The Consequences of Adulteration
to Aromatherapy & Natural Perfumery Practice.
Copyright ©Tony Burfield 2003-2005.

Part 2.

Background.
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 flavourings 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 labelled 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 artefact production via thermal degradation, and any perceived more pleasing odour effect is possibly due the increased oil complexity (via the creation of artefacts). 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 standardised (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).

Consequences.
The adulteration of essential oils leads to the following concerns:

1. Toxicity of the adulterant(s).
Phthalates such as DEP are still occasionally found as adulterants in essential oils. Phthalate esters have been withdrawn as ingredients by many cosmetics manufacturers on toxicity grounds; specific phthalates (DEHP & DBP) are classified by the EU as reproductive toxicants. Whilst consumer pressure groups campaign for awareness in this area (see for example: http://www.nottoopretty.org/); the other side of the argument can be viewed on http://cms.phthalates.com/index.asp?page=3.

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.
Addition of racemic synthetics to natural essential oils may distort the enantiomeric ratios of the naturally occurring substances within the make-up of oils, and thus may have an untoward effect on the expected physiological outcome. The logic behind this may be predicted from data accrued on the contrasting physiological effects of different chiral isomers of the same substance. A few examples are given below:

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.
(-)-Carvone was reported to increase pulse rate, diastolic blood pressure and restlessness whereas (+)-carvone increased systolic and diastolic blood pressure. Traynor (2001) reports that when evaluated by Contigent Negative Variation, (+)-rose oxide confers relaxing physiological effects, whilst (-)-rose oxide (which occurs in Bulgarian Rose oil and geranium oils) possesses a significantly higher stimulatory effect.

Sugawara et al. (2000) looked at the effects of 10 mins inhalation of the different linalool isomers [(-)-linalol purifed 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 favourable impression produced a more favourable 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 odourants, may in fact change the beneficial properties of the oil.

References

Buchbauer G. (1998) “The detailed analysis of essential oils leads to the understanding of their properties” – paper presented at 20th IFSCC Congress Sept 14-18th 1998 Cannes, France and reproduced in Perf & Flav. 25, March/April 2000 pp64-67.
Guba R. (2002). “The modern alchemy of carbon dioxide extraction.” Int. J. Aromatherapy 12(3) p22.

Health Which February 2001 pp 18-20.

Huenberger E., Hongratanaworakit T., Bohm C., Weber R & Buchbauer G (2001) “Effects of chiral fragrances on human automomic nervous system parameters and self-evaluation” Chem Senses 26(3), 281-292.

Sugawara Y., Hara C., Aoki T., Sugimoto N., & Masujima (2000) “Odour distinctiveness between enantiomers of linalol: difference in perception and responces elicited by sensory test and forehead surface potential wave measurement” Chem. Senses 25, 77-84.

Traynor S. (2001) “The Musk Dilemma” Perf. & Flav. 26, Sept/Oct 2001 p31.