The Lavender Cat - Cats and Essential Oil Safety

Anthony Burfield, A.B.P., M.I.Biol., C.Biol., M.I.F.S.T., F.L.S.

Tony Burfield has now spent nearly 30 years in the aroma trade,mainly working hands-on with essential oils (their production, analysis and applications). After initially qualifying as a food scientist, he returned to academia mid-career to do a further degree in biochemistry, eventually becoming a Chartered Biologist. This was followed by a period of post-doctoral research in the microbiological biotransformation of essential oil components at Cranfield University. Now deeply involved in perfumery, natural perfumery, and with natural products generally, Tony is an aroma industry consultant, looking after the interests of various essential oil, cosmetic and fragrance clients, from the small to corporate (especially those with “green portfolio” intent).

Tony also writes, lectures and produces educational materials on aromatic topics. Tony is the author of Natural Aromatic Materials – Odours and Origins (2000) the privately published second edition of which (updated and completely revised) is to be released shortly.

A four module distance-learning diploma course on Natural Perfumery is also near completion, and will be launched imminently. Now on to the questions........

Is grain alcohol considered a dispersant when added to essential oils and water?

It is true that many essential oils, especially those containing a high proportion oxygenated substances (like say, Palmarosa oil) will dissolve in certain concentrations of aqueous grain alcohol (ethanol) to give clear solutions at room temperature. Those oils containing a high proportion of monoterpene hydrocarbons, or sesquiterpene hydrocarbons (like say myrrh oil) have a harder time dissolving, and may give opalescent or turbid solutions, or not dissolve satisfactorily at all, even with 96% ethanol. So to sum up we can say that for many oils ethanol is a good solvent, although there will be a solubility limit.

There are a couple of considerations for then using this mixture as a room spray. Firstly, I am not a prude, but the purist in me asks do you really want to be breathing in a foreign material, such as dispersed ethanol, as well as the essential oil. Secondly, there may be a small risk attached to using materials like ethanol, which has very low flash point in this sort of setting. Thirdly there are a number of chemical reactions which occur between the individual components of essential oil and alcohol itself, which may lead to artifact formation (which for our purposes here we can say is the formation of extra or un-natural substances). This area is a bit of a specialty of mine, and it is true that these reactions tend to occur much more on storage, but nevertheless it is another example of human intervention changing what nature intended. My advice is don’t go there!

Why is Benzoin touted as good for skin complaints such as cracked nipples, skin, etc? Is there truth to this although it is a known skin sensitizer? - Stacey

Benzoin is/was used as a sort of glue for wounds, enabling the fusion of torn tissue, acting as an adhesive, reducing the “gaping” tendency and generally facilitating wound repair mechanisms to commence. It is also used as a skin protectant, it reduces inflammation of the gums when applied as a tincture, volatiles from benzoin resinoid are inhaled for respiratory complaints, and it shows general antiseptic effects. With all these positive things going for it, it is a pity that in a small number of cases sensitisation problems can occur. There are tests which have show benzoin not to be a sensitiser, but we have a number of case studies where reactions have occurred possibly due to specific coniferyl esters contained in the resinoid. Since the concentration of these can vary in the product according to source, type and extraction procedure, we may have some variation in reaction. It may be advisable to carry out a patch test prior to use, but personally I would not like to see the material dropped from the aromatherpists repertoire. After all, we eat enough of the stuff (permitted in flavourings…..!).

What EO's in addition to pine become more irritating to the skin with increased oxidation? - Stacey

The reactions of individuals to potentially irritant chemicals is idiosyncratic and complex. But in general we know that certain essential oil components produce products from oxidative degeneration which cause irritation. We know with certainty that many pines have delta-3-carene present and it is the hydroperoxides which are problematic here. So does this also occur in say oxidised cypress oil, or angelica root oil which also contain delta-3-carene? Or in old citrus oils where high levels of limonene is prone to similar oxidation problems? I would say the answer is yes, with the proviso that in many of these oils, there will be an “off” smell present, which would make you think twice about using the oil anyway. The point is to monitor the shelf life of your essential oils, and not to over-order so that stock is hanging around for long periods (say no more than 6 months).

Roughly, what percentage of EO's on the aromatherapy market would you say are adulterated in some manner?

Lets put it another way. You are less likely to buy an adulterated oil if you are prepared to pay the market price for the oil, and you ask that it be pure. It never ceases to amaze me how many people are still taken in by the concept of a “bargain offer”, or the fact that the oil on offer is both cheap and pure! One of the best tests you can do on an oil is an odour assessment, and to some extent GC/Mass spec is only a confirmatory tool for the latter. Train your nose, get to know what you like and what a specific “good oil” should smell like, and I’m sure you won’t go too far wrong. As we have remarked in a previous question, badly kept oils, or aged stock, may be just as harmful in some instances as adulterated oils. There will always be adulteration, but it can be minimised by your vigilance, knowing and visiting the people you are dealing with where possible, and giving them every chance to make some sort of reasonable profit to live on without them having to be forced to cheat. Really this is what happened with lavender oil in the past. The market was never prepared to pay a realistic price for the oil: it was always undervalued, and producers had to sell other oils at better profit to cover production costs for lavender, or adulterate the lavender. It is only in the last few years that the price of lavender oil has risen to a more comfortable price for the producer. If there is a moral to the story here it is that adulteration can only be lessened when the buyers are more sympathetic to the producers situation.

I am curious about sensitization and essential oils. I am wondering if sensitization can occur in a person by diffusion alone? Or does it mainly occur by topical applications? - Dorlen

In fact I have a paper in front of me called “Allergic airborne contact dermatitis from essential oils used in aromatherapy” by M. Schaller & H.C. Korting (1994) Clinical & Experimental Dermatology 1993, 20, 143-45, which covers just this subject, where the subject was found to exhibit sensitisation to a number of previously used oils (lavender, jasmin and rosewood) and other which the subject had not been previously exposed (laurel, eucalyptus and pomerance (?). The bottom line is that once sensitisation occurs, exposure to seemingly minor amounts of substance may initiate a subsequent reaction, and the answer is to totally withdraw from oils for a period (say 6 months or more) before gradually and cautiously re-introducing them individually (with monitoring) to your environment, to see if you can now tolerate them, and hopefully benefit from them

Chemicals are absorbed by the skin into the bloodstream wouldn’t essential oils be absorbed and utilized too? Sue

Yes, but this may be a more minor route compared with inhalation. I am always saying this, so please forgive me if I’m repeating myself. The permeation of essential oils through the skin is a diffusion controlled process. It is therefore dependent on a number of factors like temperature, concentration of oil (i.e. 1-5% in carrier etc.), degree of hydration of the skin, time in contact and so on. The fact that it does occur is hardly disputable: wintergreen oil is readily absorbed by the skin for example and can lead to dangerously toxic situations in certain instances. The argument is much more about the clinical significance of the amounts absorbed, and the routes of ingress through the body. Does the localised concentration of e.o. components become significant in promoting physiological changes in nearby tissues or organs or are we considering evenly whole body model dosing effects? There are a lot of unanswered questions, but the answer to your question is that under certain circumstances we would be able to measure individual components of essential oils as markers of permeation in the blood stream, after skin absorption, and to my certain knowledge, this has been carried out.

I love the smell of wintergreen, is it still toxic if I only use it for air freshening in a diffuser and not on the skin? Pat.

Its very much a geographic thing, methyl salicylate the chief component of wintergreen is very much appreciated in birch beer, sarsaparilla, root beer and toothpaste in N. America. Other parts of the world are less keen on the taste and odour! There isn’t anything very similar in odour to methyl salicylate either, so I can’t suggest a way of weaning you off it! The answer to the toxicity question is a theoretical yes, that methyl salicylate poisoning, chronic and sub-chronic effects are known, and so the golden rule as with everything is, don’t overdo it, give yourself a complete break after a few days use, and if you feel unwell: stop. I imagine that using a diffuser for a short period in a large ventilated room is not going to cause problems on a one-off basis however. Lets put it like this: did the budgerigar fall off his perch yet?

Are all essential oils tested for safety? Phillip

No. A number of oils have been tested by RIFM and policy guidelines issued by IFRA, but these are all for oils in fragrance use. Many essential oils that are new, rare, or which exist as chemotypes are untested. Many substances which are used in aromatherapy which are not true steam distilled essential oils (CO2 extracts, hydrolates, etc) are also not tested. Looking globally, it is revealed more and more that many essential oils from different geographic origins have analytical components which may be missing, depleted or emphasised according to source. I am in fact compiling facts about these at present, and the extent to which chemotypes both exist and are used has surprised me

Clearly we need a new policy on this now. By saying that we, as a profession, are unable to use certain oils because there is no formal safety testing is not coming to grips with the reality of aromatherapy practice, which is already out there using many untested oils. Also the profession stagnates if new materials are denied. The counterbalance to this is that regulation and a code of practice on raw materials of the trade is a must for any serious minded profession, not the least to protect the practitioner from lawsuits! I think the answer must be a predictive assessment of some of these (new) materials, gathering as much information as is possible, pending ultimate testing. Hopefully as the years proceed, we will see some initiatives on this (watch this space!). I know we wandered a long way from the question, but at least we have covered some of the current issues around the subject.

If essential oils can be toxic then why is the FDA allowing them on the market? - Kathy

The FDA has to balance traditional use, and personal freedom against other issues like public safety, judicious use application. Any government department can only expect co-operation if the policies they propound are sound and reasonable, otherwise there is a public backlash, as recently happened with their unpopular stand on ginger extracts. It has been said that the potato would never get through as a newly introduced food material if traditional use had not been established (for example green potatoes are linked with spina bifida etc.). So in reality the FDA has to take a view that in proper use many seemingly toxic oils benefit mankind enormously when used in the appropriate dilutions for flavourings, in perfumes, in aromatherapy, and in herbal medicine and a multitude of other areas.

Does the medical field know how to treat toxic reaction to essential oils? Do aromatherapists? - Cindy

By toxic reactions I assume you mean health- or life-threatening situations. Many hospitals and some trade unions and other bodies have their own data-bases or access to national data-bases on chemical substances and poisons. In an emergency situation it may be possible to glean data from these, but many cases of poisoning are treated asymptomatically anyway.

In the UK we have the COSHH regulations which split substances into a number of categories for handling: sensitisers, irritants, marine pollutants, toxic, very toxic, carcinogenic, inflammable etc. with the idea of minimising risks by sensible handling in the first place. All deliveries of essential oils from suppliers are legally required to have health and safety data sheets accompanying them, and if you think the data is insufficient you have the legal right to demand full and proper information. Use this right!

The real answer to your question is that in practice health and safety information is poorly available, in many companies chasing invoices seems to take priority over composing good health and safety documents for individual materials! Aromatherapists have access to information through their professional bodies, and should agitate to see that the information supplied is to a high standard (often it isn’t). It is my opinion that in general, detailed information on the toxicity of essential oils is sparse; for example the effects of inhalation, sub-chronic toxicity etc. are virtually uncharted territory in the literature. But by all means keep asking questions!

What chemical reaction takes place in the skin to cause certain essential oils to make the skin photosensitive? - Lianna

Basically we are looking at compounds which are absorbed into the epidermal layer, absorb ultra-violet light, and them re-transmit the energy to the lower epidermis at a later time causing an excessive tanning reaction. New studies on rue oil being currently carried out, for example, show psoralens to be involved in this process.

The answer is that if photo-toxic materials must be used, keeping out of sunlight, or preferably any light and keeping the affected area totally covered up for 12-18 hours is vital, longer if possible. A better policy is not to use phototoxic materials at all, but to find substitutes! Many severe phototoxic oils are now effectively removed from the market: verbena oil and fig leaf absolute are rarely seen now, but many which can provoke strong reactions are used extensively: for example tagettee, expressed lime and expressed bergamot oils

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