Toxicology of essential oils reviewed

Sadly, many of the books published on the topic of aromatherapy have not been written by scientists or toxicologists and this has meant that there is a great deal of poor quality information circulating which has propagated and found its way on to the internet. The use of the phrase “not tested on animals” is not only illegal but is also totally without truth, since in nearly all cases these essential oils have been tested on animals at one time or another in the past. The LD50 value (lethal dose 50%) using animals (usually based on rats or mice) gives a value for the death of half the animals tested. An LD50 of 2 g/kg refers to the total weight of material tested/body mass of test animal that caused death in half the number tested. Thus, if a human weighed 70 kg then it might be expected that 140 g could be consumed before it was fatal. The idea that because a material is natural it therefore must be safe could not be further from reality. There are essential oils that are so toxic that they should never be consumed or applied to the skin without extreme caution. The risks of sensitisation, irritation, phototoxicity or being an abortifacient are fact. Essential oils contain a rich blend of highly functional molecules some of which are beneficial and others which are not.

General considerations

Finding the results of the oral and dermal studies is very time consuming and I have compiled an overview of the oils and their effects in a spreadsheet format (see pages following this article). This compilation will allow a quick review as to the suitability of an oil in a given product.