At almost 850 pages, there’s plenty of reading here. Unfortunately, this book is replete with errors. There are innumerable mis-spellings of the names of chemicals. Terpinen-4-ol is an alcohol, not a phenol, and bergamotene is a terpene, not a furanocoumarin. On page 374 we read that “Coumarins are thought to be antispasmodic, as are many other esters.” Coumarin is not an ester. Stewart mentions that myrrh oil is rich in ‘furanoid compounds’ – well yes, it is indeed rich in FURANS, and he goes on to say that “furanoid compounds can amplify ultraviolet light and can make an oil phototoxic.” (p23/24). Well, I don’t know why he wants myrrh oil to be phototoxic, but it isn’t, because it contains no FURANOCOUMARINS. Using the term ‘furanoid compounds’ fails to make a vital distinction – between (phototoxic) furanocoumarins, and (non-phototoxic) furans.
In some cases Stewart seems to have copied mistakes from other sources, without realizing they were mistakes. l-Limonene is quite often given instead of d-limonene, and methyleugenol has curiously disappeared as an essential oil constituent altogether – Stewart does not list it a constituent of any of the oils it is actually found in! Furanocoumarins are frequently cited that may indeed be present in the plant but are not found in the essential oil.
He has made a valiant effort to list the components of 113 essential oils, but the method he used – combining data from various books – is risky. The end result is said to represent a ‘typical’ essential oil, but is rather hit-and-miss, and in many cases does not represent any existing essential oil at all. Some of the total percentages add up to more than 100%. Reporting constituent chemistry from different sources is a challenge I am often confronted with myself, but there are more elegant solutions.
Stewart is highly critical of what he calls the ‘British School’ of aromatherapy, because it espouses the idea that some essential oils can be dangerous, and because, according to Stewart, it “relies on scientific research on animals”. However, he does take on board the idea that some furanocoumarins are phototoxic. Stewart perhaps does not realize that phototoxicity in essential oils is almost entirely based on RIFM research using pigs, and much of the ‘French’ information about essential oil constituents that Stewart cites is based on animal research. If the book was properly referenced, this would be obvious. He also criticizes the British for “usually applying only certain compounds isolated from essential oils rather than the whole oil.” (p4) It is difficult to fathom from where he plucked this outrageous notion!
There is a massive amount of information here, but there is not a single scientific reference to back up any of it. The result is an uncomfortable mix of fact and fiction. The book perpetuates the myth that any dangers of essential oils (apart from phototoxicity) only apply to what he calls ‘perfume grade’ oils, which, according to Stewart, British aromatherapists like to use! I’m not sure then, who buys all the independently certified organic essential oils sold in Britain. There is no ‘perfume grade’ of essential oil (on either side of the Atlantic), nor is there a ‘therapeutic grade‘.