifications are also published in the European Pharmacopoeia 4th edn 2002 (Eur.
Pharm 4th edn); United States Pharmacopoeia (USP); also the pharmacopoeia’s of
individual nations such as China, India etc. Earlier editions of The British
Pharmaceutical Codex (BPC), such as BPC 1949, contain many essential oil
standards still in use today.
*An example is ISO 3515 for Oil of Lavender (2001) which includes minimum and maximum percentages of thirteen natural components, and their occurrence in French (spontaneous and clonal), Bulgarian, Russian, Australian and ‘other origin’, lavender oils. Limits for lavandulyl acetate, for example, are set at 2.0-5.0% in Bulgarian lavender oil by the standard.
Holistic aromatherapists demand that “pure” and “complete” oils are used, rather than oils only distilled for economically short periods e.g. tea tree oil. It is now suggested that in some cases longer distillations may be disadvantageous e.g. for tea tree oil distillation again, increases, the proportion of sesquiterpenes rises and these are considered by some researchers as responsible for adverse skin reactions when applied topically. Secondly unnecessary energy ‘wastage’ associated with excessively long distillation times may not be seen currently as a particularly “deep green” strategy!
Many essential oils used in aromatherapy are particular to that industry, and not necessarily extensively used elsewhere e.g. Ravensara aromatica, Rosemary oil verbenone chemotype, Helichrysum italicum ssp. serotinum etc.
As well as “pure and natural”, the words “wild-crafted”, “organic” and “clinical grade” are frequently over-hyped descriptor terms used by both aromatherapy and by “naturals” traders, which need more careful definition prior to professional endorsement.
Types of adulteration.
1. Addition of single raw materials. This simple form of adulteration can be conveniently divided into two groups:
“Invisibles” – i.e. those materials undetectable
by a gas chromatograph (GC) analysis operating under routine conditions to
“Invisibles”: an example of this type is the deliberate addition of vegetable or mineral oil to essential oils (Nour-el-Din et al. 1977) - rapeseed oil in the EU is a particularly cheap vegetable oil which has been used for this purpose. Theoretically the “total area” of the detectable components of the oil’s gas chromatogram should be reduced by this latter type of adulteration, creating suspicion for the analyst and the need for further investigation. These adulterant materials may be revealed by aqueous alcohol solubility tests, and their presence further verified by using a different GC column & operating conditions (to detect mineral oil), or by derivatisation (for example the use of a methylating agent for vegetable oils – whereby the volatile methyl esters of the fatty acid components of glyceryl esters are revealed by subsequent GC analysis).
“Visible” diluents in this context include a number of solvents and perfumery materials. For example the following have been found in commercial essential oils: in a few instances resulting in a warning or prosecution by regulatory authorities:
Abitol (a primary hydroabietyl alcohol) – often
used for extending resinoids.
Use of materials like isotridecyl acetate (ITDA, Fixateur 404Ô), Herculyn D and Abitol, can be moderately difficult to spot, because the materials may show a myriad of late-eluting small peaks on a GC trace representing their different constituent isomers, which could be overlooked by an inexperienced analyst especially at low levels.
In all the above instances of “visible” and “non-visible” adulterants, the added material is merely a diluent, and makes no odor contribution of its own. Addition of 10-14% of such a material may pass un-noticed if the material is evaluated against a retained standard solely on an odor basis – even by an expert nose – but it will in all probability be revealed by subsequent physio-chemical testing e.g. added vegetable oil in patchouli oil can often be revealed by a solubility test in 90% alcohol at 20°C.
2. The addition of cheaper essential oils and
Bergamot oil (Citrus bergamia): addition of
lemon oil, rectified ho oil (Cinnamomum
And also addition of these synthetics to “convert” one oil to another:
Basil oil exotic: add linalol to convert to
Basil oil Sweet (Arctander 1960).
3. The addition of cheap (nature identical) synthetics to oils that naturally contain these materials. Little detailed guidance has been previously published in this area. The older work of Arctander (1960) mentions a number of adulteration practices, but the sophistication of customer quality control procedures probably means that of the noted practices are now too obvious for today’s market. Looking at other published material on adulteration, Singhal et al. (2001) remarks on the adulteration of spice oils by simple additions of single raw materials e.g. the addition of synthetic citral to Litsea cubeba oil. My own guide to questionable practices include the following:
Anise oil (Pimpinella spp.): addition of
technical grade anethol.
Boelens (1997) described four types of odorants in essential oils: character compounds, essential compounds, balance compounds and artifacts. Adulterants such as monoterpene hydrocarbons, being balance compounds in Boelens scheme above, do little for the characteristic odor of the cut oils, since the added materials have little odor value in themselves. In practice, the addition of certain adulterants “flattens” the odor profile of the authentic oil, or otherwise dilutes or represses some true character, sparkle and richness. To compensate for this, a practiced oil counterfeiter will add small amounts of character compounds. Taking the example of Cypress oil Cupressus sempervirens var. stricta, the oil is often adulterated by the addition of the monoterpene hydrocarbons a-pinene and d-3-carene, which creates a crude terpinic aspect. The addition of a small amount of deca-2-(E),4-(Z)-dienyl isovalerate to the somewhat insipid cutting agent, will give a better impression of the oil’s normal character, a lead which follows on from the work of Garnero et al. (1978) who identified the compound above in cypress shoots, and found it strongly reminiscent of the typical odor of cypress oil.
Commercial oils, adulterated by such synthetics, can often fool the less sophisticated nose, or satisfy those oil customers buying to a price, where authenticity is sometimes not a primary consideration. Depending on exact market conditions, some oils have a selling price which is so cheap that it is generally unrewarding for a trader to reconstitute, or even add, nature identicals to the product, except for some solvent-like diluents. This category includes the following oils:
Sweet orange oil (Citrus sinensis)
Other oils are difficult to reconstitute with anything other than diluents because the major components are not commercially available; this class of oils includes patchouli oil, vetiver oil and to some extent ginger oil.
4. The addition of isolates or natural
components to essential oils e.g. the addition of pure natural eucalyptol ex
E. globulus oil (Eucalyptus globulus) to rosemary oil (Rosemarimus officinalis)
or rectified ho oil (very high in
5. The addition of bases or reconstituted essential oils to genuine oils & absolutes. It is particularly economically attractive to extend high value floral absolutes such as rose (Rosa spp.), jasmin (Jasminum grandiflora other spp.) and osmanthus (Osmanthus fragrans var. auranticus), and the more valuable oils such as neroli oil and rose otto, and this practice occurs extensively within the trade.
6. The addition of individual unnatural
components to oils and aromatic raw materials.
Adulteration: the purposeful addition of cheaper alternative oils, oil fractions, by-products, isolates, natural or non-natural synthetics etc., to reduce the cost price of the oil.
Extending: a term for adulteration almost implying a degree of legitimacy.
Isolate: a specific fraction of an essential oil. May be composed of a single chemical e.g. eugenol from Clove oil.
Organic oil: a more expensive essential oil, which has been derived from vegetable matter which has been grown in a pesticide free environment, but which still liable to have a pesticide content reflecting background contamination/incorporation.
Reconstituted oil: An oil made from nature identical synthetics, to look like analytically as far as possible -, and to give an accurate odor impression of -, the named essential oil.
COMMON ADULTERATIONS OF ESSENTIAL OILS
(from Aromatherapy for Natural Health and Beauty by Cecilia Salvesen)
ANISEED: Often adulterated with fennel and dill.
BASIL: Often by addition of synthetic linalool to exotic basil oils.
BERGAMOT: Synthetic linalyl acetate, linalool, limonene, synthetic or natural citral, terpinyl acetate, diethyl phthalate, bitter orange, lime.
CAJEPUT: Replaced by eucalyptus. Added: terpinyl acetate, terpinyl propionanate, terpineol, esters.
CALENDULA: Commercial oil not easily available; may be macerated.
CAMPHOR: Not likely because of wide availability and low cost, but PKC can vary widely.
CEDAR: Blending of the different kinds fairly common.
CHAMOMILE (GERMAN): Addition of synthetic chamazulene. Solvent extracted oil can be added grade oils to improve colour.
CINNAMON BARK OIL: Often cut with leaf oil, canella bark oil, clove leaf oil, eugenol, cinnamic aldehyde. Substituted with cassia oil. Also kerosene fuel oil.
CITRONELLA: Unlikely because of low cost.
CLARY SAGE: Easily synthesized; cut with synthetic linalyl acetate, linalool, lavender oil, bergamot mint oil.
CLOVE: Bud oil often cut or substituted with leaf oil. Synthetic eugenol and caryophyllene cost more, therefore not used as adulterants.
DILL: Cut with limonene, carvone, caraway.
EUCALYPTUS: Generally not justified due to low cost of oil, but possibility of cutting with synthetic cineole. Often redistilled for pharmaceutical rating.
FENNEL: Often adulterated with bitter fennel, synthetic trans-anethole, fenchone, methylchavicol, limonene.
FRANKINCENSE: Synthetic components often added, especially alpha-pinene. Quality of oils varies, depending on extraction and locale.
GERANIUM: Often cut with palmarosa, citronella, synthetic components.
GINGER: Can be adulterated with galanga oil, but due to wide availability of ginger, not often done.
JASMINE: Commonly adulterated or synthesized: ylang-ylang, benzyl acetate, indole, cinnamic aldehyde, fractions.
JUNIPER: True oil is rare, usually fermented. Cut with pinene, camphene, myrcene, turpentine oil fractions, wood and twig oil.
LAVENDER: Often adulterated by acetylated lavandin, aspic, synthetic linalool, linalyl acetate, Ho leaf fractions, rosewood.
LEMON: Folded or washed. Cut with orange, distilled lemon oil, concentrated juice from vacuum extraction, synthetic limonene, citral, dipentene. BHA, BHT.
LEMONGRASS: Cheap, so unlikely to be adulterated with synthetic citral. Occasionally cut with litsea in China. Occasionally substituted with jammu oil.
LINDEN BLOSSOM: Macerated oil may be sold as essential oil.
LITSEA: Occasionally substituted with lemongrass. Any other unlikely.
MELISSA: Most commercial oils adulterated. Often with lemon, lemongrass, citronella, isolated aldehydes, lemon, verbena and fractions.
MYRRH: Often adulterated with opoponax.
NEROLI: Easily adulterated, especially with synthetic linalyl acetate, linalool, nerol, nerolidol, petitgrain and its terpenoids, bitter orange.
NUTMEG: Terpenes often added, especially from nutmeg, myristicin from other sources, terpenes from tea tree
ORANGE (SWEET): BHA, BHT; often fractionated, distilled orange oil is added, or sweet and bitter are mixed.
PALMAROSA: Can be adulterated with ginger grass.
PATCHOULI: Often cut with cedarwood, clove oil, terpenes, methyl abietate, vetiver residues, castor oil, residues, gurjun balsam and others.
PEPPERMINT: The most adulterated oil. Usually with cornmint (difficult to detect even at 85%).
PETITGRAIN: Often adulterated with lemongrass, synthetic citral, lemon oil and others.
PINE NEEDLE: Can be cut with camphene, pinenes, isobornyl acetate.
ROSE: Adulteration is sophisticated and difficult to detect. Often adulterated with palmarosa, citronella, many fractions, synthetic and natural.
ROSEMARY: Extra eucalyptol often added, as well as terpenes from cypress, camphor, eucalyptus, sage and synthetic terpineol.
ROSEWOOD: Often adulterated with Ho wood and Ho leaf oil, synthetic linalool and linalyl acetate. Ho is similar to rosewood in effect, therefore adulteration is ecologically positive.
SAGE: Often adulterated with American cedarwood and palmarosa.
SANDALWOOD: Often cut with amyris, araucaria, cedarwood, castor and copaiba. Also diluted with glyceryl acetate, benzyl benzoate and synthetic copies.
TEA TREE: Often blended with other tea tree oils to attain standards set. Terpinen-4-ol often added, along other terpenes.
THYME: Can be adulterated with oregano. White thyme often contains compounds of pine, rosemary, eucalyptus, red thyme and terpenes.
TURPENTIN / OCEAN PINE: Marine pollutant (synthesized turpentine used to remove paint).
VETIVER: Often adulterated with other grass roots at distillation. Also cut with vetiverol, terpenes, cedarwood, amyris.
YLANG YLANG: Very easily adulterated with, Peru balsam, copaiba, inferior fractionations and synthetics. Different grades are mixed.
Copied with permission from Aromatherapy for Natural Health and Beauty by
Cecilia Salveson. Cecilia Salveson is a Qualified Therapeutic Aromatherapist and
Reflexologist and Practitioner of Complementary Medicine. She is the founder of
the Natural Health and Beauty School in South Africa and is also the Regional
Director for the International School of Reflexology and Meridian Therapy. She
has written numerous books and articles.
The Consequences of
Aromatherapists and natural perfumers have long required that their essential
oil’s are genuine, but conversely, the essential oil trade has traditionally
offered oils to the perfumery and flavorings trades on a “buyer beware”
principle. Therefore, the finding in the Health Which report (Health Which 2001)
on aromatherapy oils, citing a case where a labeled sandalwood oil turned out
to be a synthetic sandalwood aroma chemical, cannot come as a complete surprise.
Whilst many essential oils used in aromatherapy are sourced from commercial oil trade outlets, other items are offered by smaller dedicated aromatherapy oil producers. In attempt to make themselves uniquely positioned in the oil market, aromatherapy oil suppliers have previously boasted that their oils are distilled longer and under gentler conditions to produce superior oils. This is a complete nonsense – longer treatment can only encourage greater artifact production via thermal degradation, and any perceived more pleasing odor effect is possibly due the increased oil complexity (via the creation of artifacts). Even more curious is the easy acceptance of hype that CO2 extracts are suitable for the aromatherapy community. In many cases the CO2 extracts are of unknown composition and toxicity, extractions are not standardized (depending on operating conditions CO2 extracts can resemble either resinoids or essential oils, and all stages in between) and the use of any co-solvents during processing is often omitted by suppliers. Furthermore the concentration of pesticide residues during the CO2 extraction of spices are from seven to fifty three times greater than the values obtained by use of conventional solvents, according to Guba R. (2002).
1. Toxicity of the adulterant's).
Traces of residual organic solvents (such as hexane and cyclohexane) in oils and absolutes are found as a result of extraction & co-distillation practices.
The presence of pesticides in tainted essential oil’s in cosmetics has been described as a serious health & safety issue by Buchbauer (1998); their inevitable presence in aromatherapy oils is an unresolved issue.
2. The interference of adulterants on the expected physiological or psychophysiological effects of the essential oil.
Point 2 above has long been a concern of aromatherapists, but proof of adverse effects has been harder to find, although the following section below might furnish the beginnings of a case:
Chiral Issues from added adulterants.
Huenberger et al. (2001) have demonstrated that
inhalation of (+)-limonene caused increases in systolic blood pressure and
changed alertness and restlessness in subjects, whereas (-)-limonene only
affected blood pressure.
Sugawara et al. (2000) looked at the effects of 10 mins inhalation of the different linalool isomers [(-)-linalol purified from lavender, (+)-linalol from coriander, and synthetic (+/-)-linalol] inhaled before and after work. Effects were examined by sensory scoring and portable forehead surface EEG measurements. They found inhaling (-)-linalol after hearing environmental sounds produced a more favorable impression produced a more favorable impression in the sensory test but was accompanied by a greater decrease in beta waves after than before work. Conversely with mental work, there was a tendency for agitation accompanied by an increase in beta waves. (+/-)-Linalol gave results similar to (-)-linalol, but (+)-linalol gave the reverse results.
Buchbauer (1998) maintains that each constituent of an essential oil contributes to the beneficial or adverse effects of the oil. I contend that changing the distribution of chiral components of oils by deliberate adulteration with racemic synthetic odorants, may in fact change the beneficial properties of the oil.
We want to remind you that Bella Mira Essential Oils Would never adulterate any of our essential oils. We use these on our children!