I first came across essential oils at the tender age of 18. I was working, appropriately enough, in a still room in a 16th Century living history event all dressed up in a long dress, cap and apron. A stillroom used to be where herbs were processed and preserved, soaps and preserves were made and where the still to make spirits or essential oils might be found. One day a lady playing a way more important role than us swept in with a toothache, looking for the clove oil. Clove has been traditionally used to numb toothache. Now, before anyone could say anything she just picked up a thimble size container and downed it. The look of horror that came over her as it hit her mucus membranes was never to be forgotten. Fortunately, the still room was managed by a qualified medical herbalist who took appropriate action.

Fast forward to 2016. Now a qualified aromatherapist, I watched in almost equal horror as a visiting essential oil rep from Latvia demonstrated how safe essential oils were by dropping neat frankincense oil on her tongue in front of me. Apparently, she did it every day.

Back in 1998 my clinical aromatherapy tutor happened to be a professor of toxicology and perfumer who carried out her own research into the microbial and calming or rousing actions of various oils.

Some oils have GRAS status, meaning generally regarded as safe. Oils also have LD50 ratings. LD50 is the amount of any substance that has to be given to a number of animals to cause the death of 50% of the sample and is stated in grams per kg of body weight. A rating of at least 5g per Kg is considered non-toxic.

Sweet basil oil can be found at an LD50 of 1.4g/Kg when given orally to a rat or 0.5g/Kg administered dermally (via the skin) to a rabbit whereas Bergamot is listed respectively at more than 10g/Kg and 20g/Kg. I do not condone animal testing but give these values to demonstrate how toxicity varies. Bergamot, while non-toxic in general is phototoxic due to the presence of furocoumarins, (as are most citrus oils to varying degrees). Don’t go anywhere near a sunbed or out in the sun for 12 hours after applying bergamot oil, even diluted. Fairly scary pictures can be found on Facebook or YouTube showing what can happen in the worst cases.

Essential oils are tiny volatile aromatic hydrocarbons, which are fat-soluble and can cross the blood-brain barrier. Their chemical information goes straight from the nose into the part of the brain that regulates emotions, memory and reproduction. It is potentially possible that constituents of them can be stored and accumulate in, for example, fatty tissue in the body. They are chemically active, some of their chemicals may create hormone-like effects.

Lavender and tea tree have been found to have estrogen-like effects, something to bear in mind for men especially as they may block the production of male sex hormones.

The oxide 1-8 cineole is a known sensitiser and a major constituent in the very popular Rosemary oils and Eucalyptus globulus. Its presence in tea tree is apparently controlled and reduced for this reason.

I personally want to keep using essential oils for the whole of my life, which is why I limit their use. I don’t use them all day every day, I aim to work in a ventilated environment. I take note of the advice not to apply undiluted to the skin. I don’t ingest them. And I do this because I know from personal contacts that overuse, over time, can lead to sensitisation. And once that happens it is possibly the last time you may be able to use that oil or oils with similar constituents, ever.

Rosemary Pharo has been practising aromatherapy since 1998 and is also a Reiki Teacher living in Bromley. She sits on the Aromatherapy Profession Specific Board for CNHC.

Aromatherapy and Essential Oils (PDQR) Patient Summary. PubMed https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0032518/#!po=42.5000 accessed 29/10/2017

Aroma Science. The Chemistry & Bioactivity of Essential Oils. Dr Maria Lis-Balchin 1995, Amberwood Publshing

Henley DV, Lipson N, Korach KS, Bloch CA. Prepubertal Gynecomastia Linked to Lavender and

Tea Tree Oils. New Eng J Med. 2007;356:479-85

Sample material safety data sheet for Cinnamon Oil

http://www.sciencelab.com/msds.php?msdsId=9923334 Accessed 29/10/2017