Question (by Lora Carbo Cantele): Can you clarify why using a topical (such as a roll-on) that contains say a 5% dilution of EOs on a very small location may be unsafe? In your book you list the maximum % of a given EO, but there are some that say using an EO in excess of your recommendation is ok if it is used on a very small area (size of a dime or less). I remember you saying that was incorrect. Can you tell me why? (PS> read the book-this issue still clear as mud)
Answer: Some topical maximum dilutions are for adverse skin reactions, and these don’t change – they apply universally. So for example, the maximum for Lemongrass oil is 0.7% dilution, and it doesn’t make much difference what area of skin this is applied to because the maximum is based on the concentration of essential oil. (This is measured as micrograms of essential oil per square centimeter of skin.)
Other maximum dilutions are for internal toxicities (e.g. neurotoxicity or fetotoxicity) and these are flexible as they depend on the amount of essential oil that gets into the body, not the concentration of oil on the skin. For these, the more oil that is applied, and the greater the area of skin covered, the lower the dilution must be, and vice versa.
Maximums for internal toxicities in Essential Oil Safety are based on the assumption of maximum possible whole body application – 30 ml of base oil + essential oil. So if you only use 10 ml for example, the maximum can be increased by 3 times.